JP2013238850A - Multifunctional image acquisition apparatus and kester prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to acquire a plurality of images of respective specific functions in synchronization with one another by use of a single imaging apparatus and, moreover, to select various specific functions.SOLUTION: A multifunctional image acquisition apparatus includes a Kester prism 20 in the shape of a triangular prism. An incident image light beam is made incident from a first face M1 in perpendicular and split into first to third parallel emission image light beams W1 to W3 emitted from a second face M2 in perpendicular. Another incident image light beam can be made incident on the Kester prism 20 and a fourth emission light beam can be emitted from the second face M2 in perpendicular. Each of the emission image light beams W1 to W4 is imaged while they are synchronized by a CCD camera 30. An optical filter can be selectively disposed with respect to each emitted image light beam.

Description

  The present invention relates to a multifunctional image acquisition device including a color image and a Kester prism.

  When information is extracted from an image by image processing, a certain function may be given by passing an image through an optical filter, while calculation processing may be performed based on a plurality of images having different specific functions.

  Patent Document 1 discloses a technique in which three images having different phases are obtained in a form divided in three directions, and each of the three divided images is acquired by individual cameras (that is, a total of three cameras). Yes. However, in this case, it is necessary to separately perform synchronization among a plurality of cameras, and not only an increase in the number of cameras installed, but also a great deal of labor is required for image processing including synchronization processing. Patent Document 2 discloses that an image is divided into two or more spatially separated spectral images. Since this division uses a polarization beam splitter, the incident light is always specified. It will be divided into linearly polarized light.

JP-A-9-281441 (Patent No. 3000518) JP 2005-523447 A (Patent No. 4398735)

  By the way, for example, when visualizing fluid disturbance by image processing, it is possible to perform visualization by image processing using interference fringes formed by interference between reference light and image light after passing through the fluid. In this case, it is required to acquire a plurality of images having different phases (phase shifted) for visualization, and the images are required to be synchronized with each other. In Patent Document 1, an increase in the number of cameras and a process for synchronization are separately required. Moreover, in the thing of patent document 2, since only a linearly polarized light is obtained since the polarizing beam splitter is utilized, a specific function will be limited and it will become low versatility.

  The present invention has been made in view of the above circumstances, and a first object of the present invention is to be able to acquire a plurality of images having a specific function in a synchronized state by a single imaging device. Furthermore, it is an object of the present invention to provide a multi-function image acquisition apparatus that can select various specific functions. A second object of the present invention is to provide a Kester prism suitable for use in the above-mentioned multifunctional image acquisition device or the like.

In order to achieve the first object, the following solution is adopted in the present invention. That is, as described in claim 1,
A Kester prism having a regular triangular prism shape having a first surface, a second surface, and a third surface;
A spectroscopic prism that splits incident image light into a first light beam and a second light beam that are parallel to each other and makes the two light beams vertically incident on the first surface;
One imaging device disposed facing the second surface;
With
The Kester prism has a first divided surface extending perpendicularly to the second surface by joining a plurality of prisms,
A reflective film and a first internal optical filter are set on the first divided surface,
The first light beam is incident on the first internal optical filter from the first surface, so that the first light beam is divided into two light beams of reflected light and straight light, and the two light beams are finally emitted images. Light is emitted vertically from each of the second surfaces as light,
The second light flux is reflected light by being incident on the reflective film from the first surface, and finally is emitted image light emitted perpendicularly from the second surface,
The imaging device captures each of the emitted image light at the same time to obtain a plurality of images at the same time.
It is like that.

  According to the above solution, a plurality of images corresponding to a plurality of output image lights of the output image light passing through the first internal optical filter and the output image light not passing through the first internal optical filter are completely synchronized. Can be obtained in the state. Moreover, it can reduce in cost and size as a whole. A different specific function can be individually given to each outgoing image light by appropriately selecting an optical filter corresponding to the outgoing image light. For example, when performing image processing using interference fringes, the present invention uses a polarizing plate that passes only a light beam polarized in a specific direction as an optical filter and is phase-shifted by making the polarization angles different from each other. It is extremely suitable for acquiring a plurality of images in a completely synchronized state and performing subsequent image processing. The optical filter that can give a specific function to a plurality of outgoing image lights may be a case where an optical filter is provided for only one outgoing image light, and each of the optical filters for two outgoing image lights. May be provided, or an optical filter may be provided for all outgoing image light. As described above, the present invention also has an advantage that the number of output image light provided with the optical filter can be arbitrarily selected.

A preferred mode based on the above solution is as described in claim 2 and the following claims. That is,
The Kester prism further includes a third divided surface extending perpendicularly to the second surface and having a second internal optical filter on the opposite side of the first surface across the first divided surface. Have
The first light beam is incident on the first internal optical filter from the first surface, so that the first light beam is divided into two light beams of reflected light and straight light, and the reflected light is used as the first outgoing image light. Emitted vertically from the second surface,
The straightly traveling light that has traveled straight through the first internal optical filter is incident on the second internal optical filter, so that it is split into two light fluxes of reflected light and straight traveling light, respectively from the second surface. A second emission image light and a third emission image light emitted vertically;
The emitted image light corresponding to the second light flux is set as a fourth emitted image light, and the imaging device simultaneously captures the first to fourth emitted image lights to obtain four images simultaneously.
(Corresponding to claim 2). In this case, four images can be acquired simultaneously corresponding to the four outgoing image lights parallel to each other.

  An external optical filter is disposed between each of the first emission image light to the third emission image light and the imaging device (corresponding to claim 3). In this case, three processed images processed by the external optical filter and a raw image not processed by the external optical filter can be acquired simultaneously.

  The external optical filter is a polarizing plate, a color filter, a band pass filter, a phase plate, an RGB filter, a UV / IR cut filter, a dichroic filter, an ND filter, an antireflection film, a half mirror, or a combination thereof. (Corresponding to claim 4). In this case, a specific example for providing a specific function is provided.

The external optical filters provided for the first to third emission image lights are polarizing plates having different polarization angles, and images captured by the imaging unit are phase-shifted with each other.
The fourth outgoing image light is incident on the imaging means without being subjected to a polarization action.
(Corresponding to claim 5). In this case, the intensity (brightness) of the emitted light can be obtained by the fourth emitted light in addition to the images having three phase shifts, which is extremely preferable in the subsequent image processing.

The Kester prism has (1) the first division perpendicular to the second surface through an intersection of the first surface and the third surface as a division surface to be a joining surface of the plurality of prisms. A surface, (2) a second divided surface that passes through the intersection of the first divided surface and the second surface, and is parallel to the first surface, and (3) the second divided surface and the third surface The third divided surface orthogonal to the second surface through an intersection with the surface of
Incident image light that has passed through the first surface is branched into a first straight light beam and a first reflected light beam by the first internal optical filter, and the first reflected light beam is totally reflected by the first surface. And the first emission image light emitted from the second surface after being
The first straight light beam passes through the second split surface and is branched into a second straight light beam and a second reflected light beam by the second internal optical filter, and the second reflected light beam is the second split surface. And is the second emission image light that is totally reflected by and emitted from the second surface,
The second straight light beam is totally reflected by the third surface and is emitted from the second surface as third emitted image light,
After the second light flux is reflected by the reflective film, it is totally reflected by the first surface and is emitted from the second surface as the fourth emission image light.
(Corresponding to claim 6). In this case, a specific structure of the Kester prism for obtaining the fourth output image light is provided. In addition, since it is configured as a single block as a whole, it is easy to handle and is preferable in terms of miniaturization. Furthermore, the optical path length in the Kester prism can be made equal between the first to fourth outgoing image lights. In addition to the above, since the reflecting surface is configured using the split surface of the first divided surface, the shape of the prism constituting the Kester prism is made as much as possible compared to the case where the reflecting surface is configured by a portion other than the split surface. This is preferable for a simple shape.

  The first surface, the third surface, and the surface on which the second reflected light beam is totally reflected by the second split surface are each provided with a phase control film that reduces the phase change that occurs during total reflection. (Claim 7). In this case, it is preferable for preventing the phase shift of each outgoing light. In addition, the phase control film can serve as an antireflection film, which is preferable in terms of preventing strength reduction due to reflection and reducing stray light.

The first inner filter and the second inner filter are respectively color separation films, and the second surface in a state where the first emission image light to the third emission image light are color-coded into three colors. Emanating from
The fourth emission image light is emitted from the second surface without being color-coded,
This is done (corresponding to claim 8). In this case, the color images classified into three colors are simultaneously captured by the first to third emission image lights. At the same time, an image corresponding to the fourth output image light is also picked up. However, since the fourth output image light has a wide wavelength band, for example, an optical filter that selects a desired wavelength is selected. As a result, a vivid color image of four colors can be acquired.

  A color filter is provided between the second surface and the imaging device so as to allow only the fourth emission image light to pass therethrough and pass a color different from the colors of the first to third emission image lights. (Corresponding to claim 9). In this case, it is preferable for obtaining a vivid color image of four colors.

In order to achieve the second object, the following solution is adopted in the present invention. That is, as described in claim 10,
A Kester prism having a regular triangular prism shape having a first surface, a second surface, and a third surface,
The Kester prism has (1) a first divided surface orthogonal to the second surface passing through an intersection of the first surface and the third surface as a divided surface to be a joint surface of the plurality of prisms. And (2) a second divided surface parallel to the first surface through an intersection of the first divided surface and the second surface, and (3) the second divided surface and the third surface. A third divided surface orthogonal to the second surface through an intersection with the surface,
A reflective film and a first internal optical filter are set on the first divided surface,
A second internal optical filter is set on the third divided surface;
The first light beam that has passed perpendicularly through the first surface is branched into a first straight light beam and a first reflected light beam by the first internal optical filter, and the first reflected light beam is reflected on the first surface. First emitted image light emitted from the second surface after being totally reflected,
The first straight light beam passes through the second split surface and is branched into a second straight light beam and a second reflected light beam by the second internal optical filter, and the second reflected light beam is the second split surface. And is the second emission image light that is totally reflected by and emitted from the second surface,
The second straight light beam is totally reflected by the third surface and is emitted from the second surface as third emitted image light,
The second light beam incident on the first surface in parallel with the first light beam is reflected by the reflective film, and then totally reflected by the first surface, so that the fourth surface through the second surface is the fourth light beam. Emitted as emitted image light,
It is like that. According to the above solution, a Kester prism suitable for use in a multi-function image acquisition apparatus corresponding to claim 2 is provided.

  According to the present invention, at least three images provided with a specific function can be acquired on one screen in a completely synchronized state. Further, by appropriately selecting an optical filter, a specific function can be individually given to an image corresponding to each emitted light, and the versatility becomes extremely high.

BRIEF DESCRIPTION OF THE DRAWINGS Whole explanatory drawing which shows one Embodiment of this invention. The detail of the part enclosed by D of FIG. 1, which shows the detail of the Kester prism part of this invention. FIG. 3 is an exploded view of the Kester prism shown in FIG. 2. The 2nd Embodiment of this invention is shown, and the figure corresponding to FIG.

  In FIG. 1, 1 is a laser transmitter (for example, He-Ne system). The laser transmitted from the laser transmitter 1 passes through the spatial filter 2, the lens 3, and the reflection mirror 4, enters the beam splitter 5 as parallel light, and is split into two light beams by the beam splitter 5.

  One light beam from the beam splitter 5 is converted to a P wave, which is incident on the beam splitter 7 via the reflection mirror 6. Further, the other light beam passing through the beam splitter 5 is converted into an S wave, which is incident on the beam splitter 7 via the reflection mirror 8. These light beams are used as incident image light for a Kester prism described later.

  One light beam that has passed through the beam splitter 5 is, for example, reference light, and the other light beam is detection light that passes through the test target substance. That is, for example, when measuring the turbulent state of air by an object, the optical path is set so that the detection light passes behind the object installed in a wind tunnel through which laminar air flows. Further, the inside of the wind tunnel is heated to form a temperature distribution state having a temperature difference in the vertical direction, for example. When laminar air flows through a certain object in the wind tunnel, the air is disturbed by the certain object, so that the temperature distribution state behind the certain object changes. When there is a temperature change, the refractive index of air changes and the phase of the detection light changes. Then, interference occurs between the reference light and the detection light whose phase has been changed, and interference fringes can be formed. However, since the reference light is an S wave and the detection light is a P wave, If both lights are simply condensed, it is difficult to confirm the interference fringes in the image, and an interference fringe image having a high contrast is acquired by forming an optical path to be described later. The P wave can be used as reference light, and the S wave can be used as detection light.

  As will be described later, the incident image light that has passed through the beam splitter 7 passes through the spectroscopic prism 10 and the Kester prism 20 and enters a CCD camera 30 serving as an imaging unit.

  FIG. 2 is an enlarged view of a portion after passing through the beam splitter 7 in FIG. 1 (D portion in FIG. 1). The spectral prism 10 splits the incident image light from the beam splitter 7 into a first light beam V1 and a second light beam V2 that are parallel to each other in the emission state, and each of the light beams V1 and V2 to the Kester prism 20 respectively. Make it incident. The intensity (brightness) of each of the light beams V1 and V2 is set to be substantially equal to each other, and the spectroscopic prism 10 includes a non-polarizing beam splitter film that bisects while maintaining the polarization state of incident light. ing. Since such a spectral prism 10 itself is well known, detailed description thereof is omitted.

  As will be described later, the Kester prism 20 branches the first light beam V1 into three light beams, and these three light beams are parallel to each other and are directed to the same direction in the first to third output image lights W1 to W3. It has the function to emit as. The Kester prism 20 has a function of emitting the second light beam V2 as the fourth emitted light W4 that is parallel to the first to third emitted image lights W1 to W3 and goes in the same direction without being branched. .

  Details of the Kester prism 20 will be described with reference to FIGS. First, the Kester prism 20 is generally formed in a regular triangular prism shape having a regular triangular cross section, and has a first surface M1, a second surface M2, and a third surface M3. Three vertices (intersections between the surfaces M1 to M3) of the Kester prism 20 are indicated as α1, α2, and α3.

  As shown in FIG. 3, the Kester prism 20 is configured by joining a total of four prisms P <b> 1 to P <b> 4 each having a triangular prism shape, and the joint surface becomes a split surface. This division plane is set as follows. First, the first divided surface B1 that is orthogonal to the second surface M2 passes through the vertex α2 that is the intersection of the first surface M1 and the third surface M3. Further, the second divided surface B2 parallel to the first surface M1 passes through the intersection point β1 between the first divided surface B1 and the second surface M2. A minute air gap is provided on the second divided surface B2. Furthermore, it has a third divided surface B3 that passes through the intersection β2 between the second divided surface B2 and the third surface M3 and is orthogonal to the second surface M2. The first divided surface B1 and the third divided surface B3 function as a half mirror surface that serves as an internal optical filter. The two split surfaces B1 (excluding the reflection surface H) and the B3 surface are formed of a non-polarizing beam splitter film.

  A phase control film is provided on the total reflection surfaces of the first surface M1, the third surface M3, and the second divided surface B2 to reduce a phase change caused by total reflection. This phase control film has an antireflection function at normal incidence and also has an effect of reducing stray light.

  The first light beam V1 from the spectroscopic prism 10 is made into a circularly polarized state by the quarter wavelength plate 15, and then incident perpendicularly to the first surface M1 of the Kester prism 20 (a quarter wavelength plate 15). Is not necessary). The first light beam V1 is divided into two equal parts, including the polarization direction, in the reflected light V21 and the straight light V22 on the first split surface B1. The reflected light V21 is totally reflected by the first surface M1, and then emitted vertically from the second surface M2, and this emitted light is used as the first emitted image light W1.

  The straight light V22 that has passed through the first split surface B1 in the first light beam V1 is incident on the second split surface B2 perpendicularly and passes therethrough, and then is reflected by the reflected light V31 and the straight light V32 on the third split surface B3. Branch off. The reflected light V31 is totally reflected by the second divided surface B2, and then is emitted perpendicularly from the second surface M2, and this emitted light is used as the second emitted image light W2.

  The straight traveling light V32 that has passed through the third divided surface B3 is totally reflected by the third surface M3, and then is emitted perpendicularly from the second surface M2, and this emitted light is used as the third emitted image light W3. The

  The second light beam V2 from the spectroscopic prism 10 is also incident on the Kester prism 20, and because of this second light beam V2, a reflecting surface H is formed on a part of the first dividing surface B1 of the Kester prism 20. (In FIGS. 2 and 3, the reflective film is drawn with a thick line to clarify its existence, but it is actually a thin film). The position where the reflecting surface H is formed is near the position where the second light beam V2 is incident (near the apex α2), and a portion other than the optical path of the first light beam V1 is selected. In addition, although the reflective surface H is given to the prism P2 in FIG. 3, it can also be given to the prism P1.

  The second light beam V2 is incident perpendicular to the first surface M1 near the reflecting surface H. Then, after being reflected by the reflecting surface H, it is totally reflected by the first surface M1 and emitted perpendicularly from the second surface M2, and this emitted light becomes the fourth emitted image light W4.

  The emitted image lights W1 to W4 emitted perpendicularly to the second surface M2 are incident on the CCD camera 30 from positions parallel to each other and shifted from each other along the second surface M2. That is, the CCD of the CCD camera 30 is indicated by reference numeral 31, and this CCD 31 extends elongated along the second surface M2. Images corresponding to the respective outgoing image lights W1 to W4 are obtained as four images arranged in a single plane in the CCD 31. For this reason, four images displayed on one CCD can be subjected to calculation between pixels in the same CCD. Images corresponding to the respective outgoing lights W1 to W4 can be clearly distinguished by the pixel position of the CCD 31. Image separation positions corresponding to the emitted lights W1 to W4 are indicated by reference numerals 31a to 31c.

  Between the Kester prism 20 and the CCD camera 30, optical filters 41 to 43 serving as a plurality of external optical filters are disposed. The optical filter 41 is disposed corresponding to the outgoing light W1, and only the outgoing light W1 passes through it. The optical filter 42 is disposed corresponding to the outgoing light W2, and only the outgoing light W2 passes through it. The optical filter 43 is disposed corresponding to the outgoing light W3, and only the outgoing light W3 passes therethrough. An optical filter is not provided for the outgoing light W4.

  Each of the optical filters 41 to 43 is a polarizing plate in the embodiment of FIG. 2, and the polarization angles (polarization directions) thereof are shifted from each other by 120 degrees. The polarization angles of the optical filters 41 to 43 as the polarizing plates are indicated by arrows shown in a round frame in FIG. As a result, the CCD camera 30 obtains an image of interference fringes whose phases are shifted by 120 degrees. Further, the fourth outgoing image light W4 is not provided with an optical filter, and the intensity (brightness) of the outgoing light is acquired. Note that the optical path lengths from incidence to emission in the Kester prism 20 are equal to each other between the outgoing lights W1 to W4.

  By using a high-speed CCD camera 30 (for example, a camera having several tens of frames per second or several hundred to several thousand frames can be used), a phenomenon that changes within a very short time has a function. A plurality of images can be acquired simultaneously. If the Kester prism system of the present invention is adopted, there is no limit value for the frame rate. Therefore, in the method of the present invention, the upper limit for high-speed shooting is attributed to the performance of the CCD camera and not to the system of the present invention. Of course, as the image pickup means, a camera other than the CCD camera 30, for example, a camera using a CMOS image sensor used for a high-speed camera, a film camera, or the like can be used as appropriate.

  FIG. 4 shows a second embodiment of the present invention, and the same components as those in the previous embodiment are denoted by the same reference numerals, and redundant description thereof is omitted. In the present embodiment, the present invention is applied as a multi-function image acquisition device for color, and three output image lights W1, W2, and W3 emitted in parallel with each other from the second surface M2 are red, green, and blue. It is as color light separated into colors. That is, a color separation film is used for the first dividing surface B1 of the Kester prism 20 instead of the half mirror surface. As a result, the first light beam V1 that has traveled straight on the half mirror surface of the spectroscopic prism 10 is the straight light from which the blue reflected light V21 (that is, the first outgoing light W1) and the blue wavelength component are removed from the first split surface B1. Spectroscopy to V22.

  The third divided surface B3 is also provided with a color separation film in place of the half mirror, and the straight light V22 is reflected by the third divided surface B3 with the green reflected light V31 (that is, the second outgoing image light W2). The light is split into red light V32 (that is, the third outgoing image light W3).

  The second light beam V2 dispersed by the spectroscopic prism 10 is reflected by the reflecting surface H, and is emitted as the fourth emission image light W4 without being color-separated (that is, as white light including all wavelengths). The emitted image lights W1 to W4 are simultaneously captured as color images by the imaging device 30.

  In the second embodiment described above, images are decomposed for each of the wavelengths of the three colors R (red), G (green), and B (blue). In order to further improve the color reproducibility, some attempts have been made to expand to four colors. According to the present embodiment, since the fourth emission image light W4 includes the wavelengths of all the color components, by using the optical filter CF having a predetermined wavelength characteristic with respect to the fourth emission image light W4, It is possible to display colors more vividly (color imaging) including intermediate colors.

  As a modification of FIG. 4, a color separation film is used on the splitting surface of the spectroscopic prism 10, and the first light beam V1 includes, for example, a wavelength component from green to red, and the second light beam V2 includes other wavelength components. It can also be used. In this case, the fourth outgoing light W4 does not include wavelength components of all colors, but the luminous flux that becomes the fourth outgoing light W4 is not further color-coded (spectral) by the Kester prism 20, so The four outgoing lights W4 can have a wide wavelength band.

  Although the embodiment has been described above, the present invention is not limited to the embodiment, and can be appropriately changed within the scope described in the scope of claims. For example, the invention includes the following cases. . The second light beam V2 emitted from the spectroscopic prism 10 may be incident on the Kester prism 20 after passing through the polarizing plate. The Kester prism 20 may be configured such that only incident image light corresponding to the first light beam V1 is incident, and the CCD camera 30 acquires three synchronized images side by side (in this case, spectral The prism 10 and the reflecting surface H are not required). An optical filter may be provided for the fourth outgoing light W4.

  As an internal optical filter or an external optical filter, in addition to a polarizing plate, a color filter, a band pass filter, a phase plate, an RGB filter, a UV / IR cut filter, a dichroic filter, an ND filter, an antireflection film, a half mirror, etc. Or a combination thereof. For example, in the present invention, one image is duplicated into four, each having a different optical function by an arbitrary optical filter, and an image can be acquired by a single CCD system of 1 CCD. For example, by using a color filter as the optical filter, four images of each color can be taken side by side on one CCD.

  Further, it is possible to obtain a phase shift image by obtaining the three images with specific polarization angles and performing image processing. Further, if a band-pass filter is used, spectroscopic measurement is also possible. The acquisition of a plurality of images as described above can be performed using an existing camera system such as a high-speed camera. In other words, by exchanging the optical filter, it is possible to simultaneously acquire an image having any specific function such as a high-speed color photograph, a phase shift image, or a spectral image in any combination (for example, a phase shift image and Spectral images are acquired at the same time). By using a high-speed camera as the image acquisition unit, high-speed shooting and optical filter replacement are possible. The test substance is not limited to a fluid such as air or water, and any appropriate substance can be selected as long as it can pass light. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention is suitable as an image acquisition device used for analyzing fluid flow or the like, or as a small color image acquisition device. It is particularly suitable for high-speed and unsteady fluid phenomena such as shock waves, combustion, and plasma.

10: Spectral prism 20: Kester prism 30: CCD camera (imaging means)
31: CCD
41-43: Optical filter S wave: Detection light P wave: Reference light H: Reflecting surface M1: First surface M2: Inner surface M3: Third surface B1: First divided surface B2: Second divided surface B3: Third divided surface W1: First outgoing image light W2: Second outgoing image light W3: Third outgoing image light W4: Fourth outgoing image light P1 to P4: Prism (for Kester prism configuration)

Claims (10)

A Kester prism having a regular triangular prism shape having a first surface, a second surface, and a third surface;
A spectroscopic prism that splits incident image light into a first light beam and a second light beam that are parallel to each other and makes the two light beams vertically incident on the first surface;
One imaging device disposed facing the second surface;
With
The Kester prism has a first divided surface extending perpendicularly to the second surface by joining a plurality of prisms,
A reflective film and a first internal optical filter are set on the first divided surface,
The first light beam is incident on the first internal optical filter from the first surface, so that the first light beam is divided into two light beams of reflected light and straight light, and the two light beams are finally emitted images. Light is emitted vertically from each of the second surfaces as light,
The second light flux is reflected light by being incident on the reflective film from the first surface, and finally is emitted image light emitted perpendicularly from the second surface,
The imaging device captures each of the emitted image light at the same time to obtain a plurality of images at the same time.
A multi-function image acquisition apparatus characterized by that. In claim 1,
The Kester prism further includes a third divided surface extending perpendicularly to the second surface and having a second internal optical filter on the opposite side of the first surface across the first divided surface. Have
The first light beam is incident on the first internal optical filter from the first surface, so that the first light beam is divided into two light beams of reflected light and straight light, and the reflected light is used as the first outgoing image light. Emitted vertically from the second surface,
The straightly traveling light that has traveled straight through the first internal optical filter is incident on the second internal optical filter, so that it is split into two light fluxes of reflected light and straight traveling light, respectively from the second surface. A second emission image light and a third emission image light emitted vertically;
The emitted image light corresponding to the second light flux is set as a fourth emitted image light, and the imaging device simultaneously captures the first to fourth emitted image lights to obtain four images simultaneously.
A multi-function image acquisition apparatus characterized by that. In claim 2,
An external optical filter is disposed between each of the first emission image light to the third emission image light and the imaging device. In claim 3,
The external optical filter is a polarizing plate, a color filter, a band pass filter, a phase plate, an RGB filter, a UV / IR cut filter, a dichroic filter, an ND filter, an antireflection film, a half mirror, or a combination thereof. A multi-function image acquisition apparatus characterized by that. In claim 3,
The external optical filters provided for the first to third emission image lights are polarizing plates having different polarization angles, and images captured by the imaging unit are phase-shifted with each other.
The fourth outgoing image light is incident on the imaging means without being subjected to a polarization action.
A multi-function image acquisition apparatus characterized by that. In any one of Claims 2 thru | or 5,
The Kester prism has (1) the first division perpendicular to the second surface through an intersection of the first surface and the third surface as a division surface to be a joining surface of the plurality of prisms. A surface, (2) a second divided surface that passes through the intersection of the first divided surface and the second surface, and is parallel to the first surface, and (3) the second divided surface and the third surface The third divided surface orthogonal to the second surface through an intersection with the surface of
Incident image light that has passed through the first surface is branched into a first straight light beam and a first reflected light beam by the first internal optical filter, and the first reflected light beam is totally reflected by the first surface. And the first emission image light emitted from the second surface after being
The first straight light beam passes through the second split surface and is branched into a second straight light beam and a second reflected light beam by the second internal optical filter, and the second reflected light beam is the second split surface. And is the second emission image light that is totally reflected by and emitted from the second surface,
The second straight light beam is totally reflected by the third surface and is emitted from the second surface as third emitted image light,
After the second light flux is reflected by the reflective film, it is totally reflected by the first surface and is emitted from the second surface as the fourth emission image light.
A multi-function image acquisition apparatus characterized by that. In claim 6,
The first surface, the third surface, and the surface on which the second reflected light beam is totally reflected by the second split surface are each provided with a phase control film that reduces the phase change that occurs during total reflection. A multi-function image acquisition apparatus characterized by that. In claim 1,
The first inner filter and the second inner filter are respectively color separation films, and the second surface in a state where the first emission image light to the third emission image light are color-coded into three colors. Emanating from
The fourth emission image light is emitted from the second surface without being color-coded,
A multi-function image acquisition apparatus characterized by that. In claim 8,
A color filter is provided between the second surface and the imaging device so as to allow only the fourth emission image light to pass therethrough and pass a color different from the colors of the first to third emission image lights. A multi-function image acquisition device characterized by that. A Kester prism having a regular triangular prism shape having a first surface, a second surface, and a third surface,
The Kester prism has (1) a first divided surface orthogonal to the second surface passing through an intersection of the first surface and the third surface as a divided surface to be a joint surface of the plurality of prisms. And (2) a second divided surface parallel to the first surface through an intersection of the first divided surface and the second surface, and (3) the second divided surface and the third surface. A third divided surface orthogonal to the second surface through an intersection with the surface,
A reflective film and a first internal optical filter are set on the first divided surface,
A second internal optical filter is set on the third divided surface;
The first light beam that has passed perpendicularly through the first surface is branched into a first straight light beam and a first reflected light beam by the first internal optical filter, and the first reflected light beam is reflected on the first surface. First emitted image light emitted from the second surface after being totally reflected,
The first straight light beam passes through the second split surface and is branched into a second straight light beam and a second reflected light beam by the second internal optical filter, and the second reflected light beam is the second split surface. And is the second emission image light that is totally reflected by and emitted from the second surface,
The second straight light beam is totally reflected by the third surface and is emitted from the second surface as third emitted image light,
The second light beam incident on the first surface in parallel with the first light beam is reflected by the reflective film, and then totally reflected by the first surface, so that the fourth surface through the second surface is the fourth light beam. Emitted as emitted image light,
Kester Prism characterized by that.

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