JPH0528940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an imaging device, and particularly to an imaging device configured to scan a sample with a linear light beam.

(Prior Art) Conventionally, as an imaging device that converts optical image information of a sample into an electrical signal, solid-state imaging uses a two-dimensional array of light-receiving elements and sequentially reads signals from each light-receiving element to form an image signal. Imaging devices using such elements have been put into practical use. This imaging device using a two-dimensional solid-state image sensor uniformly irradiates the sample and projects the image of the sample onto the image sensor, and has a simple configuration.
It has the advantage of being able to obtain image signals, and has come to be used for various purposes.

Furthermore, as another imaging device, a light beam converged into a minute spot is deflected two-dimensionally to scan the sample surface, and the reflected light or transmitted light from the sample is detected by a photodetector such as a photo-detector. Optical scanning imaging devices that form optical information as image signals have been put into practical use. This optical scanning imaging device is configured to scan the sample with a microscopic spot-shaped light beam, so it is possible to prevent the generation of stray light, obtain high-resolution image signals, and adjust the brightness and contrast of the image electrically. It is adjustable and has a wide range of uses.

On the other hand, the conventional imaging device described above is a monochrome imaging device, which has the disadvantage that it cannot detect information regarding the color of the sample. Therefore, there is a strong demand for the development of a color imaging device with a simple configuration that can also detect information regarding the color of a sample.

Although the imaging device having the above-mentioned configuration has the advantage of being able to take images with a simple configuration, there are various problems when it is used as a color imaging device. For example, an optical scanning type imaging device has a disadvantage in that it is difficult to scan a sample with light beams of three primary colors in a consistent manner, which tends to cause misalignment between the light beams in the horizontal and vertical directions, that is, color misalignment. For this reason, if there is a shift in the vertical direction, a registration error will occur, and if there is unevenness in the scanning speed in the horizontal direction, the three primary colors and the image will be distorted, making it impossible to accurately reproduce the color information of the sample. An inconvenience was occurring. Furthermore, in order to scan the sample surface at high speed with a light beam, a highly sensitive photosensitive element must be used as a light receiving element, which has the drawback of making the apparatus larger and more expensive. On the other hand, in imaging devices using two-dimensional solid-state image sensors, it is difficult to obtain high-resolution image signals due to the low resolution of the two-dimensional solid-state image sensor, and the drawback is that the resolution is insufficient for applications such as defect inspection equipment. There is. In addition, two-dimensional solid-state image sensors have low sensitivity and require a powerful light source, which also has the disadvantage of increasing the size of the device.

The present inventor has solved the above-mentioned drawbacks, and has made it possible to scan the three primary color light beams on a sample in a consistent manner, and to achieve high resolution without causing distortion in the image even if the scanning speed of each light beam varies. The present invention provides a compact and inexpensive color imaging device that can obtain images of 100 to 1000 yen (Japanese Patent Application No. 76611/1983).

This color imaging device includes a plurality of light sources that emit a plurality of light beams of different color components, a first deflection means that deflects the plurality of light beams emitted from these light sources in the main scanning direction, and a first deflection means that deflects the plurality of light beams emitted from the light sources in the main scanning direction. Said first
A common second deflection means commonly deflects in a direction orthogonal to the scanning direction by the deflection means, and the light beams deflected by the first and second deflection means are converged into a minute spot shape and directed onto the sample. A projection objective lens, a color separation optical system that separates the reflected light or transmitted light from the sample into each color component, and a plurality of elements are arranged one-dimensionally in the main scanning direction and are separated into each component. The present invention is characterized by comprising a plurality of linear image sensors each receiving a luminous flux and outputting a photoelectric output signal in synchronization with each other.

In this color imaging device, each of the three primary color light beams is vibrated at high speed in the X direction of the sample by the first deflection means, and each light beam is transmitted to a common second
The three primary color light beams are made incident on the deflection means and deflected in the Y direction perpendicular to the X direction to combine the three primary color light beams into one light beam. The combined light beam is converged into a minute spot through an objective lens and projected onto the sample, and the sample is scanned in the X and Y directions. Then, the reflected light or transmitted light from the sample is separated into each color component by a color separation optical system, and is made to enter a linear image sensor arranged for each color component. Each linear image sensor has a configuration in which multiple elements are arranged one-dimensionally in a direction corresponding to the X direction, which is the main scanning direction, and each image sensor sequentially reads out the amount of charge accumulated in each element in synchronization. The sensor is configured to output a photoelectric output signal.

(Problems to be Solved by the Invention) The color imaging device proposed by the applicant described above deflects a light beam emitted from a laser light source in the main scanning direction using an acousto-optic element, and deflects a light beam emitted from a laser light source in the main scanning direction using a vibrating mirror. Since the beam is deflected in the scanning direction and projected onto the sample through the objective lens, the sample can be scanned with a minute spot-shaped light beam, and a clear, high-resolution image can be obtained.

However, since an acousto-optic element that performs main scanning is expensive, a configuration in which an acousto-optic element is used to perform main scanning has the disadvantage that the imaging device becomes expensive. Furthermore, an acousto-optic device requires the light beam emitted from a light source to enter the light beam with high precision at a predetermined angle of incidence, and even a slight deviation in the angle of incidence makes it impossible to scan the sample accurately. The disadvantage was that assembly and adjustment of the elements was troublesome.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an imaging device that can reproduce image information of a sample without using an acousto-optic element and can obtain clear images.

(Means for Solving the Problems) An imaging device according to the present invention includes a light source that emits a light beam, an expander that expands the light beam emitted from the light source, and a light beam that is orthogonal to the main scanning direction from the expander. It has a cylindrical lens that focuses only in the sub-scanning direction and a beam deflection mirror,
a deflection device that deflects the light beam focused by the cylindrical lens in the sub-scanning direction; and an objective lens that projects the light beam from the deflection device as a linear light beam onto the sample and receives reflected light from the sample. and a linear image sensor in which a plurality of light receiving elements are arranged one-dimensionally in the main scanning direction, and which receives light emitted from the objective lens and outputs a photoelectric output signal; The reflected light is imaged on the linear image sensor through the deflection device, and the charges generated in each light receiving element of the linear image sensor are sequentially read out at a predetermined readout frequency. .

(Function) In the present invention, the light beam emitted from the light source is made into a thin linear light beam extending in the main scanning direction using a cylindrical lens, and this linear light beam is deflected by a vibrating mirror to perform the sub-scanning. Do this. As a result, the entire surface of the sample is scanned by a thin linear light beam, the linear reflected light or transmitted light from the sample is received by a linear image sensor, and the charges accumulated in each light receiving element are read out in a predetermined manner. read out at a frequency to form a photoelectric output signal. With this configuration, an acousto-optic element is not required, the cost of the device can be reduced, and assembly and adjustment can be facilitated.

(Example) FIG. 1 is a diagram showing the configuration of an example of an imaging device according to the present invention. A light beam emitted from a laser light source 1 is expanded into a parallel beam by an expander 2 and is made incident on a cylindrical lens 3. This cylindrical lens 3 has the function of converging the light beam only in the sub-scanning direction perpendicular to the main scanning direction (direction perpendicular to the plane of the paper), and the light beam emitted from the cylindrical lens 3 extends in the main scanning direction. The light beam becomes a thin line, passes through the half mirror 4, and enters the vibrating mirror 5. This vibrating mirror 5 rotates in the direction of arrow a or b to deflect the light beam in the sub-scanning direction (parallel to the plane of the paper) at a constant frequency. The linear light beam reflected by the vibrating mirror 5 passes through the imaging lens 6 and the relay lens 7, enters the objective lens 8, becomes a thin linear light beam extending in the main scanning direction, and enters the sample 9. As a result, the sample 9 is scanned by the linear light beam in the sub-scanning direction at a constant scanning frequency. That is, in the present invention, instead of performing main scanning with a minute spot-shaped light beam, a linear light beam extending in the main scanning direction is projected onto the sample to perform equivalent main scanning. As a result, the entire surface of the sample 9 is scanned by the light beam in the same manner as when the sample 9 is scanned by the light beam in the form of a minute spot in the main scanning direction and the sub-scanning direction. In this example, it is assumed that optical information of the sample 9 is obtained based on reflected light from the sample 9. The reflected light from the sample 9 is focused by the objective lens 8, passes through the relay lens 7 and the imaging lens 6, is reflected again by the vibrating mirror 5, is reflected by the half mirror 4, and extends in a direction corresponding to the main scanning direction. The light enters the linear image sensor 10 in the form of a thin linear beam. This linear image sensor 10 is arranged at the imaging position of the imaging lens 6, and has a configuration in which a plurality of light receiving elements are arranged one-dimensionally in a direction corresponding to the main scanning direction.
Therefore, as shown in FIG. 2, the linear beam 11 from the sample 9 is projected onto the linear image sensor 10 along the arrangement direction of each of the light receiving elements 10a to 10n. The accumulated charges are read out sequentially at a predetermined readout frequency to form an image signal. With this configuration, since the sample is scanned with a thin linear light beam extending in the main scanning direction, a clear image can be formed without being adversely affected by uneven scanning speed in the main scanning direction.

FIG. 3 is a block diagram showing the configuration of an example of the drive circuit. A synchronizing circuit 20 for generating vertical and horizontal synchronizing signals V and H is connected to a clock generating circuit 21 to supply a horizontal synchronizing signal H. The clock generation circuit 21 generates a clock signal for reading out the charge accumulated in each light receiving element of the linear image sensor 10 based on the supplied horizontal synchronizing signal H, and uses this reading clock signal to output the electric charge accumulated in each light receiving element of the linear image sensor 10. Supply to 10. Furthermore, a vibrating mirror drive circuit 22 for controlling the drive of the vibrating mirror 5 is connected to the synchronizing circuit 20 to supply a vertical synchronizing signal V, and a processor circuit 23 is further connected to supplying vertical and horizontal synchronizing signals V and H. do. In the linear image sensor 10, the amount of charge corresponding to the amount of light reflected from the sample 9 is accumulated in each element, so the amount of charge is read out based on the readout clock signal and the amplifier 24 connected to the linear image sensor 10 is loaded. The vertical and horizontal synchronizing signals V and H supplied from the processor circuit 23 are applied to form an image signal. The image signal is then supplied to the monitor 25 for display or recorded on the VTR 26.

FIG. 4 is a diagram showing an embodiment in which the imaging device according to the present invention is applied to a color imaging device. A red light source 31, a green light source 32, and a blue light source 33 are arranged to emit three primary colors of red, green, and blue and a light beam, respectively. In this example, 633n is used as the red light source 31.
A He-Ne laser that emits light with a wavelength of m is used, and an Ar laser that emits light with a wavelength of 488 nm is used as the green light source 32.
A He-Cd laser that emits light with a wavelength of 442 nm is used as the blue light source 33. Each light source 31
It is assumed that all the light beams emitted from 33 are linearly polarized. The light beam emitted from the red light source 31 is expanded into a parallel beam by an expander 34 and enters a first cylindrical lens 35 . This first cylindrical lens 35 is a lens that has a convergence effect on the incident light beam only in the sub-scanning direction orthogonal to the main-scanning direction, and the light beam becomes a thin linear beam extending in the main-scanning direction after exiting. .
The light beam emitted from the first cylindrical lens 35 is directed to the first cylindrical lens 35, which acts as a beam splitter.
The light passes through the deflection prism 36 and the quarter-wave plate 37, respectively, and enters the first dichroic prism 38. This first dichroic prism 3
8 reflects only green light and transmits light in other wavelength ranges. The red light beam that has passed through the first dichroic prism 38 passes through a second dichroic prism 39 that reflects only blue light, and enters the vibrating mirror 40. This vibrating mirror 40 is
A red light beam, a green light beam, and a blue light beam are used in common, and each light beam is deflected in the sub-scanning direction (direction of the paper surface) orthogonal to the main-scanning direction of the sample. The red light beam reflected by the vibrating mirror 40 passes through the imaging lens 41 and the relay lens 42 and enters the sample 44 at the objective lens 43 as an extremely thin linear light beam extending in the main scanning direction. As a result, the sample 44 is scanned in the sub-scanning direction at a predetermined scanning frequency by the thin linear red light beam extending in the main-scanning direction. In this example, sample 4
The optical information of the sample shall be obtained by detecting the reflected light from 4. The reflected light from the sample 44 is again focused by the objective lens 43, passes through the relay lens 42 and the imaging lens 41, and enters the vibrating mirror 40 again.
After being reflected by this vibrating mirror 40, the second and first
The light passes through the dichroic prisms 39 and 38, and further passes through the quarter-wave plate 37, and enters the first deflection prism 36. The light beam incident on the deflection prism 36 passes through the 1/4 wavelength plate 37 twice, so its deflection plane is rotated by 90°, and the deflection plane 36
reflected by the first linear image sensor 45
The beam enters the beam as a thin linear beam. This linear image sensor 45 is arranged at the imaging position of the imaging lens 41, and has a configuration in which a plurality of light receiving elements are arranged in a direction corresponding to the main scanning direction, and charges accumulated in each light receiving element are sequentially read out at a predetermined readout frequency. shall be read out.

Next, scanning with green light will be explained. The light beam emitted from the green light source 32 is
6, the light beam is expanded into a parallel light beam, and then enters the second cylindrical lens 47, where it is converged only in the sub-scanning direction and output as a linear beam. The green light beam emitted from the second cylindrical lens 47 passes through the second deflection prism 48, is reflected by the right angle prism 49, passes through the 1/4 wavelength plate 50, and enters the first dichroic prism 38. do. Since this first dichroic prism 38 reflects only green light, the incident green light beam is reflected and enters a common optical path, passes through the second dichroic prism 39, and enters the vibrating mirror 40. . The vibrating mirror 40 deflects the red light beam in the sub-scanning direction, and passes through the imaging lens 41 and relay lens 42 to the objective lens 43.
The beam is focused into a fine linear beam and enters the sample 44. As a result, the portion of the sample 44 scanned by the red light beam is simultaneously scanned by the green light beam. The reflected light from the sample 44 is again focused by the objective lens 43, passes through the relay lens 42 and the imaging lens 41, is reflected by the vibrating mirror 40, and is further reflected by the second dichroic prism 3.
9 through the first dichroic prism 38
reflect. Thereafter, it passes through the 1/4 wavelength plate 50 again, the deflection plane changes by 90°, is reflected by the right angle prism 49, and is further reflected by the deflection plane 48a of the second deflection prism 48.
The light is reflected by the beam and enters the half mirror 51. Then, the transmitted light is transmitted to the second linear image sensor 5.
The reflected light enters the focus detection device 53 and is used for detecting the focus of the objective lens 43.

This second linear image sensor 56 is similarly arranged at the imaging position of the imaging lens 41, and has a configuration in which a plurality of light receiving elements are arranged one-dimensionally in a direction corresponding to the main scanning direction of the sample 44, and each light receiving element is arranged one-dimensionally in a direction corresponding to the main scanning direction of the sample 44. The first charge accumulated in the element is read out in synchronization with the linear image sensor 45.

Next, scanning with blue light will be explained. The color beam emitted from the blue light source 33 is transmitted to the expander 54.
The light beam is made into an expanded parallel light beam and enters the third cylindrical lens 55. This third cylindrical lens 55 also has a convergence effect only in the sub-scanning direction, similar to the first and second cylindrical lenses 35 and 47. The light beam emitted from the third cylindrical lens 55 becomes a thin linear beam, passes through the third deflection prism 56, is reflected by the right angle prism 57, and further passes through the 1/4 wavelength plate 58 to form the second beam. Reflected by dichroic prism 39,
They enter a common optical path, enter a common vibrating mirror 40, and are deflected in the sub-scanning direction in the same way as the red and green beams. Furthermore, the objective lens 43 passes through the imaging lens 41 and the relay lens 42 to form a thin linear light beam extending in the main scanning direction and enters the sample 44. As a result, red, green, and blue light beams are combined. As a result, a thin linear scanning beam extending in the main scanning direction is formed, and the sample 44 is scanned in the sub-scanning direction by this linear scanning beam. The blue reflected light from the sample 44 is again focused by the objective lens 43, and then passed through the relay lens 4.
2 and an imaging lens 41 before entering the vibrating mirror 40 . Then, it is reflected by this vibrating mirror 40,
It is reflected by the second dichroic prism 39, deviates from the common optical path, passes through the 1/4 wavelength plate 58, the deflection plane changes by 90°, and is reflected by the right angle prism 57 and the deflection prism 56, forming the third linear image. The beam enters the sensor 59 as a linear beam. Similarly, this third linear image sensor 59 also has an imaging lens 4.
A plurality of light receiving elements are arranged one-dimensionally in a direction corresponding to the main scanning direction, and the charges accumulated in each light receiving element are transferred to the first and second image forming positions.
It is read out in synchronization with the linear image sensors 45 and 52. With this configuration, the three light beams are not adversely affected by the scanning ram etc. in the main scanning direction, and since the configuration uses a common vibrating mirror for sub-scanning, color shift in the sub-scanning direction is eliminated. A clear image without color shift can be obtained in both the main scanning direction and the sub-scanning direction.

The present invention is not limited to the embodiments described above, but is capable of numerous modifications and deviations. For example, in the above-described embodiment, the optical information of the sample is obtained based on the light reflected from the sample, but it is also possible to obtain the optical information of the sample using the transmitted light from the sample.

Further, as a means for deflecting the light beam, any deflecting means such as a polygon mirror can be used.

(Effects of the Invention) The effects of the present invention explained above are summarized as follows.

(1) Since the sample is scanned with a single thin linear light beam, the sample can be scanned over the entire surface using just one deflection means, simplifying the configuration of the optical system. This makes assembly and adjustment easier, and costs can be reduced. In particular, since an acousto-optic element that is expensive and difficult to assemble and adjust is unnecessary, it is possible to further reduce costs and simplify assembly and adjustment.

(2) Since the sample is scanned by deflecting a thin linear light beam extending in the main scanning direction in the sub-scanning direction, it is possible to eliminate adverse effects caused by uneven scanning speed in the main scanning direction.

(3) If a laser light source is used as the light source, a phase difference will occur due to the unevenness of the sample, and this will result in an interference effect, making it possible to obtain an image with high contrast in the depth direction of the sample.

(4) Compared to a configuration that scans with a tiny spot-shaped light beam, the resolution is slightly lower at high magnification;
It is sufficiently practical when observing at low magnification, even though the resolution may be low.

(5) Since the linear light beam is deflected at high speed by a deflection device and projected onto the sample, the sample can be scanned at high speed, and images of the sample can be captured in real time at television rates, and still images can be captured. can also be imaged.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an example of an imaging device according to the present invention, FIG. 2 is a diagram showing the shape of a beam projected onto a linear image sensor, and FIG. 3 is a diagram showing the configuration of an example of a drive circuit. 4 are diagrams showing an embodiment in which the imaging device of the present invention is applied to a color imaging device. 1... Laser light source, 2, 34, 46, 54...
Expander, 3, 35, 47, 55...Cylindrical lens, 4,51...Half mirror,
5,40...Vibrating mirror, 6,41...Imaging lens, 7,42...Relay lens, 8,43...Objective lens, 9,44...Sample, 10,45,5
2, 59... Linear image sensor, 31... Red light source, 32... Green light source, 33... Blue light source,
36, 48, 56... Deflection prism, 37, 5
0, 58... 1/4 wavelength plate, 38, 39... dichroic prism.

[Claims]

1. A fine adjustment circuit for the clock frequency in a laser printer, which drives a laser emitter with the print data read based on the clock frequency for determining the speed of the print data, and scans the obtained laser light on the photoreceptor. a change signal creation circuit that creates a frequency change signal assigned to each of a plurality of time blocks obtained by equally dividing the scanning time of the printing area on the photoreceptor to a progressive value whose polarity is reversed with respect to the center of the photoreceptor; a variable frequency divider circuit that divides a constant oscillation frequency signal of an oscillator by each frequency division ratio corresponding to the frequency change signal; and a constant frequency signal from the oscillator as a modulated signal and an output of the variable frequency divider circuit. A modulation circuit that modulates a frequency signal as a modulation signal, and a speed of print data that corresponds to a change in the scanning speed of the laser beam on the photoreceptor by extracting only a predetermined frequency component of the output frequency signal of the modulation circuit. A frequency fine adjustment circuit for a laser printer, comprising a bandpass filter for obtaining the clock frequency signal for determination. 2. The laser printer according to claim 1, wherein the modulation circuit is a balanced modulation circuit configured using an exclusive OR gate.