JP6927708B2 - Imaging equipment, imaging methods, programs and recording media - Google Patents

Description

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

As an imaging device for photographing a subject, a spectroscopic camera that acquires a plurality of spectral information and generates an image based on the acquired spectral information is used. As a means for acquiring spectral information, a wavelength selection filter that changes the transmission wavelength according to the applied voltage is used. For example, a camera equipped with a wavelength tunable filter control device has been proposed in which capacitive electrodes are formed on two optical substrates constituting a tunable filter, and the capacitance depending on the substrate spacing is detected and controlled to maintain the target spacing. (For example, Patent Document 1).

JP-A-2002-277758

When operating a spectroscopic camera having a wavelength selection filter, it is desirable to be able to monitor whether light of a desired wavelength is actually transmitted. However, the above-mentioned conventional spectroscopic camera has a problem that the wavelength of light passing through a wavelength tunable filter (wavelength selection filter) cannot be monitored.

As an example of the problem to be solved by the present invention, there is a problem that the wavelength of light transmitted through the wavelength selection filter cannot be monitored.

The invention according to claim 1 is provided with an optical system that collects light from a subject, an image pickup element that receives light collected by the optical system, and an applied voltage on the optical path of the optical system. A first wavelength selection unit that selectively transmits light having a wavelength corresponding to the distance by changing the distance between the pair of reflecting surfaces according to the distance, and an irradiated light provided within the image pickup angle of the image pickup element. A diffuser plate that reflects or transmits, and a second wavelength selection unit that receives light reflected by the diffuser plate or light transmitted through the diffuser plate and selectively transmits light having a wavelength corresponding to the light receiving position. It is characterized by having.

The invention according to claim 8 is the imaging method using the imaging apparatus according to claim 1, wherein the step of changing the applied voltage, the step of irradiating the diffuser with light, and the step of being reflected by the diffuser are reflected. The step of receiving the light transmitted through the first wavelength selection unit among the light transmitted through the diffuser plate or the light transmitted through the first wavelength selection unit by the second wavelength selection unit, and the light transmitted through the second wavelength selection unit are received by the image pickup element. It is characterized by having a step of receiving light and a step of detecting the wavelength of light transmitted through the first wavelength selection unit based on the wavelength of light transmitted through the second wavelength selection unit.

The invention according to claim 9 is the image pickup apparatus according to claim 1, wherein the computer is subjected to a step of changing the applied voltage, a step of irradiating the diffuser with light, and light reflected by the diffuser. Alternatively, the step of receiving the light transmitted through the first wavelength selection unit among the light transmitted through the diffuser plate by the second wavelength selection unit and the light transmitted through the second wavelength selection unit are received by the image pickup element. It is characterized in that the step and the step of detecting the wavelength of the light transmitted through the first wavelength selection unit based on the wavelength of the light transmitted through the second wavelength selection unit are executed.

It is sectional drawing which shows the structure of the spectroscopic camera 10 of this invention. It is a figure which shows typically how the light transmitted through an optical system 11 is received by the image sensor 16 and LVF17. It is a figure which shows the arrangement example of the white diffusion plate. It is a figure which shows typically the structure (a) of LVF17 and the spectrum (b) of the transmission wavelength thereof. It is a figure which shows the example of the image of the subject and LVF obtained by the image sensor. It is a flowchart which shows the processing operation of transmission wavelength monitoring processing. It is a figure which shows typically the state of light transmission and light reception when the background of a subject is dark. It is a figure which shows typically the state of light transmission and light reception when there is a traffic light in the background of a subject. It is a figure which shows typically the state of light transmission and light reception when there is a light-dark pattern in the background of a subject. It is a figure which shows the example of the image of the subject and LVF obtained by the image sensor when there is a pattern of light and dark in the background of the subject.

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

FIG. 1 is a cross-sectional view showing the configuration of the spectroscopic camera 10. The spectroscopic camera 10 is, for example, an imaging device that irradiates an object X as a subject with light and receives light reflected from the object X or light transmitted through the object X to perform imaging. The spectroscopic camera 10 has a function of monitoring the wavelength of light that has passed through a wavelength selection filter provided on the optical path.

The spectroscopic camera 10 includes an optical system 11, a lens barrel unit 12, a diffuser plate 13, illumination units 14a and 14b, and a light receiving unit 15.

The optical system 11 includes a first lens L1 and a second lens L2 (imaging lens) made of a convex lens. The first lens L1 is, for example, an objective lens arranged at a position where light from a subject is incident (that is, the incident side of the optical system 11). The second lens L2 is arranged, for example, at a position where light from the subject is emitted (that is, the emission side of the optical system 11). A wavelength selection filter FP is provided at the pupil position of the optical system 11.

The wavelength selection filter FP is composed of, for example, a Fabry-Perot type interference filter. As shown in FIG. 2, the wavelength selection filter FP is composed of reflective films RF1 and RF2, which are a pair of reflective surfaces arranged opposite to each other, and selectively transmits light having a wavelength corresponding to the distance between the reflective films. .. The wavelength selection filter FP sets the wavelength of the transmitted light by receiving the application of the voltage V and changing the distance between the opposing surfaces of the reflection films RF1 and RF2 (hereinafter referred to as the gap GP between the reflection surfaces). It is configured to be possible. The wavelength selection filter FP is arranged, for example, between the first lens L1 and the second lens L2, which are a pair of lenses of the optical system 11.

Referring to FIG. 1 again, the lens barrel portion 12 has a transparent and tubular shape (for example, a trapezoidal tubular shape). One bottom surface of the lens barrel portion 12 is adjacent to the optical system 11, and a subject arrangement region SA and a diffusion plate 13 which are regions for arranging the subject are arranged on the other bottom surface (tip portion).

Since FIG. 1 is a cross-sectional view, the diffusion plate 13 is shown as if it were composed of a pair of plate pieces. However, in reality, as shown in the perspective view of FIG. 3, the diffuser plate 13 is arranged so as to surround the subject arrangement area SA.

Referring to FIG. 1 again, the subject arrangement region SA and the diffuser plate 13 are both positions where the illumination light is irradiated from the illumination units 14a and 14b, and the angle of view AV (that is, the imaging range of the spectroscopic camera 10) is AV (that is,). , The image pickup angle of view of the image pickup element 16) so as not to overlap each other. For example, the diffuser plate 13 is provided on the bottom surface of the lens barrel portion 12 and at a position that is a peripheral portion of the angle of view AV, and the subject arrangement area SA is provided at a position closer to the center portion of the angle of view AV. That is, the diffuser plate 13 is arranged at a position in the angle of view AV where the angle of the optical system 11 with respect to the central axis CA is large, and the subject arrangement area SA is provided at a position where the angle is small. Further, the subject arrangement area SA and the diffuser plate 13 are both provided on the same bottom surface of the lens barrel portion 12, and the distances from the optical system 11 are substantially the same. The diffuser plate 13 is composed of, for example, a white diffuser plate whose spectral reflectance is constant over the entire target wavelength range.

The illumination portions 14a and 14b are provided on the bottom surface of the lens barrel portion 12 opposite to the bottom surface on which the diffuser plate 13 is arranged. The illumination units 14a and 14b are composed of, for example, white illumination that irradiates white light, and have an irradiation angle that uniformly irradiates not only the subject arrangement region SA but also the region where the diffuser plate 13 exists.

The light receiving unit 15 includes an image sensor 16, an LVF (Linear Variable Filter) 17, and a detection unit 18. The image sensor 16 is an element that receives light that has passed through the optical system 11 and converts it into electronic information to obtain an image, and is provided on the optical path of the light that has passed through the optical system 11.

As shown in FIG. 4A, the LVF 17 is composed of a substrate 20 and a thin film 21 having a wedge-shaped thickness change. The LVF 17 is a filter element having a property of linearly changing light having a wavelength to be transmitted according to a position on the filter. For example, when white light including light having wavelengths λ1, λ2, λ3, λ4 and λ5 is incident on LVF17, the light having wavelengths λ1 to λ5 transmits different positions on LVF17, respectively. Therefore, as shown in FIG. 4B, the spectrum of the light transmitted through the LVF 17 has a waveform having a different center wavelength depending on the position on the filter.

That is, the LVF 17 is a filter that selectively transmits light having a wavelength corresponding to the light receiving position, and when the wavelength selection filter FP is a "first wavelength selection filter", the LVF 17 has properties as a "second wavelength selection filter". Has.

Referring to FIG. 1 again, in the LVF 17, after the light reflected by the diffuser plate 13 or the light transmitted through the diffuser plate 13 (hereinafter, these are collectively referred to as the light from the diffuser plate 13) has passed through the wavelength selection filter FP. It is provided on the optical path of. For example, the LVF 17 is provided at the end of the light receiving surface of the image sensor 16 as shown in the figure. The light transmitted through the LVF 17 is received by the image sensor 16.

The detection unit 18 detects the wavelength of the light by confirming which position of the LVF 17 the light that has passed through the wavelength selection filter FP has passed. Specifically, the detection unit 18 determines the wavelength of the light actually transmitted through the wavelength selection filter FP based on the emission line formed in the image at the position corresponding to the LVF 17 in the image obtained by the image sensor 16. To detect.

FIG. 5 is a diagram showing an example of an image of the subject and the LVF 17 obtained by the image sensor 16. An image SP of the subject and an image BP of the background are formed in the central portion of the image. An image WP of the diffuser plate 13 reflected in the angle of view AV is formed on the peripheral edge of the image. Further, an image LP of LVF 17 is formed at a position on the image WP of the diffuser plate 13 at the edge of the image. The detection unit 18 detects which position on the LVF 17 the light that has passed through the wavelength selection filter FP has passed, based on the position of the emission line BL formed on the LP. As a result, the wavelength of the light that has passed through the wavelength selection filter FP is monitored.

Next, the processing operation of the monitoring process will be described with reference to the flowchart of FIG.

First, the applied voltage V applied to the wavelength selection filter is changed to set the gap GP between the reflection surfaces of the wavelength selection filter FP (step S101).

Next, the subject (object X) arranged in the diffuser plate 13 and the subject arrangement area SA is irradiated with illumination light (step S102). The illumination light is reflected (or transmitted) by the subject and the diffuser plate 13 and is incident on the optical system 11. Of the light incident on the optical system 11, light having a wavelength corresponding to the gap GP between the reflecting surfaces of the wavelength selection filter FP passes through the wavelength selection filter FP and is incident on the light receiving unit 15.

The LVF 17 receives the light from the diffuser plate 13 (step S103). The image sensor 16 further receives the light transmitted through the LVF 17 (step S104). Of the light that has passed through the optical system 11, light other than the light received by the LVF 17 is directly received by the image sensor 16 without passing through the LVF 17.

The detection unit 18 detects the wavelength of the light that has passed through the LVF 17 based on the image obtained by the image sensor 16. As a result, the wavelength of the light that has actually passed through the wavelength selection filter FP is detected (step S105).

By the above processing, the wavelength of the light actually passed through the wavelength selection filter FP can be obtained. Therefore, according to the spectroscopic camera 10 of this embodiment, it is possible to monitor the wavelength of the light that has actually passed through the wavelength selection filter FP.

Further, since the spectroscopic camera 10 of this embodiment has a diffuser plate 13 at the peripheral portion in the angle of view AV, the transmission wavelength of the wavelength selection filter FP can be accurately monitored as compared with the spectroscopic camera without the diffuser plate 13. Can be done. FIGS. 7 to 10 are views showing the state of light transmission and light reception when the diffuser plate 13 is not provided for comparison with the present embodiment.

FIG. 7 is a diagram schematically showing how light is transmitted and received when the background of the subject is dark in a spectroscopic camera that does not have a diffuser plate 13, unlike the spectroscopic camera 10 of the present embodiment. The amount of light from the dark background DB (shown as B2 and B3 in the figure) is smaller than the light from the subject along the central axis CA of the optical system 11 (shown as B1 in the figure). Therefore, since a sufficient amount of light for illuminating the LVF 17 is not incident on the LVF 17, the transmitted wavelength cannot be accurately monitored.

FIG. 8 is a diagram schematically showing how light is transmitted and received when there is an object such as a traffic light that emits light having a specific wavelength component in the background of the subject in a spectroscopic camera that also does not have a diffuser plate 13. Is. For example, when light of three kinds of wavelength components is emitted from the traffic light TL, it cannot pass through the wavelength selection filter FP depending on the wavelength of the light (indicated as B3 in the figure) emitted from the position corresponding to LVF17. There is a possibility that the light incident on the LVF 17 will disappear. Therefore, it is also not possible to accurately monitor the transmitted wavelength.

FIG. 9 is a diagram schematically showing the state of light transmission and light reception when there is a light-dark pattern in the background of the subject in a spectroscopic camera that also does not have the diffuser plate 13. The amount of light (B2, B3) from the light / dark background pattern PB is smaller than that of the light (B1) from the subject. Therefore, since a sufficient amount of light for illuminating the LVF 17 is not incident on the LVF 17, the transmitted wavelength cannot be accurately monitored. Further, as shown in FIG. 10, since the emission line BL formed on the image LP of the LVF 17 is an image reflecting the pattern of light and dark, it is not possible to accurately detect and monitor the transmission wavelength.

On the other hand, in the spectroscopic camera 10 of the present embodiment, the diffuser plate 13 is arranged on the peripheral portion (the outer peripheral portion of the subject arrangement region SA) in the angle of view AV, and the wavelength is selected based on the light from the diffuser plate. The wavelength of light that has passed through the filter FP is detected. Therefore, the transmission wavelength can be monitored regardless of the background of the subject.

The embodiment of the present invention is not limited to that shown in the above examples. For example, in the above embodiment, the example in which the diffuser plate 13 is provided on the bottom surface (tip portion) of the lens barrel portion 12 has been described, but the present invention is not limited to this, and the diffuser plate 13 is reflected in the angle of view AV. It suffices if it is retained. At that time, it is desirable that the diffuser plate 13 is held at a position where the distance from the optical system 11 substantially coincides with the distance between the subject arrangement region SA and the optical system 11.

Further, in the above embodiment, an example in which the diffuser plate 13 is composed of a white diffuser plate is shown, but the present invention is not limited to this, and a diffuser reflector plate capable of reflecting or transmitting light in a wide wavelength range is used as the diffuser plate 13. Can be done.

Further, in the above embodiment, an example in which the illumination units 14a and 14b irradiate the subject arranged in the diffuser plate 13 and the subject arrangement area SA with the illumination light has been described. However, the spectroscopic camera 10 may not have the illumination units 14a and 14b, and may have a configuration in which the diffuser plate 13 and the subject are illuminated by external illumination light such as sunlight.

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

10 Spectroscopic camera 11 Optical system 12 Lens barrel 13 Diffusing plates 14a, 14b Illumination 15 Light receiving 16 Image sensor 17 LVF
18 Detection unit 20 Substrate 21 Thin film

Claims (13)

An optical system that collects light from the subject,
An image sensor that receives the light collected by the optical system and
A first wavelength selection unit provided on the optical path of the optical system, which changes the interval between the pair of reflecting surfaces according to the applied voltage and selectively transmits light having a wavelength corresponding to the interval.
A diffuser plate provided within the image pickup angle of view of the image sensor and reflecting or transmitting the irradiated light,
It has a second wavelength selection unit that receives light reflected by the diffuser plate or light transmitted through the diffuser plate and selectively transmits light having a wavelength corresponding to the light receiving position.
The second wavelength selection unit is an image pickup apparatus provided at an end of a light receiving surface of the image pickup device. A region for arranging the subject and having a subject arranging region provided within the imaging angle of view of the image sensor.
The imaging device according to claim 1, wherein the diffusion plate is provided at a position that is a peripheral edge of the imaging angle of view and does not overlap with the subject arrangement region. Based on the light received on the imaging device is transmitted through the second wavelength selection portion, to claim 2, characterized in that it comprises a detector for detecting a wavelength of light transmitted through the first wavelength selection portion The imaging device described. The imaging device according to claim 2, wherein the subject arrangement region and the diffuser plate are provided at positions where the distances from the optical system are substantially the same. The optics include a pair of lenses
The imaging device according to any one of claims 2 to 4, wherein the first wavelength selection unit is arranged between the pair of lenses. The imaging apparatus according to any one of claims 2 to 5, further comprising a subject arrangement area and an illumination unit that irradiates the diffuser plate. The imaging device according to any one of claims 1 to 6, wherein the diffuser is a white diffuser. The imaging device according to any one of claims 1 to 7, wherein the image pickup apparatus is a spectroscopic camera. The imaging method using the imaging apparatus according to claim 1.
The step of changing the applied voltage and
The step of irradiating the diffuser with light and
A step of receiving the light reflected by the diffuser plate or the light transmitted through the diffuser plate that has passed through the first wavelength selection unit by the second wavelength selection unit.
The step of receiving the light transmitted through the second wavelength selection unit with the image sensor,
A step of detecting the wavelength of the light transmitted through the first wavelength selection unit based on the wavelength of the light transmitted through the second wavelength selection unit.
An imaging method characterized by having. In the imaging device according to claim 1, the computer
The step of changing the applied voltage and
The step of irradiating the diffuser with light and
A step of receiving the light reflected by the diffuser plate or the light transmitted through the diffuser plate that has passed through the first wavelength selection unit by the second wavelength selection unit.
The step of receiving the light transmitted through the second wavelength selection unit with the image sensor,
A step of detecting the wavelength of the light transmitted through the first wavelength selection unit based on the wavelength of the light transmitted through the second wavelength selection unit.
A program characterized by executing. A recording medium for recording the program according to claim 10. The first aspect of the present invention is characterized in that the detection unit includes a detection unit that detects the wavelength of the light transmitted through the first wavelength selection unit based on the light transmitted through the second wavelength selection unit and received by the image sensor. The imaging device described. The optics include a pair of lenses
The imaging device according to claim 12, wherein the first wavelength selection unit is arranged between the pair of lenses .

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