JP2023010706A - Spectroscopic camera, imaging method, program and recording medium - Google Patents

Abstract

PURPOSE: To provide a spectroscopic camera with which it is possible to obtain high-accuracy images.

CONSTITUTION: A spectroscopic camera comprises: an optical system composed of a pair of lenses; a wavelength selection unit composed of one filter that has a pair of reflection planes disposed facing the pupil positions of the optical system, causes the interval between the pair of reflection planes to change in accordance with an applied voltage, and selectively passes light with a wavelength that corresponds to the interval; a lens array which includes n lenses (n is a natural number), each of which condenses the light passing through the optical system and the wavelength selection unit; and an imaging element provided at a conjugate position with the wavelength selection unit and having n divided imaging regions that receive light condensed by the n lenses. All the light incident via the pair of lenses and received by the imaging element pass through said one filter.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a spectroscopic camera, an imaging method, a program, and a recording medium.

A plenoptic camera is used as a spectroscopic camera capable of acquiring a plurality of pieces of spectral information simultaneously and generating an image based on the acquired spectral information. In a plenoptic camera, a measuring device has been proposed in which a plurality of bandpass filters with different spectral transmittances are arranged near the aperture position of the main lens in order to measure the spectral spectrum (for example, Patent Document 1).

JP 2015-132594 A

In the above-described prior art, since a multispectral image is obtained using a finite number of fixed bandpass filters, there is a problem that continuous spectra cannot be obtained.

Also, a technique for continuously changing the wavelength of light transmitted through a pair of reflecting surfaces by continuously changing the distance between the reflecting surfaces has been known for a long time. This technique has a problem that the half-value width of the transmitted wavelength is deteriorated if the parallelism between the reflecting surfaces and the surface precision are poor.

One of the problems to be solved by the present invention is the deterioration of wavelength selectivity due to manufacturing variations in a spectroscopic camera that selects a transmission wavelength by changing the distance between a pair of reflecting surfaces. mentioned.

The invention according to claim 1 has an optical system comprising a pair of lenses, and a pair of reflecting surfaces arranged opposite to each other at a position of a pupil of the optical system, and the pair of reflecting surfaces are arranged in response to an applied voltage. a wavelength selection section consisting of one filter that selectively transmits light of a wavelength corresponding to the spacing by changing the distance between the surfaces; An imaging device having a lens array having lenses (n is a natural number), and n divided imaging regions provided at positions conjugated to the wavelength selection section and receiving light condensed by the n lenses. and , wherein all of the light incident through the pair of lenses and received by the imaging device is transmitted through the first filter.

The invention according to claim 10 is the imaging method by the spectroscopic camera according to claim 1, wherein the step of making light of a predetermined wavelength incident on the optical system; and obtaining information on nonuniformity of transmission wavelengths of the wavelength selection unit based on information on luminance distribution of each pixel in the n divided imaging regions of the imaging device. a step of capturing an image of a subject to obtain a captured image; and a step of performing image correction on the captured image based on information on non-uniformity of the transmission wavelength.

The invention according to claim 11 is the spectroscopic camera according to claim 1, wherein the computer comprises a step of causing light of a predetermined wavelength to enter the optical system; causing an imaging device to receive light; obtaining information on nonuniformity of transmission wavelengths of the wavelength selection unit based on information on luminance distribution of each pixel in the n divided imaging regions of the imaging device; and obtaining a captured image, and performing image correction on the captured image based on information on non-uniformity of the transmission wavelength.

1 is a diagram showing a configuration of a spectroscopic camera 10 of Example 1. FIG. 4 is a diagram schematically showing how light from an object point is received by an image sensor 13; FIG. 4 is a diagram schematically showing how light from one point on the pupil EYE of the optical system 11 is received by the image sensor 13. FIG. FIG. 10 is a diagram showing an example of arranging a physical aperture in the pupil; FIG. 10 is a diagram schematically showing that an image similar to that obtained by arranging a physical aperture in the pupil can be obtained by selecting a pixel region; FIG. 5 is a diagram showing a comparison of the intensity and half-value width of transmitted light between a case where the gap between reflecting surfaces is substantially uniform and a case where the gap is non-uniform near the edge. It is a figure which shows the example in the case of arranging an aperture stop just before a filter. It is a flowchart which shows the processing operation of pre-photographing. FIG. 10 is a diagram schematically showing an example of irradiating light of a single wavelength in pre-imaging. It is a figure which shows typically the example in the case of mounting|wearing a band-pass filter in the front position of the optical system 11, and irradiating illumination light in preliminary imaging|photography. FIG. 10 is a diagram schematically showing an example in which a band-pass filter is attached to a position in front of the wavelength selection filter FF and illumination light is emitted in pre-imaging. 4 is a flow chart showing the processing operation of actual photographing; FIG. 10 is a diagram showing the configuration of a spectroscopic camera 20 of Example 2; FIG. 4 is a cross-sectional view showing an example of a configuration in which a plurality of bandpass filters having the same transmission wavelength are provided; FIG. 4 is a cross-sectional view showing an example of a configuration in which a plurality of bandpass filters with different transmission wavelengths are provided; FIG. 4 is a cross-sectional view showing an example of a configuration in which a plurality of bandpass filters with different half-value widths are provided; FIG. 10 is a diagram schematically showing how an image is captured when dust is attached to the wavelength selection filter;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of each embodiment and the attached drawings, substantially the same or equivalent parts are denoted by the same reference numerals.

FIG. 1 is a cross-sectional view showing the configuration of a spectroscopic camera 10 according to the first embodiment. The spectroscopic camera 10 captures an image by, for example, irradiating an object X (object) with light and receiving light reflected from the object X or light transmitted through the object X. FIG. The spectroscopic camera 10 includes an optical system 11 , a camera 14 including a microlens array 12 and an image sensor 13 , and an image processing section 15 . The microlens array 12 is arranged at a position conjugate with the object X. Also, the image sensor 13 is arranged at a position conjugate with the pupil of the optical system 11 .

The optical system 11 includes a first lens L1 and a second lens L2, which are convex lenses, for example. A wavelength selection filter FF is arranged at the position of the pupil of the optical system 11 between the first lens L1 and the second lens L2. The optical system 11 has a mechanism (focusing mechanism) capable of adjusting the distance according to the position of the object X, and is adjusted so as to maintain the conjugate relationship between the object X and the microlens array 12 .

The first lens L1 is arranged on the side where the light from the object X is incident (hereinafter referred to as the incident side), and the second lens L2 is arranged on the side where the light is emitted to the microlens array 12 (hereinafter referred to as the exit side). ). Light from the object X passes through the first lens L1, the wavelength selection filter FF, and the second lens L2 and converges on the microlens array 12. FIG.

The wavelength selection filter FF is composed of, for example, a Fabry-Perot interference filter. The wavelength selection filter FF is composed of reflective films RF1 and RF2 arranged opposite to each other, and transmits light having a wavelength corresponding to the distance between the reflective films. The wavelength selection filter FF receives a voltage V and changes the distance d between the opposing surfaces of the reflection films RF1 and RF2 (hereinafter referred to as the gap d between the reflection surfaces) to change the wavelength of the transmitted light. It is configured so that it can be set selectively.

It is ideal that the gap d between the reflecting surfaces in the wavelength selection filter FF is formed to be a uniform interval. (hereinafter referred to as non-uniformity of the gap d between the reflecting surfaces) exists. The spectroscopic camera 10 of this embodiment has a function of correcting the captured image according to the non-uniformity of the gap d between the reflecting surfaces.

The microlens array 12 is composed of n (n is a natural number) microlenses arranged vertically and horizontally. Light from different points on object X impinges on different microlenses. Each microlens corresponds to a "pixel" in an ordinary camera, and the number of microlenses corresponds to the "number of pixels" in an ordinary camera. Each microlens of the microlens array 12 receives light that has passed through the optical system 11 and converges it on the image sensor 13 .

The image sensor 13 is an imaging element that receives light condensed by the microlens array 12 and converts it into electronic information to obtain a captured image. The image sensor 13 is composed of n divided imaging regions corresponding to each microlens of the microlens array 12 . Light incident on each microlens of the microlens array 12 is received by the corresponding divided imaging area of the image sensor 13 . Light incident on different microlenses is received by different divided imaging areas, and the divided imaging areas where light is received do not overlap.

FIG. 2 is a diagram schematically showing how the image sensor 13 receives light from one point (referred to as an object point P) on the object X. As shown in FIG. Light from the object point P passes through different areas on the first lens L1, the pupil EYE, and the second lens L2, enters the microlens ML2 of the microlens array 12, and is received by the divided imaging area R2. . The brightness value of the image of the object point P is represented by the sum of the brightness values of all the pixels within the divided imaging region R2. Therefore, by acquiring the sum of luminance values of all pixels in each divided imaging region, the same imaging result (captured image) as an image captured by a normal camera having an image sensor arranged at the position of the microlens can be obtained.

FIG. 3 is a diagram schematically showing how light from one point on the pupil EYE of the optical system 11 is received by the image sensor 13. As shown in FIG. Light from one point on the pupil EYE (that is, light incident on one point on the pupil EYE) passes through different regions of the second lens L2 and different microlenses of the microlens array 12 and reaches each of the image sensors 13. The light is condensed at the same point in the divided imaging area.

Referring to FIG. 1 again, the image processing unit 15 is composed of, for example, a CPU (Central Processing Unit) or the like, and performs image correction processing on the image of the object X acquired by the image sensor 13 . Specifically, the image processing unit 15 selects a pixel region according to the luminance distribution in each divided imaging region of the image sensor 13 obtained by pre-shooting, and uses only the information of the selected pixel region to image the object X. Construct a captured image. In pre-shooting, the image processing unit 15 records the signal received by the image sensor 13 in a storage unit (not shown) such as a memory while sweeping the voltage applied to the wavelength selection filter FF, for example. Based on the signal information of , a luminance distribution indicating the non-uniformity of the transmission wavelength of the wavelength selection filter FF (that is, the non-uniformity of the gap d of the reflecting surface) is obtained. That is, the image processing unit 15 has a function as a detection unit that detects non-uniformity of transmission wavelengths of the wavelength selection filter FF.

The luminance distribution in the divided imaging regions of the image sensor 13 represents what kind of luminance distribution the light incident on the corresponding microlenses of the microlens array 12 has when passing through the pupil. Therefore, if the luminance value of light incident on a certain microlens is calculated as the sum of specific pixel regions in the corresponding divided imaging regions, the light passing through the specific region of the pupil (the region corresponding to the pixel region in the divided imaging regions) to obtain the intensity of the received light. Furthermore, if the brightness values of all microlenses are calculated as the sum of the same pixel areas of the corresponding divided imaging areas, an image of light that has passed through a specific area of the pupil can be obtained. As a result, an image similar to that obtained by arranging a physical aperture having a predetermined shape in the pupil of the optical system 11, for example, can be obtained.

FIG. 4 is a diagram showing an example in which a physical aperture AP having a heart-shaped shape is arranged at the pupil position of the optical system. In each divided imaging area of the image sensor 13, an image obtained by inverting the heart shape (ie, the shape of the opening AP) upside down is obtained.

On the other hand, in the spectroscopic camera 10 of this embodiment, by calculating the luminance value using only the selected pixel area, a physical aperture (in the figure, , a heart-shaped opening) can be obtained without arranging a physical opening.

By the way, the Fabry-Perot interference filter that constitutes the wavelength selective filter FF is an interference filter that is composed of a set of parallel reflecting films. Change. Let R be the reflectance of the reflecting surface, h ₀ be the gap between the reflecting surfaces, and λ be the wavelength of the incident light.

A reflective surface with R=1 has a value only when λ= _2h0 and becomes a perfect monochromatic filter that does not pass other wavelengths. However, since R<1 in practice, a certain range of wavelengths with λ= _2h0 as the central wavelength is allowed to pass. Its half width FWHM (Full Width at Half Maximum) is represented by the following equation (2). In the limit of R→1, FWHM→0.

In the limit of R→1, FWHM→0. However, even if the reflectance R is 1, the transmitted light is not completely monochromatic because the gaps between the reflecting surfaces are non-uniform in the actually manufactured Fabry-Perot filter.

6A and 6B compare the intensity and half-value width of transmitted light between an ideal case where the gap between the reflecting surfaces is almost uniform and a case where the gap is non-uniform near the edges. It is a diagram showing.

As shown in FIG. 6(a), when the gap has a uniform value (d=h ₀ ) in all regions within the reflective surface of the filter, the wavelength of transmitted light at all locations within the reflective surface is 2h ₀ , and the half width is almost zero.

On the other hand, as shown in FIG. 6B, when the gap is non-uniform, light with a wavelength other than λ _{= 2h0} is transmitted in the region where d≠h0, and the half-value width becomes wider.

In order to improve such spread of the half-value width, it is generally considered to dispose an aperture stop immediately before or after the filter. For example, as shown in FIG. 7A, by arranging an aperture stop immediately before the filter, light can be transmitted only in a region where the gap around the optical axis is uniform, and the half-value width can be improved. However, although this method can improve the half width, the amount of transmitted light is reduced.

If the gap between the reflecting surfaces is asymmetrical with respect to the optical axis and the aperture stop is arranged symmetrically with respect to the optical axis as shown in FIG. Therefore, as shown in FIG. 7C, it is necessary to arrange an aperture stop according to the unevenness of the gap. However, it is difficult to arrange an appropriate aperture stop because the part of the filter that is actually non-uniform varies depending on the filter.

On the other hand, in the spectroscopic camera 10 of this embodiment, it is possible to compose an image by selectively using only specific pixel regions in each divided imaging region of the image sensor 13 . Therefore, it is possible to obtain an image using only the light that has passed through the region where the distance between the reflection films RF1 and RF2 of the wavelength selection filter FF is uniform without providing a physical aperture stop.

Next, a method for picking up an image and selecting a pixel region by the spectroscopic camera 10 of this embodiment will be described. First, preliminary photography before photography (actual photography) of a subject will be described with reference to the flowchart of FIG. 8 and FIG.

In the pre-photographing, as shown in FIG. 9, the screen SC is irradiated with light of a _single wavelength λ1 emitted from the laser LR through the lens L3 (step S101).

The spectroscopic camera 10 photographs the screen SC while sweeping the voltage V applied to the wavelength selection filter FF. The image processing unit 15 records the signal received by the image sensor 13, which is an imaging device (step S102).

By changing the voltage V applied to the wavelength selection filter FF, the interval between the reflecting films RF1 and RF2 is changed. The image of each divided imaging area of the image sensor 13 becomes the brightest when the interval is such that the light of wavelength λ1 passes through the _most . At this time, a region with high brightness in the image VD obtained in the divided imaging region is _a region in which the corresponding region on the pupil passes light of wavelength λ1, and the gap d between the reflecting surfaces (that is, the reflection (spacing between membranes RF1 and RF2) reflects a uniform area.

The image processing unit 15 acquires the luminance distribution of the divided imaging regions reflecting the non-uniformity of the gap d between the reflecting surfaces of the wavelength selection filter (non-uniformity of transmission wavelengths) based on the recorded multiple pieces of signal information. (step S103).

It should be noted that when pre-shooting for pixel region selection is performed, instead of using the screen SC illuminated with laser light of a single wavelength, the screen SC is illuminated with sunlight, halogen light, or the like, with wavelength λ ₁ . The image may be captured through a bandpass filter that allows light to pass through.

For example, as shown in FIG. 10, at the time of pre-shooting, _a bandpass filter that transmits light of wavelength λ1 is placed on the optical path in front of the optical system 11 (that is, in front of the first lens L1) as viewed from the incident side. A BPF is arranged to irradiate illumination light WL for photographing, and the band-pass filter BPF is removed for actual photographing. Accordingly, it is possible to acquire the information of the pixel regions showing the luminance distribution according to the gap between the reflection surfaces of the wavelength selection filter FF, and to compose an image using only the pixel regions with high luminance. Further, as shown in FIG. 11, a band-pass filter BPF may be placed on the optical path in front of the wavelength selection filter for pre-photographing. That is, the bandpass filter BPF should be placed on the optical path.

Next, actual photography for photographing a subject will be described with reference to the flowchart of FIG.

First, the spectroscopic camera 10 is set on the subject (object X) (step S201). The spectroscopic camera 10 takes an image of the object X while sweeping the voltage V applied to the wavelength selection filter FF (step S202). At that time, unlike the pre-photographing, the subject is photographed using illumination light such as sunlight or white light instead of light of a single wavelength. Then, the image processing unit 15 records the signal received by the image sensor 13, which is an imaging element.

The image processing unit 15, based on the information indicating the non-uniformity of the gap d between the reflecting surfaces of the wavelength selection filter (that is, the information on the luminance distribution in the divided imaging area) obtained by pre-imaging, determines the reflected light during actual imaging. First image information obtained by receiving light passing through an area where the inter-surface gap d is uniform and second image information obtained by receiving light passing through an area with non-uniform gap d are calculated. (step S203). The image processing unit 15 obtains a final captured image based on the first image information and the second image information (step S204).

As described above, according to the spectroscopic camera 10 of the present embodiment, the image information indicating the luminance distribution corresponding to the gap d between the reflecting surfaces of the wavelength selection filter FF is acquired in the preliminary photographing, and the luminance value is obtained in the preliminary photographing. By selectively using only the high pixel regions, it is possible to obtain a captured image formed using only the light that has passed through the region where the gap d between the reflection surfaces of the wavelength selection filter FF is uniform. Therefore, even if the filter has regions with non-uniform transmission wavelengths, it is possible to acquire a highly accurate image.

FIG. 13 is a cross-sectional view showing the configuration of the spectroscopic camera 20 according to the second embodiment. The spectroscopic camera 20 of the present embodiment differs from the spectroscopic camera 10 of the first embodiment in that a band-pass filter BPF is fixedly provided on the exit-side surface of one of the microlenses constituting the microlens array 12. different.

A band-pass filter BPF having a transmission wavelength λ ₁ (the center wavelength of the pass band is λ ₁ ) is provided on the surface of the microlens ML 1 located at the end of the microlens array 12 on the output side (that is, the surface on the image sensor 13 side). is provided. The microlens ML1 functions as a pixel selection microlens, and the other microlenses function as imaging microlenses.

The image sensor 13 has a divided imaging area R1 corresponding to the microlens ML1 of the microlens array 12 . The divided imaging area R1 is provided at a position corresponding to the microlens ML1 (for example, the edge of the image sensor). The divided imaging region R1 functions as a divided imaging region for pixel selection, and the other divided imaging regions function as divided imaging regions for imaging.

When the object X is photographed, _only the light of wavelength λ1 out of the light incident on the microlens ML1 passes through the bandpass filter BPF and is received by the divided imaging region R1 of the image sensor 13 . Therefore, in the divided imaging region R1, an image VD for pixel selection having a luminance distribution reflecting the gap d between the reflecting surfaces of the wavelength selection filter FF is obtained.

On the other hand, light that has passed through areas other than the microlenses ML1 of the microlens array 12 is received by other divided imaging areas of the image sensor 13 without passing through the bandpass filter BPF. Therefore, in the divided imaging regions of the image sensor 13 other than the divided imaging region R1, a normal captured image of the object X can be obtained.

The image processing unit 15 performs image correction processing on the captured image obtained outside the divided imaging region R1 based on the image information of the image VD for pixel selection obtained in the divided imaging region R1. Specifically, the image processing unit 15 selects a pixel area according to the luminance distribution shown in the image VD for pixel selection, and constructs a captured image of the object X using only the selected pixel area.

Therefore, according to the spectroscopic camera 20 of the present embodiment, unlike the first embodiment in which it is necessary to perform imaging in two steps of preliminary imaging and actual imaging, only a pixel region with high luminance is used in one imaging. A captured image can be obtained.

Note that, unlike the above configuration, a configuration in which a plurality of bandpass filters BPF are provided may be used. For example, as shown in FIG. 14, two bandpass filters BPF each having a transmission wavelength (the center wavelength of the passband) of λ ₁ are provided on the surfaces of the microlenses at both ends of the microlens array 12 on the output side, Two corresponding divided imaging regions (divided imaging regions R1 and Rx) are set as divided imaging regions for pixel selection. Accordingly, since a plurality of images VD for pixel selection are obtained, pixel selection can be performed with high accuracy.

Further, as shown in FIG. 15, a configuration may be adopted in which a plurality of bandpass filters BPF1 (transmission wavelength λ ₁ ) and BPF2 (transmission wavelength λ ₂ ) having different transmission wavelengths are provided. The image for pixel selection in the divided imaging region R1 and the image for pixel selection in the divided imaging region Rx are obtained when different voltages V are applied to the wavelength selection filter FF. For example, when the voltage V=V1, an image VD1 for pixel selection is obtained in the divided imaging region _R1 , and when the voltage V ₌ V2, an image VD2 for pixel selection is obtained in the divided imaging region Rx. Even in this case, pixels can be selected based on a plurality of images for pixel selection, so pixel selection can be performed with high accuracy.

Also, a configuration may be employed in which a plurality of band-pass filters having different half-value widths are provided. For example, as shown in FIG. 16(a), a bandpass filter BPFA having a transmission wavelength center of λ ₁ and a half width of W ₁ and a transmission wavelength center of λ ₁ and a half width of W ₂ A band-pass filter BPFB is provided on the exit-side surface of the microlenses at both ends of the microlens array 12 . If half-value width W ₂ >half-value width W ₁ , as shown in FIG. the amount of light increases. Therefore, based on the image VD1 for pixel selection obtained in the divided imaging region A and the image VD3 for pixel selection obtained in the divided imaging region B, pixel selection with priority on half width and pixel selection with priority on amount of transmitted light are switched. be able to.

The embodiments of the present invention are not limited to those shown in Examples 1 and 2 above. For example, in the above embodiment, a configuration has been described in which a pixel region with a high luminance value is selected from among the divided imaging regions of the image sensor 13 and image processing is performed while a certain voltage V is applied to the wavelength selection filter FF. For example, when an image such as that shown in FIG. 9 is obtained in a divided imaging area when a certain monochromatic light is incident, only the pixels in the pixel area with high brightness (area represented by white in the figure) are taken as effective pixels. , and other areas (areas represented by gray and black in the figure) are discarded. However, since the pixel region with high luminance changes by changing the voltage applied to the wavelength selection filter FF, it is also possible to obtain image information by adding information on a plurality of voltages.

For example, the voltage applied to the wavelength selection filter FF (hereinafter referred to as the applied voltage) is changed around V= _V1 , and the luminance value of the pixel region represented in _gray when the applied voltage is V1 is changed to the applied voltage. It is assumed that the luminance value of the pixel region, which was maximized at V2 and _displayed in black at the applied voltage V1 _, became maximum at the applied voltage _V3 . In this case, by adding the information of the pixel region at each voltage value and calculating the luminance value of the corresponding microlens, an image of wavelength λ ₁ can be obtained from the information of the entire surface of the wavelength selection filter FF. Light loss can be further reduced. In order to obtain image information of one wavelength in this manner, a plurality of applied voltages and pixels (pixel regions) in divided imaging regions corresponding to the applied voltages are used, thereby maximizing light utilization efficiency. , the half width can be improved.

Further, it can be said that the gray area at the applied voltage V1 is information of _another wavelength λ2 _, and the black area is information of another wavelength _λ3 . It is possible to obtain Therefore, by storing this information in a memory (not shown) or the like while sweeping the applied voltage V, and finally adding the information of the same wavelength to calculate the luminance value of each microlens, Similar results can be obtained.

Since the wavelength selection filter FF is arranged in the pupil portion of the optical system 11 in the present invention, the light passing through a certain coordinate in the pupil uniformly enters all the microlenses of the microlens array 12 . Therefore, if the gap d between the reflecting surfaces of the wavelength selection filter FF has an uneven portion (unevenness), which part of the filter the light passes through and enters the microlens array 12 changes depending on the time. Since the timing at which the light enters each microlens is the same, the image obtained by the image sensor 13 is not uneven. In addition, if there is dirt or a defective portion on the filter, the luminance is reduced by the area of the dirt or defect, but no pixel defect occurs in the image obtained by the image sensor 13 .

Further, according to the spectroscopic camera of the present invention, even if dust or the like adheres to the wavelength selection filter, it is possible to photograph the subject while avoiding this. For example, as shown in FIG. 17, when dust GB adheres to the wavelength selection filter FF, when the screen SC illuminated with the illumination light WL such as white light is photographed, all the divided imaging regions of the image sensor 13 are captured. Garbage GB will be reflected. Therefore, by selecting a pixel area while avoiding an area in which the dust GB is reflected, it is possible to perform shooting while avoiding the dust GB. In addition to dust, it is also possible to deal with foreign matter whose location is unpredictable, such as dirt and scratches.

Further, in the above embodiments, the spectroscopic cameras 10 and 20 have the microlens array 12 in which n microlenses are arranged vertically and horizontally. However, the type and arrangement of lenses are not limited to this, and the spectroscopic camera may have a lens array having n lenses.

In addition, in the second embodiment, an example in which the bandpass filter is provided on the surface of the microlens on the exit surface side has been described, but the position where the bandpass filter is arranged is not limited to this. It suffices if it is arranged on the optical path of light. In addition, it is sufficient if they are arranged at positions corresponding to any one of the n microlenses, not limited to the microlenses at both ends.

Moreover, the series of processes described in each of the above embodiments can be performed by computer processing according to a program stored in a recording medium such as a ROM.

10, 20 spectral camera 11 optical system 12 microlens array 13 image sensor 14 camera 15 image processing unit

Claims (12)

an optical system consisting of a pair of lenses;
It consists of a pair of reflective surfaces arranged opposite to each other at the position of the pupil of the optical system, and the distance between the pair of reflective surfaces is changed according to the applied voltage to selectively emit light of a wavelength corresponding to the distance. a wavelength selection unit consisting of one filter that transmits;
a lens array each having n lenses (n is a natural number) for condensing light that has passed through the optical system and the wavelength selector;
an imaging device provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light condensed by the n lenses;
has
A spectroscopic camera, wherein all of the light incident through the pair of lenses and received by the imaging element is transmitted through the first filter. 2. The spectroscopic camera according to claim 1, further comprising a detection section for detecting non-uniformity of transmission wavelengths of said wavelength selection section based on an image picked up by said imaging device. 3. The spectroscopic camera according to claim 2, wherein the detector detects non-uniformity of transmission wavelengths of the wavelength selector based on a luminance value of each pixel of the image. 4. The spectroscopic camera according to claim 2, further comprising an image processing section that performs image correction on the image according to the non-uniformity of the transmission wavelength of the wavelength selection section detected by the detection section. The image processing unit controls the brightness of pixels that have received light that has passed through a portion of the pair of reflecting surfaces of the wavelength selection unit where the distance between the pair of reflecting surfaces of the wavelength selection unit is uniform in at least one of the n divided imaging regions of the imaging device. 5. The spectroscopic camera according to claim 4, wherein the image correction is performed based on the value and the luminance value of a pixel that received light that has passed through the portion where the distance between the pair of reflecting surfaces is uneven. Having at least one bandpass filter on the optical path of the optical system,
The detection unit detects non-uniformity of transmission wavelengths of the wavelength selection unit based on an image captured by a divided imaging region that receives light that has passed through the bandpass filter among the n divided imaging regions. 6. The spectroscopic camera according to any one of claims 2 to 5, characterized in that: 7. The spectroscopic camera according to claim 6, wherein the bandpass filter is provided on an optical path of light condensed by any of the n lenses of the lens array. Having a plurality of bandpass filters with different transmission wavelengths,
7. The spectroscopic camera according to claim 6, wherein each of said plurality of band-pass filters is provided on an optical path where a different lens among said n lenses of said lens array converges light. a storage unit that stores information about non-uniformity of transmission wavelengths of the wavelength selection unit;
an image processing unit that performs image correction on the image captured by the imaging element based on the information about the non-uniformity stored in the storage unit;
2. The spectroscopic camera according to claim 1, comprising: An imaging method using the spectroscopic camera according to claim 1,
injecting light of a predetermined wavelength into the optical system;
a step of causing the imaging element to receive light of the predetermined wavelength while changing the applied voltage;
Based on the information of the luminance distribution for each pixel in the n divided imaging regions of the imaging device,
a step of obtaining information on non-uniformity of transmission wavelengths of the wavelength selector;
a step of imaging a subject to obtain a captured image;
a step of performing image correction on the captured image based on the information on the non-uniformity of the transmission wavelength;
An imaging method comprising: 2. The spectroscopic camera of claim 1, wherein the computer comprises:
injecting light of a predetermined wavelength into the optical system;
a step of causing the imaging element to receive light of the predetermined wavelength while changing the applied voltage;
a step of obtaining information on non-uniformity of transmission wavelengths of the wavelength selection unit based on information on luminance distribution for each pixel in the n divided imaging regions of the imaging device;
a step of imaging a subject to obtain a captured image;
a step of performing image correction on the captured image based on the information on the non-uniformity of the transmission wavelength;
A program characterized by causing the execution of A recording medium on which the program according to claim 11 is recorded.

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