JP7765586B2 - Imaging system, inspection device, and imaging method - Google Patents

Description

The present invention relates to an imaging system, an inspection device, and an imaging method.

Patent Document 1 discloses an inspection device that uses a line sensor to inspect rolled material. In this inspection device, the line rate of the line sensor is changed depending on the conveying speed of the rolled material. Patent Document 2 discloses an imaging device that uses multiple line cameras.

Japanese Patent Application Laid-Open No. 2008-292345 Japanese Patent Application Laid-Open No. 2008-5370

In Patent Documents 1 and 2, a line sensor is used to capture an image of a sample. For example, by using the line sensor to detect light from a moving sample, a two-dimensional image of the sample can be captured.

The reflectivity of a sample can vary depending on the wavelength. In particular, when inspecting thin films used in semiconductor devices, wavelength dependency is significant. Therefore, the reflectivity of sample S may be high in the first wavelength band and low in the second wavelength band. In such cases, it can be difficult to properly capture images in different wavelength bands.

This disclosure has been made in consideration of these problems, and provides an imaging system, inspection device, and imaging method that can properly image samples.

An imaging system according to one aspect of this embodiment includes a light source that generates illumination light to illuminate a sample; a first line sensor that detects reflected light in a first wavelength band and has a plurality of light-receiving pixels arranged in a line to detect reflected light from the sample over a first exposure time; a second line sensor that detects reflected light in a second wavelength band and has a plurality of light-receiving pixels arranged in a line to detect reflected light from the sample over a second exposure time; a scanning mechanism that moves the detection positions of the first and second line sensors relative to the sample; and a processing unit that generates an image of the sample based on the detection results of the first and second line sensors when scanned by the scanning mechanism.

In the above imaging system, the first line sensor and the second line sensor may be monochrome sensors.

In the above imaging system, the reflectance of the sample for light in the first wavelength band may be lower than the reflectance of light in the second wavelength band, and the first exposure time may be longer than the second exposure time.

The above imaging system may further include a third line sensor that includes a plurality of pixels arranged in a line to detect reflected light from the sample at a third exposure time and detects reflected light in a third wavelength band.

In the above imaging system, the first wavelength band may be a red wavelength band, the second wavelength band may be a green wavelength band, and the third wavelength band may be a blue wavelength band.

An inspection device according to one aspect of this embodiment includes the imaging system described above, and inspects the sample based on an image of the sample captured by the imaging system.

An imaging method according to one aspect of this embodiment includes the steps of generating illumination light to illuminate a sample, scanning the illumination position of the illumination light relative to the sample, detecting reflected light in a first wavelength band using a first line sensor having a plurality of light-receiving pixels arranged in a line to detect reflected light from the sample at a first exposure time, detecting reflected light in a second wavelength band using a second line sensor having a plurality of light-receiving pixels arranged in a line to detect reflected light from the sample at a second exposure time, and generating an image of the sample based on the detection results of the first line sensor and the second line sensor when the scanning is performed.

In the above imaging method, the second line sensor and the second line sensor may be monochrome sensors with different detection wavelength bands.

In the above imaging method, the reflectance of the sample for light in the first wavelength band may be lower than the reflectance of light in the second wavelength band, and the first exposure time may be longer than the second exposure time.

In the above imaging method, reflected light in a third wavelength band may be detected by a third line sensor having a plurality of pixels arranged in a line so as to detect reflected light from the sample at a third exposure time.

In the above imaging method, the first wavelength band may be a red wavelength band, the second wavelength band may be a green wavelength band, and the third wavelength band may be a blue wavelength band.

This disclosure provides an imaging system, inspection device, and imaging method that can properly image a sample using a line sensor.

1 is a schematic diagram showing an inspection device using an imaging system according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing the pixel size of a sample image captured by a line sensor.

Embodiments of the present invention will be described below with reference to the drawings. The following description illustrates preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, parts with the same reference numerals indicate substantially similar content.

An inspection device using an imaging system according to an embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing the configuration of an inspection device 100 according to an embodiment. As shown in FIG. 1, the inspection device 100 includes a light source 11, a beam splitter 12, an objective lens 13, a dichroic mirror 15, a dichroic mirror 16, and a drive stage 40. Furthermore, the inspection device 100 includes a lens 21, a lens 22, a lens 23, a first line sensor 31, a second line sensor 32, a third line sensor 33, and a processing unit 50.

The first line sensor 31, second line sensor 32, and third line sensor 33 detect red (R), green (G), and blue (B) light, respectively. Note that Figure 1 uses an XYZ three-dimensional Cartesian coordinate system for explanation. The XY plane is a direction parallel to the surface (imaging surface) of the sample S. The Z direction is a direction perpendicular to the surface of the sample S, and corresponds to the optical axis direction of the objective lens 13. The Y direction corresponds to the arrangement direction of the light-receiving pixels in the first line sensor 31, second line sensor 32, and third line sensor 33. The X direction corresponds to the scanning direction of the sample S.

The drive stage 40 scans the sample S in the X direction. During scanning in the X direction, the first line sensor 31, second line sensor 32, and third line sensor 33 detect reflected light from the sample S. Each of the first line sensor 31, second line sensor 32, and third line sensor 33 has multiple light-receiving pixels arranged in a row along the Y direction. This makes it possible to capture a two-dimensional image in the X and Y directions.

First, the illumination optical system that illuminates the sample S will be described. The light source 11 generates illumination light L1 for illuminating the sample S. Various light sources, such as a lamp light source, LED (Light Emitting Diode), or laser light source, can be used as the light source 11. The light source 11 may be a line light source. Alternatively, line-shaped illumination light L1 can be generated by using a slit or cylindrical lens. Furthermore, illumination light L1 is preferably a white light source that includes red (R), green (G), and blue (B) light. Alternatively, the light source 11 may be configured by combining multiple monochromatic light sources. For example, illumination light L1 may be formed by combining light from monochromatic R, G, and B light sources.

Illumination light L1 from light source 11 enters objective lens 13 via beam splitter 12. Beam splitter 12 is, for example, a half mirror that transmits approximately half of the incident light and reflects the other half. Therefore, approximately half of illumination light L1 from light source 11 passes through beam splitter 12 and enters objective lens 13.

The objective lens 13 focuses the illumination light L1 onto the sample S. A linear illumination area with the Y direction as the longitudinal direction is formed on the sample S. In other words, the linear area of the sample S is illuminated with the illumination light L1.

The sample S is placed on the driving stage 40. The driving stage 40 is, for example, an XYZ three-dimensional driving stage. The driving stage 40 scans the sample S in the X direction, which is the scanning direction. This allows the position of the linear illumination area on the sample S to be changed. In other words, the illumination area on the sample S, with its longitudinal direction in the Y direction, moves relatively in the X direction, allowing an XY image (two-dimensional image) to be captured.

The reflected light L2 reflected by the sample S passes through the objective lens 13 and enters the beam splitter 12. The beam splitter 12 reflects approximately half of the incident reflected light L2. The reflected light L2 reflected by the beam splitter 12 enters the dichroic mirror 15.

The dichroic mirror 15 splits the reflected light L2 according to wavelength. Of the reflected light L2, the light that passes through the dichroic mirror 15 is referred to as reflected light L3, and the light that is reflected by the dichroic mirror 15 is referred to as reflected light L13. The dichroic mirror 15 reflects light in the blue wavelength band and transmits light in the green and red wavelength bands. Therefore, the reflected light L3 that passes through the dichroic mirror 15 contains light in the red wavelength band and light in the green wavelength band. In other words, the reflected light L3 that passes through the dichroic mirror 15 does not contain light in the blue wavelength band.

Reflected light L3 that passes through dichroic mirror 15 is incident on dichroic mirror 16. Dichroic mirror 16 splits reflected light L3 according to wavelength. Reflected light L3 that passes through dichroic mirror 16 is referred to as reflected light L11, and reflected light L3 that is reflected by dichroic mirror 16 is referred to as reflected light L12. Dichroic mirror 16 reflects light in the green wavelength band and transmits light in the red wavelength band. Therefore, reflected light L11 that passes through dichroic mirror 16 contains light in the red wavelength band. In other words, reflected light L11 that passes through dichroic mirror 16 does not contain light in the blue and green wavelength bands.

The reflected light L11 that passes through the dichroic mirror 16 is refracted by the lens 21 and enters the first line sensor 31. The lens 21 is an imaging lens that focuses the reflected light L11 on the light-receiving surface of the first line sensor 31. Therefore, an image of the illuminated area of the sample S is formed on the light-receiving surface of the first line sensor 31.

The first line sensor 31 can capture an image of the illuminated area of the sample S. The first line sensor 31 detects red light from the reflected light L2 reflected by the sample S. The first line sensor 31 may also have a color filter that transmits light in the red wavelength band.

The reflected light L12 reflected by the dichroic mirror 16 contains light in the green wavelength band. In other words, the reflected light L12 does not contain light in the blue or red wavelength bands. The reflected light L12 reflected by the dichroic mirror 16 is refracted by the lens 22 and enters the second line sensor 32. The lens 22 is an imaging lens that focuses the reflected light L12 on the light-receiving surface of the second line sensor 32. Therefore, the illuminated area of the sample S is imaged on the light-receiving surface of the second line sensor 32.

The second line sensor 32 can capture an image of the illuminated area of the sample S. The second line sensor 32 detects green light from the reflected light L2 reflected by the sample S. The second line sensor 32 may also have a color filter that transmits light in the green wavelength band.

The reflected light L13 reflected by the dichroic mirror 15 contains light in the blue wavelength band. In other words, the reflected light L13 does not contain light in the red and green wavelength bands. The reflected light L13 reflected by the dichroic mirror 15 is refracted by the lens 23 and enters the third line sensor 33. The lens 23 is an imaging lens that focuses the reflected light L13 on the light-receiving surface of the third line sensor 33. Therefore, the illuminated area of the sample S is imaged on the light-receiving surface of the third line sensor 33.

The third line sensor 33 can capture an image of the illuminated area of the sample S. The third line sensor 33 detects blue light from the reflected light L2 reflected by the sample S. The third line sensor 33 may also have a color filter that transmits light in the blue wavelength band. The first line sensor 31 to the third line sensor 33 are monochrome sensors. The first line sensor 31 to the third line sensor 33 may have different detection wavelength bands. For example, the detection wavelength band can be set by providing a color filter on the light receiving surface of the sensor or in the optical path.

In this way, the first line sensor 31 detects the reflected R light L11. The second line sensor 32 detects the reflected G light L12, and the third line sensor 33 detects the reflected B light L13. Furthermore, because the reflected light is split by the dichroic mirror 15 and the dichroic mirror 16, the first line sensor 31 to the third line sensor 33 can simultaneously detect each of the RGB lights. The light-receiving pixels of the first line sensor 31 to the third line sensor 33 output signals indicating gradation values corresponding to the amount of detected light. The first line sensor 31 to the third line sensor 33 output detection signals corresponding to the amount of detected light to the processing unit 50.

For example, the processing unit 50 is a computer equipped with a processor, memory, etc. The processing unit 50 performs processing for imaging and inspection using a computer program. That is, the processing unit 50 is equipped with memory for storing programs, a processor such as a CPU, etc. The processor may execute the inspection program to perform the processing described below and defect detection processing.

The processing unit 50 stores the detection signals from the first line sensor 31 to the third line sensor 33 in a memory or the like. The processing unit 50 also controls the drive stage 40. Therefore, the processing unit 50 stores the detection signals in association with the scanning position of the drive stage 40. The detected amount of reflected light is associated with XY coordinates. This allows the processing unit 50 to generate an XY image (two-dimensional image) of the sample S.

The processing unit 50 generates an image of R of the sample S based on the detection signal of the first line sensor 31. The processing unit 50 generates an image of G of the sample S based on the detection signal of the second line sensor 32. The processing unit 50 generates an image of B of the sample S based on the detection signal of the third line sensor 33. The processing unit 50 generates images of different wavelength bands based on the detection signals from each line sensor. Furthermore, the processing unit 50 may generate a color image by combining the detection signals of each of RGB.

The reflectance of the sample S can vary depending on the wavelength. In particular, when inspecting thin films used in semiconductor devices, wavelength dependency is significant. Therefore, in this embodiment, the exposure time is changed for each of the first line sensor 31 to the third line sensor 33. In other words, the first line sensor 31 to the third line sensor 33 detect reflected light using different exposure times.

Figure 2 will be used to explain pixel size depending on the exposure time. Figure 2 is a diagram that shows the pixel size of each RGB image. In Figure 2, the horizontal direction is the scanning direction of the drive stage 40, and the vertical direction is the line direction of the line sensor. The scanning direction corresponds to the X direction in Figure 1. The line direction is the pixel array direction, which corresponds to the Y direction in Figure 1. Figure 2 shows RGB images from top to bottom.

The exposure time of the first line sensor 31 is T1, the exposure time of the second line sensor 32 is T2, and the exposure time of the third line sensor 33 is T3. Assume that B has the highest reflectance and R has the lowest reflectance of sample S. The exposure time T1 for R, which has low reflectance, is the longest, and the exposure time T3 for B, which has high reflectance, is the shortest. The exposure time T2 for G is shorter than the exposure time T1 for R, and longer than the exposure time T3 for B.

In the scanning direction, pixel size on the sample S is proportional to the product of the exposure time of the line sensor and the scanning speed of the drive stage. On the sample S, pixel Pr of the first line sensor 31, which has the longest exposure time, has the largest pixel size. Pixel Pb of the third line sensor 33, which has the shortest exposure time, has the smallest pixel size. Pixel Pg of the second line sensor 32 has a smaller pixel size than pixel Pr and a larger pixel size than pixel Pb. Therefore, when capturing an image of the entire sample S or the same area, the number of pixels (image size) will differ between the RGB images. Note that the pixel size in the line direction is the same.

The longer the exposure time, the greater the amount of detected light accumulated in the light-receiving pixels, but the lower the resolution. By changing the line rate of the line sensor for each color, it is possible to match the exposure time at which each of the RGB colors is sensitive. For example, for R, which has low reflectance, the first line sensor 31 can perform detection with high sensitivity. For B, which has high reflectance, the third line sensor 33 can perform detection with high sensitivity and high resolution.

In addition, the first line sensor 31 to the third line sensor 33 simultaneously detect reflected light from the illumination area. This allows three RGB images to be captured simultaneously, shortening the capture time. This enables high-speed capture while maintaining appropriate resolution for each color. This allows inspections to be completed in a short time.

The processing unit 50 performs inspection for each RGB image. Since the sample S can be inspected based on captured images of multiple colors, highly accurate inspection is possible. There are no particular limitations on the type of inspection using the captured images. In other words, known methods and algorithms can be used to inspect the sample S. For example, the processing unit 50 performs defect inspection by comparing the captured image with a reference image. Alternatively, the processing unit 50 performs defect inspection by comparing captured images of the same pattern. In this way, pattern defects, foreign matter inspection, etc. can be performed.

Furthermore, in a sample S having multiple layers of films stacked on it, it is possible to detect peeling of only a specific film. In other words, since the reflectance of each film is different, peeling can be detected for each film by using images captured in multiple colors. The inspection device 100 according to this embodiment is suitable for inspecting semiconductor devices having multiple thin films stacked on top of each other.

In addition, machine learning such as deep learning can be used as an algorithm for defect inspection. The processing unit 50 may use a filter for image analysis on the captured image. The processing unit 50 can perform inspection using a different filter for each color. The processing unit 50 applies a different filter to each color and allows the filter to learn. Therefore, even if the image size differs for each color, highly accurate inspection can be performed based on each captured image.

The exposure times of the first line sensor 31 to the third line sensor 33 may be set in advance according to the reflectance of the sample S. Alternatively, at least one of the first line sensor 31 to the third line sensor 33 may be a line sensor with a fixed exposure time. In this case, a line sensor with an exposure time appropriate for the reflectance of the sample S may be used. Alternatively, a line sensor with a variable exposure time may be used. In this case, the processing unit 50 or the like can change the exposure time according to the sample S. Alternatively, the user may adjust the exposure time.

While the above embodiment captures three RGB images, two or more images may be captured. That is, a first captured image may be captured in accordance with the detection results of a first line sensor that detects reflected light in a first wavelength band, and a second captured image may be captured in accordance with the detection results of a second line sensor that detects reflected light in a second wavelength band. Furthermore, if the reflectance of light in the first wavelength band is lower than the reflectance of light in the second wavelength band, the first exposure time is set to be longer than the second exposure time. This allows images in different wavelength bands to be captured with appropriate detection sensitivity. The first and second wavelength bands do not have to be completely different wavelength bands, and may partially overlap. Alternatively, all or part of the first wavelength band may be included in the second wavelength band.

Colors with high reflectivity have shorter exposure times, and colors with low reflectivity have longer exposure times. The two line sensors have different exposure cycles (line rates). Colors with high reflectivity have higher resolution at higher line rates. Colors with low reflectivity have lower resolution at lower line rates. Therefore, the exposure time can be set according to the reflectivity. Additionally, the detection bandwidth can be different for each line sensor. In this case, the exposure time can be set according to the detection bandwidth.

In addition, images may be captured in four or more wavelength bands, not just three. For example, four line sensors may be provided to detect the first through fourth wavelength bands. Images may also be captured in colors other than RGB.

In the above explanation, the reflected light L2 is split by dichroic mirror 15 and dichroic mirror 16, but it may be split by other methods. For example, the reflected light may be split by a half mirror, various beam splitters, or a prism. In this case, a color filter or the like may be placed in the optical path of the split reflected light. The first line sensor 31 to the third line sensor 33 may also be an integrally formed three-line camera.

1, the driving stage 40 is used as a scanning mechanism that moves the detection positions of the first line sensor 31 and the second line sensor 32 relative to the sample S. However, scanning may be performed by a scanning mechanism other than the driving stage 40. For example, a driving means that drives an optical system including the light source 11, the beam splitter 12, and the objective lens 13 may be used as the scanning mechanism.

Furthermore, the pixel size can be set more flexibly than with sensor binning operations. In other words, with sensor binning operations, the pixel size of different images is limited to integer multiples. In contrast, in this embodiment, the exposure time can be set to a value other than an integer multiple, so the pixel size of different images is not limited to integer multiples.

In addition, by combining images with different periods, the effects of moire patterns can be reduced. Furthermore, since phase-shifted images can be obtained, this method can be applied to super-resolution technology.

Some or all of the processing of the processing unit 50 may be performed by a computer program. The above-mentioned program can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R/Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory)). The program may also be supplied to a computer via various types of transient computer-readable media. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transient computer-readable medium may be supplied to a computer via a wired communication path such as an electric wire or optical fiber, or via a wireless communication path.

The above describes an embodiment of the present invention, but the present invention includes appropriate modifications that do not impair its objects and advantages, and is not limited to the above embodiment.

100 Inspection device 11 Light source 12 Beam splitter 13 Objective lens 15 Dichroic mirror 16 Dichroic mirror 21 Lens 22 Lens 23 Lens 31 First line sensor 32 Second line sensor 33 Third line sensor 40 Driving stage 50 Processing unit Pr R pixel Pg G pixel Pb B pixel S Sample

Claims (13)

a light source that generates illumination light for illuminating the sample;
a first line sensor including a plurality of light-receiving pixels arranged in a line so as to detect reflected light from the sample for a first exposure time, the first line sensor detecting reflected light in a first wavelength band;
a second line sensor including a plurality of light-receiving pixels arranged in a line so as to detect reflected light from the sample at a second exposure time different from the first exposure time, and detecting reflected light in a second wavelength band;
a scanning mechanism that moves the detection positions of the first and second line sensors relative to the sample;
a processing unit that generates an image of the sample in accordance with a detection result of the first line sensor and a detection result of the second line sensor when scanning is performed by the scanning mechanism,
the first image captured by the first line sensor is a two-dimensional image having a first pixel size and a first number of pixels; the second image captured by the second line sensor is a two-dimensional image having a second pixel size different from the first pixel size and a second number of pixels different from the first number of pixels;
An imaging system wherein the processing unit generates the first image and the second image of the same region of the sample. a branching means for branching the reflected light from the sample into three beams according to wavelength;
a third line sensor including a plurality of light-receiving pixels arranged in a line so as to detect the reflected light of a third wavelength band branched by the branching means for a third exposure time different from the first and second exposure times,
the first line sensor detects the reflected light of the first wavelength band split by the splitting means,
the second line sensor detects the reflected light of the second wavelength band split by the splitting means,
the first image has the first pixel size according to the first exposure time;
the second image has the second pixel size according to the second exposure time;
the third image captured by the third line sensor has a third pixel size corresponding to the third exposure time, and is a two-dimensional image having a third number of pixels different from the first number of pixels and the second number of pixels;
The imaging system of claim 1, wherein the processing unit generates a color image of the sample based on the detection results of the first line sensor, the second line sensor, and the third line sensor when scanning with the scanning mechanism. a first lens that collects the reflected light of the first wavelength band split by the splitting means and forms an image of the illumination area of the sample on a light receiving surface of a first line sensor;
a second lens that collects the reflected light of the second wavelength band split by the splitting means and forms an image of the illumination area of the sample on a light receiving surface of a second line sensor;
a third lens that collects the reflected light of the third wavelength band split by the splitting means and forms an image of the illumination area of the sample on a light receiving surface of a third line sensor,
The imaging system according to claim 2 , wherein the processing unit combines detection signals of the first image, the second image, and the third image to generate a color image of the sample. The imaging system described in claim 2 or 3, wherein the first line sensor, the second line sensor, and the third line sensor are monochrome sensors. the first wavelength band is a red wavelength band,
5. The imaging system according to claim 2, wherein the second wavelength band is a green wavelength band, and the third wavelength band is a blue wavelength band. An imaging system described in any one of claims 1 to 5, wherein the reflectance of the sample for light in the first wavelength band is lower than the reflectance of light in the second wavelength band, and the first exposure time is longer than the second exposure time. The imaging system according to any one of claims 1 to 6 is provided,
An inspection apparatus that inspects the sample based on an image of the sample captured by the imaging system. generating illumination light to illuminate the sample;
scanning the illumination position of the illumination light relative to the sample;
detecting reflected light of a first wavelength band by a first line sensor having a plurality of light-receiving pixels arranged in a line so as to detect reflected light from the sample for a first exposure time;
detecting reflected light in a second wavelength band by a second line sensor having a plurality of light-receiving pixels arranged in a line so as to detect reflected light from the sample for a second exposure time different from the first exposure time;
generating a first image and a second image of the same region of the sample according to the detection results of the first line sensor and the detection results of the second line sensor when the scanning is performed;
the first image captured by the first line sensor is a two-dimensional image having a first pixel size and a first number of pixels;
An imaging method in which the second image captured by the second line sensor has a second pixel size different from the first pixel size and is a two-dimensional image with a second number of pixels different from the first number of pixels. a splitting means for splitting the reflected light from the sample according to wavelength;
detecting the reflected light of the third wavelength band split by the splitting means using a third line sensor having a plurality of light-receiving pixels arranged in a line so as to detect the reflected light of the third wavelength band split by the splitting means for a third exposure time different from the first and second exposure times;
the first line sensor detects the reflected light of the first wavelength band split by the splitting means,
the second line sensor detects the reflected light of the second wavelength band split by the splitting means,
the first image has the first pixel size according to the first exposure time;
the second image has the second pixel size according to the second exposure time;
the third image captured by the third line sensor has a third pixel size corresponding to the third exposure time, and is a two-dimensional image having a third number of pixels different from the first number of pixels and the second number of pixels;
9. The imaging method according to claim 8, wherein a color image of the sample is generated based on the detection results of the first line sensor, the second line sensor, and the third line sensor when the scanning is performed. a first lens that collects the reflected light of the first wavelength band split by the splitting means and forms an image of the illumination area of the sample on a light receiving surface of a first line sensor;
a second lens that collects the reflected light of the second wavelength band split by the splitting means and forms an image of the illumination area of the sample on a light receiving surface of a second line sensor;
a third lens that collects the reflected light of the third wavelength band split by the splitting means and forms an image of the illumination area of the sample on a light receiving surface of a third line sensor,
The imaging method according to claim 9 , wherein detection signals of the first image, the second image, and the third image are combined to generate a color image of the sample. The imaging method described in claim 9 or 10, wherein the first line sensor, the second line sensor, and the third line sensor are monochrome sensors. the first wavelength band is a red wavelength band,
The imaging method according to any one of claims 9 to 11, wherein the second wavelength band is a green wavelength band, and the third wavelength band is a blue wavelength band. An imaging method described in any one of claims 8 to 12, wherein the reflectance of the sample for light in the first wavelength band is lower than the reflectance of light in the second wavelength band, and the first exposure time is longer than the second exposure time.