JP2014075669A - Multi-band camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-band camera which can obtain precise spectral data without the need to precisely measure a spectral characteristic of a filter, that of a lens and sensitivity of a light receiving element.SOLUTION: A multi-band camera includes: a bandpass filter including four or more transmission regions having transmission wavelength ranges with mutually different wavelengths as centers; and a plurality of photoelectric conversion elements which are two-dimensionally arranged, receive light beams that transmit through the four or more transmission regions and output light reception signals. The bandpass filter controls intensity of the light beams which are made incident on the plurality of photoelectric conversion elements for each wavelength so that the light reception signals corresponding to the light beams which are outputted from the plurality of photoelectric conversion elements and transmit through the four or more transmission regions become almost the same signals when the light beams having uniform spectral intensity in an imaging wavelength region transmit through the four or more transmission regions and are made incident on the plurality of photoelectric conversion elements.

Description

  The present invention relates to a multiband camera.

  2. Description of the Related Art Conventionally, multiband cameras that capture an image of a subject in a plurality of different wavelength bands and acquire spectral data of the subject are known. For example, Patent Document 1 describes a multiband image photographing apparatus using a filter such as a liquid crystal tunable filter as a color separation filter, in which color unevenness and light amount unevenness are removed.

JP 2001-145116 A

  In the prior art, due to the difference in sensitivity of the light receiving element in each wavelength band, there is a problem that the dynamic range is narrower than other bands, especially in areas where the sensitivity of the light receiving element is weak, resulting in image data containing noise. there were. Therefore, there is a problem that accurate spectral data cannot be obtained unless the exposure amount and gain of the camera are adjusted and the noise suppression parameter is adjusted by image processing.

  The multi-band camera according to claim 1 is a two-dimensionally arranged bandpass filter having four or more transmission regions having transmission wavelength regions centered on different wavelengths, and the four or more transmission regions. A plurality of photoelectric conversion elements that receive the transmitted light and output a light reception signal, and the band-pass filter transmits light having a uniform spectral intensity in the imaging wavelength region through the four or more transmission regions. When the light enters the plurality of photoelectric conversion elements, the received light signals respectively corresponding to the light transmitted through the four or more transmission regions output from the plurality of photoelectric conversion elements have substantially the same signal level. Furthermore, the intensity of light incident on the plurality of photoelectric conversion elements is adjusted for each wavelength.

  According to the present invention, accurate spectral data can be obtained for each wavelength band without the need to adjust the exposure amount or gain of the camera or the noise suppression parameter by image processing.

It is a block diagram which shows the structure of the multiband camera to which this invention is applied. It is a schematic diagram of the optical system with which the multiband camera 1 is provided. FIG. 4 is a schematic view of an optical filter 13 and a third lens 23 as viewed from the subject 11 side. It is a figure explaining the spectral transmission characteristic of the optical filter. It is a block diagram which shows the structure of the multiband camera which concerns on the 2nd Embodiment of this invention. 2 is a schematic diagram of a light receiving element array 17 and a microlens array 15. FIG. It is a schematic diagram of the optical system with which the multiband camera 2 is provided. It is a figure which shows the real image formed in an imaging surface shape by a micro lens. It is a figure which shows the preparation method of calibration data. It is a block diagram which shows the structure of the multiband camera which concerns on the 3rd Embodiment of this invention. 2 is a schematic diagram illustrating a configuration of an optical system of a multiband camera 6. FIG.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a multiband camera to which the present invention is applied. The multiband camera 1 includes a first lens 21, a second lens 22, an optical filter 13, four third lenses 23a to 23d, four light receiving element arrays 17a to 17d, a control device 51, a memory 52, and a display device 53. Prepare.

  In FIG. 1, the first lens 21, the second lens 22, the third lenses 23a to 23d, and the like are illustrated as one lens, but each of these lenses may be a lens group including a plurality of lenses. .

  The optical filter 13 is provided with four transmission regions 14a to 14d having different wavelengths at the center of the transmission wavelength region. The configuration of the optical filter 13 will be described in detail later. In the multiband camera 1, four third lenses 23a to 23d and four light receiving element arrays 17a to 17d are provided so as to correspond to the four transmission regions 14a to 14d, respectively. This light receiving element array may be used by dividing one light receiving element array into four.

  Each of the light receiving element arrays 17a to 17d is an image pickup element such as a CCD or a CMOS, and a plurality of light receiving elements (photoelectric conversion elements) 16 are two-dimensionally arranged on an image pickup surface facing the third lenses 23a to 23d. . Each of the light receiving element arrays 17a to 17d outputs a light receiving signal corresponding to the amount of subject light received by each of the plurality of light receiving elements 16 arranged on the imaging surface.

  The control device 51 includes a CPU and its peripheral circuits, and controls the entire multiband camera 1 by reading and executing a predetermined control program from a storage medium (not shown). The control device 51 further generates multiband image data in a predetermined imaging wavelength region based on the four light receiving signals respectively output from the four light receiving element arrays 17a to 17d. Multiband image data is data in which the spectral intensity of a subject for each of a plurality of wavelength bands (wavelength regions) included in an imaging wavelength region is recorded.

  The memory 52 is a volatile storage medium. The control device 51 stores the generated multiband image data and temporary data associated with the generation of the multiband image data in the memory 52. The display device 53 includes a display screen such as a liquid crystal display, and displays image data and the like on the display screen according to the control of the control device 51.

(Description of optical system)
FIG. 2 is a schematic diagram of an optical system provided in the multiband camera 1. The first lens 21, the second lens 22, and the optical filter 13 are respectively disposed along the optical axis Ax. The first lens 21 forms an intermediate image 11 a of the subject 11 between the first lens 21 and the second lens 22.

  The intermediate image 11a is further passed through the second lens 22 and each of the four transmission regions 14a to 14d of the optical filter 13 by each of the four third lenses 23a to 23d, thereby providing four light receiving element arrays 17a. To 17d are imaged as subject images 11b. For example, light from the point P on the optical axis Ax of the subject 11 passes through the first lens 21 and passes through the point Pa on the optical axis Ax, and each of the second lens 22 and the four transmission regions 14a to 14d. , And enters the point Pb on the imaging surface of each of the four light receiving element arrays 17a to 17d.

  FIG. 3 is a schematic view of the optical filter 13 and the third lens 23 as viewed from the subject 11 side. The optical filter 13 includes four transmission regions 14a to 14d arranged in 2 rows and 2 columns. Each transmissive region is separated by a light shielding member 18. The light shielding member 18 is chrome-plated, for example, and shields light from the subject 11. Thereby, the subject light from the subject 11 does not pass through the transmission regions 14a to 14d and does not enter the light receiving element arrays 17a to 17d.

  The four transmission regions 14a to 14d are configured such that different wavelengths are the center of the transmission wavelength region. In the present embodiment, the transmission region 14a transmits light having a wavelength of 390 nm (nanometer) to 490 nm, and the transmission region 14b transmits light having a wavelength of 490 nm to 590 nm. Similarly, the transmission region 14c transmits light having a wavelength of 590 nm to 690 nm, and the transmission region 14d transmits light having a wavelength of 690 nm to 790 nm.

  That is, the imaging wavelength region of the multiband camera 1 is 390 nm to 790 nm, and the optical filter 13 can transmit light in the imaging wavelength region in four different wavelength bands.

  The subject light having a wavelength of 390 nm to 490 nm transmitted through the transmission region 14a is incident on the third lens 23a, and forms an image 11b on the imaging surface of the light receiving element array 17a. The light receiving element array 17a captures the image 11b and outputs a light receiving signal corresponding to subject light in a wavelength band of 390 nm to 490 nm. Similarly, the light receiving element arrays 17b to 17d output light receiving signals corresponding to subject light in a wavelength band that passes through the transmission regions 14b to 14d, respectively.

  That is, the four light receiving element arrays 17a to 17d output light receiving signals corresponding to each of the four wavelength bands for the subject 11. The control device 51 creates multiband image data by a well-known method based on the four types of received light signals thus obtained.

(Description of optical characteristics of optical filter 13)
FIG. 4 is a diagram for explaining the spectral transmission characteristics of the optical filter 13. In order to create precise multiband image data, when light having the same intensity is incident on each of the four transmission regions 14a to 14d, the same signal level is obtained from the four light receiving element arrays 17a to 17d. It is desirable to output a light receiving signal having FIG. 4A is a graph showing the output of this ideal light reception signal, where the horizontal axis represents the wavelength of the incident light and the vertical axis represents the signal level of the light reception signal output in accordance with the incident light. Represents.

  As shown in FIG. 4A, when subject light having a uniform intensity is incident over the entire imaging wavelength region, a light receiving signal 30a output from the light receiving element array 17a and a light receiving signal 30b output from the light receiving element array 17b. It is desirable that the light receiving signal 30c output from the light receiving element array 17c and the light receiving signal 30d output from the light receiving element array 17d have substantially the same characteristics.

  However, in reality, the high sensitivity characteristics of the four light receiving element arrays 17a to 17d are not uniform over the entire imaging wavelength region, and thus an ideal output as shown in FIG. 4A cannot be obtained. . An example of the spectral sensitivity characteristics of the light receiving element arrays 17a to 17d is shown in FIG.

  Therefore, the multiband camera 1 of the present embodiment obtains a uniform light reception signal as shown in FIG. 4A by adjusting the transmitted light amount of the subject light in the four transmission regions 14a to 14d of the optical filter 13. I am trying to do it. In the following description, the optical filter 13 configured to obtain such a light reception signal is referred to as “optimized”.

  FIG. 4C is a graph showing the spectral transmittance of the optimized optical filter 13, where the horizontal axis represents the wavelength of the incident light and the vertical axis represents the transmittance of the incident light. As shown in FIG. 4C, the spectral transmittance 32a of the transmissive region 14a, the spectral transmittance 32b of the transmissive region 14b, the spectral transmittance 32c of the transmissive region 14c, the spectral transmittance 32d of the transmissive region 14d, Have different peak sizes. This is because the four transmission regions 14a to 14d transmit a relatively large amount of light in the wavelength region where the sensitivity of the light receiving element arrays 17a to 17d is relatively high, and the light of the wavelength region where the sensitivity of the light receiving element arrays 17a to 17d is high. Therefore, it is made to transmit little. By configuring the optical filter 13 in this way, it is possible to obtain a light reception signal close to the ideal one shown in FIG.

  In the above description, the spectral sensitivity characteristics of the light receiving element arrays 17a to 17d have been described. However, in actuality, the spectral sensitivity characteristics of the first lens 21, the second lens 22, and the third lens 23 are further taken into consideration. It is necessary to design the filter 13. In other words, the four transmission regions 14a to 14d of the optical filter 13 are configured to transmit different wavelength bands, and subject light of each wavelength band having the same intensity is transmitted through the optical system to be 4 The intensity of transmitted light is adjusted for each wavelength so that the received light signals output from the respective light receiving element arrays 17a to 17d have the same signal level when entering the two light receiving element arrays 17a to 17d. Yes.

  Although it is difficult to finely control the transmittance for each wavelength as described above with a conventional interference filter (for example, a bandpass filter), it is possible to form a thin film in tens to hundreds of layers. If so, the optical filter 13 having the transmittance as shown in FIG. 4C can be manufactured. For example, the applicant of the present application applies and uses an automatic error correction system capable of forming a highly accurate multi-layer laminated structure of thin films of SiO 2 and Nb 2 O 5 in a sputtering apparatus. According to this automatic error correction system, by measuring the error after film formation and correcting the film thickness of the subsequent layers, film formation of tens to hundreds of layers is performed with high accuracy, and finally The desired spectral transmission characteristics (for example, those shown in FIG. 4C) can be brought to the limit.

  Since the interference type optical thin film filter is dependent on the incident angle, it is desirable to consider the incident angle of the subject light in advance when designing the optical filter 13.

The multiband camera according to the first embodiment described above provides the following operational effects.
(1) The optical filter 13 has four transmission regions 14a to 14d each having a transmission wavelength region centered on different wavelengths. Each of the four light receiving element arrays 17a to 17d includes a plurality of photoelectric conversion elements that are two-dimensionally arranged and receive light transmitted through the four transmission regions 14a to 14d and output light reception signals. The optical filter 13 is output from the plurality of photoelectric conversion elements when light having a uniform spectral intensity in the imaging wavelength region passes through the four transmission regions 14a to 14d and enters the plurality of photoelectric conversion elements. The intensity of the light incident on the plurality of photoelectric conversion elements is adjusted for each wavelength so that the received light signals respectively corresponding to the light transmitted through the four or more transmission regions have substantially the same signal level. Since it did in this way, exact spectral data can be obtained, without having to measure correctly the spectral characteristic of a filter, the spectral characteristic of a lens, the sensitivity of a light receiving element, etc.

(2) The optical filter 13 is configured by laminating a plurality of optical thin films. Since it did in this way, it becomes possible to implement | achieve adjustment of the intensity | strength of the light for every wavelength with high precision.

(3) The control device 51 generates image data corresponding to the imaging wavelength region based on the light reception output. Since it did in this way, the spectral characteristic of the to-be-photographed object for every wavelength band can be obtained with high precision.

(4) The four light receiving element arrays 17a to 14d receive subject light having different wavelength bands, and output light receiving signals corresponding to the wavelength bands. Since it did in this way, the light reception signal of the subject light corresponding to four wavelength bands can be obtained by one photographing, and the spectral data of one subject can be obtained by one photographing.

(Second Embodiment)
FIG. 5 is a block diagram showing a configuration of a multiband camera according to the second embodiment of the present invention. In the following description, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  The multiband camera 2 includes an interchangeable lens 48 including a first lens 21, a second lens 22, and an optical filter 13, and a camera body 50 including a mount portion 49 to which the interchangeable lens 48 is attached in an interchangeable manner. The mount portion 49 has a known mount mechanism such as a bayonet mount.

  In the multiband camera 2 of the present embodiment, unlike the first embodiment, the optical filter 13 is provided at the position of the pupil between the first lens 21 and the second lens 22. In the present embodiment, the interchangeable lens 48 is replaceable, and the optical filter 13 is installed so as to be replaceable in order to cope with this. That is, there are a plurality of types of optical filters 13, and the interchangeable lens 48 is provided with an insertion / extraction mechanism that allows an arbitrary optical filter 13 to be installed. When exchanging the interchangeable lens 48, the user of the multiband camera 2 selects an appropriate optical filter 13 corresponding to the combination of the camera body 50 and the interchangeable lens 48 and installs it on the interchangeable lens 48.

  FIG. 6 is a schematic diagram of the light receiving element array 17 and the microlens array 15. In the present embodiment, the camera body 50 includes a single light receiving element array 17 and a microlens array 15 installed facing the imaging surface of the light receiving element array 17.

  The microlens array 15 includes a large number of microlenses ML arranged in a two-dimensional manner. Each microlens ML has a size that covers at least a plurality of light receiving elements 16 among the many light receiving elements 16 included in the light receiving element array 17. That is, the subject light that has passed through each of the first lens 21, the optical filter 13, and the second lens 22 and has entered one of the microlenses ML is incident on the plurality of light receiving elements 16 covered by the microlens ML. To do.

  The microlens array 15 is disposed at the + Z side of the imaging optical system and at the conjugate position of the subject 11. Each microlens ML is circular, and its focal length is about several tens to several hundreds of micrometers (micrometers). Although FIG. 6 shows 25 microlenses ML arranged in a square, the microlens array 15 actually has a larger number of microlenses ML. Further, the shape and arrangement of the microlenses ML are merely examples, and may be different from those in FIG. For example, square or hexagonal microlenses ML may be used, or the microlenses ML may be arranged in a staggered arrangement.

(Description of optical system)
FIG. 7 is a schematic diagram of an optical system provided in the multiband camera 2. Hereinafter, the optical system of the multiband camera 2 will be described by taking light beams L1 and L2 from a certain point P on the subject 11 shown in FIG. 7 as an example. In FIG. 7, only the principal rays of the light beams L1 and L2 are drawn for easy understanding. In FIG. 7, the distance between the microlens array 15 and the light receiving element array 17 is exaggerated to be larger than the actual distance.

  As shown in FIG. 7, light beams L <b> 1 and L <b> 2 from one point P of the subject 11 pass through the first lens 21 and enter the optical filter 13. For example, the light beam L1 transmits through the transmission region 14a of the optical filter 13, and the light beam L2 transmits through the transmission region 14c of the optical filter 13. At this time, only light having a wavelength region of 390 nm to 490 nm contained in the light beam L1 passes through the optical filter 13. Similarly, only light having a wavelength region of 590 nm to 690 nm that is included in the light flux L2 passes through the optical filter 13.

  The light beams L 1 and L 2 that have passed through the optical filter 13 pass through the second lens 22 and enter a certain point Pc on the microlens array 15. Here, since the microlens array 15 is arranged at a conjugate position with the subject 11, a real image of the subject 11 is formed on the microlens array 15. Note that the focus adjustment of the optical system can be performed by moving only the first lens 21 on the subject 11 side along the optical axis Ax. For this reason, both the light beam L1 and the light beam L2 from the same point P are incident on the same microlens among many microlenses provided in the microlens array 15.

  The respective light receiving elements 16 arranged on the imaging surface of the light receiving element array 17 are respectively arranged at a conjugate position or in the vicinity of the conjugate position with the optical filter 13. Here, since the focal length f of the microlens ML is orders of magnitude shorter than the focal length of the second lens 22, the position conjugate with the transmission regions 14a and 14c is near the focal position of the microlens ML. Furthermore, since the light receiving element 16 is disposed at or near the focal plane of the microlens ML, a real image of the transmission regions 14a to 14d is formed on the light receiving element 16 by each microlens ML.

  FIG. 8A is a plan view of a real image formed in the shape of an imaging surface by a microlens as viewed from the Z direction (direction along the optical axis Ax). In FIG. 8A, the outline of a specific microlens ML1 on which the real image 133 is formed so as to overlap the light receiving element 16 and the real image 133 arranged on the imaging surface of the light receiving element array 17 is schematically illustrated. . FIG. 8B is a cross-sectional view of the real image 133 shown in FIG.

  As shown in FIG. 8, the microlens ML1 forms real images (conjugate images) 140a to 140d of the transmission regions 14a to 14d included in the optical filter 13 on the imaging surface of the light receiving element array 17. In FIG. 8, the real images 140a to 140d of the transmissive areas 14a to 14d are formed on the four light receiving elements 16, respectively. However, depending on the size of the transmissive areas 14a to 14d, the magnification of the microlens ML1, etc. The image may be formed only on one light receiving element 16 or may be formed on a number of light receiving elements 16 other than four.

  The real image 140a of the transmissive area 14a is composed of a light beam that has passed through the transmissive area 14a. In other words, light in a wavelength region of 390 nm to 490 nm transmitted through the transmission region 14a is incident on the four light receiving elements 16 on which the real image 140a of the transmission region 14a is formed. Similarly, the real images 140b to 140d are made of light beams that have passed through the transmission regions 14b to 14d, respectively, and light in a wavelength region corresponding to the spectral transmission characteristics of each transmission region is incident on the corresponding light receiving element 16.

  In order to obtain the wavelength characteristic of the subject 11, the control device 51 first obtains the wavelength characteristic of the light beam L1 from the light reception output of the light receiving element 16 on which only the light beam L1 transmitted through the transmission region 14a is incident. Similarly, for the other transmission regions 14b to 14d, the wavelength characteristic of the light beam is obtained from the light reception output of the light receiving element 16 on which the light beam transmitted through the transmission region is incident.

(Description of the calibration method of the multi-band camera 2)
In the multiband camera 2 of the present embodiment, the interchangeable lens 48 and the optical filter 13 can be replaced. Therefore, it is preferable to calibrate the received light signal output from the light receiving element array 17 when measuring the wavelength characteristics of each wavelength region, in order to suppress the influence of errors due to individual differences in each part. Hereinafter, a calibration method by the control device 51 will be described.

  A plurality of calibration data is stored in advance in a storage medium (not shown) in the camera body 50. Each calibration data is data corresponding to specific imaging conditions. Note that the imaging condition in the present embodiment refers to a combination of the illumination condition and the interchangeable lens 48. The illumination condition is a condition for specifying the characteristics of the illumination light of the subject, for example, under a clear sky or under a cloudy sky. That is, when there are M types of illumination conditions and N types of interchangeable lenses 48 in the storage medium in the camera body 50, M × N pieces of calibration data are stored.

  When measuring the wavelength characteristic, the control device 51 specifies the current imaging condition (that is, the illumination condition and the interchangeable lens 48), and reads calibration data corresponding to the imaging condition from the storage medium. Based on the read calibration data and auxiliary calibration data described later, the light reception signal output from the light receiving element array 17 is corrected.

  FIG. 9 is a diagram showing a method for creating calibration data. When the calibration data is created, a color sample 5 is prepared as a reference subject. As the color sample 5, for example, a Munsell color chart is used. The illumination device 4 irradiates the color sample 5 with illumination light, images the color sample 5 with the multiband camera 2 (acquires a received light signal from the light receiving element array 17), and reflects the color sample 5 with the spectral radiance meter 3. Measure the spectrum.

  At this time, an interchangeable lens 48 corresponding to the calibration data to be created is attached to the camera body 50, and the optical filter 13 is replaced with one corresponding to the interchangeable lens 48 and the camera body 50. The illumination light emitted from the illumination device 4 is assumed to be light that matches the illumination conditions corresponding to the calibration data to be created. Calibration data can be created from the received light signal and the reflection spectrum thus obtained by a known method.

  Next, auxiliary calibration data will be described.

  As described above, a plurality of calibration data corresponding to a plurality of imaging conditions is prepared in advance, but calibration data corresponding to all imaging conditions cannot be prepared in advance. Therefore, the control device 51 uses the data for correcting the imaging condition (illumination condition) that is the basis of the calibration data based on the actual imaging condition (illumination condition), which is called auxiliary calibration data, when measuring the wavelength characteristics. The measurement result of the wavelength characteristic is further corrected.

  That is, when measuring the wavelength characteristic, the control device 51 first (1) obtains a light reception signal from the light receiving element array 17, and then (2) the measurement result of the wavelength characteristic of the subject based on the light reception signal and calibration data. Is calculated. (3) The final measurement result is obtained by correcting the calculation result based on the auxiliary calibration data.

  Auxiliary calibration data is created under the same lighting conditions as actual shooting. First, the multiband camera 2 is used to measure the wavelength characteristics of a standard white plate with a known reflectance. Next, the illumination spectrum of the current photographing environment is calculated from the measurement result. Then, auxiliary calibration data is created by comparing the illumination spectrum corresponding to the illumination condition at the time of calibration data creation and the illumination spectrum of the current imaging environment. By creating auxiliary calibration data in this way and correcting the measurement result of the wavelength characteristics with the auxiliary calibration data, the number of calibration data stored in a storage medium (not shown) can be reduced.

The multiband camera according to the second embodiment described above provides the following operational effects.
(1) The interchangeable lens 48 is configured such that the optical filter 13 is replaceably attached. Since it did in this way, the optimal optical filter 13 for the combination of each optical system and the light receiving element array 17 can always be utilized.

(2) The mount 49 is attached so that the interchangeable lens 48 can be replaced. Since it did in this way, the optimal optical system according to a to-be-photographed object can be selected, and the convenience of the multiband camera 2 improves.

(3) A storage medium (not shown) stores a plurality of calibration data created by measuring the light reception output of the light receiving element array 17 for each predetermined photographing condition. The control device 51 selects one of the plurality of calibration data based on the imaging condition, and corrects the light reception output from the light receiving element array 17 based on the selected calibration data. Since it did in this way, the precision of spectral data can be raised.

(Third embodiment)
FIG. 10 is a block diagram showing a configuration of a multiband camera according to the third embodiment of the present invention. In the following description, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  The multiband camera 6 includes an optical filter 13, four lenses 24a to 24d, and four light receiving element arrays 17a to 17d. The subject light that has passed through the four transmission regions 14a to 14d provided in the optical filter 13 is incident on each of the four lenses 24a to 24d. The subject light that has passed through the four lenses 24a to 24d is incident on each of the four light receiving element arrays 17a to 17d.

  FIG. 11 is a schematic diagram showing the configuration of the optical system of the multiband camera 6. The subject light transmitted through the transmission region 14a is incident on the light receiving element array 17a through the lens 24a. The space from the lens 24a to the light receiving element array 17a is separated from the other three lenses 24b to 24d and the three light receiving element arrays 17b to 17d by the wall member 25. The same applies to the other transmission regions 14b to 14d.

  In the multiband camera 6 configured as described above, similarly to the multiband camera 1 of the first embodiment, the wavelengths transmitted through the transmission regions 14a to 14d from the four light receiving element arrays 17a to 17d, respectively. A light reception signal corresponding to the subject light of the band can be obtained. That is, the four light receiving element arrays 17a to 17d output light receiving signals corresponding to each of the four wavelength bands for the subject 11. The control device 51 creates multiband image data by a well-known method based on the four types of received light signals thus obtained.

  According to the multiband camera of the third embodiment described above, the same operational effects as the multiband camera of the first embodiment can be obtained.

  Although the embodiments of the present invention have been described above, the following modifications are also within the scope of the present invention, and one or more of the modifications can be combined with the above-described embodiments.

(Modification 1)
In each of the above-described embodiments, the imaging wavelength region of 390 nm to 790 nm is divided into four different wavelength bands, and multiband image data including data of each wavelength band is created. The present invention is not limited to such an embodiment. For example, multiband image data may be created for other imaging wavelength regions, and the number of wavelength band divisions may be greater than four.

(Modification 2)
The generation of multiband image data may not be performed inside the multiband camera. For example, an arithmetic device that generates multiband image data from a light reception signal is provided outside the multiband camera, and the light reception signal itself is input from the multiband camera to the arithmetic device via a portable storage medium or an electric communication line. May be.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

1, 2, 6 ... multi-band camera, 13 ... optical filter, 14a, 14b, 14c, 14d ... transmission region, 16 ... light receiving element, 17, 17a, 17b, 17c, 17d ... light receiving element array, 51 ... control device, 52 ... Memory, 53 ... Display device

Claims (6)

A bandpass filter having four or more transmission regions each having a transmission wavelength region centered on different wavelengths;
A plurality of photoelectric conversion elements that are two-dimensionally arranged and receive light transmitted through the four or more transmission regions and output light reception signals;
The band-pass filter is configured such that when light having a uniform spectral intensity in the imaging wavelength region passes through the four or more transmission regions and enters the plurality of photoelectric conversion devices, the plurality of photoelectric conversion devices The intensity of light incident on the plurality of photoelectric conversion elements is adjusted for each wavelength so that the received light signals respectively corresponding to the light transmitted through the four or more transmission regions to be output have substantially the same signal level. Multiband camera characterized by that. The multi-band camera according to claim 1, wherein
The band-pass filter is configured by laminating a plurality of optical thin films. The multiband camera according to claim 1 or 2,
A multiband camera comprising a filter mounting portion to which the bandpass filter is replaceably mounted. In the multiband camera as described in any one of Claims 1-3,
A multiband camera, comprising: a lens attachment portion to which an optical system including the bandpass filter is attached in a replaceable manner. In the multiband camera as described in any one of Claims 1-4,
A storage unit for storing a plurality of calibration data created by measuring the light reception outputs of the plurality of light receiving elements for each predetermined imaging condition;
A correction unit that selects any one of the plurality of calibration data based on imaging conditions, and corrects the light reception output based on the selected calibration data;
A multiband camera characterized by comprising: In the multiband camera as described in any one of Claims 1-5,
A multiband camera, comprising: an image data generation unit configured to generate image data corresponding to the imaging wavelength region based on the light reception output.

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