JP2022050396A - 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-definition images.

CONSTITUTION: The spectroscopic camera comprises: an optical system composed of a pair of lenses; a wavelength selection unit having a pair of reflection planes arranged facing each other at the pupil position of the optical system, for changing the interval of the pair of reflection planes according to an applied voltage and selectively passing light of the wavelength that corresponds to the interval through; a lens array having n lenses (n is a natural number), each condensing the light having passed through the optical system and the wavelength selection unit; an imaging element having n divided imaging regions for receiving the light condensed by the n lenses and provided at the conjugate position with the wavelength selection unit; and a detection unit for detecting the nonuniformity of the passed light of the wavelength selection unit on the basis of the images imaged by the imaging element.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

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

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

JP-A-2015-132594

In the above-mentioned conventional technique, since a multispectral image is acquired by a finite number of fixed bandpass filters, there is a problem that a continuous spectrum cannot be acquired.

Further, a technique for continuously changing the wavelength of light transmitted through the pair of reflecting surfaces 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 width of the transmission wavelength deteriorates if the parallelism between the reflecting surfaces and the surface accuracy are poor.

One example of the problem to be solved by the present invention is the deterioration of wavelength selectivity due to manufacturing variations and the like in a spectroscopic camera that selects a transmission wavelength by changing the distance between a pair of reflective surfaces. Can be mentioned.

The invention according to claim 1 has an optical system composed of a pair of lenses and a pair of reflective surfaces arranged so as to face each other at the positions of the pupils of the optical system, and the pair of reflections is applied according to an applied voltage. A wavelength selection unit that changes the surface spacing and selectively transmits light with a wavelength corresponding to the spacing, and n lenses (n is a natural number) that collects light that has passed through the optical system and the wavelength selection section, respectively. ), An image pickup element provided at a position conjugate with the wavelength selection unit and having n divided image pickup regions for receiving light focused by the n lenses, and the image pickup element. It is characterized by having a detection unit for detecting non-uniformity of transmission wavelength of the wavelength selection unit based on an image captured by the lens.

The invention according to claim 8 comprises an optical system composed of a pair of lenses and a pair of reflective surfaces arranged so as to face each other at the positions of the pupils of the optical system, and the pair of reflective surfaces are arranged according to an applied voltage. A wavelength selection unit that selectively transmits light with a wavelength corresponding to the interval, and n lenses (n are natural numbers) that collect light that has passed through the optical system and the wavelength selection unit, respectively. A lens array having the above lenses, an image pickup element provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses, and the wavelength selection unit. A storage unit that stores information regarding non-uniformity of transmission wavelengths, and an image processing unit that corrects an image captured by the image pickup element based on the information regarding the non-uniformity stored in the storage unit. It is characterized by having.

The invention according to claim 9 comprises an optical system composed of a pair of lenses and a pair of reflective surfaces arranged so as to face each other at the positions of the pupils of the optical system, and the pair of reflective surfaces are arranged according to an applied voltage. A wavelength selection unit that selectively transmits light with a wavelength corresponding to the interval, and n pieces (n is a natural number) that collect light that has passed through the optical system and the wavelength selection unit, respectively. A spectroscopic camera comprising a lens array having the above lenses and an image pickup element provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses. A step of incident light of a predetermined wavelength into the optical system, a step of causing the image pickup element to receive light of the predetermined wavelength while changing the applied voltage, and the n elements of the image pickup element. Based on the information of the brightness distribution for each pixel in the divided imaging region of the above, a step of obtaining information on the non-uniformity of the transmission wavelength of the wavelength selection unit, a step of imaging a subject to obtain an image, and a step of the transmission wavelength. It is characterized by having a step of performing image correction on the captured image based on the non-uniformity information.

The invention according to claim 10 comprises an optical system composed of a pair of lenses and a pair of reflective surfaces arranged so as to face each other at the positions of the pupils of the optical system, and the pair of reflective surfaces are arranged according to an applied voltage. A wavelength selection unit that selectively transmits light with a wavelength corresponding to the interval, and n pieces (n is a natural number) that collect light that has passed through the optical system and the wavelength selection unit, respectively. A spectroscopic camera comprising a lens array having the above lenses and an image pickup element provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses. In the computer, a step of incident light of a predetermined wavelength into the optical system, a step of causing the image pickup element to receive light of the predetermined wavelength while changing the applied voltage, and the n divisions of the image pickup element. A step of obtaining information on the non-uniformity of the transmission wavelength of the wavelength selection unit based on information on the brightness distribution for each pixel in the image pickup region, a step of capturing an image of a subject to obtain an image captured image, and a step of obtaining the non-uniformity of the transmission wavelength. It is characterized in that the step of performing image correction on the captured image is executed based on the sex information.

It is a figure which shows the structure of the spectroscopic camera 10 of Example 1. FIG. It is a figure which shows typically how the light from an object point is received by the image sensor 13. It is a figure which shows typically how the light from one point on the pupil EYE of an optical system 11 is received by an image sensor 13. It is a figure which shows the example of the case where the physical opening is arranged in the pupil. It is a figure which shows schematically that the image similar to the arrangement of a physical opening in a pupil can be obtained by selecting a pixel area. It is a figure which compares the case where the gap between the reflecting surfaces is substantially uniform, and the case where the gap is non-uniform near the end, with respect to the intensity and the half width of the transmitted light. It is a figure which shows the example of the case where the aperture stop is arranged immediately in front of a filter. It is a flowchart which shows the processing operation of a pre-shooting. It is a figure which shows typically the example of the case of irradiating the light of a single wavelength in the pre-photographing. It is a figure which shows typically the example of the case where the bandpass filter is attached to the position in front of the optical system 11 in the pre-photographing, and the illumination light is irradiated. It is a figure which shows typically the example of the case where the bandpass filter is attached to the position in front of the wavelength selection filter FF in the pre-shooting, and the illumination light is irradiated. It is a flowchart which shows the processing operation of the actual shooting. It is a figure which shows the structure of the spectroscopic camera 20 of Example 2. FIG. It is sectional drawing which shows the example of the structure which provided a plurality of bandpass filters of the same transmission wavelength. It is sectional drawing which shows the example of the structure which provided a plurality of bandpass filters with different transmission wavelengths. It is sectional drawing which shows the example of the structure which provided a plurality of bandpass filters with different half widths. It is a figure which shows typically the state of an image | photographing when dust adhered to a wavelength selection filter.

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

FIG. 1 is a cross-sectional view showing the configuration of the spectroscopic camera 10 according to the first embodiment. The spectroscopic camera 10 performs imaging by, for example, irradiating an object X (subject) with light and receiving light reflected from the object X or light transmitted through the object X. 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 arranged at a position conjugate with the object X. Further, the image sensor 13 is arranged at a position conjugate with the pupil of the optical system 11.

The optical system 11 includes, for example, a first lens L1 and a second lens L2 made of a convex lens. 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 the side which emits the light to the microlens array 12 (hereinafter referred to as the emission side). ) Is placed. The light from the object X is focused 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 type 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 the application of a 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) to change the wavelength of the transmitted light. It is configured so that it can be set selectively.

Ideally, the gap d between the reflecting surfaces in the wavelength selection filter FF is formed so as to have a uniform interval, but it is actually a non-uniform portion due to variations during manufacturing and assembly. (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 the object X is incident on different microlenses. Each of the microlenses corresponds to a "pixel" in a normal camera, and the number of microlenses corresponds to a "pixel count" in a normal camera. Each microlens of the microlens array 12 receives the light that has passed through the optical system 11 and condenses it on the image sensor 13.

The image sensor 13 is an image pickup device that receives light collected by the microlens array 12 and converts it into electronic information to obtain an image pickup image. The image sensor 13 is composed of n divided imaging regions corresponding to each microlens of the microlens array 12. The light incident on each microlens of the microlens array 12 is received in the corresponding divided imaging region of the image sensor 13. The light incident on the different microlenses is received in different divided imaging regions, and the received divided imaging regions are configured so as not to overlap.

FIG. 2 is a diagram schematically showing how light from one point of the object X (referred to as the object point P) is received by the 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 brightness values of all the pixels in each divided imaging region, the same imaging result (captured image) as the image captured by a normal camera in which the image sensor is 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. Light from one point on the pupil EYE (ie, 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 of each of the image sensors 13. Focuses on the same spot 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 display the object X. Consists of the captured image. In the 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, and a plurality of recorded signals are recorded. Based on the signal information of, the luminance distribution showing 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 for detecting the 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 what kind of luminance distribution the light incident on the corresponding microlens of the microlens array 12 passed through the pupil. Therefore, if the luminance value of the light incident on a certain microlens is calculated as the sum of the specific pixel regions of the corresponding divided imaging regions, it passes through the specific region of the pupil (the region corresponding to the pixel region in the divided imaging region). The intensity of the received light can be obtained. Further, if the luminance values of all the microlenses are calculated as the sum of the same pixel regions of the corresponding divided imaging regions, an image by light passing through a specific region of the pupil can be obtained. As a result, 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 can be obtained.

FIG. 4 is a diagram showing an example in which a physical opening 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 in which the heart-shaped shape (that is, the shape of the opening AP) is inverted up and down can be obtained.

On the other hand, in the spectroscopic camera 10 of the present embodiment, by calculating the brightness value using only the selected pixel region, as shown in FIG. 5, a physical opening (in the figure, in the figure) in the pupil of the optical system 11 is obtained. , An image similar to the case where the heart-shaped opening is arranged (in the figure, the image in which the heart-shaped opening is inverted) can be obtained without arranging the physical opening.

By the way, the Fabry-Perot type interference filter constituting the wavelength selection filter FF is an interference filter composed of a set of parallel reflecting films, and by changing the gap between the reflecting surfaces, the wavelength of transmitted light can be changed. Change. Assuming that 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).

On the reflective surface of R = 1, it is a complete monochromatic filter that has a value only when λ = 2h ₀ and does not allow other wavelengths to pass through. However, since R <1 actually, the wavelength in a certain range with λ = 2h ₀ as the central wavelength is passed. The half 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 transmitted light is not completely monochromatic because the gap between the reflecting surfaces is non-uniform in the actually produced Fabry-Perot filter.

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 near the end in terms of the intensity and half width of the transmitted light. It is a figure which shows.

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

On the other hand, as shown in FIG. 6B, when the gap is non-uniform, light having a wavelength other than λ = 2h ₀ is transmitted in the region where d ≠ h ₀ , and the half width is half-valued. Becomes wider.

In order to improve the spread of such a half width, it is generally considered to arrange an aperture diaphragm immediately before or after the filter. For example, as shown in FIG. 7A, by arranging the aperture diaphragm immediately in front of the filter, light can be transmitted only to a region where the gap around the optical axis is uniform, and the full width at half maximum can be improved. However, although the full width at half maximum can be improved by such a method, the amount of transmitted light becomes small.

Further, when the gap between the reflecting surfaces has an asymmetric non-uniformity with respect to the optical axis, the amount of transmitted light is further reduced by arranging an aperture diaphragm symmetric with respect to the optical axis as shown in FIG. 7 (b). Therefore, as shown in FIG. 7 (c), it is necessary to arrange an opening diaphragm according to the non-uniformity of the gap. However, it is difficult to arrange an appropriate aperture stop because which part is actually non-uniform depending on the filter.

On the other hand, in the spectroscopic camera 10 of the present embodiment, it is possible to construct an image by selectively using only a specific pixel region in each divided imaging region 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 reflective films RF1 and RF2 of the wavelength selection filter FF is uniform, without providing a physical aperture stop.

Next, a method of imaging with the spectroscopic camera 10 of this embodiment and selecting a pixel region will be described. First, the pre-shooting before shooting the subject (actual shooting) will be described with reference to the flowchart of FIG. 8 and FIG.

In the pre-photographing, as shown in FIG. 9, the light of a single wavelength λ ₁ emitted from the laser LR is applied to the screen SC 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 image sensor (step S102).

By changing the voltage V applied to the wavelength selection filter FF, the distance between the reflective films RF1 and RF2 changes. The image in each divided imaging region of the image sensor 13 becomes brightest when the interval is such that light of wavelength λ ₁ is passed through most. At this time, the region having high luminance in the image VD obtained in the divided imaging region is a region in which the corresponding region on the pupil passes through the light having the wavelength λ ₁ , and the gap d between the reflecting surfaces (that is, 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 (non-uniformity of transmission wavelength) between the reflective surfaces of the wavelength selection filter based on the plurality of recorded signal information. (Step S103).

When performing pre-shooting for selecting the pixel region, instead of using the screen SC illuminated by the laser beam of a single wavelength, the screen SC illuminated by sunlight, halogen light, or the like is used at the wavelength λ ₁ . You may shoot through a band pass filter that passes light.

For example, as shown in FIG. 10, a bandpass filter that transmits light of wavelength λ ₁ to a position on the optical path in front of the optical system 11 (that is, in front of the first lens L1) when viewed from the incident side during pre-shooting. The BPF is arranged and irradiated with the illumination light WL to perform shooting, and the bandpass filter BPF is removed during actual shooting to perform shooting. As a result, it is possible to acquire information on the pixel region showing the distribution of luminance according to the gap between the reflective surfaces of the wavelength selection filter FF, and to construct an image using only the pixel region having high luminance. Further, as shown in FIG. 11, a bandpass filter BPF may be arranged at a position on the optical path in front of the wavelength selection filter to perform pre-imaging. That is, the bandpass filter BPF may be arranged on the optical path.

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

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

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 is different from the spectroscopic camera 10 of the first embodiment in that a bandpass filter BPF is fixedly provided on the emission side surface of one of the microlenses constituting the microlens array 12. different.

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

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, the end 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 a divided imaging region for imaging.

At the time of photographing the object X, _only the light having the wavelength λ1 out of the light incident on the microlens ML1 is received by the divided image pickup region R1 of the image sensor 13 through the bandpass filter BPF. Therefore, in the divided image pickup region R1, an image VD for pixel selection 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 region other than the microlens ML1 of the microlens array 12 is received by the other divided imaging region of the image sensor 13 without passing through the bandpass filter BPF. Therefore, in the divided imaging region other than the divided imaging region R1 of the image sensor 13, a normal captured image obtained by capturing the object X can be obtained.

The image processing unit 15 performs image correction processing on the captured images obtained in areas other than the divided image pickup area R1 based on the image information of the image VD for pixel selection obtained in the divided image pickup area R1. Specifically, the image processing unit 15 selects a pixel region according to the luminance distribution shown in the image VD for pixel selection, and constitutes an captured image of the object X using only the selected pixel region.

Therefore, according to the spectroscopic camera 20 of the present embodiment, unlike the first embodiment in which the imaging is required in two steps of the pre-imaging and the actual imaging, only the pixel region having high brightness is used by one imaging. It becomes possible to obtain an captured image.

In addition, unlike the above-mentioned configuration, a configuration in which a plurality of bandpass filters BPF are provided may be provided. For example, as shown in FIG. 14, two bandpass filters BPF having a transmission wavelength (center wavelength of the pass band) of λ ₁ are provided on the emission side surface of the microlens at both ends of the microlens array 12. The corresponding two divided imaging regions (divided imaging regions R1 and Rx) are used as the divided imaging regions for pixel selection. As a result, a plurality of image VDs for pixel selection can be obtained, so that pixel selection can be performed with high accuracy.

Further, 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 image for pixel selection in the divided imaging region R1 and the image for pixel selection in the divided imaging region Rx are acquired when different voltages V are applied to the wavelength selection filter FF. For example, when the voltage V = V ₁ , the image VD1 for pixel selection is obtained in the divided imaging region R1, and when the voltage V = V ₂ , the image VD2 for pixel selection is obtained in the divided imaging region Rx. Even in this case, since the pixels can be selected based on the images for a plurality of pixel selections, the pixel selection can be performed with high accuracy.

Further, a configuration in which a plurality of bandpass filters having different full widths at half maximum are provided may be provided. For example, as shown in FIG. 16A, a bandpass filter BPFA having a transmission wavelength center of λ ₁ and a half-value width of W ₁ and a transmission wavelength center of λ ₁ and a half-value width of W ₂ are used. A band pass filter BPFB is provided on the surface on the exit side of the microlens at both ends of the microlens array 12. Assuming that the half-value width W ₂ > the 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, the half-value width priority pixel selection and the transmitted light amount priority pixel selection 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 is described in which a pixel region having a high luminance value is selected in the divided imaging region of the image sensor 13 to perform image processing 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 the pixels in the high-brightness pixel region (the region represented by white in the figure) are regarded as effective pixels. , It was decided to discard the pixel information of other areas (areas represented by gray and black in the figure). However, since the pixel region having high brightness changes by changing the voltage applied to the wavelength selection filter FF, the configuration may be such that information at a plurality of voltages is added to obtain image information.

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

Further, it can be said that the gray region when the applied voltage V ₁ is the information of another wavelength λ ₂ and the black region is the information of the further different wavelength λ ₃ , so that the information of a plurality of wavelengths is input for each applied voltage. It is possible to get it. Therefore, by holding these information in a memory (not shown) or the like while sweeping the applied voltage V, and finally adding the information of the same wavelength, the brightness value of each microlens is calculated. 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 is uniformly incident on all the microlenses of the microlens array 12. Therefore, if there is a non-uniform portion (unevenness) in the gap d between the reflective surfaces of the wavelength selection filter FF, where in the filter the light passes through the microlens array 12 changes depending on the time. Since the timing at which the light is incident on each microlens is the same, the image obtained by the image sensor 13 does not become uneven. Further, when there are stains or defects on the filter, the brightness is reduced by the area of the stains or defects, but the image obtained by the image sensor 13 does not have pixel defects.

Further, according to the spectroscopic camera of the present invention, even if dust or the like is attached to the wavelength selection filter, it is possible to take a picture of the subject while avoiding the dust or the like. For example, as shown in FIG. 17, when dust GB is attached to the wavelength selection filter FF, when the screen SC illuminated by the illumination light WL such as white light is photographed, all the divided imaging regions of the image sensor 13 are covered. Garbage GB will be reflected. Therefore, by selecting the pixel area while avoiding the area where 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 substances whose location cannot be predicted, such as dirt and scratches.

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

Further, 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, and the light is focused on the microlens. It suffices if it is arranged on the optical path of light. Further, it may be arranged at a position corresponding to any of n microlenses, not limited to the microlenses at both ends.

Further, 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 Spectroscopic camera 11 Optical system 12 Microlens array 13 Image sensor 14 Camera 15 Image processing unit

Claims (11)

An optical system consisting of a pair of lenses and
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, and light having a wavelength corresponding to the distance is selectively selected. The wavelength selection unit that transmits and
A lens array, each of which has n lenses (n is a natural number) that collects light that has passed through the optical system and the wavelength selection unit.
An image sensor provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses.
A detection unit that detects the non-uniformity of the transmission wavelength of the wavelength selection unit based on the image captured by the image sensor, and a detection unit.
A spectroscopic camera characterized by having. The spectroscopic camera according to claim 1, wherein the detection unit detects the non-uniformity of the transmission wavelength of the wavelength selection unit based on the luminance value of each pixel of the image. The spectroscopic camera according to claim 1 or 2, further comprising an image processing unit that corrects an image in the image according to the non-uniformity of the transmission wavelength of the wavelength selection unit detected by the detection unit. The image processing unit receives light that has passed through a portion of the wavelength selection unit where the distance between the pair of reflective surfaces is uniform in at least one of the n divided image pickup regions of the image sensor. The spectroscopic camera according to claim 3, wherein the image correction is performed based on the value and the luminance value of the pixel that receives the light that has passed through the 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 the non-uniformity of the transmission wavelength of the wavelength selection unit based on the image captured by the divided imaging region that receives the light that has passed through the bandpass filter among the n divided imaging regions. The spectroscopic camera according to any one of claims 1 to 4, wherein the spectroscopic camera is characterized in that. The spectroscopic camera according to claim 5, wherein the bandpass filter is provided on an optical path of light focused by any of the n lenses in the lens array. Having a plurality of the bandpass filters having different transmission wavelengths,
The spectroscopic camera according to claim 5, wherein each of the plurality of bandpass filters is provided on an optical path in which a different lens among the n lenses in the lens array collects light. An optical system consisting of a pair of lenses and
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, and light having a wavelength corresponding to the distance is selectively selected. The wavelength selection unit that transmits and
A lens array, each of which has n lenses (n is a natural number) that collects light that has passed through the optical system and the wavelength selection unit.
An image sensor provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses.
A storage unit that stores information regarding the non-uniformity of the transmission wavelength of the wavelength selection unit, and a storage unit.
An image processing unit that corrects an image captured by the image pickup device based on the information regarding the non-uniformity stored in the storage unit, and an image processing unit.
A spectroscopic camera characterized by having. An optical system consisting of a pair of lenses and
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, and light having a wavelength corresponding to the distance is selectively selected. The wavelength selection unit that transmits and
A lens array, each of which has n lenses (n is a natural number) that collects light that has passed through the optical system and the wavelength selection unit.
An image sensor provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses.
It is an image pickup method by a spectroscopic camera having
A step of incident light of a predetermined wavelength into the optical system,
A step of causing the image pickup device to receive light of the predetermined wavelength while changing the applied voltage.
A step of obtaining 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 image sensor.
The step of capturing the subject and obtaining the captured image,
A step of performing image correction on the captured image based on the information on the non-uniformity of the transmission wavelength, and
An imaging method characterized by having. An optical system consisting of a pair of lenses and
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, and light having a wavelength corresponding to the distance is selectively selected. The wavelength selection unit that transmits and
A lens array, each of which has n lenses (n is a natural number) that collects light that has passed through the optical system and the wavelength selection unit.
An image sensor provided at a position conjugate with the wavelength selection unit and having n divided imaging regions for receiving light focused by the n lenses.
In a spectroscopic camera with a computer,
A step of incident light of a predetermined wavelength into the optical system,
A step of causing the image pickup device to receive light of the predetermined wavelength while changing the applied voltage.
A step of obtaining 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 image sensor.
The step of capturing the subject and obtaining the captured image,
A step of performing image correction on the captured image based on the information on the non-uniformity of the transmission wavelength, and
A program characterized by executing. A recording medium comprising recording the program according to claim 10.

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