Spectroscopic camera, method for imaging, program, and recording medium

Abstract

PURPOSE: To provide a spectroscopic camera that can obtain a highly precise image.CONSTITUTION: A spectroscopic camera includes: an optical system made of one pair of lenses; a wavelength selection unit having a pair of reflection surfaces facing each other in the positions of pupils of the optical system, the wavelength selection unit changing the interval of the pair of reflection surfaces according to an applied voltage and selectively transmitting the light of the wavelength appropriate to the interval; a lens array having n number (n is a natural number) of lenses each collecting light that has passed through the optical system and the wavelength selection unit; and an imaging element located in a position conjugate to the wavelength selection unit, the imaging element having n number of divided imaging regions for receiving light collected by the n number of lenses.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spectroscopic camera, an imaging method, a program, and a recording medium. [Background technology]

[0002] A plenoptic camera is used as a spectroscopic camera capable of simultaneously acquiring a plurality of pieces of spectroscopic information and generating an image based on the acquired spectroscopic information. In order to measure the spectroscopic spectrum of 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 (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-132594 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned conventional technology has a problem in that it is not possible to obtain a continuous spectrum because a multispectral image is obtained using a finite number of fixed band-pass filters.

[0005] In addition, a technique has been known for a long time in which the wavelength of light transmitted through a pair of reflecting surfaces is continuously changed by continuously changing the distance between the reflecting surfaces. However, this technique has the problem that the half-width of the transmitted wavelength deteriorates if the parallelism or surface precision between the reflecting surfaces is poor.

[0006] One example of a problem that the present invention aims to solve is the problem of deterioration of wavelength selectivity due to manufacturing variations, in a spectroscopic camera that selects transmitted wavelengths by changing the distance between a pair of reflective surfaces. [Means for solving the problem]

[0007] The invention described in claim 1 is characterized by comprising an optical system consisting of a pair of lenses, a wavelength selection unit having a pair of reflective surfaces arranged opposite each other at a pupil position of the optical system, changing the distance between the pair of reflective surfaces in response to an applied voltage, and selectively transmitting light of a wavelength in accordance with the distance, a lens array having n lenses (n is a natural number) each of which collects light that has passed through the optical system and the wavelength selection unit, and an image sensor arranged in a position conjugate with the wavelength selection unit and having n divided imaging areas that receive the light collected by the n lenses. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a spectroscopic camera 10 according to a first embodiment. [Diagram 2] 2 is a diagram showing a schematic diagram of how light from an object point is received by an image sensor 13. FIG. [Diagram 3] 1 is a diagram showing a schematic diagram of how light from a point on the pupil EYE of the optical system 11 is received by the image sensor 13. FIG. [Figure 4] FIG. 13 is a diagram showing an example in which a physical aperture is arranged in the pupil. [Diagram 5] 10 is a diagram showing a schematic diagram illustrating that by selecting a pixel region, an image similar to that obtained by placing a physical aperture in the pupil can be obtained. [Figure 6] FIG. 11 is a diagram showing a comparison of the intensity and half-width of transmitted light when the gap between the reflecting surfaces is approximately uniform and when the gap is non-uniform near the ends. [Figure 7] FIG. 13 is a diagram showing an example in which an aperture stop is disposed immediately before a filter. [Figure 8] 10 is a flowchart showing a processing operation of pre-photographing. [Figure 9] FIG. 13 is a diagram illustrating an example in which light of a single wavelength is irradiated in pre-imaging. [Figure 10] FIG. 13 is a diagram illustrating an example in which a bandpass filter is attached in front of the optical system 11 and illumination light is applied in pre-photographing. [Figure 11] 13 is a diagram illustrating an example in which a bandpass filter is attached in front of a wavelength-selective filter FF in pre-imaging and illumination light is applied. FIG. [Figure 12] 10 is a flowchart showing the processing operation of actual photography. [Figure 13] FIG. 11 is a diagram illustrating a configuration of a spectroscopic camera 20 according to a second embodiment. [Figure 14] 11 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. [Figure 15] 11 is a cross-sectional view showing an example of a configuration in which a plurality of bandpass filters having different transmission wavelengths are provided. [Figure 16] 11 is a cross-sectional view showing an example of a configuration in which a plurality of bandpass filters having different half-widths are provided. [Figure 17] 10A and 10B are diagrams illustrating a typical photographing process when dust is attached to a wavelength-selective filter; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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 designated by the same reference numerals. EXAMPLES

[0010] 1 is a cross-sectional view showing a configuration of a spectroscopic camera 10 according to a first embodiment. The spectroscopic camera 10 captures an image 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 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.

[0011] The optical system 11 includes a first lens L1 and a second lens L2, which are, for example, convex lenses. A wavelength selection filter FF is disposed at the pupil position 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 a conjugate relationship between the object X and the microlens array 12.

[0012] The first lens L1 is disposed on the side where light from the object X enters (hereinafter referred to as the entrance side), and the second lens L2 is disposed on the side where light exits (hereinafter referred to as the exit side) to the microlens array 12. The light from the object X passes through the first lens L1, the wavelength selection filter FF, and the second lens L2, and is collected on the microlens array 12.

[0013] The wavelength-selective filter FF is composed of, for example, a Fabry-Perot type interference filter. The wavelength-selective filter FF is composed of reflective films RF1 and RF2 arranged opposite to each other, and transmits light of a wavelength according to the distance between the reflective films. The wavelength-selective filter FF is configured to be able to selectively set the wavelength of light to be transmitted by applying a voltage V and changing 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).

[0014] In addition, the gap d between the reflecting surfaces in the wavelength-selective filter FF is ideally formed to have a uniform interval, but due to variations during manufacturing and assembly, there are actually uneven parts (hereinafter referred to as unevenness of the gap d between the reflecting surfaces). The spectroscopic camera 10 of this embodiment has a function of correcting the captured image according to the unevenness of the gap d between the reflecting surfaces.

[0015] Microlens array 12 is composed of n microlenses (n is a natural number) arranged vertically and horizontally. Light from different points on object X is incident on different microlenses. Each microlens corresponds to a "pixel" in a normal camera, and the number of microlenses corresponds to the "number of pixels" in a normal camera. Each microlens of microlens array 12 receives light that has passed through optical system 11 and focuses the light on image sensor 13.

[0016] Image sensor 13 is an imaging element that receives light collected by microlens array 12 and converts it into electronic information to obtain a captured image. Image sensor 13 is composed of n divided imaging areas corresponding to each microlens of microlens array 12. Light incident on each microlens of microlens array 12 is received in the corresponding divided imaging area of ​​image sensor 13. Light incident on different microlenses is received in different divided imaging areas, and the divided imaging areas that are received are configured so that they do not overlap. is.

[0017] 2 is a diagram showing a schematic diagram of a state in which light from one point (referred to as object point P) of object X is received by image sensor 13. Light from object point P passes through first lens L1, pupil EYE, and different areas on second lens L2, enters microlens ML2 of microlens array 12, and is received in divided imaging region R2. The luminance value of the image of object point P is represented by the sum of the luminance values ​​of all pixels in divided imaging region R2. Therefore, by acquiring the sum of the luminance values ​​of all pixels in each divided imaging region, an imaging result (captured image) that is the same as an image captured by a normal camera with an image sensor disposed at the position of a microlens can be obtained.

[0018] 3 is a diagram showing a schematic diagram of a state in which light from a point on the pupil EYE of the optical system 11 is received by the image sensor 13. The light from a point on the pupil EYE (i.e., light incident on a point on the pupil EYE) passes through different regions of the second lens L2 and different microlenses of the microlens array 12, and is collected at the same location in each divided imaging region of the image sensor 13.

[0019] Referring again to FIG. 1, the image processing unit 15 is composed of, for example, a CPU (Central Processing Unit) 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 area according to the luminance distribution in each divided imaging area of ​​the image sensor 13 acquired by pre-capturing, and composes an image of the object X using only information of the selected pixel area. In pre-capturing, the image processing unit 15 records a signal received by the image sensor 13 in a storage unit such as a memory (not shown) while sweeping the voltage applied to the wavelength selection filter FF, for example, and obtains a luminance distribution indicating the non-uniformity of the transmission wavelength of the wavelength selection filter FF (i.e., the non-uniformity of the gap d of the reflecting surface) based on the recorded multiple signal information. That is, the image processing unit 15 functions as a detection unit that detects the non-uniformity of the transmission wavelength of the wavelength selection filter FF.

[0020] The luminance distribution in the divided imaging areas of the image sensor 13 represents the luminance distribution of the light incident on the corresponding microlens of the microlens array 12 when it passes through the pupil. Therefore, if the luminance value of the light incident on a certain microlens is calculated as the sum of the luminance values ​​of a specific pixel area of ​​the corresponding divided imaging area, the intensity of the light received after passing through a specific area of ​​the pupil (the area corresponding to the pixel area in the divided imaging area) 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 the light passing through a specific area of ​​the pupil can be obtained. This makes it possible to obtain an image similar to that obtained when, for example, a physical opening having a predetermined shape is placed in the pupil of the optical system 11.

[0021] 4 is a diagram showing an example in which a physical opening AP having a heart shape is placed at the pupil position of the optical system. In each divided imaging region of the image sensor 13, an image in which the heart shape (i.e., the shape of the opening AP) is inverted upside down is obtained.

[0022] In contrast, in the spectroscopic camera 10 of this embodiment, by calculating the brightness value using only the selected pixel region, it is possible to obtain an image similar to that obtained when a physical aperture (a heart-shaped aperture in the figure) is placed in the pupil of the optical system 11, as shown in FIG. 5 (an image obtained by inverting the heart shape in the figure), without placing a physical aperture.

[0023] The Fabry-Perot type interference filter that constitutes the wavelength-selective filter FF is an interference filter composed of a pair of parallel reflective films, and the wavelength of the transmitted light changes by changing the gap between the reflective surfaces. If the reflectance of the reflective surface is R, the gap between the reflective surfaces is h0, and the wavelength of the incident light is λ, the transmittance T(λ) of the Fabry-Perot filter is expressed by the following formula (1).

[0024]

number

[0025] A reflecting surface with R=1 has a value only when λ=2h0, and is a completely monochromatic filter that does not allow other wavelengths to pass. However, in reality, R<1, so it passes a certain range of wavelengths with λ=2h0 as the center wavelength. Its full width at half maximum (FWHM) is expressed by the following equation (2). In the limit where R→1, FWHM→0.

[0026]

number

[0027] In the limit where R → 1, FWHM → 0. However, even if the reflectance R is 1, in an actually fabricated Fabry-Perot filter, the gaps between the reflecting surfaces are not uniform, so the transmitted light is not completely monochromatic.

[0028] 6(a) and (b) are diagrams showing a comparison of the intensity and half-width of transmitted light in an ideal case where the gap between the reflecting surfaces is almost uniform, and in a case where the gap is non-uniform near the ends.

[0029] As shown in Figure 6(a), when the gap is a uniform value (d = h0) throughout the entire area of ​​the reflective surface of the filter, the wavelength of the transmitted light at every point on the reflective surface is 2h0, and the half-width is approximately 0.

[0030] In contrast, as shown in FIG. 6(b), when the gap is non-uniform, light of wavelengths other than λ=2h0 is transmitted in the region where d≠h0, and the half-width becomes wider.

[0031] In order to improve such a widening of the half-width, it is generally considered to place an aperture stop immediately before or after the filter. For example, as shown in Figure 7(a), by placing an aperture stop immediately before the filter, light is transmitted only through the area where the gap around the optical axis is uniform, and the half-width can be improved. However, although this method can improve the half-width, the amount of transmitted light is reduced.

[0032] Furthermore, if the gap between the reflecting surfaces has non-uniformity that is asymmetric with respect to the optical axis, placing an aperture stop symmetric with respect to the optical axis as in Fig. 7(b) will further reduce the amount of transmitted light, so it is necessary to place an aperture stop according to the non-uniformity of the gap as in Fig. 7(c). However, in reality, which parts are non-uniform varies depending on the filter, making it difficult to place an appropriate aperture stop.

[0033] In contrast, in the spectroscopic camera 10 of this embodiment, it is possible to construct 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 light that has passed through a region in which the intervals between the reflective films RF1 and RF2 of the wavelength-selective filter FF are uniform, without providing a physical aperture stop.

[0034] Next, a method of imaging and selecting a pixel region by the spectroscopic camera 10 of this embodiment will be described. First, pre-imaging before imaging (actual imaging) of a subject will be described with reference to the flowchart of FIG.

[0035] In the pre-photographing, as shown in FIG. 9, light of a single wavelength λ1 emitted from a laser LR is irradiated onto a screen SC via a lens L3 (step S101).

[0036] The spectroscopic camera 10 captures an image of the screen SC while sweeping the voltage V applied to the wavelength-selective filter FF. The image processor 15 records a signal received by the image sensor 13, which is an imaging element (step S102).

[0037] The interval between the reflective films RF1 and RF2 changes by changing the voltage V applied to the wavelength-selective filter FF. When the interval is set to allow the greatest amount of light of wavelength λ1 to pass, the image in each divided imaging region of the image sensor 13 becomes the brightest. 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 λ1, and reflects a region where the gap d between the reflective surfaces (i.e., the interval between the reflective films RF1 and RF2) is uniform.

[0038] The image processor 15 obtains a luminance distribution of the divided imaging regions that reflects the non-uniformity of the gap d between the reflecting surfaces of the wavelength-selective filters (non-uniformity of the transmitted wavelengths) based on the recorded signal information (step S103).

[0039] When performing pre-photography for pixel region selection, instead of using a screen SC illuminated with laser light of a single wavelength, a screen SC illuminated with sunlight, halogen light, or the like may be photographed through a bandpass filter that passes light of wavelength λ1.

[0040] For example, as shown in FIG. 10, a bandpass filter BPF that transmits light of wavelength λ1 is placed at a position on the optical path in front of the optical system 11 (i.e., in front of the first lens L1) when viewed from the incident side, and illumination light WL is irradiated to perform imaging during pre-imaging, and the bandpass filter BPF is removed during actual imaging. This allows information on pixel regions that indicate the distribution of luminance according to the gap between the reflecting surfaces of the wavelength-selective filter FF to be obtained, and an image can be constructed using only pixel regions with high luminance. Also, as shown in FIG. 11, a bandpass filter BPF may be placed at a position on the optical path in front of the wavelength-selective filter to perform pre-imaging. That is, it is sufficient that the bandpass filter BPF is placed on the optical path.

[0041] Next, actual photography of a subject will be described with reference to the flowchart of FIG.

[0042] First, the spectroscopic camera 10 is set relative to a subject (object X) (step S201). The spectroscopic camera 10 captures an image of the object X while sweeping the voltage V applied to the wavelength selection filter FF (step S202). At this time, unlike the pre-capture, the subject is captured using illumination light such as sunlight or white light, rather than light of a single wavelength. Then, the image processing unit 15 records a signal received by the image sensor 13, which is an imaging element.

[0043] Based on information indicating the non-uniformity of the gap d between the reflecting surfaces of the wavelength-selective filter obtained by the preliminary photographing (i.e., information on the luminance distribution in the divided imaging area), the image processing unit 15 calculates first image information obtained by receiving light that has passed through an area in which the gap d between the reflecting surfaces is uniform in the actual photographing, and second image information obtained by receiving light that has passed through an area in which the gap d is non-uniform (step S203).The image processing unit 15 obtains a final photographed image based on the first image information and the second image information (step S204).

[0044] As described above, the spectroscopic camera 10 of this embodiment obtains image information indicating the distribution of luminance according to the gap d between the reflecting surfaces of the wavelength-selecting filter FF in the pre-imaging, and selectively uses only pixel regions with high luminance values ​​in the pre-imaging, thereby obtaining a captured image using only light that has passed through regions in which the gap d between the reflecting surfaces of the wavelength-selecting filter FF is uniform. Therefore, even when there is a region in the filter where the transmission wavelength is non-uniform, it is possible to obtain a highly accurate image. EXAMPLES

[0045] 13 is a cross-sectional view showing a configuration of a spectroscopic camera 20 according to Example 2. The spectroscopic camera 20 of this example differs from the spectroscopic camera 10 of Example 1 in that a bandpass filter BPF is fixed to the output surface of one of the microlenses constituting the microlens array 12.

[0046] A bandpass filter BPF with a transmission wavelength λ1 (the center wavelength of the passband is λ1) is provided on the output side surface (i.e., the surface on the image sensor 13 side) of the microlens ML1 located at the end of the microlens array 12. The microlens ML1 functions as a microlens for pixel selection, and the other microlenses function as microlenses for imaging.

[0047] 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 (e.g., an end of the image sensor) corresponding to the microlens ML1. 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.

[0048] When photographing the object X, only light of wavelength λ1 among 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 is acquired, which has a luminance distribution that reflects the gap d between the reflecting surfaces of the wavelength-selecting filter FF.

[0049] On the other hand, light that passes through the areas of the microlens array 12 other than the microlens ML1 does not pass through the bandpass filter BPF, and is received by the other divided imaging areas of the image sensor 13. Therefore, in the divided imaging areas of the image sensor 13 other than the divided imaging area R1, a normal captured image of the object X is obtained.

[0050] The image processing unit 15 performs image correction processing on the captured image obtained in a region other than the divided imaging region R1 based on 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 region 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 region.

[0051] Therefore, according to the spectroscopic camera 20 of the present embodiment, unlike the first embodiment in which shooting needs to be performed in two steps, namely, pre-shooting and actual shooting, it is possible to obtain a captured image using only pixel areas with high brightness by shooting in one go.

[0052] Unlike the above configuration, a configuration in which multiple bandpass filters BPF are provided may be used. For example, as shown in Fig. 14, two bandpass filters BPF, each having a transmission wavelength (center wavelength of the passband) of λ1, are provided on the emission side surfaces of the microlenses at both ends of the microlens array 12, and the corresponding two divided imaging areas (divided imaging areas R1 and Rx) are used as divided imaging areas for pixel selection. This allows multiple images VD for pixel selection to be obtained, making it possible to perform pixel selection with high accuracy.

[0053] Also, as shown in Fig. 15, a configuration may be adopted in which a plurality of bandpass filters BPF1 (transmission wavelength λ1) and BPF2 (transmission wavelength λ2) with different transmission wavelengths are provided. An image for pixel selection in the divided imaging region R1 and an 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 = V1, an image for pixel selection VD1 is obtained in the divided imaging region R1, and when the voltage V = V2, an image for pixel selection VD2 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 that pixel selection can be performed with high accuracy.

[0054] Also, a configuration may be provided in which a plurality of bandpass filters with different half-widths are provided. For example, as shown in FIG. 16(a), a bandpass filter BPFA with a transmission wavelength centered at λ1 and a half-width W1 and a bandpass filter BPFB with a transmission wavelength centered at λ1 and a half-width W2 are provided on the emission side surfaces of the microlenses at both ends of the microlens array 12. If the half-width W2>the half-width W1, as shown in FIG. 16(b), the bandpass filter BPFA with a small half-width transmits a small amount of transmitted light, and the bandpass filter BPFB with a large half-width transmits a large amount of transmitted light. Therefore, pixel selection with half-width priority and pixel selection with transmitted light priority can be performed while switching 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.

[0055] The embodiments of the present invention are not limited to those shown in the above-mentioned Examples 1 and 2. For example, in the above-mentioned Examples, a configuration was described in which, in a state in which a certain voltage V is applied to the wavelength selection filter FF, a pixel area with a high luminance value is selected from the divided imaging area of ​​the image sensor 13 and image processing is performed. For example, when a certain monochromatic light is incident and an image as shown in FIG. 9 is obtained in the divided imaging area, it is determined that only the pixels in the pixel area with a high luminance (area represented by white in the figure) are effective pixels, and information of pixels in other areas (areas represented by gray and black in the figure) is discarded. However, since the pixel area with a high luminance changes by changing the voltage applied to the wavelength selection filter FF, information at a plurality of voltages may be added to obtain image information.

[0056] For example, suppose that the voltage applied to the wavelength-selecting filter FF (hereinafter referred to as the applied voltage) is changed around V=V1, and the luminance value of the pixel area displayed in gray at the applied voltage V1 becomes maximum at the applied voltage V2, and the luminance value of the pixel area displayed in black at the applied voltage V1 becomes maximum at the applied voltage V3. In this case, by adding the information of the pixel area at each voltage value and calculating the luminance value of the corresponding microlens, an image of wavelength λ1 can be obtained from the information of the entire surface of the wavelength-selecting filter FF, and the loss of the amount of light can be further reduced. In this way, by using multiple applied voltages and pixels (pixel areas) in the divided imaging area corresponding to those applied voltages to obtain image information of one wavelength, it is possible to improve the half-width while ensuring the maximum light utilization efficiency.

[0057] It can also be said that the gray area at the applied voltage V1 represents information on another wavelength λ2, and the black area represents information on yet another wavelength λ3, so it is possible to obtain information on multiple wavelengths for each applied voltage. Therefore, by storing this information in a memory (not shown) while sweeping the applied voltage V, and finally calculating the brightness value of each microlens by adding up the information on the same wavelength, the same result can be obtained.

[0058] In the present invention, since the wavelength-selecting filter FF is disposed in the pupil portion of the optical system 11, light that has passed through a certain coordinate in the pupil is uniformly incident on all the microlenses of the microlens array 12. Therefore, if there is an uneven portion (unevenness) in the gap d between the reflecting surfaces of the wavelength-selecting filter FF, which part of the filter the light passes through and enters the microlens array 12 will change depending on the time, but since the timing at which the light enters each microlens is the same, no unevenness will occur in the image obtained by the image sensor 13. Furthermore, if there is dirt or a defective portion on the filter, the luminance will decrease by the area of ​​the dirt or defect, but no pixel defects will occur in the image obtained by the image sensor 13.

[0059] Furthermore, according to the spectroscopic camera of the present invention, even if dust or the like is attached to the wavelength-selective filter, it is possible to avoid this and capture an image of a subject. For example, as shown in FIG. 17, if dust GB is attached to the wavelength-selective filter FF, when capturing an image of a screen SC illuminated with illumination light WL such as white light, the dust GB will be reflected in all of the divided imaging regions of the image sensor 13. Therefore, by selecting pixel regions avoiding the regions where the dust GB is reflected, it is possible to capture an image while avoiding the dust GB. In addition to dust, it is also possible to deal with foreign matter such as stains and scratches, the location of which cannot be predicted.

[0060] In the above embodiment, 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 the lenses are not limited to this, and the spectroscopic camera may have a lens array having n lenses.

[0061] In addition, in the above-mentioned second embodiment, an example in which the bandpass filter is provided on the surface of the microlens on the exit side has been described, but the position where the bandpass filter is disposed is not limited to this, and it is sufficient that the bandpass filter is disposed on the optical path of the light focused on the microlens. Moreover, it is not limited to the microlenses at both ends, and it is sufficient that the bandpass filter is disposed at a position corresponding to any one of the n microlenses.

[0062] Furthermore, the series of processes explained 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. [Explanation of symbols]

[0063] 10,20 Spectroscopic camera 11 Optical system 12 Microlens Array 13 Image Sensor 14 Camera 15 Image processing section

Claims

[Claim 1] An optical system consisting of a pair of lenses; a wavelength selection unit having a pair of reflecting surfaces arranged opposite to each other at a pupil position of the optical system, the wavelength selection unit changing a distance between the pair of reflecting surfaces in response to an applied voltage, and selectively transmitting light of a wavelength corresponding to the distance; a lens array having n lenses (n is a natural number) each of which collects light that has passed through the optical system and the wavelength selection unit; an imaging element provided at a position conjugate with the wavelength selection unit and having n divided imaging regions that receive light collected by the n lenses; A spectroscopic camera comprising:

Images