JP6979693B2 - Optical measuring device - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention provides intensity information such as permeability, reflectivity, and absorbance and optical measurement for measuring the profile of the surface state of the object to be measured and measuring and observing the surface state and internal state of cells by irradiation with laser light. An optical measuring device that simultaneously acquires distance information and accurately separates the two is suitable for a device that improves the performance of an optical device such as a microscope.

In addition to the difficulty of three-dimensional measurement of optical distance and the like with a conventional optical microscope, it has not been possible to accurately separate phase information and intensity information. For example, a phase-contrast microscope used a phase plate to convert phase information into intensity information for observation in order to clearly observe low-contrast biological cells and the like. Therefore, although the phase information can be visualized, the intensity information was also observed. As described above, the conventional phase contrast microscope is not a microscope that purely separates and observes only phase information or intensity information. The same was true for a differential interference microscope that visualizes phase information. In particular, in order to enable three-dimensional measurement, it is necessary to clearly separate the optical distance information and the intensity information, which are phase information.

On the other hand, a confocal microscope, a digital hologram microscope, and the like are known as means for detecting a conventional optical path difference.
The former confocal microscope irradiates the object to be measured with spot light so that the amount of light received by the light receiving element arranged at the confocal position via the pinhole is maximized with respect to the spot light. By moving the object to be measured, the height information and the route difference information of the object to be measured were acquired.

Further, the latter digital hologram microscope irradiates a laser beam substantially parallel to the object to be measured, collects the light diffracted by the object to be measured by an objective lens, and serves as a reference plane wave and an area such as CCD. A hologram is created by interfering with the sensor. Then, by analyzing this interference fringe by calculation, the wavefront from the original measurement object was restored and the path difference information was acquired.

However, in the former confocal microscope, basically, if there is a phase distribution in the spot light, the beam is deformed and erroneous information is obtained. In particular, it must be said that the reliability of the value is poor when the object to be measured is a cell or the like whose wavefront changes topologically such as a change in the refractive index. In addition, since it is necessary to move the objective lens and the object to be measured so that the amount of received light is maximized, real-time performance is lacking. Further, when the object to be measured has an intensity unevenness due to a change in absorption rate or a change in reflectance, the amount of light received naturally changes at the point where the intensity changes, so that the amount of light passing through the pinhole is It is not possible to determine whether the intensity has increased due to in-focus or uneven intensity, and an incorrect optical distance will be calculated.

In the latter digital hologram microscope, the light diffracted by the objective lens is condensed and interfered with the reference plane wave, the light and dark pattern is taken in by a CCD or the like, and the wavefront is reproduced by a computer for information. However, since the reference plane wave is a plane wave that has passed through a number of optical elements, even if it is a plane wave, about 1/10 of the wavelength is uneven in the plane when viewed microscopically. Even if the uneven state of the wavefront is stored in a plane for calibration or the like, it will be effectively fluctuated due to fluctuations in temperature or air density. For this reason, it was difficult to say that the interference pattern between the plane wave and the object wave that passed through different paths was reproducing the object wave in a strict sense.

On the other hand, a method of preparing a Fourier transform surface as a part of the imaging optical system, arranging a phase type spatial modulator on this surface, and applying phase modulation to the 0th-order diffracted light is described in Patent Document 1 and Non-Patent Document 1 below. 2 is disclosed. In this method, a total of four types of images in which a phase difference of 90 degrees is generated between the 0th-order diffracted light and the 1st-order diffracted light are taken by a CCD camera arranged on the image plane. Then, it is said that the optical distance is measured from the mutual calculation of these four types of images.

However, at this time, it is practically impossible to cause a phase difference only in the 0th-order diffracted light. This is because the 0th-order diffracted light is light transmitted without being modulated by the sample, but there is a low-frequency first-order diffracted light that overlaps the region of the 0th-order diffracted light, and the 0th-order diffracted light and the 1st-order diffracted light are substantially combined. This is because it cannot be distinguished. Further, it is necessary to switch the modulation of the spatial light modulator in order to acquire the images having four different phases, and the images acquired by the CCD camera are time-shifted information. Therefore, it cannot be said that it correctly reflects the change in the process that changes at a relatively high speed.

On the other hand, in order to reduce this effect as much as possible, it is conceivable to apply this method in a very narrow region near the peripheral portion of the spread of the 0th-order diffracted light. By doing so, there is a possibility that the frequency dependence of the spatial frequency and the influence of the first-order diffracted light included in the 0th-order diffracted light can be reduced. However, since only light in an extremely narrow range can be effectively acquired, the amount of light is extremely reduced, and it is difficult to obtain information with a good SN ratio.

In response to these circumstances, with the development of the micro / nanotechnology field in recent years, attention has been focused on technology for measuring three-dimensional information of fine industrial products and precision parts at high speed. In addition to this, in biology, medicine, and agriculture, there is an increasing demand for real-time acquisition of 3D profile information of biological samples as thick as cells in a living state.

However, basically all objects have different heights and refractive index distributions, and also have different absorption rates, reflectances, and the like, so that they have different intensity information and optical distance information. In the method of analyzing interference fringes including holograms, phase information is converted into interference fringe intensity information and detected by a CCD or the like, so it is essentially difficult to easily separate the original intensity information from the phase information. Is.

Japanese Patent Publication No. 2007-524075 JP-A-2015-4643 Japanese Unexamined Patent Publication No. 2013-238450 Japanese Unexamined Patent Publication No. 2017-116925 Japanese Unexamined Patent Publication No. 2017-133867

Opt.Lett.29 (21), 2503-2505 (2004) Opt.Exp.19 (2), 1016-1026 (2011)

In Japanese Patent Application Laid-Open No. 2007-524075 described above, a spatial modulator is used to generate substantially four phase differences with respect to the 0th-order diffracted light. However, it has been difficult to maintain a stable phase difference due to in-plane variations of the spatial modulator, temperature changes, and the like. Further, when a liquid crystal spatial modulator is used, it is difficult to adjust because the polarized light is rotated in addition to the phase unless the direction of the linearly polarized light and the direction of the liquid crystal molecules are correctly aligned. Further, since the spatial modulator causes four phase differences, a time lag occurs. Therefore, for a phenomenon in which the time fluctuates quickly, four phase information is acquired at different times, so that accurate information cannot be acquired.

From the above, with a conventional microscope, it is not possible to strictly separate general measurement objects whose intensity and optical distance change at the same time, so correct intensity information and optical distance information are calculated. I couldn't.

The present invention has been made in view of the above background, and by accurately separating the intensity and the optical distance based on the signal acquired from the light receiving element, the optical distance information and the transmittance, the anti-oblique ratio, the absorption ratio, etc. It is an object of the present invention to provide an optical measuring device for calculating the intensity information of the above.

The optical measuring device according to claim 1 includes a light source that irradiates coherent irradiation light and a light source.
A scanning element that scans the irradiation light from the light source and sends it to the object to be measured,
With at least two light receiving elements, each of which is located on each side with a direction perpendicular to the optical axis direction of the irradiation light as a boundary line, receives irradiation light modulated by the object to be measured during scanning, and performs photoelectric conversion. ,
An unmodulated signal as a DC component and a modulated signal as an AC component are extracted from each photoelectrically converted signal by the light receiving element, and the intensity information and phase information of the object to be measured are obtained from these unmodulated signals and the modulated signals. A measuring unit that obtains measured values for the object to be measured based on this intensity information and phase information,
including.

The operation of the optical measuring device according to claim 1 will be described below.
In the present invention, coherent irradiation light is emitted from the light source, and the scanning element scans the irradiation light and sends it to the object to be measured as a scanning beam. Further, two light receiving elements, one each located on each side of the boundary line perpendicular to the optical axis direction of the irradiation light, receive the irradiation light modulated by the object to be measured during scanning and photoelectrically change the light. Convert.

Then, the measurement unit extracts the unmodulated signal which is the DC component and the modulated signal which is the AC component of the signal photoelectrically converted by these two light receiving elements, and the measurement unit is the measurement target by these extracted signals. Obtain strength information and phase information of an object. Further, by utilizing the fact that the in-phase signal of the extracted signal is the intensity information and the opposite-phase signal is the phase information which is the optical distance information, the transmittance and the reflectance of the object to be measured are determined based on the intensity information. In addition to obtaining the measured values such as the transmittance, the measured values of the optical distance information of the object to be measured will be obtained based on the phase information.

That is, according to the present invention, the scanning element scans the irradiation light from the light source to obtain a scanning beam without receiving the light received by the CCD or the like by using a modulation element such as a special spatial modulator to change the phase of the irradiation light. The irradiation light irradiates the measurement object and is reflected or transmitted, so that the irradiation light passes through the measurement object. It is decided to perform signal conversion corresponding to electrically giving a phase change to the unmodulated signal and the modulated signal generated by this. As a result, the optical measuring device according to the present invention can completely separate the intensity information and the optical distance information of the object to be measured without using a special device or element.

As a result of the above, in the microscope or the like to which the present invention is applied, the intensity information and the optical distance information can be simultaneously acquired from the irradiation position of the scanning beam in the reflected optical system and the transmitted optical system. It is possible to perform intensity changes such as state changes of cells and microscopes and three-dimensional measurement in real time. Moreover, since the information is not from a plurality of data acquired by a plurality of CCDs or the like but from the same observation point, the processing is unrelated to the alignment due to the pixel misalignment, and different information can be reliably acquired from the same location. ..

In addition, when intensity information and height information are mixed, a laser scanning confocal microscope, which is a kind of the above-mentioned confocal microscope that calculates the height by the maximum amount of light passing through the pinhole, causes an erroneous signal. Since the optical distance information, which is the height information, can be reliably calculated by this apparatus in one scan, it has a very large feature.

Furthermore, when the present invention is applied to a transmission type microscope, as it becomes a simple device, cells, microbes, etc. are visualized with high resolution, easily and at high speed without fluorescent coloring while alive. Can be observed and measured. Moreover, since optical distance information is required from phase information and transmittance and absorption rate are required from intensity information, it has a great feature that physical quantities of some living organisms can be measured alive.

Next, according to claim 2, the signal photoelectrically converted by each of the two light receiving elements is used as the first signal, and the second signal obtained by Hilbert-converting the modulated signal of the AC component and the second signal are further used. Using the third signal converted by Hilbert, each of these converted signals is applied to the sum signal and the difference signal of the output from one light receiving element and the output from the other light receiving element of the two light receiving elements to obtain intensity information. And the optical distance information can be easily obtained.

Further, as in claim 3, it is partitioned by a boundary line along the direction perpendicular to the optical axis direction of the irradiation light and an intersection boundary line intersecting the boundary line on the optical axis of the irradiation light. The light receiving elements may be arranged in any of the regions. By doing so, the light receiving elements are arranged in the regions divided into a total of four sections.

Two of these four light receiving elements facing each other with a boundary line sandwiched between them and two elements facing each other with a crossing boundary line sandwiched between them can be examples of a pair. As for the outputs of the light receiving elements paired with each other, since the in-phase signal is the intensity information and the anti-phase signal is the optical distance information, the intensity and the optical distance information can be separated as described above. According to the present claim, a smaller and lower cost light receiving element may be adopted, and even a small amount of phase information received by this small light receiving element can be measured by the measuring unit. It will be possible to obtain.

On the other hand, as in claim 4, the scanning element is a two-dimensional scanning element that scans the irradiation light in two directions orthogonal to each other, and the object to be measured is scanned in at least one of these two directions. It is conceivable that the irradiated light is modulated. Further, as in claim 5, it is conceivable that a controller is connected to the scanning element, and the controller operates the operation of the scanning element to adjust the scanning speed and the scanning range. By doing so, not only a two-dimensional image can be obtained, but also measurement can be performed with an arbitrary modulation amount and an arbitrary range simply by changing the setting of the controller.

Further, according to claim 6, the measuring unit converts the AC component of the signal photoelectrically converted by the light receiving element into digital data, and by changing the addition amount of this data, the measured value of the measurement target is obtained. You can adjust the range you get. According to the present claim, random noise can be reduced and the accuracy of the measurement data of the intensity and the optical distance can be improved by sampling at a frequency higher than the resolution of the optical system. Further, since the scanning speed is constant, it is possible to substantially change the display area of the image by adjusting the addition amount.

From the above, it is possible to accurately quantify the information on the intensity and the optical distance inherent in the object to be measured. The measured values of this intensity and optical distance are the DC components of the sum signal and the difference signal of two light receiving elements located on both sides with the direction perpendicular to the optical axis direction of the irradiation light as the boundary line. It can be calculated from the magnitude of the AC component and the phase signal of the AC component.

Since the limit of the lateral resolution of the optical system is the upper limit of the frequency that can be detected, the frequency is sufficiently higher than the upper limit frequency when digitizing the data, and the AC component and the DC component are used for the optical resolution. It is conceivable to sample above the corresponding frequency. Random noise generated electrically or optically can be reduced by adding the data flowing in time series based on the sampled data. As a result, it is possible to improve the accuracy of the measurement data and reduce the noise in the display of the three-dimensional image.

Further, since the scanning speed is constant, by changing the number of data to be added, it is possible to enlarge or reduce the visual field range without changing the optical resolution and substantially change the range in which the image is displayed. .. Therefore, it is possible to arbitrarily express the visual field range to some extent without substantially changing the NA of the objective lens used for irradiation.

Further, if the irradiation light is reflected by the measurement object when the irradiation light passes through the measurement object as in claim 7, the light receiving element of claim 1 receives the reflected light and performs photoelectric. It will be converted. In this case, by arranging the beam splitter in the optical axis between the light source and the object to be measured, the beam splitter further reflects the irradiation light reflected by the object to be measured and returned to the light receiving element side and sends it. be able to. Further, if the irradiation light passes through the measurement object when the irradiation light passes through the measurement object as in claim 8, for example, the light receiving element of claim 1 arranged on the optical axis can be used. , This transmitted light is received and photoelectrically converted.

By completely separating the intensity information and the optical distance information in the above-mentioned reflection and transmission, the reflectance, transmittance and absorptivity can be calculated, and the optical distance, which is the product of the refractive index difference and the thickness, can be calculated as the refractive index. It is possible to separate into differences and thicknesses.

On the other hand, in claim 9, one light receiving element is located on each side of the boundary line between the transmission side and the reflection side of the measurement object, and at least each irradiation light modulated via the measurement object is emitted. The two light receiving elements received light, and the measuring unit to which the signal was input from these light receiving elements obtained the measured value for the object to be measured. By doing so, the reflected optical system and the transmitted optical system are used in combination so that the irradiation light transmits and reflects the measurement object when passing through the measurement object.

That is, by using the reflective optical system and the transmitted optical system together, the signals from at least two light receiving elements in total are compared, and the intensity information and the optical distance information are acquired, and the reflectance and the transmittance are simultaneously obtained. Since it can be measured, it is also possible to measure the light transmittance from these amounts. In particular, since the reflectance and transmittance values can be obtained simultaneously from the same location by scanning the irradiation light, the intensity information and the optical distance information from the same location can be obtained at the same time. Therefore, since there is no influence of pixel misalignment or the like, accurate transmittance, reflectance, and absorption rate can be obtained with high resolution.

As shown above, in the optical measuring device of the present invention, coherent irradiation light is emitted from a light source, and a scanning element scans the irradiation light and sends it as a scanning beam to an object to be measured. Modulate light.
Further, after obtaining an unmodulated signal and a modulated signal photoelectrically converted by the light receiving elements located one on each side with the direction perpendicular to the optical axis direction of the irradiation light as the boundary line, at least two light receiving elements Process each other's signals. As a result, the intensity information and the phase information of the object to be measured are obtained, and the quantitative intensity, the optical distance, and the like can be calculated accordingly, which is an excellent effect.

It is a block diagram of the apparatus of the catadioptric system which is considered as Example 1 of the optical measuring apparatus which concerns on this invention. It is explanatory drawing which shows the light irradiation area on the light receiving element of the reflection optical system of FIG. It is a perspective view explaining the repeated scanning of a laser beam. It is a figure which shows the graph which shows the cutoff frequency of the MTF curve in the spatial frequency obtained by the light receiving element of Example 1, FIG. 4 (A) shows the contrast of an intensity part, and FIG. 4 (B) shows the phase part. Shows contrast. It is a block diagram of the apparatus of the transmission optical system which is considered as Example 2 of the optical measuring apparatus which concerns on this invention. It is a block diagram of the apparatus of the transmission optical system which is a modification of Example 2. FIG. It is explanatory drawing which shows the light irradiation area on the light receiving element of the apparatus which is considered as Example 3 of the optical measuring apparatus which concerns on this invention. It is a schematic diagram which shows the optical system of Example 4 of the optical measuring apparatus which concerns on this invention. It is a block diagram of the apparatus which used both the reflection optical system and the transmission optical system which are considered as Example 5 of the optical measurement apparatus which concerns on this invention. It is a figure which shows the screen which displayed the intensity information of the transmission optical system of a measurement object, FIG. 10A is a screen which displays the intensity information of a transmission optical system, and FIG. 10B is FIG. 10 (A). ) Is reduced to a screen that displays four images. It is a figure which shows the screen which displayed the intensity information of the transmission optical system of an object to be measured, FIG. 11A is a screen which displays the intensity information of a transmission optical system, and FIG. 11B does not change the resolution. It is a screen that displays four parts of the image of FIG. 11A.

Hereinafter, Examples 1 to 5 of the optical measuring apparatus according to the present invention will be described in detail with reference to the drawings.

The first embodiment of the optical measuring apparatus according to the present invention will be described below with reference to FIGS. 1 and 2. This embodiment is a device of a reflected optical system that reflects a scanning beam by an object to be measured. FIG. 1 is a block diagram showing a configuration of a catadioptric system apparatus according to an embodiment.

As shown in FIG. 1, a laser light source 21 which is a light source to which a laser light which is a coherent irradiation light is irradiated (exited) and a collimator lens 22 whose aberration is corrected so that parallel light can be obtained from the laser light. And are arranged in order. Therefore, in this embodiment, the laser light emitted from the laser light source 21 is regarded as parallel light by the collimator lens 22.

Further, for the collimator lens 22, a pupil transmission lens system 25 composed of two groups of lenses, a two-dimensional scanning device 26 which is a two-dimensional scanning element for two-dimensionally scanning the input laser light, and an input laser light. Beam splitters 27, which are originally intended to separate and emit light, are arranged side by side in order. Then, as shown in FIG. 1, the optical path of the laser beam on the side toward the pupil transmission lens system 25 is defined as the optical axis L. A controller 23, which is a control means for changing the scanning range for two-dimensionally scanning the laser beam, the voltage for adjusting the scanning speed, and the like, is connected to the two-dimensional scanning device 26.

Further, a pupil transmission lens system 30 composed of two groups of lenses is located adjacent to the beam splitter 27, and an objective lens 31 is arranged next to the pupil transmission lens system 30 so as to face the measurement object G1. That is, these members are also arranged along the optical axis L. From the above, the laser beam is irradiated to the measurement object G1 along the optical axis L through the pupil transmission lens system 25, the two-dimensional scanning device 26, the beam splitter 27, the pupil transmission lens system 30, and the objective lens 31 in this order. The lens. At this time, due to the operation of the two-dimensional scanning device 26, the laser beam becomes a scanning beam and is scanned two-dimensionally on the measurement object G1.

On the other hand, a light receiving element group 29 composed of a plurality of optical sensors is arranged at a position adjacent to the beam splitter 27 in a direction orthogonal to the direction in which the optical axis L passes. Then, the scanning beam reflected by the measurement object G1 shown in FIG. 1 becomes diffracted light, and returns in the order of the objective lens 31, the pupil transmission lens system 30 and the beam splitter 27 to become parallel light. Along with this, it is reflected by the beam splitter 27 and is incident on the light receiving element group 29 along the optical axis L of the irradiation light orthogonal to the original optical axis L.

The light receiving element group 29 is not only arranged on the far field (far field) surface of the object to be measured G1, but is also composed of two light receiving elements 29A and 29B in this embodiment. However, as shown in FIG. 2, these are on a plane substantially perpendicular to the direction along the optical axis L, which is the center of the spot of the scanning beam LA, and sandwich the boundary line S passing through the optical axis L. The light receiving elements 29A and 29B are arranged respectively. That is, the light receiving element 29A is located on one side of the boundary line S, and the light receiving element 29B is located on the opposite side of the boundary line S, and the scanning beam is transmitted by being reflected by the measurement object G1. Each of these light receiving elements 29A and 29B receives LA.

Further, the light receiving elements 29A and 29B have a structure having a photoelectric conversion unit (not shown), and the light receiving elements 29A and 29B receive the scanning beam LA and perform photoelectric conversion respectively.
The above-mentioned controllers 23 that operate the light receiving elements 29A and 29B and the two-dimensional scanning device 26 are connected to the signal comparator 33, respectively. Along with this, the signal comparator 33 obtains the intensity information and the phase information of the measurement object G1 from the signals from the light receiving elements 29A and 29B and the signals from the controller 23. Then, the signal comparator 33 is connected to a data processing unit 34 that finally processes the data and obtains a measured value such as a profile of the measurement object G1. Therefore, in this embodiment, these signal comparators 33 and the data processing unit 34 are used as measurement units.

Further, the laser light source 21 is a semiconductor laser and generates coherent laser light. This laser beam is converted into a parallel luminous flux by the collimator lens 22 and incident on the pupil transmission lens system 25. At this time, the incident beam diameter of the laser beam is optimized by using a diaphragm mechanism (not shown) or the like in consideration of the balance with the pupil transmission lens system 25.

Here, in order for the pupil transmission lens system 25 arranged between the collimator lens 22 and the two-dimensional scanning device 26 to transmit the emission surface position of the collimator lens 22 to the next two-dimensional scanning device 26 in a conjugate manner. Optical system. The laser light that has passed through the pupil transmission lens system 25 becomes a scanning beam via the two-dimensional scanning device 26 and is sent to the beam splitter 27, and the scanning beam from the beam splitter 27 is the pupil of the objective lens 31. It is incident on the objective lens 31 via the pupil transmission lens system 30 that is coupled to the position.

From the above, in this embodiment, although the unmodulated laser light is emitted from the laser light source 21, the laser light converted into a scanning beam by the two-dimensional scanning device 26 is incident on the measurement object G1 to form a pattern. The modulation signal of the Fourier conversion pattern of the scanning beam is finally detected by the light receiving element group 29, which is substantially modulated by the change in intensity and the change in optical distance and is reflected by the object to be measured G1.

Further, as shown in FIG. 3, the two-dimensional scanning device 26 scans on the measurement object G1 while repeating the laser beam along the horizontal direction X and moving along the optical axis L. However, when this is repeated, two-dimensional scanning is possible by sequentially changing the scanning position along the vertical direction Y as shown in 1, 2, 3, 4, ... In FIG. The controller 23 that adjusts the operation of the two-dimensional scanning device 26 makes it possible to change the visual field range of the present device. That is, by changing the voltage at which the controller 23 controls the horizontal scanning range of the two-dimensional scanning device 26 or changing the vertical scanning range, the three-dimensional image can be freely enlarged or reduced to the viewing range. Can be adjusted. At this time, the controller 23 can change only the visual field range while keeping the lateral resolution constant.

Therefore, according to this embodiment, as shown in FIG. 3, there are irregularities such that the convex portion C exists on the surface of the measurement object G1, and there are shading such that the high-concentration portion D exists. Even in this case, the convex portion C and the high-concentration portion D can be accurately reproduced by the change in the diffraction amount and the reflection amount of the laser light scanned and irradiated by the two-dimensional scanning device 26.

The unmodulated laser light is irradiated from the laser light source 21 in this way, but the laser light obtained as a scanning beam by scanning with the two-dimensional scanning device 26 causes diffraction through the measurement object G1 and substantially. It becomes diffracted light. Of the diffracted light, the 0th-order diffracted light and the 1st-order diffracted light itself are unmodulated light, and the intensity signal of these diffracted light is an unmodulated signal.
On the other hand, the portion where the 0th-order diffracted light and the 1st-order diffracted light overlap is a signal having a phase difference between the 0th-order diffracted light and the 0th-order diffracted light, and thus becomes a modulated intensity signal. This is because each of the intensity and the optical distance can be regarded as an aggregate of a certain spatial frequency, and the overlapping portion of the 0th-order diffracted light and the 1st-order diffracted light is the spatial frequency corresponding to the 1st-order diffracted light by scanning the beam which is the irradiation light. Modulated by.

The modulated light is converted into a current having a frequency corresponding to the spatial frequency by the light receiving elements 29A and 29B as an intensity signal, and this current is converted by the current-voltage conversion circuit of the photoelectric conversion unit in the light receiving elements 29A and 29B. Convert to voltage. Therefore, the 0th-order diffracted light and the 1st-order diffracted light itself, which are unmodulated light, become DC signals, and the overlapping portion of the 0th-order diffracted light and the 1st-order diffracted light, which are modulated light, becomes an AC signal.

Next, what the signals detected by the light receiving elements 29A and 29B will be will be specifically shown below. Since the signal processing is the same not only in the reflection optical system but also in the transmission optical system and in the transmission optical system with high resolution, they will be collectively described here in the following examples.

The state of the object to be measured G1 is generally represented by the product of the intensity pattern and the optical distance pattern, and the irradiation light is diffracted by the object to be measured G1.
For simplicity, the complex amplitude E ₀ of the intensity pattern is a cosine wave pattern of pitch di, and the phase Θ of the optical distance pattern is a sine wave pattern of pitch dp. Assuming that the wavelength of the irradiation light is λ, the degree of intensity modulation is m, the difference in refractive index between the medium and the object to be measured is δn, and the thickness is h, it can be expressed as the following mathematical formula.

These patterns are irradiated with light having a wavelength of λ, and are received by the light receiving elements 29A and 29B arranged on the Fourier transform surface, which is a far field. _{In the Fourier transform surface of the complex amplitude E 0} of the intensity pattern in the pattern of the object G1 to be measured in the amplitude portion, the region on one side with respect to the optical axis L and where the first-order diffracted light and the -1st-order diffracted light do not overlap, that is, the spatial frequency. Considering a region where is relatively high, the following formula is obtained on the primary diffracted light side.

Similarly, on the Fourier transform surface of the phase portion, consider a portion having a relatively high spatial frequency on one side with respect to the optical axis and where the first-order diffracted light and the -1st-order diffracted light do not overlap. On the primary diffracted light side, a portion having a relatively high spatial frequency is given by the following formula.

Therefore, in the first-order diffraction light side, amplitude distribution E _R of light is represented by the following formula.

Here, a represents the phase information of the optical distance, and b represents the ratio of the first-order Bessel function and the zero-order Bessel function of the phase information of the optical distance. Further, as described above, m represents the degree of intensity modulation. Thus, the output I _R of the amount of light received by the first-order diffraction light side can be determined by the following equation.

Similarly, consider a portion on one side of the optical axis L where the frequency at which the first-order diffracted light and the first-order diffracted light do not overlap is relatively high. The -1 order diffracted light side, amplitude distribution E _L of the light is represented by the following formula.

Thus, the output I _L of amount of light received by the -1-order diffraction light side is represented by the following formula.

Considering the possibility that there is a slight difference in circuit gain between the primary diffracted light side and the -1st diffracted light side, the _{signal levels A 1} and A detected by inputting the _{coefficient values K 1} and K _{2 are included.} I made a difference in _{2 and generalized it.}

As described above, the strength part is in phase and the phase part is in reverse phase.
Although details are omitted, the spot diameter is larger than the spot diameter on the measurement target G1 when a light receiving element that receives light in the same region as the NA of the objective lens is used with the optical axis L as the boundary. The above formula is used for the same spatial frequency as the magnitude.

As shown in the graph shown in FIG. 4, the frequency of 1/2 of the cutoff frequency in the above-mentioned spatial frequency of the MTF curve M is shown by the dotted line T. That is, the contrast of the intensity portion shown in FIG. 4 (A) is 1/2 of the maximum value as shown by the dotted line T, and the contrast of the phase portion shown in FIG. 4 (B) is the maximum as shown by the dotted line T. It will be the same value as the value. At spatial frequencies other than these, the MTF curve M of the intensity portion is shown in FIG. 4 (A), and the MTF curve M of the phase portion is shown in FIG. 4 (B).

Therefore, the values of m and b to be obtained in the following discussion are for frequencies of 1/2 of the cutoff frequency of the spatial frequency.
On the other hand, in the application of JP-A-2015-4634, the inventors of the present application use beam scanning to identify the spatial frequency of the measurement object G1 from the photoelectrically converted frequency information and correct the MTF. Is proposing. By using this method, if the actual values of m and b are corrected, the optical distance information can be obtained via the modulation degree m and b of the intensity originally possessed by the measurement object G1.

Now, when the scanning beam is scanned at a speed v, the modulated signal corresponding to the spatial frequency rides on the scanning beam. Therefore, assuming that the detected frequencies of θ and η are fi and fp, respectively, the following formula is effective. Can be expressed in. That is, the phase of the spatial frequency is modulated as follows.

Next, the signals obtained from the primary diffracted light and the -1st diffracted light in each light receiving element are used as the first signal, and the modulated signal of the AC component of the first signal is Hilbert-converted twice in succession. And. In this case, it represents the first second signal Hilbert transformation in H1 (I _R) and H1 (I _L), a third signal Hilbert transform of second H2 (I _R) and H2 (I _L) It shall be represented by. Then, the Hilbert transform of the output obtained by the light receiving element on the primary diffracted light side and the Hilbert transform of the obtained signal by the light receiving element on the -1st diffracted light side is as follows.

Here, the first signal and whether the output of the sum of the third signal H2 which is the Hilbert transform of the two (I _R) and H2 (I _L) is a first light intensity current signal I _R and the current signal I _L of , current signal I _R, when taken out DC output I _L, as follows.

By dividing by this signal, it can be standardized.
That is, let α be α = 2b / (1 + b ² ) and β be β = 2m / (1 + m ² ).

Current signal I _R of the light-receiving output values in the first-order diffraction light side and -1 order diffracted light side, a third signal converted first signal and the Hilbert is I _L H2 (I _R) and H2 (I _L) Are as shown in the following equations. Note that θ ₀ corresponds to η and θ ₁ corresponds to θ.

Now, the amount of these converted one output and the other output I _R and -1 order diffracted light side of the light amount of which is an output first-order diffraction light side from the light receiving element from the light receiving element of the two light receiving elements each signal sum and difference signals subjected to the output I _L is given by the following equation.

Since the signals related to the intensity are in phase in this way, when these ratios are taken, only the phase signal, which is the signal of the optical distance, is obtained as shown in the following equation (3).

Further, when the ratio of the Hilbert transform of the difference signal and the two Hilbert transforms is taken, the following equations (4) and (5) are obtained.

_{Therefore, the phase θ 0} with respect to the spatial frequency of the phase of the optical distance is obtained from the equation (4), and α is obtained from the equation (3). Since α is α = 2b / (1 + b ² ) and b = J1 (a) / J0 (a), b is calculated by solving the quadratic equation for b.
Since b is associated with a, which is the maximum amplitude of the phase information of the optical distance, via the 0th and 1st order Bessel functions, a can be derived. Since b is an arbitrary value (value of b <1 and b> 1), it is appropriately selected. In particular, in the case of a transmission optical system, the difference in refractive index is very small, so J0 (a)> J1 (a), and the solution of b <1 may be selected.
The actual phase information can be obtained from the following mathematical formula.

Next, the ratio of the Hilbert transform of the sum signal and the two Hilbert transforms is as follows.

_{Therefore, the phase θ 1} with respect to the spatial frequency of intensity is obtained from Eq. (6), and β is obtained from Eq. (7). β is β = 2b / (1 + b ² ), and m is calculated by solving a quadratic equation regarding the degree of modulation m of the intensity. In this case, since the intensity modulation degree m is m <1, there is only one solution.
The actual intensity information can be obtained from 1 + mcosθ (x = 0).

_{In addition, if C 0} and C ₁ are measured by 100% reflection with a mirror or the like, b is obtained in a certain state of the object to be measured, and then C ₀ and C ₁ are measured, it is effective to m. It is possible to obtain the strength information related to. By doing so, it becomes possible to obtain a physical quantity such as reflectance.

By detecting the scanning beam passing through the object to be measured G1 by the light receiving elements 29A and 29B as described above, signals on both sides of the light receiving region divided into two are obtained, and the intensity information is obtained from both light receiving elements. The fact that the outputs are in phase and the phase information, which is the optical distance information, are out of phase between the outputs of both light receiving elements are used. Then, the original signal, the signal that has undergone the Hilbert transform once, and the signal that has undergone the Hilbert transform twice can be used to completely separate the modulation signal of the intensity information and the phase signal which is the optical distance information.

Therefore, the signal comparator 33 compares the signal photoelectrically converted by the light receiving elements 29A and 29B with the signal from the controller 23, finally processes the data, and the data processing unit 34 performs the above-mentioned calculation. As a result, it is possible to obtain measured values such as the degree of modulation of the optical distance information and the intensity information of the object to be measured G1. It should be noted that the Hilbert transform may not be used as long as it is possible to substantially separate the product of the in-phase signal including the DC signal and the AC signal and the anti-phase signal.

That is, the signal comparator 33 obtains the intensity information of the measurement object G1 by the signal obtained by photoelectrically converting the scanning beam reflected by the measurement object G1 and the signal instructing the controller 23 which is the base of the scanning beam to scan. And the phase information is obtained, and the intensity information and the phase information are sent to the data processing unit 34 including the CPU and the memory connected to the signal comparator 33.
Along with this, the data processing unit 34 records the intensity information and the phase information together with the scanning information for the plane, and easily derives the measured values of the phase information such as the intensity information and the profile information about the surface of the object to be measured G1. be able to. In this case, the above-mentioned intensity information is information that reflects the reflectance.

From the above, according to the present embodiment, the object to be measured absorbs light and has intensity information having different reflectance and transmittance, and also has optical distance information having different refractive index distribution and thickness. However, it is possible to provide a device that accurately separates both intensity information and optical distance information.

Along with this, if the optical system and signal processing of this embodiment are used, three-dimensional measurement data is acquired as optical distance information each time two-dimensional scanning is performed, and at the same time, from the three-dimensional measurement data. It is possible to obtain the strength information separately. Therefore, according to the optical system of this embodiment, it is possible to observe and measure changes in the state of cells and microorganisms, and transient changes in the surface state and internal state of these cells and the like due to the changes in the state at high speed. , Information such as transmittance, reflectance, and absorption rate can be acquired at the same time.
Furthermore, since it is possible to display a 3D stereoscopic image by using a naked-eye stereoscopic display or a 3D display using polarized glasses, which are commercialized based on optical distance information, it is possible to display a 3D stereoscopic image in education, research, and medical care. , Can be a useful device.

In this optical system, an example using one two-dimensional scanning device 26 shown in FIG. 1 has been described, but if the application requires simple data in only one direction, this two-dimensional scanning device can be used. The same effect can be obtained by replacing it with a one-dimensional scanning device. As these one-dimensional scanning devices, a galvano mirror, a resonant mirror, a rotating polygon mirror, and the like can be adopted.

Further, instead of one two-dimensional scanning device 26, two independent one-dimensional scanning devices are prepared, one for the X direction and the other for the Y direction, which are orthogonal to each other, and these are arranged before and after the pupil transmission lens system 25. By doing so, the same function as that of the two-dimensional scanning device 26 can be realized. In addition, for example, a micromirror device using the technology of a micromachine may be used. As this micromirror device, both one-dimensional and two-dimensional ones are known and commercialized. Further, one one-dimensional scanning device and a table (not shown) supporting the measurement object G1 can be adopted in a form orthogonal to each other.

As described above, the intensity of the object to be measured G1 is based on the signal photoelectrically converted by the light receiving element group 29 of the scanning beam and the reference signal for scanning by the two-dimensional scanning device 26 from the controller 23. The optical distance, which is information and phase information, can be calculated quantitatively.

Next, Example 2 of the optical measuring device according to the present invention will be described below with reference to FIG. This embodiment is a device of a transmission optical system in which a scanning beam passes through an object to be measured.
FIG. 5 is a block diagram showing an apparatus of a transmission optical system according to this embodiment. Since the main optical system is the same as the device of the reflection optical system, the description thereof is omitted, but in this device of the transmission optical system, the light collected by the objective lens 31 as compared with the first embodiment captures the object G2 to be measured. It will be transparent.

Further, in this embodiment, since the beam splitter 27 is a transmissive optical system, the beam splitter 27 is not required, and the light receiving element group 29 is arranged at a position opposite to the objective lens 31 via the measurement object G2. ing. However, as in the first embodiment, the light receiving element group 29 is not only arranged on the far field surface of the measurement object G2, but also has the same structure as the two light receiving elements 29A and 29B of the first embodiment. It is composed of 29E and 29F.

That is, in the case of this apparatus of the transmission optical system, the light receiving element group 29 is arranged on the extension line of the optical axis L of the objective lens 31 as shown in FIG. Further, as in the first embodiment, the light is received by sandwiching the boundary line S which is on a plane substantially perpendicular to the direction along the optical axis L which is the center of the spot of the scanning beam LA and passes through the optical axis L. Elements 29E and 29F are located respectively. From this, the light receiving element 29E is positioned on one side of the boundary line S, and the light receiving element 29F is positioned on the opposite side of the boundary line S. Along with this, the transmission optical system device of FIG. 5 also has substantially the same phase spatially on the light receiving element group 29 as in the reflection optical system device of FIG.

Further, the signal comparator 33 obtains the intensity information of the measurement object G2 by the signal obtained by photoelectrically converting the scanning beam transmitted by the measurement object G2 and the signal instructing the scanning of the controller 23 which is the base of the scanning beam. The phase information is obtained, and the intensity information and the phase information are sent to the data processing unit 34 including the CPU and the memory connected to the signal comparator 33. Along with this, the data processing unit 34 records the intensity information and the phase information together with the scanning information for the plane, and easily measures the intensity information and the phase information such as the profile information about the surface and the inside of the measurement object G2. Can lead to. In this case, the above-mentioned intensity information is information that reflects the reflectance.

Therefore, similarly to the first embodiment, the signal comparator 33 is based on the signal photoelectrically converted by the light receiving elements 29E and 29F constituting the light receiving element group 29 and the signal instructing the scanning by the two-dimensional scanning device 26 from the controller 23. Will obtain the intensity information and phase information of the object to be measured G2.
Then, as in the first embodiment, by performing the original signal and the Hilbert transform twice, the data is finally processed and the data processing unit 34 finally processes the data, and the data processing unit 34 transfers the optical distance, the transmittance, and the transmittance of the profile of the measurement object G2. Measured values such as rate can be substantially obtained. As a result, even in this embodiment, it is possible to completely separate the intensity information due to the transmitted light and the optical distance information.

_{Further, C 0} and C ₁ shown in the above-mentioned Example 1 are measured in a state where there is no object to be measured, b is obtained in a state where the object to be measured G 2 is present, and then C ₀ and C ₁ are measured. For example, in practice, it is possible to obtain intensity information related to the intensity modulation degree m. By doing so, it is possible to convert this intensity information into a physical quantity such as transmittance.

In particular, in a transmission optical system device as in this example, changes in the state of unstained, non-invasive, living cells can be separated into intensity information and optical distance information and observed in real time, so iPS and ES It can play a major role in testing whether cells such as cells are normal and checking for the presence of cancer cells. This is a feature that is significantly different from a measuring instrument that cannot be observed unless the living body is killed, even at a high magnification such as an electron microscope.

On the other hand, as a modification of the present embodiment, the lens 40 is shown in FIG. 6 behind the measurement object G2 on the opposite side of the measurement object G2 from the objective lens 31 and in front of the light receiving element group 29. It is conceivable to place it. That is, the scanning beam, which is the diffracted light from the object to be measured G2, is converted into parallel light by the lens 40 and then guided to the light receiving element group 29. Therefore, in this modification, as shown in FIG. 6, the Fourier transform pattern of the scanning beam transmitted through the measurement object G2 is converted into parallel light by the lens 40 and received by the light receiving element group 29. However, the lens 40 may collect light and guide the scanning beam to the light receiving element group 29.

Further, for the purpose of improving the lateral resolution, an optical system tilted with respect to the optical axis L of the objective lens 31 is arranged, and a part of the 0th-order diffracted light and the first-order diffracted light having a high spatial frequency are placed in this tilted optical system. A method for acquiring information up to a higher spatial frequency by superimposing is known in Japanese Patent Application Laid-Open No. 2013-238450. Also in this method, since it is known in advance what the MTF curves of the intensity information and the phase information will be, it is possible to acquire the intensity information and the optical distance information up to a higher spatial frequency.

Furthermore, the inventors of the present application have already shown in Japanese Patent Application Laid-Open No. 2017-116925 that the MTF curve due to the spatial frequency can be corrected by detecting a frequency such as a voltage obtained by photoelectrically converting the spatial frequency in the scanning optical system. .. By combining the method disclosed in Japanese Patent Application Laid-Open No. 2017-116925 with the embodiment of the present application, the original information possessed by the measurement objects G1 and G2 can be correctly converted into intensity information and optical distance information, and thus in an optical system. It is possible to correct the lack of information. Therefore, it is possible to separately measure the intensity information and the optical distance information with higher reliability.

On the other hand, in the embodiment of the present application, since the frequency can be measured for each scanning pixel, the spatial frequency that the observer observing the measurement objects G1 and G2 wants to emphasize can be easily set, and the desired part can be emphasized or used as the background. It is possible to display the part that is hidden. As the spatial frequency can be changed easily and flexibly in this way, the spatial frequency band is divided into several bands, and the gain can be manually set by the observer in each band, so that the image can be changed. You will be able to freely perform a kind of equalizer.

In addition, since the limit of lateral resolution of the optical system is the upper limit of the frequency that can be detected, sampling is performed at a frequency sufficiently higher than the frequency of this upper limit, and the data flowing in time series is added based on the sampled data. Therefore, random noise can be reduced. As a result, it leads to improvement of accuracy of measurement data and reduction of noise when displaying a three-dimensional image.
Further, since the scanning speed is constant, it is possible to substantially change the range in which the image is displayed by changing the number of data to be added. Therefore, it is possible to arbitrarily enlarge or reduce the visual field range to some extent without substantially changing the NA of the objective lens used for irradiation.

That is, according to this method, it has a great feature that the intensity information and the optical distance information can be changed only in the visual field range while keeping the lateral resolution constant. Furthermore, if it is used in combination with a function to change the scanning range by changing the voltage that controls the scanning range in the horizontal scanning direction for MEMS, resonance mirror, etc., which are scanning elements, the 3D image can be enlarged or reduced more freely. , Can be done without changing the horizontal resolution.

As described above, the intensity information and the optical distance information of the object to be measured can be easily and completely separated and visualized by the signal based on the scanning and the signal detected by the light receiving element 29E and the light receiving element 29F. Then, by properly processing this signal, the measured value can be calculated.
Furthermore, by using this method in combination with a method that reproduces the spatial frequency inherent in the object to be measured, intensity information such as reflectance, transmittance, and absorption rate of the object to be measured and optical distance information can be calculated more accurately. You can also do it.

Further, in the case of a transmission optical system device, visualization of cells, micro-organisms, and the like can be realized with a simple device according to the above-described embodiment, so that it can be used in education and hobby as a micro three-dimensional digitizer. By doing so, by using the recent 3D printer in combination with the apparatus according to the present embodiment, only the optical distance information without intensity information is used, and the cells remain alive without any processing such as dyeing. In the state, it becomes possible to easily represent the process of cell division and the three-dimensional stereoscopic image of the organ inside the cell of a microorganism as a three-dimensional model.

Next, Example 3 of the optical measuring device according to the present invention will be described below with reference to FIG. 7. This embodiment can be applied to a device of a reflection optical system and a device of a transmission optical system.

In Examples 1 and 2, the light receiving elements 29A and 29B or the light receiving elements 29E and 29F constituting the light receiving element group 29 are on a plane substantially perpendicular to the direction along the optical axis L of the scanning beam LA. It is located in each of the two divided regions with the boundary line S passing through the optical axis L in between. On the other hand, in this embodiment, the light receiving elements 29A to 29D divided into four as shown in FIG. 7 are used so that the respective information can be acquired in the horizontal direction and the vertical direction in the plane of the measurement objects G1 and G2. ..

That is, it was decided to arrange the light receiving elements 29A to 29D in each region partitioned by the boundary line S and the crossing boundary line KS intersecting the boundary line S on the optical axis L of the irradiation light. Then, by individually acquiring the horizontal and vertical information in the planes of the measurement objects G1 and G2 by these four light receiving elements 29A to 29D, more detailed data can be obtained.

Further, not only this, two of these four light receiving elements 29A to 29D facing each other across the boundary line S (for example, the light receiving element 29A and the light receiving element 29B) and two facing each other across the crossing boundary line KS. It is possible to acquire intensity information and optical distance information by the above-mentioned calculation using two light-receiving elements paired with each other (for example, a light-receiving element 29A and a light-receiving element 29C).

Specifically, in the outputs of the light receiving elements paired with each other, since the in-phase signal is the intensity information and the anti-phase signal is the optical distance information, the intensity and the optical distance information can be separated as described above. Along with this, a smaller and lower cost light receiving element may be adopted, and even a small amount of phase information received by this small light receiving element can be obtained by the measuring unit. In this embodiment, the structure is divided into four divided regions, but a structure in which four or more light receiving elements are adopted may be divided into four or more divided regions.

Example 4 of the optical measuring device according to the present invention will be described below with reference to FIG.
FIG. 8 is a schematic view showing the configuration of the optical measuring device of this embodiment. In this embodiment, in order to process the scanning beam transmitted through the measurement object G2 while improving the lateral resolution, for example, an inclined optical system shown in this figure is arranged under the device of the transmission optical system of Example 2. It is something to do. In FIG. 8, the optical systems such as the pupil transmission lens system 25, 30, the two-dimensional scanning device 26, the signal comparator 33, and the data processing unit 34 are not shown, and the light receiving element is replaced with the light receiving element group 29. 50 is adopted.

Then, in this embodiment, the lens 36 is installed at an angle with respect to the optical axis of the 0th-order diffracted light, which is the optical axis L of the objective lens 31. Specifically, a part of the 0th-order diffracted light and a part of the 1st-order diffracted light transmitted through the object to be measured G2 are intermediate between the optical axis L of the 0th-order diffracted light and the optical axis L1 of the 1st-order diffracted light. It is incorporated into the lens 36 in a state of being tilted only by the optical axis L3 having a tilt angle. As a result, not only a part of the 0th-order diffracted light but also a part of the 1st-order diffracted light having a higher spatial frequency than when the same lens is used is taken in, and these 0th-order diffracted light are used in the imaging optical system. Interference between the folded light and the first-order diffracted light is realized. Although not shown, in this embodiment, a similar optical system is arranged at a target position with respect to the optical axis L.

Further, in this embodiment, the lens 36 is tilted to acquire a part of the 0th-order diffracted light and a part of the 1st-order diffracted light, and the diffracted light converted into a parallel luminous flux by the lens 36 is condensed by the lens 52. The diffracted light overlaps with each other in the vicinity of the focal point due to the lens 52, and substantially interferes with each other. However, since it is not the interference between the 0th-order diffracted light and the ± 1st-order diffracted light, it is different from the image formation of the measurement object G2 itself.

On the other hand, in this embodiment, the pitch of the interference fringes can be widened by lengthening the effective focal length of the lens 52 or arranging the light receiving element 50 at a slightly defocused position. If the focal lengths of the lens 36 and the lens 52 are the same, the magnification is naturally the same, which is the spatial frequency of the object to be measured G2. On the other hand, the result of interference in the optical system of the first-order diffracted light, which is the other optical system (not shown), is an interference fringe with a shifted pitch. However, if the light receiving element is large with respect to the pitch of the interference fringes, it becomes difficult to align the element that receives ± primary diffracted light.

Therefore, by enlarging the interference fringe itself by the magnifying optical system 53 and arranging it at a position substantially equal to or slightly defocused to the size of the light receiving element 50, the intensity information becomes in-phase between the ± 1st-order diffracted lights. Since the phase information, which is the optical distance information, is naturally out of phase, the light and dark are reversed in such a way that the 0th-order diffracted light becomes a bias. By doing so, it is possible to acquire information up to a region having a high spatial frequency extremely easily, and by performing the above calculation, both intensity information and optical distance information can be acquired. This makes it possible to measure the intensity information and the optical distance with high reliability even for the measurement object G2 for which it is necessary to increase the lateral resolution. In the case of this embodiment, since the lens 52 is used, wavefront aberration to the extent that the phase difference between the 0th-order diffracted light and the 1st-order diffracted light incident on the lens 52 is directly reflected is allowed. Therefore, there is no need to use expensive lenses. Further, although not described in detail, the magnifying optical system 53 may be omitted, and the light receiving element 50 may be arranged at a defocus position defocused from the focus of the lens 52. At this time, the contrast of the interference fringes can be lowered from the wavefront distortion of the second-order wavefront, and the effect of superimposing the 0th-order diffracted light and the other diffracted light can be substantially obtained.

Here, a method for adjusting the light receiving element will be specifically described.
When the information about the object to be measured G2 is phase information, adjustments are made between the first-order diffracted light and the 0th-order diffracted light and between the -1st-order diffracted light and the 0th-order diffracted light, respectively. That is, the light receiving element is adjusted so that when one light receiving element has the maximum amount of light, the other light receiving element becomes substantially zero.
Further, when the information regarding the measurement target G2 is intensity information, the adjustment is similarly performed in the two systems between the 1st-order diffracted light and the 0th-order diffracted light and between the -1st-order diffracted light and the 0th-order diffracted light. I will do it. In this case, the light receiving element is adjusted so that when one light receiving element has the maximum amount of light, the other light receiving element also has the maximum amount.

In this embodiment, even if the lenses have slightly different focal lengths, the pitch of the interference fringes changes slightly if the amount of light received by each light receiving element does not change significantly and the wavefront aberration in the lens surface is not large. Since it is a degree, it can be used as it is. Further, the limit of the spatial frequency that can be acquired is about 1.5 times. Since this optical system is configured using only the lens system, it is very simple and resistant to disturbance.

Further, in this embodiment, each light receiving element is located on any side of the boundary line, but the light receiving element may be arranged across the boundary line. Even in this case, it is sufficient that the light receiving element is positioned so as to be offset to one side of the boundary line.

Although each embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiments, and can be variously modified and carried out without departing from the spirit of the present invention.

Example 5 of the optical measuring device according to the present invention will be described below with reference to FIG.
FIG. 9 is a schematic view showing the configuration of the optical measuring device of this embodiment. This embodiment can be applied to an apparatus for acquiring intensity information and optical distance information by using a reflected optical system and a transmitted optical system in combination.

As shown in FIG. 9, in the present embodiment, as in the first embodiment, the light receiving element group 29 composed of the two light receiving elements 29A and 29B of the reflective optical system is provided, and the objective lens 31 via the measurement object G2 is provided. It has a light receiving element group 29 of a transmissive optical system composed of two light receiving elements 29E and 29F located at positions opposite to those of the second embodiment and arranged at the same position as in the second embodiment. The other parts of this embodiment have almost the same structure as that of the first embodiment, and the light receiving elements 29A and 29B are connected to the signal comparator 33, and the two light receiving elements 29E are shown in FIG. , 29F are also connected to the signal comparator 33 in the same manner.

Therefore, in the signal comparator 33, as the reflection optical system and the transmission optical system are used in combination, the signals from these four light receiving elements 29A, 29B, 29E, and 29F are compared, and the intensity information and the optical distance information are obtained. Will get.

That is, by using the reflective optical system and the transmitted optical system together, the reflectance and the transmittance can be measured at the same time, so that the light absorption rate can be measured from these measured values. In particular, by scanning the irradiation light, the reflectance and transmittance values can be obtained simultaneously from the same location, and the intensity information and the optical distance information from the same location can be obtained. Therefore, compared to the case where the images acquired by the transmission optical system and the reflection optical system are compared using a CCD or the like, the influence of pixel misalignment or the like is completely eliminated, so that the transmittance, reflectance, and absorption rate are accurate. It will be possible to obtain high resolution.

The present embodiment relates to an image display obtained from these light receiving elements, for example, with respect to FIG. 10A, which is a screen displaying the intensity information K of the transmission optical system of the measurement object G2. As shown in FIG. 10B, for example, four images can be displayed by switching. This makes it possible to simultaneously display a plurality of different images having different qualities, for example, four.
For example, an image of the optical distance and intensity of the reflected optical system, which is combined with any one of the examples of the polarized image shown in Japanese Patent Application Laid-Open No. 2017-133867 filed by the inventors of the present application to form a total of four images. And, the image of the optical distance and the intensity of the transmission optical system may be displayed respectively.

On the other hand, in the example of FIG. 10B, the data is thinned out and the whole is displayed, but the resolution of the image G of the measurement object G2 remains the same as shown in FIGS. 11A to 11B. Then, it may be changed so that only four required part GPs in the frame portion P of FIG. 11A are displayed.
From the above, the example shown in FIG. 10B has an advantage that different parts of quality can be roughly determined in the overall image shown in FIG. 10A of the measurement object G2, and the example shown in FIG. 11B has an advantage. Then, there is an advantage that it is possible to observe and measure the part to be watched without reducing the resolution.

The optical measuring device of the present invention can not only measure the distance to the sample to be measured and the shape of the sample, but also can separate the intensity information from the optical distance information, so that the reflectance, transmittance, absorption rate, etc. It is also possible to measure the physical quantity of. In this way, it can be applied to various types of measuring instruments such as microscopes.
Further, the optical measuring device of the present invention can be applied not only to a microscope but also to various types of optical instruments and measuring instruments using electromagnetic waves having waves, and the strength of these optical instruments and measuring instruments using electromagnetic waves having waves can be applied. And 3D profile information such as height can be separated.

21 Laser light source (light source)
22 Collimator lens 23 Controller 25 Eye transmission lens system 26 Two-dimensional scanning device (scanning element, two-dimensional scanning element)
27 Beam splitter 29 Light receiving element group 29A to 29F Light receiving element 30 Eye transmission lens system 31 Objective lens 33 Signal comparator (measurement unit)
34 Data processing unit (measurement unit)
G1, G2 Measurement target L Optical axis LA Scanning beam S Boundary line KS Crossing boundary line

Claims (9)

A light source that irradiates coherent irradiation light,
A scanning element that scans the irradiation light from the light source and sends it to the object to be measured,
With at least two light receiving elements, each of which is located on each side with a direction perpendicular to the optical axis direction of the irradiation light as a boundary line, receives irradiation light modulated by the object to be measured during scanning, and performs photoelectric conversion. ,
An unmodulated signal as a DC component and a modulated signal as an AC component are extracted from each photoelectrically converted signal by the light receiving element, and the intensity information and phase information of the object to be measured are obtained from these unmodulated signals and the modulated signals. A measuring unit that obtains measured values for the object to be measured based on this intensity information and phase information,
Optical measuring device including. The signal photoelectrically converted by each of the two light receiving elements is used as the first signal.
Using the second signal obtained by Hilbert transforming the modulated signal of the AC component and the third signal obtained by further Hilbert transforming the second signal.
The optical measuring device according to claim 1, wherein each of these converted signals is applied to a sum signal and a difference signal of the output from one light receiving element and the output from the other light receiving element of the two light receiving elements. Any of claims 1 to 2, wherein the light receiving element is located in any region defined by the intersecting boundary line intersecting the boundary line on the optical axis of the irradiation light and the boundary line. The optical measuring device described in. The scanning element is a two-dimensional scanning element that scans the irradiation light in two directions orthogonal to each other, and the irradiation light irradiated to the measurement object is modulated by scanning in at least one of the two directions. The optical measuring device according to any one of claims 1 to 3. The optical measuring device according to any one of claims 1 to 4, wherein a controller is connected to the scanning element, and the controller operates the operation of the scanning element to adjust the scanning speed and the scanning range. A claim that the measuring unit adjusts a range in which a measured value for a measurement object is obtained by converting an AC component of a signal photoelectrically converted by the light receiving element into digitized data and changing the addition amount of this data. The optical measuring device according to any one of 1 to 5. A beam splitter is placed between the light source and the object to be measured.
Any of claims 1 to 6, wherein the beam splitter reflects the irradiation light reflected by the measurement object and returned from the measurement object, so that the light receiving element receives the irradiation light passing through the measurement object. Optical measuring device described in Crab. The optical measuring device according to any one of claims 1 to 6, wherein the light receiving element receives irradiation light passing through the measurement target by passing through the measurement target. The light receiving element is located on each side of the boundary line, which is the transmission side and the reflection side of the measurement object, and at least two light receiving elements each transmit the irradiation light modulated through the measurement object. The optical measuring device according to any one of claims 1 to 6, wherein the measuring unit that receives light in the light receiving element and receives a signal from these light receiving elements obtains a measured value for the object to be measured.

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