JP6714917B2 - Observation system - Google Patents

Description

The present invention relates to an observation system.

BACKGROUND ART Conventionally, as a microscopic method for realizing a high spatial resolution using an optical microscope, a modulated illumination microscopic method (SIM: Structured Illumination Microscopy) is known. In the modulation illumination microscope method, when performing observation such as measurement and appearance inspection of an observation target object, light (modulated illumination) having a striped light intensity distribution is applied to the observation target object, and by the moire effect caused by this, Information on spatial frequencies higher than the diffraction limit of the optical microscope is shifted to the low frequency side. Then, an image distribution having the information is acquired by an optical microscope, and signal processing is performed on the image distribution to reproduce high frequency information. In this way, a high resolution image can be obtained using the modulated illumination microscopy.

As an observation system using the modulated illumination microscopic method, for example, Non-Patent Document 1 discloses a laser light source, an optical path for guiding a part of laser light emitted from the laser light source to an observation object, and a remaining portion of the laser light for the observation object. There is disclosed an observation system including another optical path leading to the optical path and a stage for expanding and contracting the optical path length of the optical path. In this observation system, a part and the rest of the laser light are made to interfere with each other to generate interference fringes on the observation object, the light scattered by the observation object is imaged, and the observation object is based on the image distribution imaged. Is calculated.

By the way, in this observation system, in order to generate interference fringes having mutually different phases, the stage is operated to increase or decrease the optical path length difference of each optical path. However, in this observation system, since a laser light source having a long coherence length is used as a light source, it is difficult to visually distinguish the interference fringes from the interference fringes generated each time the phase is shifted by one wavelength. Uncertainty for each). On the other hand, in order to correctly calculate the shape distribution of the observation object, it is necessary to accurately detect the phase shift amount of the interference fringes. Therefore, in this observation system, by using a piezo actuator to drive the stage, the stage can be precisely driven with a minute displacement amount, and the phase of the interference fringe is accurately controlled to accurately detect the shift amount of the phase. doing.

Fuka Usuki, Tomohiro Takada, Kenjiro Miura, "Proceedings of the 2014 Annual Meeting of the Precision Engineering Society Spring Conference", 2014, p. 69-70

By the way, since the modulated illumination microscope method is an observation method using an optical microscope, it has the advantages that the time required for observation is shorter and nondestructive inspection is possible compared to other microscope methods. Therefore, it is desired to be carried out, for example, at a production site of a factory. However, in a production site or the like, a disturbance such as vibration or temperature change is more likely to occur than in a laboratory or the like. Therefore, in the above-described observation system, the optical path difference of each optical path may fluctuate due to vibration, or the temperature drift may cause a temperature drift. In such a case, the interference fringes and the observation object move relatively, and it becomes difficult to accurately detect the amount of phase shift of the interference fringes due to the uncertainty of each wavelength, and as a result, It becomes difficult to stably obtain a correct high resolution image. Under such circumstances, the modulated illumination microscopy is carried out only in fluorescence observation in the biological field in a laboratory or the like where disturbance is unlikely to occur.

Further, the modulation illumination microscope requires a highly accurate positioning mechanism such as a piezo actuator in order to detect the phase of the interference fringes with high accuracy, and thus is generally expensive, and it is desired to be provided at a lower cost. ..

One embodiment of the present invention is made in view of the above problems, and is to provide an observation system that is inexpensive and can stably obtain a correct high-resolution image even when a disturbance occurs. With the goal.

In order to solve the above problems, an observation system according to one aspect of the present invention includes a light source having a coherent length in a predetermined range and a first light having a first optical path length, which is a part of light emitted from the light source. A first optical path that guides the light from the light source to the observation target, and a second optical path that has a second optical path length and that guides the second light that is the rest of the light from the light source to the observation target; And an interference fringe generation unit that causes the second light to interfere with each other to generate a first interference fringe on the observation target object; a first reflected light reflected by the observation target object in the first light; A measuring unit for measuring the light intensity distribution of the second interference fringes generated by the interference of the second reflected light reflected by the observation object in the second light; and a calculation unit connected to the measuring unit. The calculation unit calculates the phase shift amount in the first interference fringes based on the displacement amount of the light intensity distribution in the second interference fringes.

According to such an observation system, the first light guided from the light source to the observation object by the first optical path and the second light guided from the light source to the observation object by the second optical path interfere with each other. The fringe generation unit interferes with each other to generate a first interference fringe. On the other hand, the first reflected light reflected by the observation object in the first light and the second reflected light reflected by the observation object in the second light interfere with each other to cause the second interference. A fringe is generated, and the light intensity distribution of the second interference fringe is measured by the measuring unit. Since the light source has a coherent length within a predetermined range, the light intensity distribution of the second interference fringe has one peak in its envelope. The displacement amount of the light intensity distribution of the second interference fringes is acquired by measuring the displacement amount of the peak of the envelope. Therefore, even when the phase of the first interference fringe is shifted by one wavelength or more, it is not affected by the uncertainty of each wavelength in the first interference fringe, and the envelope in the light intensity distribution of the second interference fringe is affected. The shift amount of the phase of the first interference fringe can be detected based on the shift amount of the peak of the line. Further, even when a disturbance such as a vibration or a temperature change occurs, the phase shift amount of the first interference fringes can be accurately detected. Thereby, the calculation unit can correctly calculate the shape distribution of the observation target. Furthermore, this observation system does not require a high-precision positioning mechanism such as a piezo actuator in order to detect the phase shift amount of the first interference fringes with high accuracy, and as an example, a comparatively comparative example such as an actuator using a stepping motor is used. Since it is possible to use a positioning mechanism with low accuracy, it is provided at low cost. As described above, it is possible to stably obtain a correct high-resolution image even when disturbance occurs due to the inexpensive system.

According to one aspect of the present invention, an inexpensive system can stably obtain a correct high-resolution image even when disturbance occurs.

It is a schematic structure figure showing an observation system concerning an embodiment of the present invention. It is a schematic side view which shows the interference fringe production|generation part of FIG. It is a schematic side view which shows the interference fringe production|generation part of FIG. It is a figure which shows the shape characteristic of the 1st interference fringe by low coherence light. FIG. 5 is a partially enlarged view of FIG. 4. It is a figure which shows the light intensity distribution measured by the measurement part. It is a figure which shows the pass band of the microscope in a frequency space. It is a figure which shows the pass band which moved to three directions in the frequency space by the modulation illumination. It is a figure which shows an example of an observation target object. It is a figure which shows the image distribution imaged by the imaging part. It is a figure which shows the image which Fourier-transformed with respect to the image distribution of FIG. It is a figure which shows the image which frequency-separated by the interference system information with respect to the image of FIG. It is a figure which shows the high resolution image which performed the image reconstruction. It is a schematic block diagram which shows the conventional observation system.

Hereinafter, preferred embodiments of an observation system according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a schematic configuration diagram showing an observation system according to an embodiment of the present invention, and FIGS. 2 and 3 are schematic side views showing an interference fringe generation unit of FIG. As shown in FIG. 1, the observation system 1 is a modulation illumination microscope capable of obtaining a high-resolution image of an observation object S by using a modulation illumination microscope method. The observation system 1 includes a light source 2, a first optical path 3 and a second optical path 4 that guide light emitted from the light source 2, and a first optical path length adjusting unit 5 provided in the middle of the second optical path 4. , The interference fringe generation unit 6 provided at the ends of the first optical path 3 and the second optical path 4, the turntable 7 on which the observation target S is placed, and the observation target S placed on the turntable. Image pickup section 8 for picking up the image, the third optical path 9 and the fourth optical path 10 for guiding the light output from the interference fringe generation section 6, and the second optical path length adjustment provided in the middle of the fourth optical path 10. Section 11, a measurement section 12 provided at the ends of the third optical path 9 and the fourth optical path 10, and an arithmetic section for calculating the shape distribution of the observation object S based on information from the imaging section 8 and the measurement section 12. 13 and.

The light source 2 is a low coherence light source. Light emitted from a low coherence light source (low coherence light) has a wider spectrum width and a shorter coherence length (coherence length) than laser light, for example. That is, the light source 2 is a light source having a shorter coherence length (for example, 1 μm or more and 100 μm or less) than a laser light source having a long coherence length (for example, about several tens of meters). The light source 2 can be, for example, an SLD (Super Luminescent Diode) light source, an LED (Light Emitting Diode) light source, or the like. In this embodiment, the light source 2 is an SLD having a wavelength of 669 nm, a spectrum full width at half maximum of 7 nm, and a coherent length of 32 μm.

The first optical path 3 is an optical path that has a first optical path length and guides the first light, which is a part of the light emitted from the light source 2, from the light source 2 to the observation object S. The second optical path 4 is an optical path that has a second optical path length and guides the second light, which is the remaining part of the light emitted from the light source 2, from the light source 2 to the observation object S. The first light and the second light are emitted from the light source 2, are branched from each other by the beam splitter 20 provided on the optical path, and reach the interference fringe generation unit 6. The first light and the second light have the same optical path between the light source 2 and the beam splitter 20 without distinction. Here, the first light is light that passes through the beam splitter 20, and the second light is light that is reflected by the beam splitter 20. The first optical path 3 and the second optical path 4 include a collimator lens 21 between the light source 2 and the beam splitter 20. As a result, the first light and the second light traveling on the first optical path 3 and the second optical path 4, respectively, are collimated by the collimator lens 21.

Another beam splitter 22 is provided on the emission side of the beam splitter 20 in the first optical path 3. The first optical path 3 has an optical path 3 a of the light reflected by the beam splitter 22 on the emission side of the beam splitter 22. As a result, the first light traveling on the first optical path 3 is transmitted through the beam splitter 20, reflected by the beam splitter 22, and then input to the interference fringe generation unit 6.

The second light traveling in the second optical path 4 reaches the first optical path length adjusting unit 5 on the emission side of the beam splitter 20, is returned by the first optical path length adjusting unit 5, and is again reflected by the beam splitter 20. To reach. The second optical path 4 has an optical path 4 a for the second light that has passed through the beam splitter 20 on the emission side of the light that has returned from the beam splitter 20. As a result, the second light traveling in the second optical path 4 is once reflected by the beam splitter 20, is returned by the first optical path length adjusting unit 5, passes through the beam splitter 20, and then interferes. It is input to the stripe generation unit 6. Thus, the first light and the second light both pass through the beam splitter once and are reflected once, so that when they reach the interference fringe generator 6, they have substantially equal light intensities. There is.

The first optical path length adjusting unit 5 has a mirror 23 and a modulator 24 that moves the mirror 23. The first optical path length adjusting unit 5 reflects the second light traveling along the second optical path 4 by the mirror 23 and returns it, and moves the mirror 23 by the modulator 24 to expand or contract the second optical path length. It is a mechanism.

The modulator 24 reciprocates the mirror 23 along the second optical path 4. Thereby, the modulator 24 expands/contracts the distance between the beam splitter 20 and the mirror 23, and as a result, expands/contracts the second optical path length. The modulator 24 is not limited to a modulator such as a piezo actuator that can control the displacement amount with extremely high accuracy, but an actuator that uses a stepping motor that has a lower displacement amount control accuracy than the piezo actuator may also be used. it can. The modulator 24 is not limited to an actuator that uses a stepping motor, and may be any mechanism that can move the mirror 23 along the second optical path 4.

The rotary table 7 includes a stage that holds the observation target S, and is arranged and arranged so that the stage is located in a horizontal plane (XY plane in the drawing). The turntable 7 holds the observation target S on the stage so that the surface of the observation target S to be observed faces upward. The turntable 7 allows the stage to rotate about an axis A in the vertical direction (Z-axis direction in the drawing). Therefore, the observation object S placed on the stage is rotatably held by the stage about the vertical axis A. The axis A is not necessarily limited to the vertical direction, but may be any direction from the observation object S to the imaging unit 8. In this case, the rotary table 7 may be arranged such that the stage is located on a plane perpendicular to the axis A and the surface of the observation object S to be observed faces the imaging unit 8 side.

The interference fringe generator 6 causes the first light and the second light to interfere with each other to generate a first interference fringe on the observation object S. The first interference fringes generated by the interference fringe generation unit 6 are used as modulated illumination (that is, standing wave illumination using light interference) in the observation system 1. FIG. 4 is a diagram showing the shape characteristic of the first interference fringes due to the low coherence light, and FIG. 5 is a partially enlarged view of FIG. Here, since the low coherence light source is used as the light source 2, the first interference fringes are generated within a range of the coherence length of the low coherence light source (for example, a range of about 30 μm) (see FIG. 4), The intensity changes in a constant cycle (see FIG. 5). The interference fringe generation unit 6 includes a first light projecting unit 30, a first light receiving unit 31, a second light projecting unit 32, and a second light receiving unit 33 that are arranged so as to surround the turntable 7.

The first light projecting unit 30 is provided at the end of the first optical path 3 and projects the first light onto the observation object S obliquely from above. The first light projecting unit 30 includes a mirror 30a and a mirror 30b, and reflects the first light traveling in a substantially horizontal direction upward in the substantially vertical direction by the mirror 30a and then obliquely downward by the mirror 30b. Then, the observation target S is projected. As an example, the first light projecting unit 30 has an incident angle with respect to the observation target S (that is, an angle formed by the optical path of the first light projected onto the observation target S and the axis A). The first light is projected so as to be 45 deg. The lower limit of the incident angle of the first light is the minimum angle within the range in which the optical path of the first light is not blocked by the objective lens 34. Further, the first light projecting unit 30 is not limited to a configuration using a mirror, and for example, a configuration in which the first optical path 3 is bent by an optical fiber to project light obliquely from above the observation object S. May be

The first light receiving unit 31 is provided at the start end of the third optical path 9 (details will be described later), and the first reflected light reflected by the observation object S in the first light is observed. Light is received obliquely above the object S. The first light receiving unit 31 is arranged at a position facing the first light projecting unit 30 with the observation object S in between. The first light receiving unit 31 includes a mirror 31a and a mirror 31b, and reflects the first reflected light received from the observation object S downward in the substantially vertical direction by the mirror 31a, and then in the substantially horizontal direction by the mirror 31b. And output to the third optical path 9. The first light receiving unit 31 is not limited to the configuration using the mirror, and for example, the first reflected light is received obliquely upward with respect to the observation object S and is bent by the optical fiber to generate the third light. It may be configured to output to the optical path 9 of.

The second light projecting unit 32 is provided at the end of the second optical path 4 and projects the second light onto the observation object S from diagonally above. The second light projecting unit 32 includes a mirror 32a and a mirror 32b, and reflects the second light traveling in a substantially horizontal direction in a substantially vertical direction by the mirror 32a and then in a diagonally downward direction by the mirror 32b. Then, the observation target S is projected. As an example, the second light projecting unit 32 has an incident angle with respect to the observation target S (that is, an angle formed by the second light projected onto the observation target S and the axis A) is 45 deg. So that the second light is projected. The lower limit of the incident angle of the second light is the minimum angle within the range where the optical path of the second light is not blocked by the objective lens 34. The second light projecting unit 32 is not limited to the configuration using a mirror, and for example, the second light path 4 is bent by an optical fiber to project light onto the observation object S obliquely from above. May be

The second light receiving unit 33 is provided at the start end of the fourth optical path 10 (details will be described later), and the second reflected light reflected by the observation target S in the second light is observed. Light is received obliquely above the object S. The second light receiving section 33 is arranged at a position facing the second light projecting section 32 with the observation object S interposed therebetween. The second light receiving unit 33 includes a mirror 33a and a mirror 33b, and reflects the second reflected light received from the observation object S downward in the substantially vertical direction by the mirror 33a and then in the substantially horizontal direction by the mirror 33b. And is output to the fourth optical path 10. The second light receiving unit 33 is not limited to the configuration using the mirror, and for example, receives the second reflected light obliquely above the observation target S and bends the second reflected light by the optical fiber to thereby obtain the fourth light. It may be configured to output to the optical path 10.

In the interference fringe generation unit 6, a first direction (X-axis direction in the drawing) in which the first light travels from the first light projecting unit 30 to the first light receiving unit 31, and a second light projecting unit 32. From the second light receiving portion 33 to the second direction (Y-axis direction in the figure) is substantially orthogonal to the observation object S in a plan view (Z-axis direction view in the figure). .. Further, in the interference fringe generation unit 6, the mirrors 30a, 30b, 31a, 31b, 32a, 32b, 33a, 33b provided in each light projecting unit and each light receiving unit are made movable, and the optimum position of the observation object S is obtained. It is possible to project the first light and the second light.

The first light and the second light projected on the observation object S by the first light projecting unit 30 and the second light projecting unit 32 respectively form a first interference fringe on the observation object S. To generate. The first optical path 3 and the second optical path 4 have a first optical path length and a second optical path length, respectively, and the first interference fringes have the first optical path length and the second optical path length. The phase differs depending on the difference in optical path length. Therefore, when the second optical path length is expanded or contracted by the operation of the first optical path length adjusting unit 5, the optical path length difference between the first optical path length and the second optical path length is expanded or contracted, and the phase of the first interference fringes is shifted. To do.

The image capturing unit 8 captures an image distribution of the light scattered by the observation object S in the first light and the second light exhibiting the first interference fringes. The imaging unit 8 is arranged above the rotary table 7 in the Z-axis direction, and images the observation object S from above. The imaging unit 8 includes an objective lens 34 and an optical microscope 35 for enlarging an image of scattered light, and a detector 36 for detecting the enlarged image of scattered light as an image distribution. As the objective lens 34, for example, a 10× (NA0.28), 20× (NA0.28), 50× (NA0.42), 100× (NA0.55) objective lens or the like can be preferably used. Further, as the detector 36, for example, a CCD camera or the like can be used.

The third optical path 9 is an optical path that has a third optical path length and guides the first reflected light of the first light, which is reflected by the observation object S, to the measurement unit 12. The fourth optical path 10 is an optical path that has a fourth optical path length and guides the second reflected light of the second light reflected by the observation object S to the measurement unit 12.

The third optical path 9 is provided with a first light receiving section 31 at its start end and a beam splitter 26 on its emission side. The third optical path 9 has an optical path 9 a of the first reflected light reflected by the beam splitter 26 on the emission side of the beam splitter 26. In the third optical path 9, another beam splitter 27 is provided on the emission side of the beam splitter 26. The third optical path 9 has an optical path of the first reflected light that has passed through the beam splitter 27 on the emission side of the beam splitter 27. As a result, the first reflected light traveling on the third optical path 9 is reflected by the beam splitter 26, transmitted through the beam splitter 27, and then input to the measurement unit 12.

The fourth optical path 10 is provided with a second light receiving portion 33 at its start end and a beam splitter 27 on its emission side. The fourth optical path 10 has an optical path 10 a for the second reflected light that has passed through the beam splitter 27 on the emission side of the beam splitter 27. Further, the second reflected light traveling on the fourth optical path 10 reaches the second optical path length adjusting unit 11 on the emission side of the beam splitter 27, is returned by the second optical path length adjusting unit 11, and is returned again. The beam splitter 27 is reached. The fourth optical path 10 has an optical path of the second reflected light reflected by the beam splitter 27, on the emission side of the light that is returned by the beam splitter 27. As a result, the second reflected light traveling on the fourth optical path 10 once passes through the beam splitter 27, is returned by the second optical path length adjusting unit 11, is reflected by the beam splitter 27, and is then reflected. , Is input to the measuring unit 12. In this way, the first reflected light and the second reflected light both pass through the beam splitter once and are reflected once, so that when they reach the measuring unit 12, they have substantially equal light intensities. There is.

The second optical path length adjusting unit 11 has a movable mirror 25. The second optical path length adjusting unit 11 is a mechanism for reflecting the second reflected light traveling on the fourth optical path 10 by the mirror 25 and folding it back, and moving the mirror 25 to expand or contract the fourth optical path length. is there. The second optical path length adjusting unit 11 moves the mirror 25 to expand or contract the distance between the beam splitter 27 and the mirror 25, and as a result, expands or contracts the fourth optical path length. The second optical path length adjusting unit 11 may be configured to manually move the mirror 23, or may be configured to be electrically driven using an actuator or the like using a stepping motor.

The measurement unit 12 is provided at the ends of the third optical path 9 and the fourth optical path 10, and measures the light intensity distribution of the second interference fringes generated by the interference of the first reflected light and the second reflected light. To do. In the present embodiment, the measurement unit 12 is an area sensor that can two-dimensionally measure the light intensity distribution of the second interference fringes.

The second interference fringes have a light intensity in accordance with the optical path difference between the optical path length from the light source 2 to the measurement unit 12 in the first light and the optical path length from the light source 2 to the measurement unit 12 in the second light. The distribution is displaced in the phase direction (ie, the direction orthogonal to each fringe). Therefore, when there is a change in the optical path difference between the light path length of the first light from the light source 2 to the measurement unit 12 and the light path length of the second light from the light source 2 to the measurement unit 12, the amount of change Can be calculated based on the amount of displacement of the light intensity distribution of the second interference fringes from the reference position. FIG. 6 is a diagram showing a light intensity distribution measured by the measuring unit. FIG. 6 shows the displacement of the light intensity distribution of the second interference fringes when the second optical path length is expanded/contracted by the first optical path length adjusting unit 5. FIG. 6A shows the light intensity distribution of the second interference fringes when the second optical path length is set to an arbitrary value (initial value), and FIG. 6B shows the second intensity. FIG. 6C shows the light intensity distribution of the second interference fringes when the first optical path length adjusting unit 5 is operated so that the optical path length changes from the initial value by 0.1 μm. 2 shows the light intensity distribution of the second interference fringes when the first optical path length adjusting unit 5 is operated so that the optical path length of the above changes from the initial value by 0.2 μm.

As described above, when the third optical path length and the fourth optical path length do not change, the optical paths of the first optical path length and the second optical path length are based on the displacement amount of the light intensity distribution of the second interference fringes. The change amount of the length difference can be calculated. Further, the phase of the first interference fringes shifts according to the amount of change in the optical path length difference between the first optical path length and the second optical path length. As described above, by measuring the displacement amount of the light intensity distribution of the second interference fringes, it is possible to obtain the accurate shift amount of the phase of the first interference fringes.

The calculation unit 13 is connected to the imaging unit 8 and the measurement unit 12, and acquires the image distribution imaged by the imaging unit 8 and the light intensity distribution of the second interference fringes measured by the measurement unit 12. Then, the calculation unit 13 calculates the phase shift amount in the first interference fringes based on the displacement amount of the light intensity distribution in the second interference fringes. In addition, the calculation unit 13 observes the phase according to the calculated phase shift amount in the first interference fringes and the first light and the second light exhibiting the first interference fringes having the phase. The shape distribution of the observation object S is calculated based on the image distribution of the light scattered by the object S.

Specifically, the calculation unit 13 performs the following processing in order to calculate the shape distribution of the observation object S based on the modulated illumination microscopy. FIG. 7 is a diagram showing the pass band of the microscope in the frequency space, and FIG. 8 is a diagram showing the pass band moved in three directions in the frequency space by the modulated illumination. In FIG. 7, k _x and k _y are frequency space coordinate systems and conceptually represent that the inside of the circle is a frequency that can be resolved by a microscope. FIG. 7A shows the pass band of the microscope at the spatial frequency, which means that it is possible to resolve up to the frequency distant from the origin by k ₁ . FIG. 7B shows the movement of the pass band due to the modulated illumination. When the observation object S is irradiated with the first interference fringes generated by the interference fringe generation unit 6, in the image distribution of the light scattered by the observation object S, the pass band is from the origin of the frequency space coordinate system. It has moved to a position separated by k ₂ . Thus, the resolution of the microscope, while so that the resolution k _{1 +} k ₂ in the arrow positive direction of k ₂ is increased, resolution k ₁ -k ₂ in the arrow negative direction k ₂ is lowered. As described above, when only a unidirectional striped pattern is used as the first interference fringe, the pass band only moves and a high-resolution image cannot be obtained as a whole. Therefore, as shown in FIG. 8, in the observation system 1, striped patterns in a plurality of directions (here, three directions) are used as the first interference fringes, and the pass band is moved in both positive and negative directions. As a result, the pass band is expanded in almost all directions in the frequency space coordinate system, and the resolution of the microscope is improved.

However, the image distribution thus obtained is a moiré signal obtained by the moiré effect, and a high frequency component cannot be directly obtained from this image distribution. Therefore, the following formula (1) is solved to perform image reconstruction processing. Here, k is a spatial frequency, f _m is a spatial frequency of modulated illumination, θ ₁ , θ ₂ , and θ ₃ are three different phases of the modulated illumination, D(k) is an imaging band, and OFT(k) is Is the optical transfer function, and S(k) is the observation object band. OFT(k) represents the point spread function defined by the objective lens 34 of the microscope, the wavelength of the light source, etc. in the frequency space by Fourier transform. According to the following formula (1), information of the observation target band was translated by ± f _m to the high frequency side is obtained. Formula (1) _{is, S (k), S (} k-f m), because it contains three unknowns of S (k + _{f m),} and acquires the three images distribution corresponding to three modulation illumination As a result, D ₁ (k), D ₂ (k), and D ₃ (k) are obtained, and the three equations are simultaneous. The thus obtained S (k), S (k -f m), S a _{(k +} f _m) By summing performs appropriate weighting, high-resolution image is reconstructed numerically. From the above, it is understood that it is necessary to correctly detect the phase of the first interference fringe (modulated illumination) in order to obtain a high resolution image using the modulated illumination microscope method.

As described above, in order to solve the above equation (1), three mutually different phases θ ₁ , θ ₂ , and θ ₃ of the modulated illumination are necessary. The measurement unit 12 continues to measure the light intensity distribution until the calculation unit 13 calculates the shift amounts of the first interference fringes corresponding to the _three different phases θ ₁ , θ ₂ , and θ ₃ of the modulated illumination. Do (repeat). Thereby, for example, even when a plurality of the _three phases θ ₁ , θ ₂ , and θ ₃ according to the shift amount calculated by the calculation unit 13 have the same phase, the above equation (1) is solved. The measurement unit 12 continues to measure the light intensity distribution until the three different phases required for the above are aligned.

Subsequently, a specific example of the observation result of the observation object S by the observation system 1 will be described.

FIG. 9 is a diagram showing an example of the observation object S. As shown in FIG. 9, the observation target S was observed using a square dot group having two kinds of pitches. The observation object S is one in which projections are periodically arranged on a flat plate. Each of the protrusions has a cubic shape with a side of 0.2 μm indicated by L1, L2, etc. in the figure. The protrusions form dot pairs (pair of dots) having a pitch of 0.4 μm shown by L3 in the figure, and these dot pairs have a pitch shown by L4 and L5 of 2.2 μm. Are arranged in.

An actuator using a stepping motor was used as the first optical path length adjusting unit 5. An actuator using this stepping motor has one pulse of 2 μm and can be divided into pulses. Here, the pulse was divided into 20 and one pulse was 0.1 μm. The wavelength λ of the light source 2 was 669 nm and the incident angle θ was 45 deg. As described above, when the actuator using the stepping motor is operated so as to change by 1 pulse (0.1 μm) and 2 pulses (0.2 μm) from the initial value, the first interference is generated. The operation values (instruction values) of the shift amount of the stripe phase were calculated to be 1.33 rad and 2.66 rad, respectively. On the other hand, at this time, the phase shift amounts of the first interference fringes detected based on the displacement amount of the light intensity distribution of the second interference fringes were 6.33 rad and 4.98 rad, respectively. As described above, it was confirmed that the actual movement amount of the actuator using the stepping motor is different from the operation value.

In order to perform image reconstruction, it suffices to know the phase of the first interference fringe when the image distribution of the scattered light is captured by the image capturing unit 8. However, in order to stably calculate the correct shift amount of the phase of the first interference fringes based on the operation value of the first optical path length adjusting unit 5, the first optical path length and the second optical path length are set high. It can be seen that it is necessary to maintain the accuracy and eliminate disturbance such as vibration of the support base.

On the other hand, in the observation system 1, the phase of the first interference fringe when capturing the image distribution of scattered light can be calculated by the measuring unit 12. Therefore, in the observation system 1, if the imaging unit 8 captures the image distribution of the scattered light and the measuring unit 12 measures the light intensity distribution of the second interference fringes, image reconstruction is performed. be able to. “Synchronization” here means that the measurement unit 12 measures the light intensity distribution of the second interference fringes when the image distribution of the scattered light by the imaging unit 8 is imaged. That is, the exposure (shutter) timings of the measurement unit 12 are aligned.

Therefore, the observation system 1 does not require a highly accurate positioning mechanism such as a piezo actuator in order to accurately detect the phase shift amount of the first interference fringes, and eliminates the influence of disturbance such as vibration and temperature change. Easy to do. As described above, in the observation system 1, it is possible to inexpensively obtain a stable high-resolution image even when a disturbance occurs.

FIG. 10 is a diagram showing an image distribution captured by the image capturing unit. In FIG. 10, the low-coherence light emitted from the light source 2 is branched into the first light traveling in the first optical path 3 and the second light traveling in the second optical path 4, and the interference fringe generator 6, the first interference fringes are generated on the observation target S, and the image distribution of the light scattered by the observation target S in the first light and the second light exhibiting the first interference fringes is imaged. The image is taken by the unit 8. 10A shows the image distribution when the second optical path length is an arbitrary value (initial value) (that is, the state of FIG. 6A). FIG. 10B is an image when the first optical path length adjusting unit 5 is operated so that the second optical path length changes from the initial value by 0.1 μm (that is, the state of FIG. 6B). Distribution. FIG. 10C is an image when the first optical path length adjusting unit 5 is operated so that the second optical path length changes from the initial value by 0.2 μm (that is, the state of FIG. 6C). Distribution. In FIG. 10, the dots can be partially resolved by the moire effect, but the resolution is not improved as a whole. FIG. 11 is a diagram showing an image obtained by performing a Fourier transform on the image distribution of FIG. 11A to 11C are images corresponding to FIGS. 10A to 10C, respectively.

FIG. 12 is a diagram showing an image obtained by performing frequency separation on the image of FIG. 11 based on interference system information. That is, FIG. 12 is calculated from the image distributions shown in FIG. 11 and the phase of the first interference fringes calculated based on the displacement amount of the light intensity distribution of the second interference fringes corresponding to these image distributions. a frequency separation images, S (k) in the above equation _{(1), S (k-} f m), which corresponds to S (k + _{f m).} 12A to 12C are images corresponding to FIGS. 11A to 11C, respectively. In the image of FIG. 12, compared with the image of FIG. 11, the high-frequency components are separated and clearly observed in FIGS. 12B and 12C, but the light intensity near the origin is reduced. ..

FIG. 13 is a diagram showing a high resolution image subjected to image reconstruction. That is, the image of FIG. 13 is an image obtained by adding the images of (a), (b), and (c) of FIG. 12 and performing inverse Fourier transform. In the image of FIG. 13, with respect to the observation object S shown in FIG. 9, each dot pair indicated by L3 is correctly separated, and the pitches indicated by L4 and L5 are also correctly represented. Therefore, it can be seen that the correct high resolution image was obtained.

Here, a conventional observation system will be described. FIG. 14 is a schematic configuration diagram showing a conventional observation system. As shown in FIG. 14, in the conventional observation system, a laser light source having a long coherent length is used as the light source 102, and the piezo actuator 124 is used as the optical path length adjusting unit 105 for expanding and contracting the optical path length of the second optical path 4. A mechanism for reciprocating the mirror 23 along the optical path 2 is used.

In such a conventional observation system, the piezo actuator 124 is used in the optical path length adjusting unit 137 in order to accurately detect the shift amount of the phase of the first interference fringe. However, in a production site or the like, a disturbance such as a vibration or a temperature change is more likely to occur than in a laboratory or the like, and for example, the optical path difference of each optical path may change due to the vibration, or a temperature drift may occur due to the temperature change. In this case, the interference fringes and the observation object move relatively, and it is difficult to accurately detect the phase shift amount of the interference fringes due to the uncertainty of each wavelength. Therefore, it is difficult for the conventional observation system to stably obtain a correct high-resolution image.

In the conventional observation system, as the interference fringe generation unit 106, a light projection unit 130 that projects the first light onto the observation target S and a position facing the light projection unit 130 via the observation target S. And a light projecting section 132 that projects the second light onto the observation object S. Further, in the conventional observation system, in addition to the observation system 1, a mirror 128 and an optical path length adjusting unit 137 for expanding and contracting the first optical path length are added to the first optical path 3, and a mirror 129 is provided in the second optical path 4. Has been added. The optical path length adjusting unit 137 is a mechanism that expands and contracts the first optical path length by moving the mirror 138. In addition, the conventional observation system includes a fixed table that fixes and holds the observation object S instead of the rotary table 7.

In the observation system 1 according to the present embodiment, the first light guided from the light source 2 to the observation target S by the first optical path 3 and the second light guided from the light source 2 to the observation target S by the second optical path 4. The second light is interfered by the interference fringe generation unit 6 to generate the first interference fringe. Then, the image distribution of the light scattered by the observation object S in the first light and the second light exhibiting the first interference fringes is imaged by the imaging unit 8. On the other hand, the first reflected light that is reflected by the observation object S in the first light and guided by the third optical path 9 and the fourth reflected light that is reflected by the observation object S in the second light The second reflected light guided by the optical path 10 interferes with each other to generate a second interference fringe. Then, the light intensity distribution of the second interference fringes is measured by the measuring unit 12. Here, when the second optical path length is expanded or contracted by the first optical path length adjusting unit 5, the phase of the first interference fringes is shifted and the light intensity distribution of the second interference fringes is displaced. Since the light source 2 has a coherent length within a predetermined range, the light intensity distribution of the second interference fringe has one peak in its envelope. The displacement amount of the light intensity distribution of the second interference fringes is acquired by measuring the displacement amount of the peak of the envelope. Therefore, even when the phase of the first interference fringe is shifted by one wavelength or more, it is not affected by the uncertainty of each wavelength in the first interference fringe, and the envelope in the light intensity distribution of the second interference fringe is affected. The shift amount of the phase of the first interference fringe can be detected based on the shift amount of the peak of the line. Further, even when a disturbance such as a vibration or a temperature change occurs, the phase shift amount of the first interference fringes can be accurately detected. Thereby, the calculation unit 13 can correctly calculate the shape distribution of the observation object S. Furthermore, the observation system 1 does not require a highly accurate positioning mechanism such as a piezo actuator in order to detect the phase shift amount of the first interference fringes with high accuracy. Since it is possible to use a positioning mechanism with low accuracy, it is provided at low cost. As described above, a correct high-resolution image can be stably obtained at low cost even when disturbance occurs.

The calculation unit 13 also calculates the shape distribution of the observation object S based on three mutually different phases and three image distributions corresponding to the three first interference fringes each having these phases. With this, it becomes possible to solve the above equation (1) based on the information of the three phases and the image distribution. As a result, in the frequency space, in addition to the information that can be resolved by the conventional optical microscope, the information in which the band of the observation object S is translated to the high frequency side by the spatial frequency of the first interference fringes can be acquired. Therefore, the calculation unit 13 can correctly calculate the shape distribution of the observation object S. Since one cycle of the first interference fringe is 2πrad, three different phases can be set to 0 rad, 2π/3rad, and 4π/3rad, which are obtained by dividing 2π into three equal parts, for example. In order to stabilize the calculation when solving the above equation (1), the larger the difference between these three phases, the better. Therefore, the three different phases are set to 0 rad, 2π/3rad, and 4π/3rad. Sometimes it is possible to perform the best image reconstruction. However, the three different phases do not necessarily have to divide 2π into three equal parts as described above. The degree to which the shape distribution of the observation object S is correctly calculated (extracted) differs depending on the values of these three phases.

Further, the measurement unit 12 continues to measure the light intensity distribution until the calculation unit 13 calculates the shift amounts corresponding to at least three different phases. Therefore, in the case where the shift amount of the first interference fringes is calculated a plurality of times by the calculation unit 13, even when the plurality of phases corresponding to the shift amounts are the same phase, the predetermined simultaneous equations are solved. It is possible to prevent a lack of information on at least three phases and image distributions required for the above. Therefore, the calculation unit 13 can correctly calculate the shape distribution of the observation object S.

Further, the interference fringe generation unit 6 is provided at the end of the first optical path 3, and the first light projection unit 30 that projects the first light onto the observation object S and the start end of the third optical path 9. And a first light receiving section 31 which is disposed at a position facing the first light projecting section 30 through the observation target S and receives the first reflected light, and at the end of the second optical path 4. A second light projecting section 32 which is provided and projects the second light onto the observation object S, and a second light projecting section which is provided at the start end of the fourth optical path 10 and through the observation object S. And a second light receiving portion 33 which is disposed at a position facing 32 and receives the second reflected light. For this reason, the first light and the second light can be surely applied to appropriate positions on the observation object S, and the first reflected light and the second reflected light are respectively supplied to the third optical path 9 and the fourth optical path. Can be surely output to the optical path 10.

In addition, the first direction in which the first light travels from the first light projecting unit 30 to the first light receiving unit 31, and the second light from the second light projecting unit 32 to the second light receiving unit 33. The traveling second direction is substantially orthogonal to the observation target S in a plan view. For this reason, the first light projecting unit 30, the first light receiving unit 31, the second light projecting unit 32, and the second light receiving unit 33 can be arranged at positions that do not interfere with each other, so that the interference fringe generation unit 6 is It is possible to have a simple configuration.

Further, a second optical path length adjusting unit 11 for expanding and contracting the third optical path length or the fourth optical path length is further provided. The second interference fringes have a light intensity distribution according to an optical path difference between the optical path length from the light source 2 to the measurement unit 12 in the first light and the optical path length from the light source 2 to the measurement unit 12 in the second light. Is displaced. Therefore, the second interference fringe needs to be adjusted so that the peak of the envelope of the light intensity distribution approaches the center of the measurement range of the measurement unit 12 by adjusting the optical path length. However, in order to fit the second interference fringes in the measurement range of the measuring unit 12, the displacement amount of the light intensity distribution of the second interference fringes can be reduced only by expanding and contracting the second optical path length by the first optical path length adjusting unit 5. It may be insufficient. Therefore, by expanding and contracting the fourth optical path length by the second optical path length adjusting unit 11, the second interference fringes can be sufficiently displaced. As described above, in the preparatory stage of observation, the operation of bringing the peak of the envelope of the light intensity distribution in the second interference fringes closer to the center of the measurement range of the measurement unit 12 is facilitated, so that the operability is improved.

Further, the coherent length of the predetermined range is shorter than the coherent length of the laser light source. For this reason, the width of the peak of the envelope in the light intensity distribution of the second interference fringes is sufficiently narrow, and it is easy to measure the amount of displacement of the peak. For this reason, since the displacement amount of the light intensity distribution of the second interference fringes can be easily acquired, it becomes easy to detect the phase shift amount of the first interference fringes with high accuracy.

Further, the coherent length in the predetermined range is 1 μm or more and 100 μm or less. For this reason, the width of the peak of the envelope in the light intensity distribution of the second interference fringes is sufficiently narrow, and it is easy to measure the amount of displacement of the peak. For this reason, since the displacement amount of the light intensity distribution of the second interference fringes can be easily acquired, it becomes easy to detect the phase shift amount of the first interference fringes with high accuracy.

The light source 2 is an SLD light source. For this reason, the width of the peak of the envelope in the light intensity distribution of the second interference fringes is sufficiently narrow, and it is easy to measure the amount of displacement of the peak. For this reason, since the displacement amount of the light intensity distribution of the second interference fringes can be easily acquired, it becomes easy to detect the phase shift amount of the first interference fringes with high accuracy.

The observation system 1 also includes a turntable 7 that holds the observation target S rotatably around an axis A extending from the observation target S toward the imaging unit 8. In this observation system 1, it is possible to calculate the shape distribution of the observation target S with higher resolution in the direction in which the phase of the first interference fringes is shifted, as compared with the conventional optical microscope. Therefore, by observing the observation object S and the first interference fringes at a plurality of relative angles in which they are relatively rotated about the axis A, the shape of the observation object S in each direction perpendicular to the axis A is observed. It is possible to stably obtain a high-resolution image with a correct distribution. Here, in the case of the above configuration, since the operation of relatively rotating the observation target S and the first interference fringes around the axis A becomes easy, the operability is improved.

As described above, the observation system 1 uses the first interference fringes of the low coherence light as the modulated illumination for irradiating the observation target S. The first interference fringes generated by the low coherence light have a narrower range in which the interference fringes are generated than the interference fringes generated by the high coherence light. Therefore, in order to observe a wide range with the observation system 1, it is necessary to scan the observation object S with the first interference fringes. However, since the piezo actuator used in the conventional observation system has a short stroke, it is difficult to observe a wide range with the conventional observation system. In addition, since the piezo actuator has a slow stroke speed, it takes a long time for observation in the conventional observation system. On the other hand, in the observation system 1, it is possible to use an actuator that uses a stepping motor that has a longer stroke and a higher stroke speed than the piezo actuator. Therefore, the observation system 1 can easily observe a wide range in a short time as compared with the conventional observation system.

The present invention is not limited to the above embodiment. For example, the measurement unit 12 may be a line sensor capable of measuring the light intensity distribution of the second interference fringes one-dimensionally along the phase direction thereof. In the measurement of the displacement amount of the peak of the envelope in the light intensity distribution of the second interference fringes, it is not always necessary to measure the second interference fringes two-dimensionally, and the second interference fringes may be measured in the phase direction. It suffices if the measurement can be performed along one dimension. Therefore, it is possible to use the measurement unit 12 as a line sensor, and in this case, when calculating the phase shift amount in the first interference fringes based on the displacement amount of the light intensity distribution in the second interference fringes, The calculation amount in the calculation unit 13 can be reduced. Further, the measurement unit 12 needs a higher frame rate than the image pickup unit 8. Since the measuring unit 12 is a line sensor, it is easy to increase the frame rate. Therefore, it is possible to easily realize a higher frame rate than the image capturing unit 8.

Further, in the above embodiment, the first optical path length adjusting unit 5 is provided in the middle of the second optical path 4 to expand and contract the second optical path length, but is provided in the middle of the first optical path 3. The first optical path length may be expanded or contracted.

Further, in the above embodiment, the second optical path length adjusting unit 11 is provided in the middle of the fourth optical path 10 to expand and contract the fourth optical path length, but is provided in the middle of the third optical path 9. The third optical path length may be expanded or contracted.

Here, an observation system according to another aspect of the present invention includes a light source having a coherent length in a predetermined range and a first light having a first optical path length, which is a part of light emitted from the light source. A first optical path having a first optical path leading to the observation target and a second optical path length, and guiding the second light that is the rest of the light from the light source to the observation target, the first optical path length or the first optical path length or A first optical path length adjusting unit for expanding and contracting the optical path length of No. 2, an interference fringe generating unit for causing the first light and the second light to interfere with each other, and generating a first interference fringe on the observation object; Of the first light and the second light exhibiting the interference fringes of the first light and the image distribution of the image distribution of the light scattered by the observation object, and the third light path length A third optical path that guides the first reflected light reflected by the observation object and a second optical path that has a fourth optical path length and that is reflected by the observation object in the second light. The light intensity distribution of the second interference fringes generated by the interference of the first reflected light and the second reflected light provided at the end of the fourth optical path and the third optical path and the fourth optical path to be guided is measured. And a calculation unit connected to the imaging unit and the measurement unit, wherein the calculation unit is based on the displacement amount of the light intensity distribution in the second interference fringes and the shift amount of the phase in the first interference fringes. Is calculated, and the shape distribution of the observation object is calculated based on the phase corresponding to the shift amount and the image distribution corresponding to the first interference fringe having the phase.

According to such an observation system, the first light guided from the light source to the observation object by the first optical path and the second light guided from the light source to the observation object by the second optical path interfere with each other. The fringe generation unit interferes with each other to generate a first interference fringe. Then, the image distribution of the light scattered by the observation object in the first light and the second light exhibiting the first interference fringe is imaged by the imaging unit. On the other hand, the first reflected light reflected by the observation object in the first light and guided by the third optical path, and the first reflected light reflected by the observation object in the second light and guided by the fourth optical path. The reflected second reflected light interferes with each other to generate a second interference fringe. Then, the light intensity distribution of the second interference fringes is measured by the measuring unit. Here, when the first optical path length or the second optical path length is expanded or contracted by the first optical path length adjusting unit, the phase of the first interference fringes is shifted and the light intensity distribution of the second interference fringes is displaced. To do. Since the light source has a coherent length within a predetermined range, the light intensity distribution of the second interference fringe has one peak in its envelope. The displacement amount of the light intensity distribution of the second interference fringes is acquired by measuring the displacement amount of the peak of the envelope. Therefore, even when the phase of the first interference fringes is shifted by one wavelength or more, it is not affected by the uncertainty of each wavelength in the first interference fringes, and the envelope in the light intensity distribution of the second interference fringes is affected. The shift amount of the phase of the first interference fringe can be detected based on the shift amount of the peak of the line. Further, even when a disturbance such as vibration or temperature change occurs, the phase shift amount of the first interference fringes can be accurately detected. Thereby, the calculation unit can correctly calculate the shape distribution of the observation target. Further, this observation system does not require a high-precision positioning mechanism such as a piezo actuator in order to detect the phase shift amount of the first interference fringes with high accuracy, and as an example, a comparatively comparative example such as an actuator using a stepping motor is used. Since it is possible to use a positioning mechanism with low accuracy, it is provided at low cost. As described above, an inexpensive system can stably obtain a correct high-resolution image even when disturbance occurs.

In the above-described embodiment, the calculation unit calculates the shape distribution of the observation object based on at least three different phases and at least three image distributions corresponding to at least three first interference fringes each having these phases. May be calculated. This makes it possible to solve a predetermined simultaneous equation by using at least three pieces of phase and image distribution information. As a result, in the frequency space, in addition to the information that can be resolved by the conventional optical microscope, the information in which the band of the observation target object is translated to the high frequency side by the spatial frequency of the first interference fringes can be acquired. Therefore, the calculation unit can correctly calculate the shape distribution of the observation object.

Further, the measurement unit may continue to measure the light intensity distribution until the calculation unit calculates shift amounts corresponding to at least three different phases. In this case, when the calculation unit calculates the shift amount of the first interference fringes a plurality of times, even if the plurality of phases corresponding to the respective shift amounts have the same phase, the predetermined simultaneous equations are solved. It is possible to prevent the required information of at least three phases and image distributions from being insufficient. Therefore, the calculation unit can correctly calculate the shape distribution of the observation object.

The interference fringe generation unit is provided at the end of the first optical path, is provided at the first light projection unit that projects the first light onto the observation target, and is provided at the start end of the third optical path. The first light receiving portion, which is arranged at a position facing the first light projecting portion through the object, receives the first reflected light, and is provided at the end of the second optical path to observe the second light. A second light projecting portion for projecting light onto the object and a fourth light path are provided at the start end of the second light projecting portion, and the second reflected light is arranged at a position facing the second light projecting portion through the observation object. And a second light receiving section for receiving the light. In this case, the first light and the second light can be reliably emitted to appropriate positions on the observation object, and the first reflected light and the second reflected light can be respectively applied to the third optical path and the fourth optical path. Can be reliably output to.

Further, a first direction in which the first light travels from the first light projecting unit to the first light receiving unit, and a second direction in which the second light travels from the second light projecting unit to the second light receiving unit. The direction of and may be substantially orthogonal to the observation object in a plan view. In this case, since the first light projecting unit, the first light receiving unit, the second light projecting unit, and the second light receiving unit can be arranged at positions that do not interfere with each other, the interference fringe generation unit has a simple configuration. be able to.

Moreover, you may further provide the 2nd optical path length adjustment part which expands/contracts a 3rd optical path length or a 4th optical path length. In this case, in the preparatory stage of performing the observation, it becomes easy to bring the peak of the envelope of the light intensity distribution in the second interference fringes closer to the center of the measurement range of the measurement unit, so that the operability is improved.

Moreover, the coherent length of the predetermined range may be shorter than the coherent length of the laser light source. In this case, since the peak width of the envelope in the light intensity distribution of the second interference fringe is sufficiently narrow, it is easy to measure the displacement amount of the peak. For this reason, since the displacement amount of the light intensity distribution of the second interference fringes can be easily acquired, it becomes easy to detect the phase shift amount of the first interference fringes with high accuracy.

Further, the coherent length in the predetermined range may be 1 μm or more and 100 μm or less. In this case, since the peak width of the envelope in the light intensity distribution of the second interference fringe is sufficiently narrow, it is easy to measure the displacement amount of the peak. For this reason, since the displacement amount of the light intensity distribution of the second interference fringes can be easily acquired, it becomes easy to detect the phase shift amount of the first interference fringes with high accuracy.

The light source may be an SLD light source or an LED light source. In this case, since the peak width of the envelope in the light intensity distribution of the second interference fringe is sufficiently narrow, it is easy to measure the displacement amount of the peak. For this reason, since the displacement amount of the light intensity distribution of the second interference fringes can be easily acquired, it becomes easy to detect the phase shift amount of the first interference fringes with high accuracy.

Further, the measuring unit may be a line sensor. In the measurement of the displacement amount of the peak of the envelope in the light intensity distribution of the second interference fringes, it is not always necessary to measure the second interference fringes two-dimensionally, and the second interference fringes may be measured in the phase direction. It suffices if the measurement can be performed along one dimension. That is, it is possible to use a line sensor as the measurement unit. In this case, when calculating the phase shift amount in the first interference fringes based on the displacement amount of the light intensity distribution in the second interference fringes, the calculation amount in the calculation unit can be reduced. Further, the measuring unit needs a higher frame rate than the image capturing unit. Since the measuring unit is a line sensor, it is easy to increase the frame rate. Therefore, it is possible to easily realize a higher frame rate than the image capturing unit.

Moreover, you may further provide the rotating stand which hold|maintains an observation target object rotatably around the axis line which goes to an imaging part from an observation target object. In this observation system, it is possible to calculate the shape distribution of the observation object with higher resolution in the direction in which the phase of the first interference fringes is shifted, as compared with the conventional optical microscope. Therefore, by observing the observation object and the first interference fringes at a plurality of relative angles in which they are relatively rotated about the axis, the correct height of the shape distribution of the observation object is obtained in each direction perpendicular to the axis. It is possible to stably obtain a resolution image. Here, in the case of the above configuration, since the operation of relatively rotating the observation target object and the first interference fringes around the axis becomes easy, the operability is improved.

One aspect of the present invention is to use an observation system as an application, and an inexpensive system can stably obtain a correct high-resolution image even when disturbance occurs.

DESCRIPTION OF SYMBOLS 1... Observation system, 2... Light source, 3... 1st optical path, 4... 2nd optical path, 5... 1st optical path length adjustment part, 6... Interference fringe generation part, 7... Rotating table, 8... Imaging part, 9... 3rd optical path, 10... 4th optical path, 11... 2nd optical path length adjustment part, 12... Measuring part, 13... Calculation part, 30... 1st light projecting part, 31... 1st light receiving part , 32... Second light projecting portion, 33... Second light receiving portion, A... Axis line, S... Observation object.

Claims (12)

A light source having a coherent length within a predetermined range,
A first optical path having a first optical path length and guiding the first light, which is a part of the light emitted from the light source, from the light source to the observation object;
A second optical path that has a second optical path length and guides the second light, which is the rest of the light, from the light source to the observation object;
An interference fringe generation unit that causes the first light and the second light to interfere with each other to generate a first interference fringe on the observation object;
Generated by the interference between the first reflected light of the first light reflected by the observation object and the second reflected light of the second light reflected by the observation object. A measurement unit for measuring the light intensity distribution of the second interference fringes,
An arithmetic unit connected to the measuring unit,
Equipped with
The arithmetic unit is
Calculating a phase shift amount in the first interference fringes based on a displacement amount of the light intensity distribution in the second interference fringes;
Observation system. A first optical path length adjusting unit for expanding and contracting the first optical path length or the second optical path length;
An image capturing unit that captures an image distribution of the light scattered by the observation object in the first light and the second light exhibiting the first interference fringes;
A third optical path having a third optical path length and guiding the first reflected light;
A fourth optical path having a fourth optical path length and guiding the second reflected light;
The measuring unit is provided at the ends of the third optical path and the fourth optical path,
The calculation unit is also connected to the imaging unit, and the shape of the observation target object based on the phase corresponding to the shift amount and the image distribution corresponding to the first interference fringes having the phase. Calculate the distribution,
The observation system according to claim 1. The arithmetic unit is
Calculating a shape distribution of the observation object based on at least three phases different from each other and at least three image distributions corresponding to at least three first interference fringes each having these phases;
The observation system according to claim 2. The observation system according to claim 3, wherein the measurement unit continues to measure the light intensity distribution until the calculation unit calculates the shift amounts corresponding to at least three different phases. The interference fringe generation unit,
A first light projecting unit which is provided at the end of the first optical path and projects the first light onto the observation object;
A first light receiving portion which is provided at a start end of the third optical path, is disposed at a position facing the first light projecting portion through the observation object, and which receives the first reflected light;
A second light projecting unit provided at the end of the second optical path for projecting the second light onto the observation object;
A second light receiving portion which is provided at a start end of the fourth optical path and which is arranged at a position facing the second light projecting portion through the observation object, and which receives the second reflected light;
Has,
The observation system according to any one of claims 2 to 4. The first direction in which the first light travels from the first light projecting unit to the first light receiving unit, and the second light from the second light projecting unit to the second light receiving unit A second direction of travel and the plane of the observation object are substantially orthogonal to each other,
The observation system according to claim 5. Further comprising a second optical path length adjusting unit for expanding and contracting the third optical path length or the fourth optical path length,
The observation system according to any one of claims 2 to 6. The predetermined range of coherent length is shorter than the coherent length of the laser light source,
The observation system according to any one of claims 1 to 7. The coherent length in the predetermined range is 1 μm or more and 100 μm or less,
The observation system according to any one of claims 1 to 8. The light source is an SLD light source or an LED light source,
The observation system according to any one of claims 1 to 9. The measuring unit is a line sensor,
The observation system according to any one of claims 1 to 10. The observation system according to any one of claims 2 to 7, further comprising a turntable that holds the observation target object rotatably around an axis extending from the observation target object toward the imaging unit.