JP6930869B2 - Imaging device, imaging method and program - Google Patents

Description

The present invention relates to an imaging device including an optical filter. The present invention also relates to an imaging method using an optical filter and a program for executing the imaging method.

Conventionally, as an optical filter, a wavelength selection filter having a characteristic of transmitting an optical component in a predetermined wavelength band from the incident light has been known. When such an optical filter is mounted on an imaging device, the imaging device functions as a spectroscopic camera or a spectroscopic measuring device. For example, Patent Document 1 discloses an optical module including a tunable interference filter and a method for driving the same.

Japanese Unexamined Patent Publication No. 2014-056073

For example, an optical filter has a pair of reflective films (reflection mirrors) facing each other at predetermined intervals. In the case of such an optical filter, light in a wavelength range corresponding to the distance (optical distance) between the pair of reflective films passes through the filter. Further, for example, a wavelength-variable optical filter having a function of changing the transmitted wavelength range (transmission characteristic) is configured to displace the pair of reflective films relative to each other.

On the other hand, the light transmitted through the optical filter has intensity peaks in a plurality of wavelength regions corresponding to the distances between the reflective films. Here, when the light transmitted through the optical filter is divided into a plurality of order components for each peak of the intensity, the plurality of order components each have a different full width at half maximum. Therefore, the plurality of order components have different amounts of light from each other.

Therefore, when only a specific component is selectively received from the plurality of order components for imaging, the brightness of the captured image differs depending on the selected component. As a result, when the component selected in the spectroscopic camera or the spectroscopic measuring device is changed according to the wavelength, the image in a part of the captured images in a wavelength range becomes excessively bright or dark as compared with the other images. It may not be possible to obtain accurate spectral information.

The present invention has been made in view of the above points, and an object of the present invention is to provide an imaging apparatus capable of accurately obtaining spectral information by suppressing a difference in brightness of captured images for each wavelength. Another object of the present invention is to provide an imaging method and a program capable of accurately obtaining spectral information by suppressing the difference in brightness of the captured image for each wavelength.

The invention according to claim 1 is a filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to an optical distance between the pair of reflecting surfaces, and a plurality of order components. When an image is taken with one order component as the target light and the first component of the plurality of order components is the target light, the image is taken with the first sensitivity and the second component is higher than the first component. When the component is the target light, it is characterized by having an imaging unit that images with a second sensitivity higher than the first sensitivity.

The invention according to claim 9 is a filter having a pair of opposing reflecting surfaces and transmitting light including a plurality of order components according to an optical distance between the pair of reflecting surfaces, and a plurality of order components. An imaging unit that takes an image with one of the order components as the target light, and an imaging unit that adjusts the amount of light incident on the filter by adjusting the aperture diameter, and the imaging unit targets the first component of the plurality of order components. When using light, the aperture diameter is set to the first diameter, and when the imaging unit targets a second component higher than the first component as the target light, the aperture diameter is set to be larger than the first diameter. It is characterized by having an optical diaphragm set to a diameter of 2.

The invention according to claim 10 is a filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to an optical distance between the pair of reflecting surfaces, and a plurality of order components. When the imaging unit that performs imaging with one of the order components as the target light and the exposure time of the target light to the imaging unit are adjusted so that the imaging unit uses the first component of the plurality of order components as the target light. Sets the exposure time to the first time, and when the imaging unit targets the second component higher than the first component as the target light, the exposure time is set to the second time longer than the first time. It is characterized by having a shutter to be set.

The invention according to claim 11 is an imaging method using a filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to an optical distance between the pair of reflecting surfaces. Therefore, for the first component of the plurality of order components, the step of imaging with the first sensitivity, and for the second component having a higher order than the first component of the plurality of order components. Therefore, it is characterized by including a step of performing imaging with a second sensitivity higher than that of the first sensitivity.

The invention according to claim 12 is a plurality of imaging devices including a filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to an optical distance between the pair of reflecting surfaces. The step of imaging the first component of the order components with the first sensitivity, and the second component having a higher order than the first component of the plurality of order components. It is characterized in that the step of performing imaging with a second sensitivity higher than the sensitivity of 1 is executed.

It is a block diagram of the image pickup apparatus which concerns on Example 1. FIG. It is sectional drawing of the optical filter of the image pickup apparatus which concerns on Example 1. FIG. It is a block diagram of the control part of the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the example of the spectrum of the transmitted light of the optical filter in the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the relationship between the characteristic of the optical filter in the image pickup apparatus which concerns on Example 1, and the peak wavelength for each order component of transmitted light. It is a figure which shows the example of the control table of the control part in the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the relationship between the image pickup wavelength region and the characteristic of an optical filter in the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the operation flow of the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the relationship between the luminance value and the image pickup sensitivity for each wavelength region in the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the timing chart of the operation state of the image pickup apparatus which concerns on Example 1. FIG. It is a figure which shows the other operation flow of the image pickup apparatus which concerns on Example 1. FIG. It is a block diagram of the image pickup apparatus which concerns on Example 2. FIG. It is a figure which shows the example of the control table of the control part in the image pickup apparatus which concerns on Example 2. FIG. It is a figure which shows the timing chart of the operation state of the image pickup apparatus which concerns on Example 2. FIG.

Examples of the present invention will be described in detail below.

FIG. 1A is a diagram schematically showing the configuration of the image pickup apparatus 10 according to the first embodiment. The overall configuration of the image pickup apparatus 10 will be described with reference to FIG. 1A. In this embodiment, the image pickup apparatus 10 is a spectroscopic camera that captures an image while dispersing the incident light L1 from the object to be imaged (subject to be imaged, hereinafter simply referred to as an object) OB. The image pickup apparatus 10 includes an optical filter (hereinafter, simply referred to as a filter) 11 and an image pickup unit 12.

The filter 11 selectively transmits the incident light L1 from the object OB and outputs the transmitted light L2. The image pickup unit 12 receives the transmitted light L2 of the filter 11 and takes an image. For example, the image pickup unit 12 includes an image sensor (imaging element) including a plurality of photoelectric conversion elements (not shown) arranged in a matrix. Each of the plurality of photoelectric conversion elements receives the transmitted light L2 and generates an electric signal corresponding to the transmitted light L2. The electric signal generated by each of the plurality of photoelectric conversion elements becomes pixel information (luminance value) of the image.

Further, in the present embodiment, the image pickup apparatus 10 is connected to an optical diaphragm (hereinafter, simply referred to as a diaphragm) 13 for adjusting the amount of incident light L1 from the object OB and an image pickup unit 12 of the transmitted light L2 of the filter 11. It has an optical shutter 14 for adjusting the exposure time of the light. The optical shutter 14 may be an electronic shutter integrated with the imaging unit 12.

Further, in this embodiment, the image pickup apparatus 10 has a light receiving optical system 15 that receives the incident light L1 from the object OB. For example, the light receiving optical system 15 includes a lens group (not shown) including a plurality of lenses including an objective lens. For example, the incident light L1 from the object OB received by the light receiving optical system 15 is light that is reflected by the object OB and incident on the light receiving optical system 15.

Further, in this embodiment, the image pickup apparatus 10 has a relay optical system 16 that relays the incident light L1 received by the light receiving optical system 15. In this embodiment, the relay optical system 16 has a pair of lenses 16A and 16B provided on the optical axis of the light receiving optical system 11. In this embodiment, the lens 16A is provided on the light receiving optical system 15 side (object OB side) of the lens 16B.

In this embodiment, the diaphragm 13 is provided between the light receiving optical system 15 and the relay optical system 16. Further, the filter 11 is provided between the lens 16A and the lens 16B in the relay optical system 16. Further, the shutter 14 is provided between the relay optical system 16 and the image pickup unit 12.

For example, the entire filter 11, the imaging unit 12, the aperture 13, the shutter 14, the light receiving optical system 15, and the relay optical system 16 can be housed in one housing as a camera unit CU.

Further, the image pickup apparatus 10 has a control unit 17 that controls the camera unit CU. In this embodiment, the control unit 17 controls the operations of the filter 11, the imaging unit 12, the aperture 13 and the shutter 14. In this embodiment, the control unit 17 generates a control signal for controlling each of the filter 11, the imaging unit 12, the aperture 13 and the shutter 14, and supplies them to each of them. Further, in this embodiment, the control unit 17 receives a signal indicating an image captured by the image pickup unit 12.

Further, in this embodiment, the image pickup apparatus 10 has a monitor 18 that displays an image captured by the image pickup unit 12. The monitor 18 receives from the control unit 17 a set of electric signals generated by each of the photoelectric conversion elements of the imaging unit 12 as an image signal IM, and images and displays the image signal IM.

FIG. 1B is a cross-sectional view of the filter 11. The configuration of the filter 11 and the control unit 17 will be described with reference to FIG. 1B. The filter 11 has a pair of reflective films (first and second reflective films) 23 and 24 that face each other at an optical distance GP. Specifically, the first and second reflective films 23 and 24 have reflective surfaces M1 and M2 facing each other. The optical distance GP is the optical distance between the pair of reflecting surfaces M1 and M2.

Further, in this embodiment, the filter 11 is configured such that the optical distance GP between the first and second reflective films 23 and 24 is variable. The control unit 17 changes the optical distance GP.

More specifically, in this embodiment, the filter 11 has a pair of translucent substrates (first and second substrates) 21 and 22 facing each other. The first and second substrates 21 and 22 are made of, for example, quartz, borosilicate glass, silicon and the like. Further, the first and second substrates 21 and 22 have a flat plate shape. In addition, in this specification, translucency means a characteristic which transmits at least a part of electromagnetic waves including light (visible light).

Further, the first and second substrates 21 and 22 have a pair of surfaces facing each other with a gap. The first and second reflective films 23 and 24 are formed on the surfaces of the first and second substrates 21 and 22, respectively. In the first and second reflective films 23 and 24, the reflective surfaces M1 and M2 facing each other face each other with an optical distance GP.

The first and second reflective films 23 and 24 of the filter 11 have an optical resonator due to their opposing reflective surfaces M1 and M2. In this embodiment, the first and second reflecting surfaces M1 and M2 constitute Fabry-Perot Etalon. Further, the first and second reflective films 23 and 24 form a filter unit (wavelength selection unit) FF in the filter 11. The first and second reflective films 23 and 24 are thin films made of, for example, Ag and an alloy containing Ag, and are transparent reflective films (reflective films).

In this embodiment, each of the first and second reflective films 23 and 24 has a circular shape. Further, the centers of the first and second reflective films 23 and 24 are arranged on the optical axis of the incident light L1. Further, each of the first and second reflective films 23 and 24 is arranged perpendicular to the optical axis of the incident light L1. Further, the first and second reflective films 23 and 24 are formed and arranged so that their surfaces facing each other are parallel to each other.

In this embodiment, the incident light L1 is incident on the filter 11 via the first substrate 21. The incident light L1 passes through the first substrate 21 and then passes through the first reflective film 23. Further, the incident light L1 repeats multiple reflections between the first and second reflective films 23 and 24.

At this time, of the incident light L1, light having a wavelength corresponding to the optical distance GP (optical gap) between the first and second reflective films 23 and 24 remains, and light having other wavelengths is attenuated. The light having the remaining wavelength passes through the second reflective film 24 as transmitted light L2. Then, the transmitted light L2 passes through the second substrate 22 and is emitted from the second substrate 22. In this way, the filter 11 transmits (outputs) the incident light L1 (incident electromagnetic wave) wavelength-selectively.

Further, in this embodiment, the first substrate 21 of the filter 11 moves along the optical axis of the incident light L1 and displaces the first reflective film 23 relative to the second reflective film 24. It has a movable portion 21A to be made to move. In this embodiment, the first substrate 21 has a thin film portion (film-like) having a smaller plate thickness than the other portions. In this embodiment, the inner portion of the thin film portion functions as the movable portion 21A. The first reflective film 23 is formed on the movable portion 21A of the first substrate 21.

Further, the filter 11 is a pair of electrodes (first and second electrodes) formed on the surfaces of the first and second substrates 21 and 22 so as to surround the first and second reflective films 23 and 24, respectively. ) 25 and 26. The first and second electrodes 25 and 26 generate an electrostatic force that moves the movable portion 21A and displaces the first reflective film 23 along the optical axis of the incident light L1. In this embodiment, the control unit 17 generates a drive voltage (filter drive voltage) VF applied between the first and second electrodes 25 and 26.

When a voltage is applied between the first and second electrodes 25 and 26, an electrostatic force (for example, electrostatic attraction) is generated between the first and second electrodes 25 and 26. In this embodiment, the thin film portion around the movable portion 21A is elastically deformed by the electrostatic force. As a result, the movable portion 21A moves together with the first reflective film 23 and the first electrode 25 along the direction perpendicular to the second reflective film 24 (for example, toward the second substrate 22).

In other words, the filter 11 has a pair of reflective films 23 and 24 (reflecting surfaces M1 and M2) facing each other at an optical distance GP and having a variable optical distance GP. Therefore, the filter 11 has a function of changing the wavelength of the transmitted electromagnetic wave (transmitted light L2). That is, the filter 11 is a tunable wavelength selection filter. Further, the control unit 17 controls the optical distance GP between the first and second reflective films 23 and 24 in the filter 11 and controls the wavelength selection characteristic of the filter 11.

FIG. 2A is a block diagram of the control unit 17. The control unit 17 has a filter control unit 31 that controls the filter 11. The filter control unit 31 generates a drive voltage VF that drives the filter 11, and supplies the drive voltage VF to the filter 11.

The control unit 17 stores the peak wavelength of the transmitted light L2 transmitted through the filter 11 in association with the drive state (drive voltage VF) of the filter 11 for each order (hereinafter, simply referred to as a storage unit) 32. Has.

Here, the transmitted light L2 and its order component will be described with reference to FIGS. 2B and 2C. First, FIG. 2B is a diagram showing a spectral transmittance characteristic of the filter 11, that is, a spectrum example of transmitted light L2 when white light having a constant intensity for each wavelength is incident. First, as shown in FIG. 2B, the transmitted light L2 can be divided into a plurality of order components having an intensity peak in a wavelength region corresponding to the optical distance GP between the first and second reflective films 23 and 24. ..

The order component of the transmitted light L2 is, for example, the peak of the intensity appearing in the transmitted light L2 as the center wavelength (peak wavelength) of the component, and from the center wavelength to the position where the intensity becomes a predetermined value (for example, half value). It can be defined as a wavelength region component including a region. For example, in the case shown in FIG. 2B, the transmitted light L2 can be decomposed into three components LC1 to LC3.

The first component LC1 is a component on the longest wavelength side of the transmitted light L2, and is hereinafter referred to as a primary component. The primary component LC1 has a first wavelength λ1 as a peak wavelength. The second component LC2 is a component on the long wavelength side next to the first component LC1 in the transmitted light L2, and is hereinafter referred to as a secondary component. The secondary component has a second wavelength λ2 shorter (smaller) than the first wavelength λ1 as a peak wavelength.

The peak wavelength of each component (for example, the first and second wavelengths λ1 and λ2) can be calculated based on the optical distance GP between the first and second reflective films 23 and 24. For example, the peak wavelength of the primary component LC1 is determined by considering a value (2GP) twice the optical distance GP and a predetermined coefficient. Further, the peak wavelength of the secondary component LC2 and the peak wavelength of the tertiary component LC3, which are higher-order components than the primary component LC1, correspond to twice and three times the peak wavelength of the primary component LC1, respectively.

In reality, there is a component of incident light L1 that is obliquely incident on the filter 11. Further, the reflecting surfaces M1 and M2 are not completely parallel planes. Due to these factors, the peak wavelengths of the secondary and tertiary components LC2 and LC3 are not exactly twice and three times the peak wavelength of the primary component L1, respectively. However, in the present specification, for the sake of clarity of explanation, an ideal state is assumed for explanation.

As described above, the filter 11 has a property of transmitting light having a plurality of order components (for example, components LC1 to LC3) having different peak wavelengths according to the optical distance GP as transmitted light L2.

Next, FIG. 2C is a diagram showing the relationship between the drive voltage VF of the filter 11 and the peak wavelength of the transmitted light L2. FIG. 2C is a diagram showing changes in the peak wavelengths λ1 and λ2 of the primary component LC1 and the secondary component LC2 when the drive voltage VF of the filter is changed.

FIG. 2C is a diagram showing an example of changes in the peak wavelengths λ1 and λ2 when the optical distance GP between the reflective films 23 and 24 in the filter 11 is configured to be smaller as the applied drive voltage VF is larger. Is. Further, although the transmitted light L2 actually contains a higher-order component than the secondary component LC2, FIG. 2C shows only the changes of the primary component LC1 and the secondary component LC2.

In this embodiment, the filter 11 is a tunable wavelength optical filter in which the peak wavelength of the transmitted light L2 changes (moves) depending on the drive voltage VF. Therefore, within the variable region of the filter 11, light having a wavelength to be imaged may be transmitted as the primary component LC1 or may be transmitted as the secondary component LC2.

Specifically, first, as shown in FIG. 2C, when the drive voltage VF of the voltage value Va is applied to the filter 11, the primary component LC1 having the peak wavelength of the wavelength λa1 and the peak wavelength of the wavelength λa2 2 The next component LC2 passes through the filter 11 as transmitted light L2.

Therefore, when transmitting transmitted light L2 having a peak wavelength of wavelength λb, the characteristics of the filter 11 should be adjusted so that any order component of transmitted light L2 has a peak wavelength at wavelength λb within an adjustable range. Just do it. Specifically, for example, by applying the drive voltage VF of the voltage value Vb1 to the filter 11, it is possible to obtain the transmitted light L2 in which the primary component LC1 has a peak wavelength at the wavelength λb. On the other hand, by applying the voltage value Vb2 to the filter 11, it is possible to obtain transmitted light L2 in which the secondary component LC2 has a peak wavelength at the wavelength λb.

The storage unit 32 has a central wavelength (for example, wavelengths λ1 and λ2) of each order component (for example, components LC1 and LC2) of the drive voltage VF of the filter 11 and the corresponding transmitted light L2 as shown in FIGS. 2B and 2C. ) Is memorized.

Referring to FIG. 2A again, the control unit 17 has an image pickup control unit 33 that controls the image pickup unit 12. The image pickup control unit 33 generates a drive voltage (imaging drive voltage) for driving the image pickup unit 12 (for example, each of the photoelectric conversion elements), and supplies this to the image pickup unit 12. Further, the image pickup control unit 33 receives an electric signal (image signal) obtained by the image pickup unit 12 taking an image of the object OB.

The control unit 17 has a target light setting unit 34 that sets a target light that is a degree component of the transmitted light L2 that the image pickup unit 12 targets (detection target). The target light setting unit 34 selects any one of the order components of the transmitted light L2 (for example, the first to third components LC1 to LC3) as the target light. The target light setting unit 34 sets the image pickup unit 12 (imaging control unit 33) to take an image of the target light.

A general image sensor has sensitivity over a predetermined wavelength range, and captures all the light in the wavelength range to generate an electric signal. In other words, when the image pickup unit 12 is configured by using a general image pickup device, it is not possible to capture only light in a specific wavelength range within the predetermined wavelength range. Therefore, the imaging device 10 may need to have a filter (not shown) for removing the order component of the transmitted light L2 other than the target light, depending on the imaging wavelength range.

For example, in order for the imaging unit 12 to image only the target light, it may be necessary to use a fixed wavelength filter such as a low-pass filter that cuts non-target order components. For example, when the primary component LC1 is taken into the image sensor as the target light, the low-pass filter may be configured so as to cut the secondary component LC2 and higher-order components.

However, as will be described later, by appropriately setting the imaging wavelength range, the divided wavelength range, the order component (target light) selected in the divided wavelength range, the sensitivity range of the image sensor, and the like. It is possible to eliminate the need for a member for removing a non-target component as described above.

The imaging unit 12 performs imaging using one component set by the target light setting unit 34 as the target light among the plurality of order components of the transmitted light L2.

The control unit 17 has a sensitivity setting unit 35 that sets the imaging sensitivity of the imaging unit 12 based on the target light of the transmitted light L2 set by the target light setting unit 34. The sensitivity setting unit 35 sets the signal amplification factor (gain) when the imaging unit 12 converts the transmitted light L2 into an electric signal based on the target light (order component) of the transmitted light L2. The sensitivity setting unit 35 issues a command to the imaging unit 12 (imaging control unit 33) to perform imaging with the set sensitivity.

Here, the imaging sensitivity of the imaging unit 12 for each order component of the transmitted light L2 set by the sensitivity setting unit 35 will be described again with reference to FIG. 2B. As shown in FIG. 2B, the primary component LC1 of the transmitted light L2 has a bandwidth of a first width W1 (half width in this embodiment). Further, the secondary component LC2 has a bandwidth of a second width W2 that is narrower (smaller) than the first width W1 which is the bandwidth of the primary component LC1.

Due to this, the primary component LC1 which is the order component on the longest wavelength side (low order) of the transmitted light L2 has the largest amount of light among the components of the transmitted light L2. Further, the larger the order of the component, the smaller the amount of light of the component. Therefore, when the light of the higher-order component is imaged, the image becomes darker than when the light of the lower-order component is imaged.

The sensitivity setting unit 35 sets the imaging sensitivity (gain) of the imaging unit 12 in consideration of the difference in the amount of light for each order component of the transmitted light L2 based on the characteristics of the filter 11. Specifically, the sensitivity setting unit 35 photographs a reference subject having a flat spectrum such as white light in advance, and the luminance values of the reference subject at the time of imaging are continuous (match) between the order components. As described above, the imaging sensitivity for each order component is set. As a result, it is possible to prevent the spectral information from becoming discontinuous before and after switching the order component of the transmitted light L2 at the time of imaging.

Further, in the present embodiment, the target light setting unit 34 of the control unit 17 divides the imaging wavelength region into a plurality of wavelength regions (divided wavelength regions), and the imaging unit 12 has any order in the divided wavelength regions. Set whether to capture the component as the target light. In the following, the boundary between adjacent wavelength regions in the divided plurality of wavelength regions may be referred to as a degree switching wavelength.

FIG. 2D is a diagram showing an example of a control table of the filter 11 and the imaging unit 12 included in the control unit 17. FIG. 2E is a diagram schematically showing the relationship between the wavelength ranges R1 and R2 obtained by dividing the imaging wavelength range TW, the order switching wavelength λS which is the boundary thereof, and the drive voltage VF of the filter 11 corresponding thereto. The control unit 17 controls the filter 11 and the imaging unit 12 based on, for example, a table as shown in FIG. 2D.

In FIG. 2D, the imaging wavelength range TW of the imaging device 10 (imaging unit 12) is set in the range of 400 nm to 750 nm, and the wavelength range R1 which is the wavelength range in which the primary component LC1 is imaged as the target light TC is 600 nm to 750 nm. An example is shown in the case where the wavelength range R2, which is the wavelength range in which the secondary component LC2 is imaged as the target light TC, is set in the range of 400 nm to 600 nm. That is, in the example shown in FIG. 2D, the order switching wavelength λS is set to 600 nm.

The imaging wavelength range TW can be set by, for example, the initial setting of the imaging device 10, or can be set by the designation from the operator.

First, the set imaging wavelength range TW is classified (divided) according to the order component of the transmitted light L2 used for imaging. For example, the imaging wavelength region TW is divided into a plurality of divided wavelength regions (for example, the first and second wavelength regions R1 and R2) in consideration of the variable range of the transmission characteristic of the filter 11 and the sensitivity range of the imaging unit 12. Will be done.

For example, the first wavelength region R1 is a wavelength region in which it is preferable to adjust the filter 11 so that the light in the first wavelength region R1 is transmitted as the primary component LC1 of the transmitted light L2. When obtaining an image within the range of the first wavelength region R1, the target light setting unit 34 sets the primary component LC1 of the transmitted light L2 as the target light TC of the imaging unit 12. Further, the filter control unit 31 is based on the information stored in the storage unit 32 so that the light within the range of the first wavelength region R1 is transmitted to the filter 11 as the primary component LC1 of the transmitted light L2. Control the filter 11.

Within the first wavelength region R1, for example, the filter control unit 31 gradually changes the drive voltage VF of the filter 11 from the voltage value VF1 to the VF2, and changes the optical distance GP from the distance GP1 to GP2. Further, the sensitivity setting unit 35 sets the first sensitivity (amplification rate or gain) SE1 as the image sensitivity SE of the image pickup unit 12. The image pickup control unit 33 controls the image pickup unit 12 with the first sensitivity SE1.

On the other hand, the second wavelength region R2 is a wavelength region on the shorter wavelength side than the first wavelength region R1. Further, the second wavelength region R2 is a region in which the filter 11 is preferably adjusted to have a characteristic of transmitting light in the second wavelength region R2 as a secondary component LC2 of the transmitted light L2.

When obtaining an image within the range of the second wavelength region R2, the target light setting unit 34 sets the secondary component LC2 of the transmitted light L2 as the target light TC of the imaging unit 12. Further, the filter control unit 31 filters based on the information stored in the storage unit 32 so that the light within the range of the second region R2 is transmitted to the filter 11 as the secondary component LC2 of the transmitted light L2. 11 is controlled.

Within the second wavelength region R2, for example, the filter control unit 31 gradually changes the drive voltage VF of the filter 11 from the voltage value VF3 to VF4, and changes the optical distance GP from the distance GP3 to GP4. Further, the sensitivity setting unit 35 sets the image sensitivity SE of the image pickup unit 12 to a second sensitivity (amplification rate or gain) SE2 higher than the first sensitivity SE1. The image pickup control unit 33 controls the image pickup unit 12 with the second sensitivity SE2. The control unit 17 of the image pickup apparatus 10 sets the control of the filter 11 and the image pickup unit 12 in this way.

The division reference of the imaging wavelength region TW can be set in advance based on the variable region of the characteristics of the filter 11 (that is, the optical distance GP). For example, when trying to transmit a transmitted light L2 having a relatively short wavelength as the primary component LC1, it is necessary to make the optical distance GP relatively small. In this case, a foreign substance that can be mixed between the reflective films 23 and 24 In some cases, the influence of the above cannot be ignored, or in some cases, a high drive voltage VF cannot be applied to the filter 11.

Further, when trying to transmit a transmitted light L2 having a relatively long wavelength as a high-order component, for example, a secondary component, it is necessary to greatly change the optical distance GP, and the parallelism of the reflecting surfaces M1 and M2 can be maintained. It will be difficult. As described above, for example, it is not preferable that the filter 11 is required to have high performance in order to satisfy these constraint conditions. The imaging wavelength range TW can be determined, for example, according to the characteristics of such a filter 11. The imaging wavelength range TW may be divided into three or more wavelength ranges.

FIG. 3 is a diagram showing an operation flow of the image pickup apparatus 10. The operation flow of the image pickup apparatus 10 will be described with reference to FIG. First, the control unit 17 determines the imaging wavelength range TW (step S11). The control unit 17 determines the imaging wavelength range TW, that is, the wavelength range (for example, upper limit and lower limit) for obtaining spectral information. For example, the imaging wavelength region TW may be the maximum imaging region included in the imaging apparatus 10, or may be the imaging region designated by the operator.

Subsequently, the control unit 17 divides the imaging wavelength region TW into the first and second wavelength regions (divided wavelength regions) R1 and R2. Further, the target light setting unit 34 of the control unit 17 sets the order component of the transmitted light L2 to be imaged for each of the first and second wavelength regions R1 and R2 (step S12).

Next, the control unit 17 controls the imaging unit 12 and sets a predetermined sensitivity SE0 as the reference sensitivity (step S13). Further, the control unit 17 controls the filter 11 and drives the filter 11 so that the characteristics change over the entire region of the imaging wavelength region TW. Then, the control unit 17 controls the image pickup unit 12 and takes an image of a reference subject in the imaging wavelength range TW with the reference sensitivity SE0. Further, the control unit 17 acquires the spectrum of the imaged reference subject as the reference spectrum from the image pickup unit 12 (step S14).

Specifically, the image pickup apparatus 10 uses, for example, white illumination light or a blank sheet of paper illuminated by the white illumination light as a reference subject, and images the reference subject with a predetermined sensitivity SE0. At this time, the filter 11 is driven by the control unit 17 so as to be transmitted by the order component corresponding to the divided wavelength region over the entire imaging wavelength region TW including the divided wavelength regions R1 and R2.

As a result, the control unit 17 acquires and stores as a reference spectrum a spectrum (luminance value) at the reference sensitivity SE0 for each order component, that is, for each of the wavelength regions R1 and R2. In this embodiment, the reference sensitivity SE0 is set to be common (constant value) over the entire imaging wavelength range TW. Further, the reference sensitivity SE0 is preferably set relatively large within a range in which the brightness value obtained when the primary component LC1 which is the lowest order component is used is not saturated.

Subsequently, the sensitivity setting unit 35 sets the image sensitivity SE of the image pickup unit 12 for each of the first and second divided wavelength regions R1 and R2 (step S15). The imaging sensitivity SE can be set based on, for example, the reference spectrum acquired in step S14.

Here, the imaging sensitivity SE set by the sensitivity setting unit 35 will be described with reference to FIG. 4A. FIG. 4A is a diagram schematically showing a reference spectrum (luminance value) of a reference subject obtained for each of the divided wavelength regions R1 and R2.

The brightness of the reference subject for each of the divided wavelength regions R1 and R2 is affected by the full width at half maximum due to the order component of the target. In other words, when a subject originally having a constant spectrum as a reference subject is imaged with different order components as the target light TC, the brightness of the obtained images (pixels) is different from each other.

Therefore, for example, as shown in FIG. 4A, the luminance of the reference subject shows a substantially constant luminance value BR1 in the divided wavelength region R1, that is, in the range in which imaging is performed using the primary component LC1. On the other hand, in the divided wavelength region R2 in which imaging is performed using the secondary component LC2 higher than the primary component LC1, the luminance value BR2 is substantially constant and lower than the luminance value BR1. Further, the reference spectrum has a step at the boundary between the divided wavelength regions R1 and R2. The sensitivity setting unit 35 sets the imaging sensitivity SE for each of the divided wavelength regions R1 and R2 of the imaging unit 12 based on the brightness values BR1 and BR2.

For example, the sensitivity setting unit 35 sets the first and second sensitivities SE1 and SE2 so that the brightness values BR1 and BR2 in the divided wavelength regions R1 and R2 match. Specifically, the sensitivity setting unit 35 sets the second sensitivity SE2 higher than the first sensitivity SE1 according to the equation SE2 = SE1 × (BR1 / BR2). As a result, as shown in FIG. 4A, the imaging sensitivity SE can be set so that the luminance value in the divided wavelength region R2 is the same as the luminance value BR1 in the divided wavelength region R1.

Considering that accurate spectral information can be obtained over the entire imaging wavelength range TW, it is preferable that the first sensitivity SE1 is set so that the brightness value when the reference subject is imaged is not saturated. That is, as shown in FIG. 4A, it is preferable that the luminance value BR1 of the reference subject in the divided wavelength region R1 is set to be less than the saturation luminance value BR0. In this way, the sensitivity setting unit 35 sets the imaging sensitivity SE of the imaging unit 12 of the divided wavelength regions R1 and R2.

Further, as the reference subject used when setting the sensitivity, it is preferable that the reference subject has a flat reflection spectrum over the entire imaging wavelength range TW, such as the above-mentioned white light or blank paper.

Referring to FIG. 3 again, the filter control unit 31 and the image pickup control unit 33 of the control unit 17 control the filter 11 and the image pickup unit 12 with the characteristics set for each divided wavelength range. The filter 11 and the imaging unit 12 (and the aperture 13 and the shutter 14) are driven and controlled by the control unit 17, and the imaging operation is performed.

Specifically, first, for the first divided wavelength region R1 in which the primary component LC1 is the target light TC, the imaging sensitivity SE of the imaging unit 12 is set to the first sensitivity SE1 of the object OB. Imaging is performed (step S16). Next, for the second divided wavelength region R2 in which the secondary component LC2 is the target light TC, the imaging sensitivity SE of the imaging unit 12 is set to the second sensitivity SE2, and the object OB is imaged ( Step S17).

Subsequently, the control unit 17 receives the image signal IM from the image pickup unit 12 and stores it (step S18). For example, the control unit 17 performs appropriate processing on the image signal IM in response to a request from the operator, and supplies a two-dimensional image of a specific wavelength, spectrum information of a specific pixel, and the like to the monitor 18. The monitor 18 performs a display process of these information (step S19). In this way, the image pickup apparatus 10 performs the image pickup operation.

FIG. 4B is an example of a timing chart of the drive voltage VF supplied to the filter 11 at the time of imaging by the imaging unit 12, the optical distance GP of the filter 11, and the imaging sensitivity SE of the imaging unit 12. The timing t1 in FIG. 4 corresponds to the timing of the start of imaging (start of step S15 in FIG. 3).

As shown in FIG. 4B, at the timing t1, the drive voltage VF is set to the voltage value VF1, and the optical distance GP becomes the distance GP1 corresponding to the voltage value VF1. For example, at timing t1, the drive voltage VF is the highest, which results in the smallest optical distance GP. Therefore, at the timing t1, the first and second reflective films 23 and 24 are in the closest state.

Between the timing t1 and the timing t2, the drive voltage VF is supplied to the filter 11 so that the drive voltage VF gradually decreases from the voltage value VF1 to the voltage value VF2. As a result, the optical distance GP gradually increases from the distance GP1 to the distance GP2.

Between the timing t1 and the timing t2, the primary component LC1 of the transmitted light L2 is set as the target light TC, and the first wavelength region R1 is imaged. Therefore, the imaging sensitivity SE of the imaging unit 12 is set to the first sensitivity SE1 (low sensitivity).

For example, in the case of the setting shown in FIG. 2D, at the timing t1, the filter 11 is driven so that the center wavelength (first wavelength λ1) of the primary component LC1 of the transmitted light L2 is 600 nm. Then, at the timing t2, the filter 11 is driven so that the center wavelength of the primary component LC1 is 750 nm.

Next, at the timing t3, imaging of the second wavelength region R2 is started. At this timing t3, the drive voltage VF of the filter 11 is set to the voltage value VF3, and the optical distance GP increases up to the distance GP3. Then, the drive voltage VF gradually decreases until the voltage value VF4 is reached at the timing t4, and the optical distance GP gradually increases until the distance GP4 is reached at the timing t4. Further, between the timing t3 and the timing t4, the imaging sensitivity SE of the imaging unit 12 is set to the second sensitivity SE2 (high sensitivity).

In this embodiment, the case where the filter 11 is a tunable filter has been described, but the filter 11 is not limited to the case where the filter 11 is a tunable filter. For example, the filter 11 may be a fixed wavelength filter. The filter 11 has a property of transmitting light having a plurality of order components (for example, components LC1 to LC2) according to the optical distance GP of the first and second reflective films 23 and 24 as transmitted light L2. good.

Further, in this embodiment, the case where the filter 11 has the first and second reflective films 23 and 24 has been described, but the filter 11 is not limited to the case where the filter 11 has the first and second reflective films 23 and 24. The filter 11 may have a pair of reflecting surfaces M1 and M2 facing each other. The filter 11 may have a characteristic of transmitting light of a plurality of order components according to the optical distance GP between the pair of reflecting surfaces M1 and M2 as transmitted light L2.

Further, in this embodiment, the case where the image pickup device 10 has the control unit 17 has been described, but the image pickup device 10 does not have to have the control unit 17. The image pickup unit 12 of the image pickup apparatus 10 may be configured to take an image with an image pickup sensitivity SE corresponding to the order component (target light TC) of the transmitted light L2 to be imaged.

As described above, the image pickup apparatus 10 has a pair of reflecting surfaces M1 and M2, and has a plurality of order components (for example, a primary component LC1 and a secondary component LC2) according to the optical distance GP between the pair of reflecting surfaces M1 and M2. A filter 11 that transmits light L2 including), and an imaging unit 12 that captures an image using one of the plurality of order components as the target light TC.

Further, when the first component (for example, the primary component LC1) of the plurality of order components is the target light TC, the imaging unit 12 takes an image with the first sensitivity SE1 and is higher than the first component. When the next second component (for example, the secondary component LC2) is the target light TC, the image is taken with the second sensitivity SE2 higher than the first sensitivity SE1.

Therefore, the difference in the brightness of the captured image due to the difference in the half-value width (that is, the amount of light) of the order component of the transmitted light L2 of the filter 11 set (selected) for each wavelength (wavelength range) is suppressed, and the spectral information is accurate. It is possible to provide an image pickup apparatus 10 capable of obtaining the above.

Further, the filter 11 has a configuration in which the peak wavelength of each of the plurality of order components is changed by adjusting the optical distance GP between the pair of reflecting surfaces M1 and M2. Further, when the optical distance GP is adjusted so that the target light TC becomes the first component (for example, the primary component LC1), the imaging unit 12 takes an image with the first sensitivity SE1 and the target light TC becomes the second component. When the optical distance GP is adjusted so as to have the component (for example, the secondary component LC2), the image is taken with the second sensitivity SE2. Therefore, even if the filter 11 is a tunable filter, by adjusting the imaging sensitivity SE according to which order component of the transmitted light L2 the target light TC is, each image (each component or each wavelength). ) Difference in brightness is suppressed.

Further, the imaging wavelength region TW of the imaging unit 12 is divided into a first divided wavelength region R1 and a second wavelength region R2 on the shorter wavelength side than the first divided wavelength region R1. Further, the optical distance GP between the pair of reflecting surfaces M1 and M2 in the filter 11 is the peak of the first component (for example, the primary component LC1) when the imaging unit 12 takes an image of the first divided wavelength region R1. When the wavelength is adjusted to be included in the first divided wavelength region R1 and the imaging unit 12 takes an image of the second divided wavelength region R2, the peak wavelength of the second component (for example, the secondary component LC2) becomes It is adjusted so as to be included in the second divided wavelength region R2.

In other words, even when the filter 11 is driven to obtain continuous spectral information (image), the control unit 17 has a plurality of divided wavelength regions (wavelength region R1 and) according to the order component using the imaging wavelength region TW. It is divided into R2), and the imaging unit 12 is controlled by an imaging sensitivity SE that is different for each divided wavelength range. Therefore, continuous spectral information with a small difference in brightness can be obtained.

Further, in the first and second sensitivities SE1 and SE2, the brightness value obtained when an image of a reference subject (for example, white light) different from the object OB is obtained is between the first and second wavelength ranges R1 and R2 ( For example, it is set to match at the boundary between the two. Therefore, the brightness of the image is substantially constant between the wavelength ranges R1 and R2, that is, between the order components used for imaging.

Further, considering that the sensitivity can be easily and accurately set, the reference subject is preferably a subject having a flat reflection spectrum in the imaging wavelength range TW. In other words, the control unit 17 controls the imaging operation of the imaging unit 12 to image a subject having a flat reflection spectrum in the imaging wavelength range TW as the reference subject prior to imaging the object OB, thereby. It is preferable to set the first and second sensitivities SE1 and SE2. This makes it possible to set an appropriate sensitivity.

Further, for example, as shown in FIG. 4B, the optical distance GP between the pair of reflecting surfaces M1 and M2 in the filter 11 is adjusted only in the direction of gradually increasing. Therefore, the operation of the filter 11 (displacement of the reflective film) is stable.

The configuration, operation flow, and timing chart of the image pickup apparatus 10 described above are merely examples. For example, the image pickup apparatus 10 does not have to have the light receiving optical system 15, the relay optical system 16, and the monitor 18.

Further, the imaging wavelength range TW may be classified into three or more wavelength ranges. Further, the imaging operation by the imaging unit 12 is not limited to the case where the first wavelength region R1 on the longest wavelength side is performed first, and may be performed with an imaging sensitivity SE different for each target light TC.

Further, for example, by going through steps S16 and S17 shown in FIG. 3, it is possible to provide an imaging method using, for example, a filter 11 and an imaging unit 12.

That is, the imaging method according to the present invention has a pair of reflecting surfaces M1 and M2 facing each other, and a plurality of order components (for example, primary components LC1 and 2) according to the optical distance GP between the pair of reflecting surfaces M1 and M2. An imaging method using a filter 11 that transmits light containing the secondary component LC2), in which the first component (for example, the primary component LC1) of the plurality of order components is imaged with the first sensitivity SE1. And the second sensitivity SE2, which is higher than the first sensitivity SE1, with respect to the second component (for example, the secondary component LC2) having a higher order than the first component among the plurality of order components. Includes steps to perform imaging.

Further, for example, the present invention can be realized as a program for causing a general image pickup apparatus to perform the above-mentioned method. That is, the program according to the present invention has a pair of reflecting surfaces M1 and M2 facing each other, and a plurality of order components (for example, primary components LC1 and secondary components) according to the optical distance GP between the pair of reflecting surfaces M1 and M2. A step of imaging a first component (for example, the primary component LC1) of a plurality of order components with a first sensitivity SE1 on an imaging device including a filter 11 that transmits light containing the component LC2). , A step of imaging a second component (for example, a secondary component LC2) having a higher order than the first component among a plurality of order components with a second sensitivity SE2 higher than the first sensitivity SE1. And to execute.

Therefore, it is possible to provide an imaging method and a program capable of accurately obtaining spectral information by suppressing the difference in brightness of the captured image for each wavelength.
[Modification example]
FIG. 5 is a flow chart showing another operation example by the image pickup apparatus 10 as a modification of this embodiment. The image pickup apparatus 10 may operate according to the flow as shown in FIG. That is, the control unit 17 may be configured to control the filter 11, the imaging unit 12, and the like as shown in FIG. The flow shown in FIG. 5 is a preferable imaging operation flow in consideration of obtaining more accurate spectral information of the object OB.

In this modification, the same operation is performed up to step S15 (sensitivity setting) shown in FIG. After setting the sensitivity by the sensitivity setting unit 35, the control unit 17 controls the filter 11 and the imaging unit 12, and in the divided wavelength region R1, the first sensitivity SE1 in the divided wavelength region R1 sets the reference subject (illumination light or the illumination light). An illuminated blank sheet) is imaged and stored (step S21). Next, the control unit 17 controls the filter 11 and the imaging unit 12 to image the reference subject with the second sensitivity SE2 in the divided wavelength region R2 (step S22).

In other words, the imaging unit 12 captures the reference subject under the same conditions as those for imaging the object OB. In addition, steps S21 and 22 may be performed continuously as the same step.

Subsequently, the control unit 17 controls the filter 11 and the imaging unit 12, and performs the same operations as in steps S16 and S17 shown in FIG. That is, the object OB is actually imaged under various set conditions.

Next, the control unit 17 calculates the spectrum of the object OB based on the images of the reference subject and the object OB captured at the same wavelength (step S23). Specifically, in this embodiment, the spectrum obtained by imaging the object OB is obtained by multiplying the reflection spectrum of the object OB by the spectrum of the illumination light, that is, the spectrum of the incident light incident on the object OB. It is a thing.

Therefore, in consideration of obtaining spectral information which is an accurate spectrum of the object OB, the spectrum (brightness value for each wavelength) of the reference subject, for example, the white light (or the white paper illuminated by the white light) described above is used as the target. It is preferable to perform an operation of dividing from the imaging spectrum of the object OB.

In this modification, the brightness value of the reference subject imaged at the spectral wavelength (selected wavelength) at the time of imaging the image is divided for each of the images obtained by spectroscopically and imaging the object OB for each wavelength. As a result, the spectrum (spectral information) of the object OB based on the spectrum of the reference subject is calculated.

The control unit 17 stores the spectrum information of the object OB calculated in step S23 (step S24). This step S24 can be executed, for example, in place of step S18 in FIG. Then, for example, in response to a request from the operator, the spectrum information is displayed (step S19). The image pickup apparatus 10 may perform the image pickup operation in this way.

As described above, the imaging unit 12 images the reference subject with the first and second sensitivities SE1 and SE2 for each of the first and second divided wavelength regions R1 and R2, respectively (steps S21 and S22). .. Then, the control unit 17 calculates the spectrum of the object OB based on the reference subject spectrum obtained for each wavelength (step S23).

In other words, the control unit 17 controls the imaging operation of the imaging unit 12 to image the imaging wavelength range TW of the reference subject different from the object OB prior to imaging the object OB, and the object OB and the subject OB. The reflection spectrum of the object OB is calculated based on the imaging spectrum of the reference subject. Therefore, it is possible to accurately obtain only the spectral information of the object OB. For example, it is possible to minimize the influence of the individual characteristics of the imaging unit 12 and the influence of the quantization error and the dark current on the captured image of the object OB using higher-order components.

Further, also in this modification, in consideration of obtaining accurate spectral information of the object OB, the first and second sensitivities SE1 and SE2 are in a range in which the brightness value obtained when the reference subject is imaged is not saturated. It is preferable to set within. That is, it is preferable that the imaging unit 12 images the object OB with a sensitivity within a range in which the brightness value obtained at the time of imaging the reference subject is not saturated as each of the first and second sensitivities SE1 and SE2. As a result, the brightness value for each pixel in almost all the captured images is not saturated, and the spectral information of the object OB can be obtained more accurately.

FIG. 6A is a block diagram of the image pickup apparatus 40 according to the second embodiment. FIG. 6B is a diagram showing an example of a control table of the camera unit CU by the control unit 41. The image pickup device 40 has the same filter 41, image pickup unit 42, aperture 43, and shutter 44 as the image pickup device 10. Further, the image pickup apparatus 40 has a control unit 45 for controlling them. The control unit 45 has a filter control unit 31, a storage unit 32, an image pickup control unit 33, and a target light setting unit 34 similar to the control unit 17.

Further, in the present embodiment, the control unit 45 controls the diaphragm 43 and adjusts the diaphragm diameter DM of the diaphragm 43, and the diaphragm diameter DM of the diaphragm 43 according to the target light TC of the transmitted light L2. It has a diaphragm diameter setting unit 52 for setting. Further, the control unit 45 sets the shutter control unit 53 that controls the shutter 43 and adjusts the exposure time EX of the transmitted light L2 to the imaging unit 12, and the exposure time EX according to the target light TC of the transmitted light L2. It has an exposure time setting unit 54.

In other words, the control unit 45 controls the aperture 43 and the shutter 44 according to the order component of the transmitted light L2 to be imaged, and adjusts the amount of the transmitted light L2 imaged by the imaging unit 42.

In this embodiment, when the primary component LC1 is the target light TC, the control unit 45 sets the aperture diameter DM to the first diameter DM1 and operates the image pickup unit 42. On the other hand, when the secondary component LC2 (a component higher than the primary component LC1) is the target light TC, the control unit 45 sets the aperture diameter DM to a second diameter DM2 larger than the first diameter DM1. The imaging unit 42 is operated.

That is, the control unit 45 increases the aperture diameter DM (for example, decreases the aperture value (F value)) as the order of the components of the transmitted light L2 increases. As a result, the control unit 45 increases the amount of transmitted light L2 received by the image pickup unit 42.

Further, in this embodiment, when the primary component LC1 is the target light TC, the control unit 45 sets the exposure time EX to the first time EX1 and operates the imaging unit 12. On the other hand, when the secondary component LC2 (a component higher than the primary component LC1) is the target light TC, the control unit 45 sets the exposure time EX to the second time EX2, which is longer than the first time EX1. The imaging unit 42 is operated.

That is, the control unit 45 lengthens the exposure time EX (for example, slows down the shutter speed) as the order of the components of the transmitted light L2 increases. As a result, the control unit 45 increases the amount of transmitted light L2 received by the image pickup unit 42.

Further, as shown in FIG. 6B, the control unit 45 classifies the imaging wavelength region TW of the imaging apparatus 40 into the first and second wavelength regions R1 and R2. Then, the control unit 45 sets the aperture diameter DM to the first aperture diameter DM1 by the aperture diameter setting unit 52 at the time of imaging of the first wavelength region R1. Further, the control unit 45 sets the exposure time EX to the first time EX1 by the exposure time setting unit 54 at the time of imaging in the first wavelength region R1.

Further, the control unit 45 sets the aperture diameter DM to the second aperture diameter DM2 by the aperture diameter setting unit 52 at the time of imaging of the second wavelength region R2. Further, the control unit 45 sets the exposure time EX to the second time EX2 by the exposure time setting unit 54 at the time of imaging in the second wavelength region R2.

FIG. 7 is an example of a timing chart of the drive voltage VF supplied to the filter 41 at the time of imaging by the imaging unit 42, the optical distance GP of the filter 41, the aperture diameter DM of the aperture 43, and the exposure time EX of the transmitted light L2. At the timings t1 to t4 of FIG. 7, the states of the drive voltage VF and the optical distance GP of the filter 41 change in the same manner as in FIG.

On the other hand, in this embodiment, as shown in FIG. 7, the aperture diameter DM is set to the first diameter DM1 (small diameter) between the timing t1 and the timing t2. Further, between the timing t3 and the timing t4, the aperture diameter DM is set to the second diameter DM2 (large diameter).

Further, between the timing t1 and the timing t2, the exposure time EX is set to the first time EX1 (short time). Further, between the timing t3 and the timing t4, the exposure time EX is set to the second time EX2 (long time).

Considering that the amount of transmitted light L2 received by the imaging unit 42 is adjusted, only one of the aperture diameter DM and the exposure time EX may be adjusted.

As described above, in this embodiment, the image pickup apparatus 40 has an aperture 43 and a shutter 44. Further, the image pickup apparatus 40 sets one order component among the plurality of order components of the transmitted light L2 transmitted through the filter 41 as the target light TC, and sets the aperture diameter DM or the exposure time EX according to the target light TC. It has a control unit 45 that operates the image pickup unit 42.

That is, the image pickup apparatus 40 includes a plurality of filters 41 having a pair of reflecting surfaces M1 and M2 facing each other and transmitting light including a plurality of order components according to the optical distance GP between the pair of reflecting surfaces M1 and M2. The image pickup unit 42 that takes an image with one of the order components of the order light TC as the target light TC, and the aperture diameter DM is adjusted to adjust the amount of light of the incident light L1 to the filter 41, and the image pickup unit 42 has a plurality of orders. When the first component (for example, the primary component LC1) of the components is the target optical TC, the aperture diameter DM is set to the first diameter DM1, and the imaging unit 41 has a higher order than the first component. When the component 2 (for example, the secondary component LC2) is the target light TC, it has an optical diaphragm 43 that sets the diaphragm diameter DM to a second diameter DM2 larger than the first diameter DM1.

Therefore, when imaging each of the plurality of order components of the transmitted light L2 having different light amounts, the difference in brightness of the captured images can be suppressed by adjusting the light amount of the incident light L1.

Further, the image pickup apparatus 40 includes a plurality of filters 41 having a pair of reflecting surfaces M1 and M2 facing each other and transmitting light including a plurality of order components according to the optical distance GP between the pair of reflecting surfaces M1 and M2. The imaging unit 42 that performs imaging with one of the order components of the target light TC as the target light TC, and the exposure time EX of the target light TC to the imaging unit 42 are adjusted, and the imaging unit 42 is among the plurality of order components. When the first component (for example, the primary component LC1) is the target light TC, the exposure time EX is set to the first time EX1, and the imaging unit 42 sets the exposure time EX to the second component (secondary component higher than the first component). For example, when the secondary component LC2) is the target light TC, it has a shutter 44 that sets the exposure time EX to the second time EX2, which is longer than the first time EX1.

Therefore, the amount of light of the transmitted light L2 received by the imaging unit 12 is adjusted by adjusting the exposure time of the plurality of components of the transmitted light L2 having different amounts of light to the imaging unit 12. Can be done. Therefore, it is possible to suppress the difference in brightness of the captured image.

By adjusting the aperture diameter DM or the exposure time EX for each order component of the transmitted light L2 in this way, the difference in brightness of the captured image for each wavelength is suppressed, and an imaging device capable of accurately obtaining spectral information. 40 can be provided.

Further, even when the filter 41 is driven to obtain continuous spectral information (image), in the imaging device 40, the imaging wavelength region TW has a plurality of wavelength regions (wavelength region R1 and It is divided into R2). Further, the aperture 43 or the shutter 44 operates with a different aperture diameter DM or exposure time EX for each wavelength range. Therefore, continuous spectral information with a small difference in brightness can be obtained.

In addition, this Example may be operated in combination with the image pickup apparatus 10 of Example 1. For example, the imaging sensitivity SE of the imaging unit 12 may be adjusted and the aperture diameter DM may be adjusted according to the target light TC of the transmitted light L2.

10, 40 Imaging device 11, 41 Optical filter 12, 42 Imaging unit 13, 43 Optical aperture 14, 44 Shutter

Claims (12)

A filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to the optical distance between the pair of reflecting surfaces.
Each have a, an imaging unit including a plurality of image pickup element according to the first wavelength region and the second imaging wavelength range the wavelength range of the first short wavelength side than the wavelength range,
When imaging in the first wavelength region, the image pickup unit sets the sensitivity of the plurality of image pickup devices to the first sensitivity with the first component of the plurality of order components as the target light. When taking an image in the second wavelength region, the sensitivity of the plurality of image pickup devices is set to be higher than that of the first sensitivity by using a second component higher than the first component as the target light. An image pickup device characterized in that an image is taken by setting a high second sensitivity. The filter, each peak wavelength of the plurality of order components by previous SL optical science distance is adjusted has a configuration that varies,
When the optical distance is adjusted so that the target light becomes the first component, the imaging unit takes an image with the first sensitivity, and the target light becomes the second component. The imaging device according to claim 1, wherein when the optical distance is adjusted, imaging is performed with the second sensitivity. Before Symbol Light Science distance in the filter, when the imaging unit captures an image of the first wavelength region is adjusted such that the peak wavelength of said first component is included in the first wavelength region, The second aspect of claim 2, wherein when the imaging unit performs imaging in the second wavelength region, the peak wavelength of the second component is adjusted so as to be included in the second wavelength region. Imaging device. The first and second sensitivities are characterized in that the brightness values obtained when an image of a reference subject different from the imaged object is imaged are set so as to match between the first and second wavelength ranges. The imaging apparatus according to claim 3. The imaging operation of the imaging unit is controlled, and a subject having a flat reflection spectrum in the imaging wavelength range is imaged as the reference subject prior to imaging the imaged object, thereby reducing the first and second sensitivities. The imaging apparatus according to claim 4, further comprising a control unit to be set. By controlling the imaging operation of the imaging unit, imaging of the imaging wavelength range of a reference subject different from the imaging object is performed prior to imaging the imaging object, and based on the imaging spectrum of the imaging object and the reference subject. The imaging apparatus according to claim 3, further comprising a control unit for calculating a reflection spectrum of the imaged object. The imaging device according to claim 6, wherein the first and second sensitivities are set within a range in which the luminance value obtained when the reference subject is imaged is not saturated. The image pickup apparatus according to prior Symbol optical science distance, any one of claims 3 to 7, characterized in that it is adjusted so as to gradually increase in the filter. A filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to the optical distance between the pair of reflecting surfaces.
An imaging unit that performs imaging using one of the plurality of order components as the target light, and an imaging unit.
When the aperture diameter is adjusted to adjust the amount of light incident on the filter and the imaging unit uses the first component of the plurality of order components as the target light, the aperture diameter is set to the first diameter. When the imaging unit uses a second component higher than the first component as the target light, the aperture diameter is set to a second diameter larger than the first diameter. An imaging device characterized by having an aperture. A filter having a pair of opposing reflecting surfaces and transmitting light containing a plurality of order components according to the optical distance between the pair of reflecting surfaces.
An imaging unit that performs imaging using one of the plurality of order components as the target light, and an imaging unit.
The exposure time of the target light to the imaging unit is adjusted, and when the imaging unit uses the first component of the plurality of order components as the target light, the exposure time is set to the first time. When the imaging unit uses a second component higher than the first component as the target light, a shutter that sets the exposure time to a second time longer than the first time. An imaging device characterized by having. A filter having a pair of reflecting surfaces facing each other and transmitting light containing a plurality of order components according to the optical distance between the pair of reflecting surfaces, and a filter having a first wavelength region and the first wavelength region, respectively. Is an imaging method using an imaging unit including a plurality of imaging elements having a second wavelength region on the short wavelength side as an imaging wavelength region.
When imaging in the first wavelength region, the step of setting the sensitivity of the plurality of image pickup devices to the first sensitivity with the first component of the plurality of order components as the target light and performing imaging. When,
When imaging in the second wavelength region, the sensitivity of the plurality of image pickup devices is higher than that of the first sensitivity by using a second component higher than the first component as the target light. An imaging method including a step of setting the sensitivity of the image to perform imaging. A filter having a pair of reflecting surfaces facing each other and transmitting light containing a plurality of order components according to the optical distance between the pair of reflecting surfaces, and a filter having a first wavelength region and the first wavelength region, respectively. In an imaging device including an imaging unit including a plurality of imaging elements having a second wavelength region on the short wavelength side as an imaging wavelength region .
When imaging in the first wavelength region, the step of setting the sensitivity of the plurality of image pickup devices to the first sensitivity with the first component of the plurality of order components as the target light and performing imaging. When,
When imaging in the second wavelength region, the sensitivity of the plurality of image pickup devices is higher than that of the first sensitivity by using a second component higher than the first component as the target light. A program characterized by executing the steps of setting the sensitivity of the image sensor and performing imaging.

Images