Computer, program, and method

Abstract

To correctly derive the wavelength of light to acquire an appropriate image.SOLUTION: A measuring device 1 comprises: a tilted dichroic mirror 11 that transmits or reflects light from a sample according to its wavelength to separate the light, and has a predetermined edge transition width being the width of a wavelength range where its transmittance and reflectance change according to a change of the wavelength; a total reflection mirror 12 that reflects one of the rays of light transmitted or reflected by the tilted dichroic mirror 11; an image pick-up device 14 that picks up an image of the other of the rays of light transmitted or reflected by the tilted dichroic mirror 11 in a first imaging area, and picks up an image of the light reflected by the total reflection mirror 12 in a second imaging area different from the first imaging area; and a control unit 80 that corrects the images picked up in the first imaging area and second imaging area based on optical characteristics related to the changes of the transmittance and reflectance relative to the wavelength in the tilted dichroic mirror 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an imaging unit and a measuring device. [Background technology]

[0002] There is known an imaging unit that separates light from an object according to wavelength and captures the separated wavelengths in different imaging regions (see, for example, Patent Document 1). In the imaging unit described in Patent Document 1, the wavelengths are separated by a dichroic mirror, which is an optical element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-235332 A Summary of the Invention [Problem to be solved by the invention]

[0004] The dichroic mirror described in Patent Document 1 separates light having a wavelength shorter than a certain wavelength from light having a longer wavelength, and generally has a transmittance of 100% or 0% regardless of wavelength. When using such a dichroic mirror, for example, when trying to separate light having a narrow wavelength range, it is considered that the desired separation cannot be performed according to the wavelength. As a configuration that can also handle the separation of light having such a narrow wavelength range, there is a dichroic mirror having a wide wavelength band (having an edge transition width) in which the transmittance (and reflectance) changes according to the change in wavelength. A dichroic mirror having an edge transition width can also appropriately separate light having a narrow wavelength range.

[0005] Here, in a dichroic mirror having an edge transition width, the optical characteristics change depending on, for example, the angle of incidence of light. As a result, in an imaging unit using a dichroic mirror having an edge transition width, the wavelength of light cannot be accurately derived, and there is a risk that a correct captured image cannot be obtained.

[0006] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide an imaging unit and a measuring device that can accurately derive the wavelength of light and obtain an appropriate image. [Means for solving the problem]

[0007] An imaging unit according to one embodiment of the present invention includes a separation optical element that separates light from an object by transmitting or reflecting it according to its wavelength, and has a predetermined edge transition width, which is the width of a wavelength band in which the transmittance and reflectance change according to change in wavelength; a reflective optical element that reflects one of the lights transmitted or reflected by the separation optical element; an imaging section that images the other of the lights transmitted or reflected by the separation optical element in a first imaging area and images the light reflected by the reflective optical element in a second imaging area different from the first imaging area; and a processing section that corrects the images captured in the first imaging area and the second imaging area based on optical characteristics related to the changes in transmittance and reflectance with wavelength in the separation optical element.

[0008] In the imaging unit according to one aspect of the present invention, a separation optical element having a predetermined edge transition width is used, and the captured image is corrected based on the optical characteristics related to the change in transmittance and reflectance with respect to the wavelength in the separation optical element. When a separation optical element having a predetermined edge transition width is used, light with a narrow wavelength width can be properly separated, but the optical characteristics may change depending on the angle of incidence of light on the separation optical element, for example, so that the wavelength of light may not be accurately derived and a proper image may not be obtained. In this regard, in the imaging unit according to one aspect of the present invention, the images captured in the first and second imaging regions are corrected based on the optical characteristics related to the change in transmittance and reflectance with respect to the wavelength, i.e., the characteristics related to the edge transition width of the separation optical element, so that a corrected captured image can be obtained in consideration of the optical characteristics unique to the separation optical element having the edge transition width. This allows the wavelength of the light separated by the separation optical element (light captured in the first and second imaging regions) to be properly derived and a proper (accurate) image to be obtained.

[0009] The processing unit may store in advance correction data that takes into account optical characteristics related to changes in transmittance and reflectance with respect to wavelength in the separation optical element, and may use the correction data to correct the images captured in the first imaging region and the second imaging region. With this configuration, the captured images can be easily and appropriately corrected based on the correction data stored in advance.

[0010] The processing unit may receive correction data that takes into account optical characteristics related to changes in transmittance and reflectance with respect to wavelength in the separation optical element, and may correct the images captured in the first imaging region and the second imaging region using the correction data. With this configuration, the captured images can be appropriately corrected based on the correction data obtained, for example, by executing software or inputting the correction data from an external source such as the Internet, without preparing the correction data in advance.

[0011] The processing unit may correct color spots caused by the angle of incidence of light to the separation optical element. When a separation optical element having an edge transition width is used, the optical characteristics of the separation optical element change according to the angle of incidence to the separation optical element, which causes color spots in the captured image. In this regard, by correcting the color spots, it is possible to obtain an appropriate image with reduced color spots.

[0012] The processing unit may correct the shift in the detection wavelength caused by the boundary between the wavelength band in which the transmittance and reflectance change with the change in wavelength and the wavelength band in which the transmittance and reflectance do not change with the change in wavelength. Such a boundary has optical characteristics different from those of the wavelength band in which the transmittance and the like change with the change in wavelength. For this reason, if the wavelength is derived using the same calculation formula as for the wavelength band in which the transmittance and the like change with the change in wavelength, the derived result may differ from the original wavelength. In this regard, by correcting the shift in the detection wavelength caused by such a boundary, the wavelength of light can be accurately derived and an appropriate image can be obtained.

[0013] The imaging section may be a single imaging element having a first imaging region and a second imaging region, thereby making it possible to obtain a plurality of captured images with a simple configuration using a single imaging element.

[0014] A measurement device according to one aspect of the present invention includes the imaging unit described above, and an analysis section that analyzes a processing result in the imaging unit including an image corrected by the processing section. Effect of the Invention

[0015] According to the present invention, the wavelength of light can be accurately derived and an appropriate image can be acquired. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a plan view showing a schematic diagram of a measuring device according to an embodiment of the present invention. [Diagram 2] 2 is a side view showing a schematic diagram of a camera system included in the measuring device of FIG. 1. [Diagram 3] 1A and 1B are diagrams illustrating the spectrum of light and the characteristics of an inclined dichroic mirror. [Figure 4] FIG. 2 is a diagram illustrating a correction unit. [Diagram 5] 13 is a graph for explaining correction of a calculated wavelength. [Figure 6] 1 is a flowchart of a correction method. [Figure 7] 13A and 13B are diagrams illustrating the characteristics of an inclined dichroic mirror according to a modified example. [Figure 8] FIG. 13 is a diagram illustrating a camera system according to a modified example. [Figure 9] FIG. 13 is a diagram illustrating a camera system according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0018] FIG. 1 is a plan view showing a measuring device 1 according to the present embodiment. The measuring device 1 is a camera unit (imaging unit) configured to be able to image a sample. The measuring device 1 separates light (e.g., observation light) from the sample according to wavelength components, and images the light of each wavelength component using the imaging elements 14, 24, and 34 corresponding to each wavelength component. The measuring device 1 performs a quality judgment of the sample by analyzing the image (imaging result) captured by the imaging elements 14, 24, and 34. The sample may be a light-emitting element such as an LED, a mini LED, a μLED, an SLD element, a laser element, a vertical cavity laser element (VCSEL), or an OLED, or may be a light-emitting element that adjusts the emission wavelength by a fluorescent material containing nanodots or the like. When the sample is a light-emitting element, the quality judgment of the sample means, for example, performing a quality judgment of the sample based on color spot information between a plurality of light-emitting elements.

[0019] As shown in Fig. 1, the measuring device 1 includes a camera system 2 and a control device 80 (processing unit, analysis unit). Details of the camera system 2 will be described with reference to Fig. 2. Fig. 1 is a plan view of the measuring device 1 including the camera system 2, and Fig. 2 is a side view of the camera system 2.

[0020] As shown in FIG. 1 and FIG. 2, the camera system 2 includes a first imaging unit 10, a second imaging unit 20, a third imaging unit 30, an infinity correction lens 40, a dichroic mirror 50, and a dichroic mirror 60. Although not shown in FIG. 1 and FIG. 2, the camera system 2 includes an objective lens (not shown) for observing a sample, and one or more bandpass filters (not shown) for removing light outside a desired wavelength range. The camera system 2 separates light into wavelength components roughly corresponding to the three primary colors, and captures the light of each wavelength component. For example, the first imaging unit 10 captures light of 380 to 500 nm including a blue wavelength component. The second imaging unit 20 captures light of 500 to 650 nm including a green wavelength component. The third imaging unit 30 captures light of 650 to 830 nm including a red wavelength component.

[0021] The infinity correction lens 40 is a collimator lens that converts the incident light from the sample into parallel light. The infinity correction lens 40 is aberration-corrected so that parallel light can be obtained. The parallel light output from the infinity correction lens 40 is incident on the dichroic mirror 50.

[0022] The dichroic mirror 50 is a mirror made of a special optical material, and separates the light from the sample by transmitting or reflecting it according to its wavelength. The dichroic mirror 50 reflects, for example, light of a specific wavelength and transmits light of other wavelengths. Specifically, the dichroic mirror 50 reflects, for example, light of a wavelength less than 500 nm and transmits light of other wavelengths (light of a wavelength of 500 nm or more). The light reflected by the dichroic mirror 50 is guided to the first imaging unit 10. The light transmitted through the dichroic mirror 50 is incident on the dichroic mirror 60.

[0023] The dichroic mirror 60 is a mirror made of a special optical material, and separates the light from the sample by transmitting or reflecting it according to its wavelength. The dichroic mirror 60 reflects, for example, light of a specific wavelength and transmits light of other wavelengths. Specifically, the dichroic mirror 60 reflects, for example, light of a wavelength of 500 nm or more and less than 650 nm and transmits light of other wavelengths (light of a wavelength of 650 nm or more). The light reflected by the dichroic mirror 60 is guided to the second imaging unit 20. The light transmitted through the dichroic mirror 60 is guided to the third imaging unit 30.

[0024] The first imaging unit 10 includes an inclined dichroic mirror 11 (separating optical element), a total reflection mirror 12 (reflective optical element), an imaging lens 13, and an imaging element 14 (imaging section).

[0025] The inclined dichroic mirror 11 is a mirror made of a special optical material, and separates light from a sample by transmitting or reflecting it according to the wavelength. The inclined dichroic mirror 11 reflects light of a specific wavelength, for example, and transmits light of other wavelengths. Specifically, the inclined dichroic mirror 11 reflects light of 380 to 500 nm among the light of less than 500 nm reflected by the dichroic mirror 50, and transmits light of other wavelengths. FIG. 3 is a diagram for explaining the spectrum of light and the characteristics of the inclined dichroic mirror 11. In FIG. 3, the horizontal axis indicates the wavelength, and the vertical axis indicates the spectral intensity (in the case of the spectrum of light) and the transmittance (in the case of the inclined dichroic mirror 11). As shown in the characteristic X4 of the inclined dichroic mirror 11 in FIG. 3, in the inclined dichroic mirror 11, the light transmittance (and reflectance) changes gradually in response to the change in wavelength in a specific wavelength band (the wavelength band of wavelengths λ1 to λ2), and the light transmittance (and reflectance) is constant in wavelength bands other than the specific wavelength band (i.e., on the lower wavelength side than the wavelength λ1 and the higher wavelength side than the wavelength λ2) regardless of the change in wavelength. In other words, in the specific wavelength band (the wavelength band of wavelengths λ1 to λ2), the light transmittance changes monotonically increasing (the reflectance changes monotonically) in response to the change in wavelength. Since the transmittance and the reflectance are negatively correlated in that when one changes in the direction of increasing, the other changes in the direction of decreasing, the terms "transmittance (and reflectance)" may be used hereinafter simply as "transmittance". Note that "the light transmittance is constant regardless of the change in wavelength" includes not only the case where it is completely constant, but also the case where the change in transmittance for a change in wavelength of 1 nm is 0.1% or less, for example. On the wavelength side lower than the wavelength λ1, the light transmittance is approximately 0% regardless of the change in wavelength, and on the wavelength side higher than the wavelength λ2, the light transmittance is approximately 100% regardless of the change in wavelength. Note that "the light transmittance is approximately 0%" includes a transmittance of approximately 0%+10%, and "the light transmittance is approximately 100%" includes a transmittance of approximately 100%-10%. In the following, the width of the wavelength band where the light transmittance changes depending on the change in wavelength may be described as the "edge transition width."As described above, inclined dichroic mirror 11 is a separation optical element having a predetermined edge transition width (width of wavelengths λ1 to λ2), which is the width of a wavelength band in which the transmittance changes according to a change in wavelength.

[0026] Total reflection mirror 12 is an optical element that reflects the light reflected by inclined dichroic mirror 11 in the direction of imaging lens 13 .

[0027] The imaging lens 13 is a lens that images the light that has passed through the inclined dichroic mirror 11 and the light that has been reflected by the inclined dichroic mirror 11 and further reflected by the total reflection mirror 12, and guides these lights to the imaging element 14.

[0028] The imaging element 14 captures the light transmitted through the inclined dichroic mirror 11 in a first imaging region, and captures the light reflected by the inclined dichroic mirror 11 and further reflected by the total reflection mirror 12 in a second imaging region different from the first imaging region. The imaging element 14 captures the light transmitted through the inclined dichroic mirror 11 and the light reflected by the total reflection mirror 12 by detecting an image formed by the imaging lens 13. The imaging element 14 is an imaging element for capturing light of 380 to 500 nm, and is, for example, an area image sensor such as a CCD or a MOS. The imaging element 14 may also be configured with a line sensor or a TDI (Time Delay Integration) sensor. In this embodiment, the imaging element 14 is described as a single imaging element having a first imaging region and a second imaging region, but an imaging element related to the first imaging region and an imaging element related to the second imaging region may be provided separately (two sets may be provided). In this case, two sets of imaging lenses are also provided corresponding to the imaging elements. The imaging element 14 outputs an image, which is the imaging result, to the control device 80.

[0029] The second imaging unit 20 includes the same configuration as that included in the first imaging unit 10, and includes an inclined dichroic mirror 21 (separating optical element), a total reflection mirror 22 (reflective optical element), an imaging lens 23, and an image sensor 24 (imaging section). The inclined dichroic mirror 21 has the same configuration as the inclined dichroic mirror 11 of the first imaging unit 10, except that the inclined dichroic mirror 21 reflects light of 500 to 650 nm among the light of 500 nm or more and less than 650 nm reflected by the dichroic mirror 60, and transmits light of other wavelengths. The image sensor 24 has the same configuration as the image sensor 14 of the first imaging unit 10, except that the image sensor 24 is an image sensor for capturing light of 500 to 650 nm.

[0030] The third imaging unit 30 includes the same configuration as that included in the first imaging unit 10, and includes an inclined dichroic mirror 31 (separating optical element), a total reflection mirror 32 (reflective optical element), an imaging lens 33, and an image sensor 34 (imaging section). The inclined dichroic mirror 31 has the same configuration as the inclined dichroic mirror 11 of the first imaging unit 10, except that it reflects light of 650 to 830 nm among those of 650 nm or more that have passed through the dichroic mirror 60, and transmits light of other wavelengths. The image sensor 24 has the same configuration as the image sensor 14 of the first imaging unit 10, except that it is an image sensor for capturing light of 650 to 830 nm.

[0031] Returning to Fig. 1, the control device 80 is a computer, and is physically configured to include memories such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. The control device 80 functions by executing a program stored in the memory with the CPU of a computer system. The control device 80 may be configured with a microcomputer or FPGA.

[0032] The control device 80 calculates and outputs the emission wavelength center of gravity based on the light amount of each pixel (each pixel of the image formed within the field of view) of the image, which is the imaging result, based on the imaging results obtained in each of the first imaging unit 10, the second imaging unit 20, and the third imaging unit 30. An example of the calculation principle of the emission wavelength center of gravity will be described in detail below with reference to Fig. 2. Note that the calculation principle of the emission wavelength center of gravity based on the imaging results of the first imaging unit 10, the second imaging unit 20, and the third imaging unit 30 is the same, so the calculation of the emission wavelength center of gravity based on the imaging result of the first imaging unit 10 will be described below as an example.

[0033] As described above, the inclined dichroic mirror 11 reflects all light at wavelengths shorter than λ1 and transmits all light at wavelengths longer than λ2, and the transmittance of light changes linearly according to the wavelength in the wavelength band from λ1 to λ2. In this case, the transmittance h(λ) in relation to the wavelengths λ1 and λ2 is expressed by the following formula (1), and the reflectance 1-h(λ) is expressed by the following formula (2). h(λ)=(λ-λ1) / (λ2-λ1) (1) 1-h(λ)=(λ2-λ) / (λ2-λ1) (2)

[0034] In addition, the wavelength λ at which the reflectance becomes 50% 50% It is clear that the equation (3) below shows that λ 50% =(λ2+λ1) / 2 (3)

[0035] When an emission spectrum f(λ) is shown by waveform X2 in FIG. 3, is between λ1 and λ2, and can be ignored at wavelengths shorter than λ1 and longer than λ2 (for example, when the characteristics of a bandpass filter (not shown) are shown by waveform X1 in FIG. 3 and the wavelength band of the emission spectrum f(λ) is limited), the following equation (4) is established if it is assumed that the amount of reflected light and the amount of transmitted light are equal. ∫f(λ)h(λ)dλ=∫f(λ)(1-h(λ))dλ (4) Transforming equation (4) gives us equation (5) below. 2∫f(λ)h(λ)dλ=∫f(λ)dλ (5)

[0036] Substituting equation (1) into equation (5), we get 2∫f(λ)(λ-λ1) / (λ2-λ1)dλ=∫f(λ)dλ Further dividing both sides by 2∫f(λ)dλ / (λ2-λ1), we get ∫f(λ)(λ-λ1)dλ / ∫f(λ)dλ= (λ2-λ1) / 2 ∫f(λ)λdλ / ∫f(λ)dλ= (λ2+λ1) / 2 (6) It becomes.

[0037] Considering equation (3), the right-hand side of equation (6) is λ 50% It is clear that the left side of the equation is the center of gravity of f(λ), which is an arbitrary function in general. f From the above, for any spectrum that passes through a dichroic mirror whose transmittance is inclined linearly with respect to wavelength, if the amount of transmitted light is equal to the amount of reflected light, the center of gravity λ of the spectrum is f is λ 50% As shown in the figure.

[0038] Next, consider the second emission spectrum g(λ) (waveform X3 in Figure 3). The emission spectrum g(λ) is also entirely contained between λ1 and λ2. Now, calculate the difference between the normalized differences between the transmitted light and the reflected light for the emission spectra f(λ) and g(λ). Let the transmitted light of f(λ) be T f , reflected light R f , total light amount is A f , the difference between the transmitted light and the reflected light is D f In addition, the transmitted light of g(λ) is T g , reflected light R g , total light amount is A g , the difference between the transmitted light and the reflected light is D g Let the center of gravity of g(λ) be λ g In this case, T f , R f , T g , R g is the measured value, and A f , A g , D f , Dg These values ​​can also be calculated directly from the measured values. T f =∫f(λ)h(λ)dλ=∫f(λ)(λ-λ1) / (λ2-λ1)dλ (7) T g =∫g(λ)h(λ)dλ=∫g(λ)(λ-λ1) / (λ2-λ1)dλ (8) R f =∫f(λ)(1-h(λ))dλ=∫f(λ)(λ2-λ) / (λ2-λ1)dλ (9) R g =∫g(λ)(1-h(λ))dλ=∫g(λ)(λ2-λ) / (λ2-λ1)dλ (10) A f =∫f(λ)dλ (11) A g =∫g(λ)dλ (12) D f =T f -R f =2 / (λ2-λ1)*∫λf(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫f(λ)dλ (13) D g =T g -R g =2 / (λ2-λ1)*∫λg(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫g(λ)dλ (14)

[0039] Here, normalizing the difference between transmitted light and reflected light means D f A f , D g A g If the difference between them is R, then the following equation (15) holds: R=D g / A g -D f / A f ={∫g(λ)λdλ / ∫g(λ)dλ-∫f(λ)λdλ / ∫f(λ)dλ}*2 / (λ2-λ1) =2(λ g -λ f ) / (λ2-λ1) (15)

[0040] Wavelength center of gravity λ of emission spectrum f(λ) f and the wavelength centroid λ of the emission spectrum g(λ) g If the difference between these is δλ, then the following equations (16) and (17) hold. R = 2δλ / (λ2-λ1) (16) δλ=R(λ2-λ1) / 2 (17) As described above, it has been shown that the difference in the center of gravity of two arbitrary spectra f(λ) and g(λ) can be obtained from a calculation that takes into account the amount of transmitted light and the amount of reflected light.

[0041] And the center of gravity of f(λ) is λ 50% When the amount of reflected light is equal to the amount of transmitted light, D f is 0. In other words, the wavelength centroid λ of any spectrum g(λ) g is expressed by the following equation (18). λ g =δλ+λ 50% (18)

[0042] In this way, the center of gravity of the emission spectrum can be calculated from the design value of the filter, the amount of transmitted light, and the amount of reflected light. Based on the above principles, the center of gravity of the wavelengths of light incident on each pixel can be found with high accuracy.

[0043] Here, when determining the center of gravity of the wavelength of light, the derivation accuracy may be reduced due to, for example, the following factors. First, since the periphery of the lens of the image sensor 14 is dimmed, the center of gravity of the original wavelength of light may not be properly determined for the pixels at such a location. Second, the optical characteristics of the inclined dichroic mirror 11 change depending on the angle of incidence of light, and depending on the angle of incidence of light (position of the pixel in the field of view), the center of gravity of the wavelength of light may not be properly determined (color spots due to the angle of incidence may occur). Third, there is a risk of wavelength shift due to the sensitivity of the lens and the image sensor 14. To address these issues, for example, it is possible to calculate the angle of incidence of light on the inclined dichroic mirror 11 in advance and perform correction according to the angle of incidence (a solution to the second issue above). In addition, for example, it is possible to perform shading correction by applying a uniform monochromatic laser light to an irradiation surface (white object) and performing gain correction for each pixel so that it becomes uniform (a solution to the first and second issues above). It is also possible to appropriately determine the center of gravity of the wavelengths of light by reducing the inclination of the inclined dichroic mirror 11 and reflecting the light at an angle closer to 90 degrees. Furthermore, in this embodiment, the following correction is performed.

[0044] That is, the control device 80 may correct the images captured in the first and second imaging regions of the image sensor 14 based on the optical characteristics related to the changes in transmittance and reflectance with respect to the wavelength in the inclined dichroic mirror 11. The control device 80 may store in advance correction data that takes into account the optical characteristics related to the changes in transmittance and reflectance with respect to the wavelength in the inclined dichroic mirror 11, and may correct the images captured in the first and second imaging regions using the correction data. The control device 80 may receive correction data that takes into account the optical characteristics related to the changes in transmittance and reflectance with respect to the wavelength in the inclined dichroic mirror 11, and may correct the images captured in the first and second imaging regions using the correction data. The control device 80 may receive the above-mentioned correction data by executing software or by being input from an external source such as the Internet.

[0045] The generation of the above-mentioned correction data will be described with reference to FIG. 4 and FIG. 5. FIG. 4 is a diagram showing a correction unit 100 that generates the correction data. FIG. 5 is a graph for explaining the correction of the calculated wavelength (described later). Since the process of generating the correction data is similar for the first imaging unit 10, the second imaging unit 20, and the third imaging unit 30, the process of generating the correction data for the first imaging unit 10 will be described below. As shown in FIG. 4, the correction unit 100 includes a light source 101, an optical fiber 102, an FC adapter 103, a diffusion plate 104, and an objective lens 105. The correction unit 100 is used when generating correction data for the camera system 2 of the measurement device 1. It is assumed that the components of the above-mentioned camera system 2 (see FIG. 2) are provided at the rear (downstream) of the objective lens 105 of the correction unit 100 (not shown in FIG. 4).

[0046] The light source 101 is, for example, a monochromatic / narrowband light source capable of changing the wavelength. Alternatively, the light source 101 may be a plurality of laser light sources with different wavelengths, an SLD / LED, or may include a white light source and a bandpass filter. The light source 101 is capable of selecting, for example, five or more wavelengths at least within the tilt range of the tilted dichroic mirror 11 (the range in which the light transmittance (and reflectance) changes gradually according to the change in wavelength). The light emitted from the light source 101 is guided to the objective lens 105 via the optical fiber 102 and the diffusion plate 104. This allows the light from the light source 101 to be observed by the objective lens 105.

[0047] When generating correction data, images are acquired in the first and second imaging regions of the image sensor 14 at each wavelength while changing the wavelength of light emitted from the light source 101 with the above-mentioned correction unit 100 set. The effects of offset and gain unevenness due to background light and the like may be removed. The wavelength intervals may be approximately equal. Then, based on the images of the first and second imaging regions, the control device 80 derives the wavelength centroid (calculated wavelength) at each wavelength. As shown in FIG. 5(a), the control device 80 takes the wavelength λ of the light source 101 on the horizontal axis and the calculated wavelength λ' on the vertical axis. Ideally, the wavelength λ of the light source 101 and the calculated wavelength λ' are considered to have a linear relationship, but in the example shown in FIG. 5(a), the calculated wavelength λ' is significantly different from the ideal value, especially on the low wavelength side. The control device 80 further takes the calculated wavelength λ' on the horizontal axis and the calculated wavelength λ'-wavelength λ of the light source 101 on the vertical axis, as shown in FIG. 5(b). Then, the control device 80 can appropriately correct the calculated wavelength λ' on the low wavelength side that is significantly different from the ideal value as described above, by obtaining the approximation curve N of the graph in Fig. 5(b) up to about the fourth order, for example, by using the least squares method or the like. Specifically, the control device 80 obtains the corrected calculated wavelength based on the calculated wavelength λ' and the fourth-order equation of the least squares method described above. For example, the control device 80 obtains the corrected calculated wavelength by adding together the calculated wavelength λ' and the value of the fourth-order equation.

[0048] The control device 80 corrects color spots caused by the angle of incidence of light on the inclined dichroic mirror 11, for example, by using the above-mentioned correction data. The control device 80 also corrects the deviation of the detection wavelength (calculated wavelength) caused by the boundary between the wavelength band in which the transmittance and reflectance change with the change of wavelength and the wavelength band in which they do not change, for example, by using the above-mentioned correction data. Such boundaries (wavelength bands in the vicinity of λ1 and λ2 in FIG. 3) may have optical characteristics different from those of the wavelength band in which the transmittance of the inclined dichroic mirror 11 changes with the change of wavelength. For this reason, if the wavelength is derived for such boundaries using the same calculation formula as that for the wavelength band in which the transmittance changes with the change of wavelength, the calculation result may be different from the original wavelength. In this regard, the deviation of the detection wavelength caused by the boundary can be appropriately corrected by correcting the calculated wavelength λ' deviating from the ideal value using the above-mentioned correction data. The control device 80 performs a pass / fail judgment of the sample by analyzing the processing result including the corrected image.

[0049] Next, a correction method using the above-mentioned correction data will be described with reference to Fig. 6. Fig. 6 is a flowchart of the correction method. As a prerequisite for carrying out the process of Fig. 6, a correction unit 100 is installed upstream (preceding stage) of the camera system 2.

[0050] As shown in FIG. 6, first, while changing the wavelength of light emitted from the light source 101, an image 1 in a first imaging area of ​​the image sensor 14 and an image 2 in a second imaging area are acquired for each of a plurality of measurement wavelengths (step S1).

[0051] Next, a calculated wavelength is obtained from the images 1 and 2 acquired in step S1 (step S2). Specifically, the wavelength centroid (calculated wavelength) for each wavelength is obtained based on the above-mentioned formulas (1) to (18).

[0052] Next, for each measured wavelength, the difference between the measured wavelength and the calculated wavelength is calculated (step S3). Then, the calculated wavelength is corrected by, for example, using the least squares method or the like up to about the fourth order so that the difference is minimized (step S4). This completes the correction method.

[0053] The present invention is not limited to calculating the wavelength centroid using the correction method of the above embodiment. For example, a conversion map may be generated by calculating a table including correction data in advance, and the wavelength centroid may be calculated based on the conversion map and the ratio of light entering the corresponding pixel.

[0054] Next, the effects of this embodiment will be described.

[0055] The measuring device 1 of this embodiment comprises an inclined dichroic mirror 11 which separates light from a sample by transmitting or reflecting it depending on the wavelength, and which has a predetermined edge transition width, which is the width of a wavelength band where the transmittance and reflectance change depending on the change in wavelength, a total reflection mirror 12 which reflects one of the lights transmitted or reflected by the inclined dichroic mirror 11, an imaging element 14 which images the other of the lights transmitted or reflected by the inclined dichroic mirror 11 in a first imaging area, and images the light reflected by the total reflection mirror 12 in a second imaging area different from the first imaging area, and a control device 80 which corrects the images captured in the first imaging area and the second imaging area based on optical characteristics related to the changes in transmittance and reflectance with wavelength in the inclined dichroic mirror 11.

[0056] In the measuring device 1, an inclined dichroic mirror 11 having a predetermined edge transition width is used, and the captured image is corrected based on the optical characteristics related to the change in transmittance and reflectance with respect to the wavelength in the inclined dichroic mirror 11. When the inclined dichroic mirror 11 having a predetermined edge transition width is used, light with a narrow wavelength width can be appropriately separated, but the optical characteristics may change depending on the incident angle of the light to the inclined dichroic mirror 11, for example, so that the wavelength of the light may not be accurately derived and an appropriate image may not be obtained. In this regard, in the measuring device 1 according to the present embodiment, the images captured in the first and second imaging regions are corrected based on the optical characteristics related to the change in transmittance and reflectance with respect to the wavelength, that is, the characteristics related to the edge transition width of the inclined dichroic mirror 11, so that a corrected captured image can be obtained in consideration of the optical characteristics unique to the inclined dichroic mirror 11 having the edge transition width. This makes it possible to appropriately derive the wavelength of the light separated by the inclined dichroic mirror 11 (light captured in the first and second imaging regions) and obtain an appropriate (accurate) image.

[0057] The control device 80 may store in advance correction data that takes into account optical characteristics related to changes in transmittance and reflectance with respect to wavelength in the inclined dichroic mirror 11, and may use the correction data to correct images captured in the first and second imaging regions. With this configuration, captured images can be easily and appropriately corrected based on the correction data stored in advance.

[0058] The control device 80 may receive correction data that takes into account optical characteristics related to changes in transmittance and reflectance with respect to wavelength in the inclined dichroic mirror 11, and may use the correction data to correct the images captured in the first and second imaging regions. With this configuration, it is possible to appropriately correct the captured images based on correction data obtained, for example, by executing software or inputting the correction data from an external source such as the Internet, without preparing the correction data in advance.

[0059] The control device 80 may correct color spots caused by the angle of incidence of light on the inclined dichroic mirror 11. When a separation optical element having an edge transition width is used, the optical characteristics of the inclined dichroic mirror 11 change depending on the angle of incidence on the inclined dichroic mirror 11, causing a problem of color spots appearing in the captured image. In this regard, by correcting the color spots, it is possible to obtain an appropriate image with reduced color spots.

[0060] The control device 80 may correct the shift in the detection wavelength caused by the boundary between the wavelength band in which the transmittance and reflectance change with the change in wavelength and the wavelength band in which they do not change. Such a boundary has optical characteristics different from those of the wavelength band in which the transmittance and the like change with the change in wavelength. For this reason, if the wavelength is derived using the same calculation formula as for the wavelength band in which the transmittance and the like change with the change in wavelength, the derived result may differ from the original wavelength. In this regard, by correcting the shift in the detection wavelength caused by such a boundary, the wavelength of light can be accurately derived and an appropriate image can be obtained.

[0061] The imaging element 14 may be a single imaging element having a first imaging region and a second imaging region, which makes it possible to obtain a plurality of captured images with a simple configuration using a single imaging element.

[0062] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiments, the light from the sample is separated by the dichroic mirrors 50 and 60 into light containing a red wavelength component, light containing a green wavelength component, and light containing a blue wavelength component (RGB), and each of the light components is imaged by a different imaging unit, but the present invention is not limited to this. In other words, the light from the observation target (sample) may be imaged without being separated into the three colors of RGB.

[0063] In such a configuration, the inclined dichroic mirror provided in front of the area sensor, which is the imaging element, has a wavelength band (edge ​​transition width) in which the light transmittance (and reflectance) changes with changes in wavelength, which corresponds to all three colors of RGB, and is, for example, 400 to 900 nm.

[0064] FIG. 7 is a diagram for explaining the characteristics of the inclined dichroic mirror according to the modified example. In FIG. 7, the horizontal axis indicates wavelength, and the vertical axis indicates transmittance (in the case of the inclined dichroic mirror) and spectrum intensity (in the case of the spectrum of light). In the example shown in FIG. 7, in a specific wavelength band (a wavelength band of 400 to 900 nm), the transmittance (and reflectance) of light changes gradually according to the change in wavelength, and in wavelength bands other than the specific wavelength band (i.e., on the wavelength side lower than 400 nm and higher than 900 nm), the transmittance (and reflectance) of light is constant regardless of the change in wavelength. As shown in FIG. 7, in the inclined dichroic mirror, the wavelength band (edge ​​transition width) in which the transmittance (and reflectance) of light changes according to the change in wavelength includes all of the wavelength band of light containing a red wavelength component (wavelength band shown on the right side in FIG. 7), the wavelength band of light containing a green wavelength component (wavelength band shown in the center in FIG. 7), and the wavelength band of light containing a blue wavelength component (wavelength band shown on the left side in FIG. 7).

[0065] An example of a camera system (imaging unit) using an inclined dichroic mirror having the characteristics shown in Fig. 7 will be described with reference to Fig. 8. Fig. 8 is a diagram showing a camera system 90A according to a modified example.

[0066] As shown in FIG. 8, the camera system 90A includes an inclined dichroic mirror 91 (separating optical element), a finite focal lens (finite focal correction lens) 92A, a bandpass filter 93, an area sensor 94 (second imaging section), and an area sensor 95 (first imaging section).

[0067] The finite focal lens 92A is a lens that collects light (emission) from a sample 150 (object) to be observed. The distance from the finite focal lens 92A to the area sensor 94 and the distance from the finite focal lens 92A to the area sensor 95 are set to predetermined values. The light that passes through the finite focal lens 92A is incident on the inclined dichroic mirror 91.

[0068] The bandpass filter 93 is provided, for example, in front of (upstream of) the finite focal lens 92A, and is a filter that removes light outside a predetermined wavelength range. The bandpass filter 93 removes, for example, light with a wavelength outside the range of 400 to 900 nm. A plurality of bandpass filters 93 may be provided. The bandpass filter 93 may be provided in the region indicated by the dashed line in FIG. 8, that is, in the region behind (downstream) the finite focal lens 92A and in front of (upstream) the inclined dichroic mirror 91, or in the region behind (upstream) the area sensors 94 and 95 and in the region behind (downstream) the inclined dichroic mirror 91. When the bandpass filters 93 are provided in front of the area sensors 94 and 95, respectively, the two bandpass filters 93 have the same characteristics. The camera system 90A may be provided with a plurality of bandpass filters 93 that are configured to be switchable according to the light from the sample 150. In this case, the plurality of bandpass filters 93 filter different wavelength bands (details will be described later).

[0069] The inclined dichroic mirror 91 is a mirror made of a special optical material, which separates the light from the sample 150 by transmitting and reflecting it according to the wavelength, and the transmittance and reflectance change in a predetermined wavelength width. In the inclined dichroic mirror 91, as shown in Fig. 7, the wavelength band (edge ​​transition width) in which the transmittance (and reflectance) of light changes according to the change in wavelength includes all of the wavelength band of light containing a red wavelength component, the wavelength band of light containing a green wavelength component, and the wavelength band of light containing a blue wavelength component. In other words, the "predetermined wavelength width" of the inclined dichroic mirror 91 described above includes all of the wavelength band of light containing a red wavelength component, the wavelength band of light containing a green wavelength component, and the wavelength band of light containing a blue wavelength component.

[0070] The area sensor 94 captures the light reflected by the inclined dichroic mirror 91. The area sensor 95 captures the light transmitted by the inclined dichroic mirror 91. The wavelength range to which the area sensors 94 and 95 are sensitive corresponds to a wavelength band (edge ​​transition width) in which the transmittance (and reflectance) of light changes according to the change in wavelength in the inclined dichroic mirror 91. The area sensors 94 and 95 are, for example, monochrome sensors or color sensors (details will be described later). The imaging results (images) by the area sensors 94 and 95 are output to a control device (not shown). The process of determining the wavelength center of gravity, the correction process, and the process of determining the quality of the sample in the control device (not shown) may be the same as the processes in the control device 80 described in the embodiment, for example.

[0071] The correction process will be described. When light is incident obliquely on the inclined dichroic mirror 91 or the bandpass filter 93 (when not at the pupil position of the objective lens), the light incident on each pixel is not entirely transmitted, but only partially, and a problem may occur in that the transmitted wavelength is shifted due to unevenness in the in-plane uniformity of the inclined dichroic mirror 91 or the bandpass filter 93. On the other hand, when light from multiple directions is incident on the inclined dichroic mirror 91 and the wavelength characteristics are distorted from a straight line, there is an effect of smoothing the wavelength characteristics. As a countermeasure against unevenness in the inclined dichroic mirror 91 or the bandpass filter 93, it is possible to measure and correct the shift from the incident wavelength by uniformly injecting light of the same wavelength into the field of view in advance and calculating the in-plane wavelength distribution.

[0072] As specific examples of the above-mentioned camera system 90A, the following three examples are possible.

[0073] First, the camera system 90A may be configured to include one type of bandpass filter 93 (one type of wavelength band range to be filtered) and area sensors 94, 95 which are monochrome sensors. In this case, the bandpass filter 93 removes light with wavelengths outside the range of 400 to 900 nm, for example. In such a configuration, the light incident on the area sensors 94, 95 may be a mixture of the three colors RGB. In this case, the control device (not shown) obtains an averaged wavelength centroid of the light of the wavelength band (light in which the three colors RGB are mixed) transmitted through the bandpass filter 93. In addition, when the light of different wavelength bands (the light of each of the RGB) is spatially separated (does not overlap on the image), the control device (not shown) can obtain the wavelength centroid with high accuracy for each wavelength band. Specifically, the wavelength centroid of the color of each pixel of a TV, display, etc. can be obtained with high accuracy in nm units by this embodiment.

[0074] Secondly, the camera system 90A may be configured to include multiple types of bandpass filters 93 that filter different wavelength bands from each other, and area sensors 94, 95 that are monochrome sensors. In this case, the multiple types of bandpass filters 93 are provided so as to be removable (switchable) in accordance with the light emitted from the sample 150. In such a configuration, when light having a broadened spectrum (superimposed) is output from the sample 150, the multiple types of bandpass filters 93 are switched and used, so that the control device (not shown) can obtain the wavelength centroid of only light in a specific wavelength band (a wavelength band corresponding to each bandpass filter 93). That is, the control device (not shown) obtains the wavelength centroid of only the red wavelength component when the bandpass filter 93 that removes light of wavelengths other than the wavelength band of the red wavelength component (e.g., 700 to 900 nm) is set, obtains the wavelength centroid of only the green wavelength component when the bandpass filter 93 that removes light of wavelengths other than the wavelength band of the green wavelength component (e.g., 550 to 700 nm) is set, and obtains the wavelength centroid of only the blue wavelength component when the bandpass filter 93 that removes light of wavelengths other than the wavelength band of the blue wavelength component (e.g., 400 to 550 nm) is set. Specifically, for a light source that realizes a white LED by using, for example, a blue LED and a fluorescent agent, the second configuration makes it possible to obtain the wavelength centroid of only the blue LED and the wavelength centroid of only the fluorescent agent.

[0075] Thirdly, the camera system 90A may be configured to include one type of bandpass filter 93 (one type of wavelength band range to be filtered) and area sensors 94, 95 which are color sensors. In this case, the bandpass filter 93 removes light with wavelengths outside the range of 400 to 900 nm, for example. In such a configuration, the light incident on the area sensors 94, 95 which are color sensors may be a mixture of the three colors RGB. The color sensor is equipped with a Bayer filter (a filter of the three colors RGB) for each pixel. This allows each light receiving element of the area sensors 94, 95 which are color sensors to acquire light with only red wavelength components, light with only green wavelength components, and light with only blue wavelength components, respectively. With such a configuration, it is possible to appropriately determine the wavelength center of gravity for a color expressed by overlapping a plurality of wavelengths (i.e., it is possible to appropriately perform inspection). Usually, the color of printing or light emission is made by overlapping the three colors RGB to suit the human eye. By calculating the wavelength center of gravity for each color overlapped in this way, it is possible to accurately inspect the mixed color. It is to be noted that the center of gravity of more wavelengths may be simultaneously inspected by further combining a hyperspectral camera as the imaging unit. The hyperspectral camera is composed of, for example, a spectroscope and an imaging unit.

[0076] Another example of a camera system (imaging unit) using an inclined dichroic mirror having the characteristics shown in Fig. 7 will be described with reference to Fig. 9. Fig. 9 is a schematic diagram showing a camera system 90B according to another modified example. The following mainly describes the differences from the configuration shown in Fig. 8.

[0077] 9, the camera system 90B includes an inclined dichroic mirror 91 (separating optical element), an afocal lens (infinity correction lens) 92B, a bandpass filter 93, an area sensor 94 (second imaging unit), an area sensor 95 (first imaging unit), and imaging lenses 96 and 97. The inclined dichroic mirror 91 and the area sensors 94 and 95 are similar to those in the camera system 90A described above.

[0078] The afocal lens 92B is a collimator lens that converts light (emission) from the sample 150 (object) to be observed into parallel light. The afocal lens 92B is aberration-corrected so that parallel light can be obtained. The parallel light output from the afocal lens 92B is incident on the inclined dichroic mirror 91.

[0079] The imaging lens 96 is a lens that forms an image of the light transmitted through the inclined dichroic mirror 91 on the area sensor 94. The imaging lens 97 is a lens that forms an image of the light transmitted through the inclined dichroic mirror 91 on the area sensor 95.

[0080] The bandpass filter 93 is provided, for example, behind (downstream) the afocal lens 92B and in front (upstream) of the tilted dichroic mirror 91, and is a filter that removes light outside a predetermined wavelength range. The bandpass filter 93 removes light with wavelengths outside the range of 400 to 900 nm, for example. A plurality of bandpass filters 93 may be provided. The bandpass filter 93 may be provided in the region shown by the dashed line in FIG. 9, that is, in the region in front (upstream) of the afocal lens 92B, in the region in front (upstream) of the area sensors 94, 95 and in the region in front (upstream) of the imaging lenses 96, 97, or in the region in front (upstream) of the imaging lenses 96, 97 and in the region in front (upstream) of the imaging lenses 96, 97 and in the region in front (upstream) of the tilted dichroic mirror 91. The bandpass filters 93 provided in front of the area sensors 94, 95 have the same characteristics, and the bandpass filters 93 provided in front of the imaging lenses 96, 97 have the same characteristics.

[0081] As for the camera system 90B using the afocal lens 92B, the above-mentioned three aspects are considered as specific aspects, similar to the camera system 90A.

[0082] As described above, the camera system (imaging unit) of the modified example includes a separation optical element that separates light from an object by transmitting and reflecting it according to the wavelength, and whose transmittance and reflectance change over a predetermined wavelength range, a first imaging section that images the light transmitted through the separation optical element, and a second imaging section that images the light reflected by the separation optical element.

[0083] In this way, by using a separation optical element whose transmittance and reflectance change according to wavelength, it is possible to appropriately separate light with a narrow wavelength width, and to appropriately determine the wavelength center of gravity according to the imaging result in the imaging unit. Also, unlike the aspect described in the embodiment, it is possible to configure the light that has passed through the separation optical element to be received directly by the imaging unit (first imaging unit and second imaging unit), thereby realizing miniaturization of the camera system.

[0084] In the camera system according to the modified example, the wavelength ranges to which the first and second imaging units are sensitive correspond to the wavelength ranges to which the transmittance and reflectance change in the separation optical element. With this configuration, it is possible to properly obtain the change (difference) in wavelength from the imaging results in the imaging units, and to properly determine the wavelength centroid.

[0085] Moreover, the camera system according to the modified example includes a plurality of types of bandpass filters that are configured to be switchable according to the light from the object. For example, in the case where the object outputs light having a broadened spectrum (superimposed), the control device (not shown) can obtain the wavelength centroid of only light of a specific wavelength band (wavelength band corresponding to each bandpass filter) by switching between the plurality of types of bandpass filters. That is, the control device (not shown) can obtain the wavelength centroid of only the red wavelength component when a bandpass filter that removes light of wavelengths other than the wavelength band of the red wavelength component is set, obtain the wavelength centroid of only the green wavelength component when a bandpass filter that removes light of wavelengths other than the wavelength band of the green wavelength component is set, and obtain the wavelength centroid of only the blue wavelength component when a bandpass filter that removes light of wavelengths other than the wavelength band of the blue wavelength component is set. [Explanation of symbols]

[0086] 1...measuring device (imaging unit), 11, 21, 31...inclined dichroic mirror (separating optical element), 12, 22, 32...total reflection mirror (reflective optical element), 14, 24, 34...imaging element (imaging section), 80...control device (processing section, analysis section).

Claims

1. wavelength λ 1 and wavelength λ 2 A calculation process for determining the transmitted light amount T and the reflected light amount R of the measurement light from an image obtained by capturing the measurement light separated by an optical element whose transmittance changes monotonically according to a change in wavelength in the range of The wavelength λ of the optical element 1 and the wavelength λ 2 , the amount of transmitted light T, the amount of reflected light R, and the wavelength λ 1 and the wavelength λ 2 The wavelength λ is the middle wavelength in the range 50% and a calculation process for determining a wavelength difference δλ between the wavelength center of gravity of the measurement light and the measured wavelength.

2. In the calculation process, the λ 50% 2. The computer according to claim 1, wherein the wavelength center of gravity of the measurement light is determined from a sum of the wavelength difference δλ and the wavelength difference δλ.

3. 3. The computer according to claim 1, wherein the calculation process is performed for each pixel included in the image, and the arithmetic process is performed for each pixel.

4. 3. The computer according to claim 1, further comprising a process for correcting the image in accordance with an incident angle of the measurement light on the optical element.

5. The computer according to claim 1 or 2, further executing a process for correcting the image based on optical characteristics of the optical element.

6. 3. The computer according to claim 1, further comprising a process for performing shading correction on the image by performing the gain correction for each pixel.

7. wavelength λ 1 and wavelength λ 2 A calculation process for determining the transmitted light amount T and the reflected light amount R of the measurement light from an image obtained by capturing the measurement light separated by an optical element whose transmittance changes monotonically according to a change in wavelength in the range of The wavelength λ of the optical element 1 and the wavelength λ 2 , the amount of transmitted light T, the amount of reflected light R, and the wavelength λ 1 and the wavelength λ 2 The wavelength λ is the middle wavelength in the range 50% and a calculation process for determining a wavelength difference δλ between the wavelength center of gravity of the measurement light and the measured wavelength.

8. In the calculation process, the computer 50% and the wavelength difference δλ, to obtain a wavelength centroid of the measurement light.

9. 9. The program according to claim 7, further comprising causing the computer to perform the calculation process for each pixel included in the image, and to perform the arithmetic process for each pixel.

10. 9. The program according to claim 7, further causing the computer to execute a process of correcting the image in accordance with an angle of incidence of the measurement light on the optical element.

11. 9. The program according to claim 7, further causing the computer to execute a process of correcting the image based on optical characteristics of the optical element.

12. 9. The program according to claim 7, further causing the computer to execute a process of performing shading correction on the image by performing the gain correction for each pixel.

13. wavelength λ 1 and wavelength λ 2 a calculation step of calculating a transmitted light amount T and a reflected light amount R of the measurement light from an image obtained by capturing the measurement light separated by an optical element whose transmittance changes monotonically according to a change in wavelength in the range of The wavelength λ of the optical element 1 and the wavelength λ 2 , the amount of transmitted light T, the amount of reflected light R, and the wavelength λ 1 and the wavelength λ 2 The wavelength λ is the middle wavelength in the range 50% and a calculation step of determining a wavelength difference δλ between the wavelength center of gravity of the measurement light and the measured wavelength.

14. In the calculation step, the λ 50% and the wavelength difference δλ, to determine the wavelength centroid of the measurement light.

15. 15. The method according to claim 13, wherein the calculation step is performed for each pixel included in the image, and the operation step is performed for each of the pixels.

16. The method according to claim 13 or 14, further comprising a step of correcting the image in accordance with an incident angle of the measurement light on the optical element.

17. 15. The method of claim 13 or 14, further comprising the step of: correcting the image based on optical properties of the optical element.

18. 15. The method of claim 13 or 14, further comprising the step of performing shading correction on the image by performing the pixel-by-pixel gain correction.

Images