WO2018143340A1

WO2018143340A1 - Spectroscopic camera, image capturing method, program, and recording medium

Info

Publication number: WO2018143340A1
Application number: PCT/JP2018/003400
Authority: WO
Inventors: 佐藤　充; 加園　修
Original assignee: パイオニア株式会社
Priority date: 2017-02-02
Filing date: 2018-02-01
Publication date: 2018-08-09
Also published as: JPWO2018143340A1; JP2021063824A; JP2022050396A; JP2024028237A; JP2023010706A; JP7164694B2

Abstract

This spectroscopic camera includes: an optical system comprising a pair of lenses; a wavelength selecting unit which includes a pair of reflecting surfaces disposed facing one another at the position of a pupil of the optical system, which causes a gap between the pair of reflecting surfaces to vary in accordance with an applied voltage, and which selectively allows light having a wavelength corresponding to the gap to pass; a lens array having n (where n is a natural number) lenses each of which condenses the light that has passed through the optical system and the wavelength selecting unit; and an image capturing element which is provided in a position that is conjugate to the wavelength selecting unit and has n divided image capturing regions which receive the light condensed by the n lenses.

Description

Spectroscopic camera, imaging method, program, and recording medium

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 that can simultaneously acquire a plurality of spectroscopic information and generate an image based on the acquired spectroscopic information. In a plenoptic camera, a measuring apparatus has been proposed in which a plurality of bandpass filters having different spectral transmittances are arranged in the vicinity of a stop position of a main lens in order to measure a spectral spectrum (for example, Patent Document 1).

JP2015-132594A

The above-described conventional technique has a problem that a continuous spectrum cannot be acquired because a multispectral image is acquired by a finite number of fixed bandpass filters.

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

As an example of the problem to be solved by the present invention, in a spectroscopic camera that selects a transmission wavelength by changing the interval between a pair of reflecting surfaces, a problem of deterioration in wavelength selectivity due to manufacturing variation or the like is an example. Can be mentioned.

The invention according to claim 1 has an optical system composed of a pair of lenses and a pair of reflecting surfaces arranged opposite to each other at the position of the pupil of the optical system, and the pair of reflections according to an applied voltage. A wavelength selection unit that selectively transmits light having a wavelength according to the interval, and n pieces (n is a natural number) that collects light that has passed through the optical system and the wavelength selection unit. And a lens array provided at a position conjugate with the wavelength selection unit and having n divided imaging regions that receive light collected by the n lenses. It is characterized by.

A tenth aspect of the invention is an imaging method using the spectroscopic camera according to the first aspect of the invention, the step of entering light of a predetermined wavelength into the optical system, and the light of the predetermined wavelength while changing the applied voltage. And receiving the information on the non-uniformity of the transmission wavelength of the wavelength selection unit based on the information of the luminance distribution for each pixel in the n divided imaging regions of the imaging device, And imaging a subject to obtain a captured image, and performing image correction on the captured image based on non-uniformity information of the transmission wavelength.

According to an eleventh aspect of the present invention, in the spectroscopic camera according to the first aspect, the step of causing the computer to enter the optical system with light having a predetermined wavelength, and the light having the predetermined wavelength while changing the applied voltage. A step of causing the imaging device to receive light, a step of obtaining non-uniformity of transmission wavelength of the wavelength selection unit based on information of luminance distribution for each pixel in the n divided imaging regions of the imaging device, and a subject And obtaining a picked-up image, and performing image correction on the picked-up image based on information on the non-uniformity of the transmission wavelength.

1 is a diagram illustrating a configuration of a spectroscopic camera 10 of Example 1. FIG. It is a figure which shows typically a mode that the light from an object point is received by the image sensor. FIG. 4 is a diagram schematically illustrating a state in which light from a point on the pupil EYE of the optical system 11 is received by an image sensor 13. It is a figure which shows the example at the time of arrange | positioning the physical opening part to a pupil. It is a figure which shows typically that the image similar to having arrange | positioned the physical opening part to the pupil by selection of a pixel area is obtained. It is a figure which compares and shows the case where the gap between reflective surfaces is substantially uniform, and the case where a gap is non-uniform | heterogenous in the edge part vicinity regarding the intensity | strength and half value width of transmitted light. It is a figure which shows the example in the case of arrange | positioning an aperture stop just before a filter. It is a flowchart which shows the processing operation | movement of prior imaging | photography. It is a figure which shows typically the example in the case of irradiating the light of a single wavelength in prior imaging | photography. It is a figure which shows typically the example in the case of attaching a band pass filter in the position before the optical system 11, and irradiating illumination light in prior imaging | photography. It is a figure which shows typically the example in the case of attaching a band pass filter in the position before wavelength selection filter FF, and irradiating illumination light in prior imaging | photography. It is a flowchart which shows processing operation | movement of real imaging | photography. FIG. 6 is a diagram illustrating a configuration of a spectroscopic camera 20 according to a second embodiment. It is sectional drawing which shows the example of a structure provided with multiple band pass filters with the same transmission wavelength. It is sectional drawing which shows the example of the structure which provided multiple band pass filters from which a transmission wavelength differs. It is sectional drawing which shows the example of a structure provided with two or more band pass filters from which a half value width differs. It is a figure which shows typically the mode of imaging | photography when dust has adhered to the wavelength selection filter.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of each embodiment and the accompanying drawings, substantially the same or equivalent parts are denoted by the same reference numerals.

FIG. 1 is a cross-sectional view illustrating the configuration of the spectroscopic camera 10 according to the first embodiment. For example, the spectroscopic camera 10 irradiates the object X (subject) with light and receives light reflected from the object X or transmitted through the object X to perform imaging. 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 unit 15. The microlens array 12 is disposed at a position conjugate with the object X. The image sensor 13 is disposed 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 made of, for example, a convex lens. A wavelength selection filter FF is disposed 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) that can adjust 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 disposed on the side on which light from the object X is incident (hereinafter referred to as the incident side), and the second lens L2 is disposed on the side that emits light to the microlens array 12 (hereinafter referred to as the emission side). ). The light from the object X is condensed on the microlens array 12 through the first lens L1, the wavelength selection filter FF, and the second lens L2.

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

It is ideal that the gap d between the reflection surfaces in the wavelength selection filter FF is formed so as to have a uniform interval. However, in practice, it is a non-uniform portion due to variations in manufacturing and assembly. (Hereinafter referred to as non-uniformity of the gap d between the reflecting surfaces). The spectroscopic camera 10 of this embodiment has a function of correcting a captured image in accordance with 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 the object X is incident on different microlenses. Each of the micro lenses corresponds to “pixels” in a normal camera, and the number of micro lenses corresponds to “number of pixels” in a normal camera. Each microlens of the microlens array 12 receives light that has passed through the optical system 11 and focuses it on the image sensor 13.

The image sensor 13 is an image sensor that receives light collected 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 areas corresponding to the microlenses of the microlens array 12. Light incident on each microlens of the microlens array 12 is received by the corresponding divided imaging region of the image sensor 13. Lights that have entered different microlenses are received by different divided imaging regions, and the received divided imaging regions do not overlap.

FIG. 2 is a diagram schematically showing a state in which light from one point of object X (referred to as object point P) is received by image sensor 13. The light from the object point P passes through different regions 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 region R2. . The luminance value of the image of the object point P is represented by the sum of the luminance values of all the pixels in the divided imaging region R2. Therefore, by acquiring the sum of the luminance values of all the pixels in each divided imaging region, the same imaging result (captured image) as that obtained by an ordinary camera in which an image sensor is arranged at the position of the microlens can be obtained.

FIG. 3 is a diagram schematically showing how the image sensor 13 receives light from one point on the pupil EYE of the optical system 11. 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 then passes through each of the image sensors 13. Condensing light at the same location 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) and performs an image correction process on the image of the object X acquired by the image sensor 13. Specifically, the image processing unit 15 selects a pixel area according to the luminance distribution in each divided imaging area of the image sensor 13 obtained by the pre-photographing, and uses only the information on the selected pixel area for the object X. Configure the captured image. In the pre-photographing, 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 applied voltage to the wavelength selection filter FF, for example, The 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 based on the signal information of That is, the image processing unit 15 has a function as a detection unit that detects non-uniformity of the transmission wavelength of the wavelength selection filter FF.

The luminance distribution in the divided imaging region of the image sensor 13 represents the luminance distribution when the light incident on the corresponding microlens of the microlens array 12 passes through the pupil. Therefore, if the luminance value of light incident on a certain microlens is calculated as the sum of the specific pixel areas of the corresponding divided imaging area, it passes through a specific area of the pupil (area corresponding to the pixel area in the divided imaging area). Thus, the intensity of the received light can be obtained. Furthermore, if the luminance values of all the microlenses are calculated as the sum of the same pixel areas of the corresponding divided imaging areas, an image of light passing through a specific area of the pupil can be obtained. Thereby, for example, an image similar to the case where a physical opening having a predetermined shape is arranged in the pupil of the optical system 11 is obtained.

FIG. 4 is a diagram showing an example in which a physical aperture AP having a heart shape is arranged at the pupil position of the optical system. In each divided imaging region of the image sensor 13, an image obtained by inverting the top and bottom of the heart shape (that is, the shape of the opening AP) is obtained.

On the other hand, in the spectroscopic camera 10 of the present embodiment, by calculating the luminance value using only the selected pixel region, as shown in FIG. 5, a physical aperture (in the figure, the pupil of the optical system 11). An image similar to that in the case where the heart-shaped openings are arranged (in the figure, an image obtained by inverting the heart-shaped top and bottom) can be obtained without arranging physical openings.

By the way, the Fabry-Perot interference filter constituting the wavelength selection filter FF is an interference filter composed of a pair of parallel reflection films. By changing the gap between the reflection surfaces, the wavelength of the transmitted light is changed. Change. When the reflectance of the reflecting surface is R, the gap between the reflecting surfaces is h ₀ , and the wavelength of the incident light is λ, the transmittance T (λ) of the Fabry-Perot filter is expressed by the following equation (1).

The reflection surface of R = 1 has a value only when λ = 2h ₀ and is a complete monochromatic filter that does not pass other wavelengths. However, since R <1 in practice, a certain range of wavelengths with λ = 2h ₀ as the center wavelength is allowed to pass. The full width at half maximum (FWHM) is expressed 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 gap between the reflecting surfaces is not uniform in the Fabry-Perot filter that is actually produced, so that the transmitted light does not become a complete single color.

6 (a) and 6 (b) compare the ideal case where the gap between the reflecting surfaces is almost uniform and the case where the gap is non-uniform in the vicinity of the end with respect to the intensity and half width of the transmitted light. FIG.

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

On the other hand, as shown in FIG. 6B, when the gap is not uniform, light having a wavelength other than λ = 2h ₀ is transmitted in the region where d ≠ h ₀ , and the half-value width Becomes wider.

In order to improve the spread of the half width, it is generally considered that an aperture stop is arranged 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 to a region where the gap around the optical axis is uniform, and the half width can be improved. However, although this method can improve the half-value width, the amount of transmitted light is reduced.

If the gap between the reflecting surfaces has a non-uniformity that is asymmetric with respect to the optical axis, the amount of transmitted light can be further reduced by arranging an aperture stop that is symmetric with respect to the optical axis as shown in FIG. Therefore, as shown in FIG. 7C, it is necessary to arrange an aperture stop corresponding to the gap non-uniformity. However, in practice, it is difficult to arrange an appropriate aperture stop because different parts are different depending on the filter.

On the other hand, in the spectroscopic camera 10 of the present embodiment, an image can be configured by selectively using only a specific pixel area in each divided imaging area of the image sensor 13. Therefore, it is possible to obtain an image using only light that has passed through a 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 area by the spectral camera 10 of the present embodiment will be described. First, pre-photographing before photographing a subject (actual photographing) 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 having a single wavelength λ ₁ emitted from the laser LR via the lens L3 (step S101).

The spectroscopic camera 10 takes an image of the screen SC while sweeping the voltage V applied to the wavelength selection filter FF. The image processing unit 15 records a signal received by the image sensor 13 that is an image sensor (step S102).

By changing the voltage V applied to the wavelength selection filter FF, the interval between the reflection films RF1 and RF2 changes. The image of each divided imaging region of the image sensor 13 becomes brightest when the interval at which the light having the wavelength λ ₁ passes most is obtained. At this time, a region with high brightness in the image VD obtained in the divided imaging region is a region where the corresponding region on the pupil passes light of wavelength λ ₁ , and the gap d between the reflecting surfaces (that is, the reflection) The distance between the films RF1 and RF2 reflects a uniform region.

The image processing unit 15 acquires the luminance distribution of the divided imaging region reflecting the non-uniformity of the gap d (the non-uniformity of the transmission wavelength) between the reflection surfaces of the wavelength selection filter based on the plurality of recorded signal information. (Step S103).

Incidentally, when performing preparatory photographing for the pixel region selection of a single wavelength, instead of using the illuminated screen SC with a laser beam, a screen SC that is illuminated by such as sunlight or halogen light wavelength lambda ₁ of You may image | photograph through the band pass filter which passes light.

For example, as shown in FIG. 10, a band-pass filter that transmits light of wavelength λ _{1 at} a position on the optical path in front of the optical system 11 (ie, in front of the first lens L1) when viewed from the incident side during preliminary imaging. The BPF is arranged to irradiate the illumination light WL to perform imaging, and the bandpass filter BPF is removed during actual imaging. As a result, it is possible to acquire information on the pixel area indicating the luminance distribution according to the gap between the reflection surfaces of the wavelength selection filter FF, and to construct an image using only the pixel area having a high luminance. In addition, as shown in FIG. 11, a pre-shooting may be performed by arranging a bandpass filter BPF at a position on the optical path before the wavelength selection filter. That is, the band pass filter BPF may be disposed on the optical path.

Next, actual shooting for shooting 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 captures the object X while sweeping the voltage V applied to the wavelength selection filter FF (step S202). At this time, unlike the pre-photographing, the subject is photographed using illumination light such as sunlight or white light instead of light having a single wavelength. Then, the image processing unit 15 records a signal received by the image sensor 13 that is an image sensor.

The image processing unit 15 reflects in actual shooting based on information indicating the non-uniformity of the gap d between the reflection surfaces of the wavelength selection filter obtained by pre-shooting (that is, information on the luminance distribution in the divided imaging region). First image information obtained by receiving light passing through a region where the gap d between the surfaces is uniform and second image information obtained by receiving light passing through the non-uniform region 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 according to the gap d between the reflection surfaces of the wavelength selection filter FF is acquired in the pre-photographing, and the luminance value is determined in the pre-photographing. By selectively using only the high pixel region, it is possible to obtain a captured image configured using only light that has passed through a region where the gap d between the reflection surfaces of the wavelength selection filter FF is uniform. Therefore, even when there is a region where the transmission wavelength is non-uniform in the filter, it is possible to acquire a highly accurate image.

FIG. 13 is a cross-sectional view illustrating the configuration of the spectroscopic camera 20 according to the second embodiment. The spectroscopic camera 20 of the present embodiment is the same as the spectroscopic camera 10 of the first embodiment in that a bandpass 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 emission-side surface of the microlens ML1 positioned at the end of the microlens array 12 (that is, the surface on the image sensor 13 side). Is provided. The micro lens ML1 functions as a pixel selecting micro lens, and the other micro lenses function as imaging micro lenses.

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

At the time of photographing the object X, only the light having the wavelength λ ₁ out of the light incident on the micro lens ML ₁ is received by the divided imaging region R ₁ of the image sensor 13 through the band pass filter BPF. Therefore, in the divided imaging region R1, a pixel selection image VD having a luminance distribution reflecting the gap d between the reflection surfaces of the wavelength selection filter FF is acquired.

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

The image processing unit 15 performs image correction processing on a 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 pixel selection image VD, and configures 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 shooting is required in two steps of pre-shooting and actual shooting, only a pixel region with high luminance is used by one shooting. A captured image can be obtained.

Unlike the above configuration, a configuration in which a plurality of band pass filters BPF are provided may be employed. For example, as shown in FIG. 14, two bandpass filters BPF each having a transmission wavelength (passband center wavelength) of λ ₁ are provided on the surface of the microlens array 12 on the emission side of the microlens, Two corresponding divided imaging regions (divided imaging regions R1 and Rx) are set as a divided imaging region for pixel selection. Accordingly, since a plurality of pixel selection images VD are obtained, pixel selection can be performed with high accuracy.

Also, as shown in FIG. 15, a plurality of bandpass filters BPF1 (transmission wavelength λ ₁ ) and BPF2 (transmission wavelength λ ₂ ) having different transmission wavelengths may be provided. The pixel selection image in the divided imaging region R1 and the pixel selection image in the divided imaging region Rx are acquired when different voltages V are applied to the wavelength selection filter FF, respectively. For example, the image VD1 for pixel selection is obtained in the dividing imaging area R1 when the voltage V = V _1, the image VD2 for pixel selection is obtained in the dividing the imaging region Rx when the voltage V = V _2. Even in this case, since the pixels can be selected based on a plurality of images for pixel selection, the pixel selection can be performed with high accuracy.

Moreover, it is good also as a structure which provided the several band pass filter from which a half value width differs. For example, as shown in FIG. 16A, the center of the transmission wavelength is λ ₁ and the half-value width is W ₁ , and the center of the transmission wavelength is λ ₁ and the half-value width is W ₂ . Band-pass filters BPFB are provided on the exit-side surfaces of the microlenses at both ends of the microlens array 12. When the half-value width W ₂ > the half-value width W ₁ , as shown in FIG. 16B, the amount of transmitted light is small in the band-pass filter BPFA having a small half-value width, and the transmitted light is transmitted in the band-pass filter BPFB having a large half-value width. The amount of light increases. Therefore, based on the pixel selection image VD1 obtained in the divided imaging region A and the pixel selection image VD3 obtained in the divided imaging region B, the selection is performed while switching between the half-width priority pixel selection and the transmitted light amount priority pixel selection. be able to.

The embodiment of the present invention is not limited to those shown in the first and second embodiments. For example, in the above embodiment, a configuration has been described in which image processing is performed by selecting a pixel region having a high luminance value in the divided imaging region of the image sensor 13 in a state where a certain voltage V is applied to the wavelength selection filter FF. For example, when an image as shown in FIG. 9 is obtained in the divided imaging region when a certain monochromatic light is incident, only pixels in a pixel region with high luminance (region represented by white in the figure) are effective pixels. Therefore, it has been determined that information on pixels in other regions (regions represented by gray and black in the drawing) is discarded. However, since the pixel area with high luminance is changed by changing the voltage applied to the wavelength selection filter FF, the image information may be obtained by adding information at a plurality of voltages.

For example, the voltage applied to the wavelength selection filter FF (hereinafter referred to as applied voltage) is changed before and after V = V1, and the luminance value of the pixel area represented in gray at the applied voltage V ₁ is the applied voltage V. _It is assumed that the luminance value of the pixel region which is the maximum at ₂ and is represented in black at the applied voltage V ₁ is the maximum at the applied voltage V ₃ . In this case, by adding the pixel region information at each voltage value and calculating the luminance value of the corresponding microlens, an image of the wavelength λ ₁ can be obtained from the information on the entire surface of the wavelength selection filter FF, Light loss can be further reduced. In this way, in order to obtain image information of one wavelength, a plurality of applied voltages and pixels (pixel regions) in a divided imaging region corresponding to the applied voltages are used, and light utilization efficiency is ensured to the maximum. It becomes possible to improve the half width.

Further, since the gray area at the applied voltage V ₁ is information of another wavelength λ ₂ and the black area is information of another wavelength λ ₃ , information on a plurality of wavelengths is applied for each applied voltage. It is possible to obtain. Therefore, by storing the information in a memory (not shown) or the like while sweeping the applied voltage V, and finally calculating the luminance value of each microlens by adding the information of the same wavelength, Similar results can be obtained.

In the present invention, since the wavelength selection filter FF is disposed in the pupil portion of the optical system 11, the light passing through a certain coordinate in the pupil is uniformly incident on all the microlenses of the microlens array 12. Therefore, when there is a non-uniform portion (unevenness) in the gap d between the reflection surfaces of the wavelength selection filter FF, the light passing through the filter enters the microlens array 12 depending on the time. Since the timing at which light enters each microlens is aligned, the image obtained by the image sensor 13 is not uneven. In addition, when 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, it is possible to shoot a subject while avoiding this even when dust or the like is attached to the wavelength selection filter. For example, as illustrated in FIG. 17, when dust GB is attached 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 the pixel area while avoiding the area where the garbage GB is reflected, it is possible to perform shooting while avoiding the garbage GB. In addition to dust, it is also possible to deal with foreign matter whose location cannot be predicted, such as dirt and scratches.

In the above embodiment, the example in which the

spectroscopic cameras

10 and 20 have the microlens array 12 in which n microlenses are arranged vertically and horizontally has been described. However, the type and arrangement of the lenses are not limited to this, and the spectroscopic camera only needs to have a lens array having n lenses.

In the second embodiment, the example in which the bandpass filter is provided on the surface on the emission surface side of the microlens has been described. However, the position where the bandpass filter is disposed is not limited to this, and the light is condensed on the microlens. It only has to be arranged on the optical path of light. Moreover, it should just be arrange | positioned in the position corresponding to not only the microlens of both ends but n microlenses.

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

10, 20 Spectroscopic camera 11 Optical system 12 Micro lens array 13 Image sensor 14 Camera 15 Image processing unit

Claims

An optical system consisting of a pair of lenses;
The optical system has a pair of reflecting surfaces arranged opposite to each other at the position of the pupil, and changes the interval between the pair of reflecting surfaces according to the applied voltage, and selectively selects light having a wavelength according to the interval. A wavelength selector that transmits through
A lens array having n lenses (n is a natural number) that each collects light that has passed through the optical system and the wavelength selection unit;
An image sensor having n divided imaging regions that are provided at a position conjugate with the wavelength selection unit and receive the light collected by the n lenses;
A spectroscopic camera comprising:
The spectroscopic camera according to claim 1, further comprising a detection unit that detects non-uniformity of a transmission wavelength of the wavelength selection unit based on an image captured by the image sensor.
3. The spectroscopic camera according to claim 2, wherein the detection unit detects non-uniformity of a transmission wavelength of the wavelength selection unit based on a luminance value for each pixel of the image.
4. The spectroscopic camera according to claim 2, further comprising an image processing unit that performs image correction on the image according to non-uniformity of the transmission wavelength of the wavelength selection unit detected by the detection unit.
The image processing unit is configured to obtain a luminance of a pixel that has received light that has passed through a portion where the distance between the pair of reflection surfaces of the wavelength selection unit is uniform in at least one of the n divided imaging regions of the imaging element. The spectroscopic camera according to claim 4, wherein the image correction is performed based on a value and a luminance value of a pixel that has received light that has passed through a portion where the distance between the pair of reflecting surfaces is not uniform.
Having at least one bandpass filter on the optical path of the optical system;
The detection unit detects non-uniformity of the transmission wavelength 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. The spectroscopic camera according to claim 2, wherein the spectroscopic camera is used.
The spectroscopic camera according to claim 6, wherein the band-pass filter is provided on an optical path of light collected by any of the n lenses of the lens array.
A plurality of bandpass filters having different transmission wavelengths;
The spectroscopic camera according to claim 6, wherein each of the plurality of band-pass filters is provided on an optical path on which a different lens among the n lenses of the lens array collects light.
A storage unit for storing information on non-uniformity of the transmission wavelength of the wavelength selection unit;
An image processing unit that performs image correction on an image captured by the image sensor based on information on the non-uniformity stored in the storage unit;
The spectroscopic camera according to claim 1, comprising:
An imaging method using the spectroscopic camera according to claim 1,
Incident light of a predetermined wavelength into the optical system;
Receiving the light of the predetermined wavelength on the image sensor while changing the applied voltage;
Obtaining non-uniformity information of the transmission wavelength of the wavelength selection unit based on information of luminance distribution for each pixel in the n divided imaging regions of the imaging element;
Imaging a subject to obtain a captured image;
Performing image correction on the captured image based on the non-uniformity information of the transmission wavelength;
An imaging method characterized by comprising:
The spectroscopic camera according to claim 1, wherein the computer includes:
Incident light of a predetermined wavelength into the optical system;
Receiving the light of the predetermined wavelength on the image sensor while changing the applied voltage;
Obtaining non-uniformity information of the transmission wavelength of the wavelength selection unit based on information of luminance distribution for each pixel in the n divided imaging regions of the imaging element;
Imaging a subject to obtain a captured image;
Performing image correction on the captured image based on the non-uniformity information of the transmission wavelength;
A program characterized by having executed.
A recording medium for recording the program according to claim 11.