JPH09237029A - Holography image pickup device and holography display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holography image pickup device which picks up the image of a hologram having high quality by using an image pickup element having a variable visual field and relatively low space resolution and to attain display by decreasing the distortions of the original image from the hologram subjected to image pickup by this holography image pickup device. SOLUTION: A diaphragm 210 having an opening 211 of a diameter of <=λf/p is arranged on the front side focal plane of an imaging optical system 110 when a wavelength is defined as λ, image pickup resolution as (p) and the focal length of the imaging optical system 110 as (f). The object light past the opening 211 is imaged in the imaging optical system 110. The object light past the imaging optical system 110 and reference light are then interfered with each other and the image of the interference fringes is picked up. The hologram of which the image is picked up in such a manner is subjected to the image reconstruction of the object for image pickup by adopting an imaging optical system equiv. to the imaging optical system 110 at the time of the image pickup and setting the positional relation between the formed hologram and the imaging optical system according to the position relation between the imaging optical system 110 at the time of the image pickup and an image pickup plane 410.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic imaging device for recording three-dimensional information of an object, and a holographic display device for reading out the three-dimensional information of the object from the holographic imaging device and displaying a three-dimensional image of the object. It is a thing.

[0002]

2. Description of the Related Art Holographic technology has attracted attention as a technology for displaying a three-dimensional image of an object. This holographic technique is a holographic imaging technique for recording three-dimensional information of an object and an holographic imaging technique for recording an object recorded by the holographic imaging technique.
It is composed of a holographic display technique for reading out three-dimensional information of an object by reading out three-dimensional information.

The conventional holographic technology is generally constructed on the premise that the image pickup device has a high resolution in the holographic image pickup, and a holographic image pickup device using a high resolution photographic plate or a thermoplastic is used as the image pickup device. Mostly.

Since such an imaging technique is a high-level photographic technique because of its high resolution, holographic imaging requires a great deal of labor. Therefore, a holographic technique using a CCD camera, which is a relatively low-resolution image pickup device, is described in "Sato et al., Journal of the Television Society, Vol.
45, no. 7, pp. 873-875 (1991) "
(Hereinafter referred to as Conventional Example 1) and “Hashimoto, Journal of the Institute of Image Electronics Engineers of Japan
Vol. 22, no. 4, pp. 315-322 (19
91) ”(hereinafter referred to as Conventional Example 2).

Conventional Example 1 is an example of the Fresnel type holography technique which does not use a lens normally used in the holography imaging technique. In the holographic imaging technique disclosed in Conventional Example 2, an imaging lens is used and an aperture is arranged immediately in front of the object side of the imaging lens so that the spatial resolution of the real image matches the spatial resolution of the image sensor. .

Then, the interference fringe is made to capture an image by carrying both the distance information of the object in the optical axis direction and the position information in the direction perpendicular to the optical axis, and the image reproduction is read from the interference fringe.

[0007]

Since the conventional holographic imaging device and holographic display device are configured as described above, there are the following problems.

In the holographic imaging devices of Conventional Example 1 and Conventional Example 2, since the spatial resolution of the CCD is generally about 10 μm, the angle formed by the object light and the reference light is 2-3.
It must be within °. When the angle formed by the object light and the reference light becomes large, the interval between the interference fringes becomes smaller than the resolution of the image sensor, and the interference fringes cannot be imaged with good contrast.

Therefore, in Conventional Example 1, the size of the object to be imaged is about the size of the CCD, and the distance between the object to be imaged and the CCD is large. However, there is no guideline for optimizing the distance between the imaging target and the CCD, and therefore it is difficult to achieve miniaturization while maintaining performance.

Further, in the conventional example 1, since the lens is not used, the field of view cannot be made variable.

In the conventional example 2, since the diaphragm is arranged immediately before the image pickup object side of the imaging lens, the reduction system must be selected in order to increase the field of view. Therefore, when the field of view is made large, the angle of the object light with respect to the optical axis becomes larger after passing through the lens than before entering the lens.

Therefore, the aperture of the diaphragm is narrowed down in order to keep the angle between the object light and the reference light small. However, if the aperture is narrowed down, the object light cannot be effectively used. Therefore, there is a constraint that an object having a high reflectance should be selected as an imaging target and a constraint that a strong light source is required.

Further, the emission angle of the light passing through the center of the lens does not change, and the viewing angle cannot be increased.

In the holographic display devices of Conventional Example 1 and Conventional Example 2, the pixel pitch and pixel size of the CCD, which is the image pickup element, are different from the pixel pitch and pixel size of the spatial modulation element used during image reproduction.

Although the conventional example 1 employs the full-nel type hologram system, a lens is used in the display optical system. Further, Conventional Example 2 is not an image-forming type display optical system.

That is, in Conventional Example 1 and Conventional Example 2,
Since the optical system at the time of holographic imaging is different from the optical system at the time of image reproduction, the enlargement ratio depending on the position of the reproduced display image is essentially different, which causes distortion.

The present invention has been made in view of the above circumstances, and provides a holographic image pickup device which images a high quality hologram by using an image pickup device having a relatively low spatial resolution while varying the field of view. With the goal.

Another object of the present invention is to provide a holographic display device capable of displaying a hologram imaged by the holographic image pickup device of the present invention with reduced distortion of an original image.

[0019]

The holographic image pickup device of the present invention uses an optical system having a positive refractive power to make the field of view variable, such as a convex lens, and secures a necessary interval of interference fringes. In addition, the distance of the object in the optical axis direction is reflected in the interval of the interference fringes, and the position of the object in the direction perpendicular to the optical axis is reflected in the distribution range of the interference fringes. By separating the function of reflecting the position of the object in the direction perpendicular to the optical axis and adjusting the position of the image sensor in the optical axis direction, it is configured to suppress the generation of interference fringes at intervals smaller than the resolution of the image sensor.

That is, the holographic imaging device according to claim 1 is: (a) a first light source for generating light for irradiating the object, and (b) light output from the first light source for the object. As a result of the irradiation, the diaphragm means having an opening for passing the object light reflected by the image pickup object, and (c) the diaphragm means arranged at a position serving as the object-side focal plane and having a positive refractive index Imaging optical system, (d) a second light source for generating coherent light having the same wavelength as that of the object light, and (e) reference light which is a plane wave for the coherent light output from the second light source. And an interference optical system for interfering the object light and the reference light through the first imaging optical system, and (f) a first connection in the traveling direction of the reference light output from the first imaging optical system. The optical axis of the first image forming optical system is perpendicular to the optical axis of the first image forming optical system at a position separated from the focal plane on the interference optical system side of the image optical system by a first distance. Having an image plane, and an imaging means for capturing an image forming output interference light from the interference optical system,
When the wavelength of the object light = λ, the aperture diameter of the aperture means = a, the object-side focal length of the first imaging optical system = f, and the spatial resolution of the image pickup means = p, then a ≦ λ · f / p (1) is satisfied.

Here, the first light source and the second light source can be the same light source.

Further, it is possible to further comprise a first moving means for changing the first distance. In this case, according to the distance to the imaging target and the resolution of the imaging surface,
It is possible to set the optimum position for imaging.

The image pickup result of the image pickup means may be (i) the intensity of light on the image pickup surface, or (ii) the amplitude of the light wave and the phase of the light wave on the image pickup surface. In the case of the former, an intensity hologram can be obtained,
In the latter case, a complex hologram is obtained. Complex holograms are obtained by the fringe scanning method.

In the holographic imaging device of the first aspect, first, the object to be imaged is illuminated with the light output from the first light source. As a result of this irradiation, the object light, which is the light reflected by the object to be imaged, is input to the first imaging optical system via the aperture having the diameter satisfying the expression (1).

Of the light input to the image forming optical system, the chief ray that has passed through the center of the aperture, that is, the focal point of the image forming optical system on the side of the object to be imaged has an incident angle to the first image forming optical system. Depending on,
Central axis of the first imaging optical system (hereinafter also simply referred to as an optical axis)
And is output from the exit position of the first imaging optical system at a constant distance, and is vertically incident on the imaging surface along an optical path parallel to the optical axis. Further, the light that has passed through the aperture becomes light that is directed to the image formation point by passing through the image formation optical system. Therefore, the wavefront passing through the aperture becomes a spherical wave that converges from the image forming optical system to the image forming point, and becomes a divergent spherical wave after passing the image forming point.

On the other hand, the coherent light output from the second light source is input to the interference means. In the interference means, the coherent light output from the second light source is used as the reference light that is a plane wave, and then the object light and the reference light that have passed through the imaging optical system are caused to interfere with each other.

Here, the first light source and the second light source can be configured to be the same, and the light branching device can be used as the coherent light that is the source of the irradiation light and the reference light for the object to be imaged.

When the object spherical wave after passing through the imaging optical system is made to interfere with the plane wave of the same wavelength and observed in a section perpendicular to the optical axis behind the imaging optical system, the cosine wave Fresnel zone centering on the principal ray is observed. It becomes a plate, and when it connects the centers of the cosine wave Fresnel zone plates at various positions, it becomes parallel to the optical axis.

As a result, when the distances along the optical axis are the same,
The distance in the direction perpendicular to the optical axis of each bright point of the imaging object defines the distribution range of the interference fringes derived from this bright point. Further, the distance in the optical axis direction of each bright point of the imaged object defines the interference fringe spacing of the cosine Fresnel zone plate.

In the apparatus according to the first aspect, in order to suppress the occurrence of interference fringes having a space smaller than the spatial resolution of the image pickup means, that is, the unit size (hereinafter also referred to as the pitch) p of the image pickup element adopted in the image pickup means. In addition, an opening having a diameter a that satisfies the expression (1) is adopted.

Assuming that the reference light incident on the image sensor is vertically incident on the image sensor, the incident angle θ of the object light which can image the interference fringes generated on the image sensor having the pitch p within the Nyquist interval is θ. ≦ sin ⁻¹ ((λ / 2) / p) (2) must be satisfied.

On the other hand, in the apparatus according to claim 1 having an aperture with a diameter a which satisfies the relation of the expression (1), the angle between the object light and the optical axis (hereinafter also referred to as the incident angle to the image forming point) θi is , Θi <tan ⁻¹ ((λ / 2) / p) (3), and from λ> 0, θi <sin ⁻¹ ((λ / 2) / p) (4).

Therefore, in the apparatus according to the first aspect, the interference fringes can be imaged at Nyquist intervals, and information can be stored with good reproducibility based on the sampling theorem.

If the diameter a of the aperture of the device of claim 1 does not satisfy the relationship of (1), interference fringes that are not resolved may occur. In this case, the light amount of the unresolved interference fringes is recognized as a DC component, and the contrast of the resolved interference fringes is reduced. A rectangular or circular shape of the opening is convenient and practical.

A holographic display device according to a sixth aspect is a holographic display device which reproduces and displays an image of an image pickup object based on optical information imaged by the holographic image pickup device according to the first aspect. The information input means for inputting the image pickup result by the holographic image pickup device, and (b) the hologram on the image pickup surface at the time of being picked up by the holographic image pickup device based on the information notified from the information input means. A second connection in which the hologram forming portion to be formed and the (c) hologram-side focal plane are at a position separated from the hologram position by the first distance in the holographic imaging device of claim 1 in the average traveling direction of the hologram forming light. It is characterized by comprising an image optical system and (d) 0th-order light shielding means arranged at the focal point on the opposite side of the hologram side of the second imaging optical system.

Here, it is preferable to further include second moving means for changing the distance between the hologram position and the hologram-side focal plane of the second imaging optical system. In this case, in the holographic imaging device according to claim 1, even if the selected first distance is changed, an arrangement of a reproduction optical system capable of image reproduction without distortion is provided according to the changed first distance. It can be set each time.

In the case of an intensity hologram, the hologram forming section responds to (i) display means for displaying the optical image of the imaging result notified from the information input section, and (ii) the optical image displayed on the display means. The spatial light modulator in which the spatial light modulation image is written, (iii) the light source for generating the reading light with which the spatial light modulator is irradiated, and (iv) the phase or amplitude by the reading light passing through the spatial light modulator. A hologram forming optical system for inputting the modulated phase or amplitude modulated light and forming a hologram of the same size as the image pickup element of the holographic image pickup apparatus can be suitably configured with optical components.

Further, in the hologram forming section, when the image pickup result by the holographic image pickup apparatus of claim 1 is a complex hologram in which the amplitude information and the phase information of the incident light at each point on the image pickup surface are (i) information. According to the amplitude information and the phase information notified from the input unit, a phase amplitude modulation unit that performs phase modulation and amplitude modulation on the incident light and outputs the light, and (ii) generates a read light that is irradiated to the phase amplitude modulation unit. A hologram forming optical system that forms a hologram having the same size as the image pickup element of the holographic image pickup device by inputting the light source and (iii) the phase-amplitude-modulated light that is phase-amplitude-modulated by the read-out light through the phase-amplitude modulator. And can be preferably configured with optical components.

The functions of the hologram forming section, the second image-forming optical system, and the 0th-order light shielding plate can be realized by arithmetic processing using a computer.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments of the present invention, the outline of the principle adopted in the present invention will be described.

FIG. 1 is an explanatory view of the principle of the holographic imaging device of the present invention. As shown in FIG. 1, the holographic imaging device of the present invention includes (a) an imaging optical system 110 having a positive refractive power, and (b) an opening 211 near the focus of the imaging optical system 110 on the imaging target side. An aperture 210 having a (c)
An interference optical system 300 for causing the object light and the reference light to interfere with each other,
(D) The interference optical system 3 having the imaging surface 410 perpendicular to the optical axis
Image pickup device 4 for picking up an interference fringe of the interference light output from
00.

In the image pickup apparatus of FIG. 1, the object light from each bright spot (P1, P2, P3, ...) Of the image pickup object passes through the opening 211 and then enters the image forming optical system 110.

Of the light input to the image forming optical system 110, the chief ray that has passed through the center of the aperture 211, that is, the focal point of the image forming optical system 100 on the side of the object to be imaged is incident on the image forming optical system 110. Accordingly, the light is output from the exit position of the imaging optical system 110 at a constant distance from the optical axis of the imaging optical system 110, and is vertically incident on the imaging surface 410 in an optical path parallel to the optical axis. Further, the light that has passed through the aperture 211 travels through the imaging optical system 110 to be directed to the imaging points (Q1, Q2, Q3, ...) Corresponding to the respective bright points (P1, P2, P3, ...). Become light. Therefore, the wavefront that has passed through the aperture 211 is not reflected by the imaging optical system 1.
From 10 to the image forming points (Q1, Q2, Q3, ...) Converging spherical waves, and the image forming points (Q1, Q2, Q).
After passing through 3, ...), it becomes a diverging spherical wave.

FIG. 2 is an explanatory view of the incident angle of the object light on the image formation point. The object light that has entered the imaging optical system 110 through the opening 211 with the bright point P as the starting point converges on the imaging point Q. The diameter of the aperture 211 is L, L = λf / p, where λ is the wavelength of the object light f is the object-side focal length of the imaging optical system, and p is the spatial resolution of the image pickup device. The angle θ _i0 formed by the light beam and the optical axis through the imaging optical system is θ _i0 = tan ⁻¹ ((λ / 2) / p). Therefore, the angle θ _i formed between the light rays passing through the aperture 211 and passing through the imaging optical system is θ _i ≦ tan ⁻¹ ((λ / 2) / p). By the way, when A> 0 and tan ⁻¹ A <sin ⁻¹ A, θ _i <sin ⁻¹ ((λ / 2) / p), which satisfies the condition of the expression (2).

The object light that has passed through the imaging optical system 110 and the reference light that is a plane wave (coherent light having the same wavelength as the object light) are input to the interference optical system 300 and interfere with each other. The interference optical system 3
The reference light passing through 00 travels parallel to the optical axis, and
The traveling direction is set by the interference optical system 300 so that the light enters vertically to the optical axis 10.

By the way, (aperture diameter a in the present invention) <L
Therefore, in the holographic imaging device of the present invention,
Since the incident angle to the image forming point always satisfies the condition of the expression (2), the object light and the reference light (plane wave) (coherent light having the same wavelength as the object light) through the image forming optical system 110. It is possible to sample the interference fringes resulting from the interference in the interference optical system 300 at the Nyquist interval or less.

Next, the outline of the principle of hologram reproduction used in the holographic display device of the present invention will be described. The holographic display device of the present invention performs holographic display by reading out an interference fringe image captured by the above principle.

First, a case will be described in which, in holographic imaging, the imaging surface is located at the back focal plane.

FIG. 3 is a block diagram of the most basic reproducing optical system. As shown in FIG. 3, this optical system includes (a) an imaging optical system 110 equivalent to the imaging optical system 110 used in the imaging optical device, and (b) an imaging surface 4 for the imaging optical system 110.
10, a complex holography 510 arranged at one focal plane of the imaging optical system 120,
(C) The stop 220 is provided at a position corresponding to the stop 210 with respect to the image forming optical system 120, that is, at the other focal plane of the image forming optical system 120, and the stop 220 having an opening 221 equivalent to the opening 211.

With this reproducing optical system, the complex hologram 510
When parallel light, which is a conjugate wave of the reference light at the time of image pickup, that is, reading light is irradiated onto the reproduction wavefront, light having a wavefront that makes the object image formed by the image formation optical system 101 at the time of image pickup the virtual image IM1 is generated. To do. This light is input to the imaging optical system 120, and the opening 221 is provided at a position corresponding to the position of the object to be imaged at the time of image pickup.
The real image RL1 is imaged via.

At the time of reproduction, the reproduction light beam has the aperture 2
Since it concentrates in the vicinity of 21, in the reproducing optical system of FIG.
The diaphragm 220 is not always necessary.

Since no complex image is generated in the complex holography 510, the virtual image IM1 and the real image RL1 described above are used.
Other than is not played.

The real image RL1 is to be observed from the viewpoint P11 or the viewpoint P12, which is the back side of the image pickup object at the time of image pickup. Therefore, the observed image is an image obtained by reversing the reproduced image.

At the viewpoint P11 and the viewpoint P12, only a part of the real image RL1 relating to only the reproduction light which passes through the aperture 221 and is incident on each viewpoint can be observed.

The above-mentioned drawbacks of the reproducing optical system shown in FIG. 3 can be remedied. FIG. 4 is a configuration diagram of a reproducing optical system in which the drawbacks of the reproducing optical system of FIG. 3 are improved.

As shown in FIG. 4, this reproducing optical system is
(A) an imaging optical system 120 equivalent to the imaging optical system 110 used in the imaging optical device, and (b) a position corresponding to the imaging surface 410 with respect to the imaging optical system 110, that is, one of the imaging optical systems 120. Complex holography 5 placed on the focal plane of the image and rotated 180 ° about the direction perpendicular to the plane of FIG.
10 and (c) a stop 220 having an aperture 221 equivalent to the aperture 211, which is arranged at a position corresponding to the stop 210 with respect to the image forming optical system 110, that is, on the other focal plane of the image forming optical system 120. .

With this reproducing optical system, the complex hologram 510
When parallel light, which is a conjugate wave of the reference light at the time of image pickup, that is, the reading light is irradiated on, the reproduction wavefront is changed to the virtual image I in FIG.
Light of a wavefront forming a real image RL2 is generated at a target position with respect to the focal plane of M1. This light is input to the imaging optical system 120, and a virtual image IM between the imaging optical system 120 and the diaphragm 220.
It becomes the light of the wavefront which forms 2. By observing the virtual image IM2 with the aperture 221 as the viewpoint, the entire image of the image in the correct image direction is observed without distortion.

Next, the reproducing optical system for recording a hologram in the intensity recording type hologram device will be described.

FIG. 5 is a diagram showing the most basic construction of the reproduction system of the intensity hologram. As shown in FIG. 6, this reproducing optical system converts the complex hologram 510 into the intensity hologram 56.
The difference from the reproducing optical system of FIG. 3 is that only 0 is set.

The intensity hologram 560 of the reproducing optical system shown in FIG.
When the reading light is irradiated on the wavefront, a wavefront that forms a virtual image IM1 at an image-forming position similar to that in the reproduction optical system of FIG. 3 and a real image RL3 at a plane symmetrical position of the virtual image IM1 with the intensity hologram 560 as a plane of symmetry. Reproducing light having a wave front to be formed is generated.

The light of the wavefront forming the virtual image IM1 is reproduced by the imaging optical system 120 as a real image RL1 at the position of the object to be imaged at the time of image pickup. Further, the light of the wavefront forming the real image RL3 is reproduced by the imaging optical system 120 as a virtual image IM3 at a plane symmetrical position of the real image RL1 with the diaphragm 220 as a symmetry plane.

Then, with the opening 221 as the viewpoint, the virtual image IM
If 3 is observed, the entire reproduced image can be observed.

However, the image thus observed is upside down, as in the case of FIG.

This problem can be solved by the same method as that of the reproducing optical system of FIG. 4 which is the same as that of the reproducing optical system of FIG.

FIG. 6 is a block diagram of a reproducing optical system in which the problems of the reproducing optical system of FIG. 5 are improved. As shown in FIG. 6, this reproducing optical system is different in that the intensity hologram 560 is arranged rotated by 180 ° about the direction perpendicular to the paper surface.

FIG. 6 When the intensity hologram 560 of the reproducing optical system is irradiated with the reading light, the wavefront forming the real image RL2 at the same position as the reproducing optical system of FIG.
60 as a plane of symmetry and the virtual image IM at the plane symmetry position of the real image RL2.
Reproducing light having a wave front forming 4 is generated.

The light of the wavefront forming the virtual image IM4 is reproduced by the imaging optical system 120 as a real image RL4 at the position of the object to be imaged at the time of image pickup. Further, the light of the wavefront forming the real image RL2 is reproduced by the imaging optical system 120 as a virtual image IM2 at a plane symmetric position of the real image RL4 with the stop 220 as a plane of symmetry.

Then, with the opening 221 as the viewpoint, the virtual image IM
By observing No. 2, it is possible to observe the entire reproduced image in the same directional relationship as the image at the time of imaging, as in the reproducing optical system of FIG.

The case where the image pickup surface is arranged on the focal plane (focal length = f) of the image forming optical system at the time of image pickup has been described above. However, when the image pickup surface is not arranged on the focal plane of the image forming optical system at the time of image pickup. The reproduction of will be described below. In the following description, it is assumed that the image pickup surface at the time of image pickup is apart from the back focal plane of the image forming optical system by z.

FIG. 7 is a block diagram of a reproducing optical system according to FIG. 3 in which the complex hologram 510 is arranged at the position of the image pickup surface at the time of image pickup. When the reproducing optical system of FIG. 7 is irradiated with the reading light, the virtual image IM1 is formed at the imaging position of the imaging optical system during imaging (the distance from the imaging optical system to the imaging position = b).
Regenerate the light of the wavefront that forms the. At this time, the distance c between the complex hologram 510 and the virtual image IM1 is c = b- (f + z) (5).

Then, the light of the wavefront forming the virtual image IM1 is imaged by the imaging optical system 120 at the position of the object to be imaged at the time of imaging, and the real image RL1 is reproduced. In this reproducing optical system, the real image RL1, which is a reproduced image, is not distorted during image formation.

However, since the same problem as in the case of FIG. 3 described above also exists in observing the real image RL1 in FIG. 7, an improvement equivalent to that of the reproduction optical system of FIG. 4 with respect to the reproduction optical system of FIG. Adopt the reproduction optical system that is performed.

First, in the reproducing optical system of FIG. 7, the complex hologram 510 is rotated 180 ° about the direction perpendicular to the paper surface, and the complex hologram 510 is moved by a distance y and arranged. When the reading light is irradiated by this reproducing optical system, the real image RL2 is reproduced at a position obtained by rotating the virtual image IM1 by 180 ° about the same axis as the rotation axis of the complex hologram. The distance d between the real image RL2 and the imaging optical system 120
Is d = f + z−c−y = 2f + 2z−b−y (6)

In order that the wavefront forming the real image RL2 is imaged by the imaging optical system 120 and the virtual image IM2 without distortion is reproduced, the position of the real image RL2 is symmetrical with respect to the focal plane of the virtual image IM1 in FIG. Must be formed at the position. This condition is d = 2f-b (7).

Therefore, according to the equations (6) and (7), the condition for obtaining the virtual image IM2 without any difference in magnification depending on the position is y = 2z (8).

FIG. 8 is a block diagram of a reproducing optical system which satisfies the condition of the expression (8).

Even when the intensity hologram is used, the whole image of the image in the correct image direction is observed without distortion by the reproducing optical system similar to FIG.

Embodiments of the holographic imaging device and the holographic display device of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

[Embodiment of Holographic Imaging Apparatus] (First Embodiment) FIG. 9 is a block diagram of the holographic imaging apparatus according to the first embodiment of the present invention. The holographic imaging device of this embodiment is an intensity recording type imaging device. As shown in FIG. 9, in this device, (a) a light source unit 610 for generating irradiation light and reference light for irradiating an imaging target object, and (b) light output from the light source unit 610 is an imaging target object 900. As a result of irradiating the object, the diaphragm 210 having the aperture 211 through which the object light reflected by the imaging object 900 passes, and (c) the positive refractive index arranged at the position where the diaphragm 210 is the object side focal plane. Imaging optical system 110 having, and (d) Imaging optical system 110
Interference optical system 31 for interfering the object light and the reference light via the
0, and (e) the imaging surface 4 perpendicular to the optical axis of the imaging optical system 110.
An image pickup unit 400 which has an image pickup unit 400 and which picks up an image formed by the interference light output from the interference optical system 310; and (f) a storage unit 710 which inputs and stores the image pickup information output from the image pickup unit 400. (G) Transmission means 720 for inputting the imaging information output from the imaging means 400 and transmitting the imaging information toward the holographic display device.

When the wavelength of the object light = λ, the aperture diameter of the aperture means = a, the object-side focal length of the imaging optical system = f, and the spatial resolution of the image pickup means = p, then a ≦ λ. f / p (1) is satisfied.

The light source unit 610 includes (i) a laser light source 611 for generating coherent light, (ii) an optical branching device 612 for branching the light output from the laser light source 611, and (iii) an optical branching device 612. A polarizer 613 for inputting one of the lights output from, selecting a polarization direction and outputting the light, and (iv) a polarizer 6
An optical system 614 that outputs the spherical wave irradiation light toward the imaging target 900 through the light 13 and (v) an optical branching device 612.
A polarizer 615 that inputs the other light that is output from the polarizer 615 that outputs by selecting the polarization direction, and (vi) an optical system 616 that outputs the spherical wave light that has passed through the polarizer 615 toward the interference optical system 300. With.

The interference optical system 310 includes (i) optical system 616.
An optical system 311 for inputting the light through the light and converting it into a plane wave;
(Ii) The mirror 312 that reflects the light through the optical system 311 to set the optical path, and (iii) the object light through the imaging optical system 110 and the reference light through the mirror 312 are input and both are input. And a half mirror 313 that outputs the light in substantially the same direction to cause interference.

The image pickup means 400 includes (i) the interference optical system 30.
The optical image on the imaging surface 410 is provided with an analyzer 430 that inputs the interference light output from 0, selects and outputs a polarization direction, and (ii) an imaging surface 410 that receives light through the analyzer 430. And (iii) moving means 440 for moving the position of the image pickup surface 410 relative to the interference optical system 300.

When a CCD camera is used as the image pickup device 420, the image pickup optical system 110 is installed in a scanning direction so as to be inverted vertically and horizontally. In addition, the imaging surface 4
In order to prevent reflection by the protective glass of No. 10, it is preferable to use an optical fiber plate having a core diameter of not more than the imaging resolution in place of the ordinary protective glass.

In the following, the focal length f = 1 in the image forming optical system 110.
8 cm convex lens, pitch p = 11 μm
Imaging surface 410 arranged in 12 (= N) × 512
An example will be described in which the wavelength λ of the light to be used is 0.628 μm and the object to be imaged 900 is arranged approximately 46.4 cm in front of the imaging optical system 110. In this case, the imaging point of the imaging object 900 by the imaging optical system 110 is a position 29.4 cm away from the imaging optical system 110. Further, as the diameter a of the opening 211, a circle of a = λf / p = 1.0 cm was adopted.

It should be noted that the optical axis of the object light is the z-axis, the vertical direction of the paper of FIG. 9 is the y-direction, and the vertical direction of the paper is the x-direction.

The holographic imaging device of this embodiment images the intensity hologram of the imaged object 900 as follows.

First, while keeping the positional relationship between the diaphragm 210 and the imaging optical system 110, the moving means 440 sets the image pickup surface 410 at an appropriate distance L from the image pickup object 900 according to the resolution of the image pickup means. To do.

The distance L can be obtained as follows.

The illuminating light output from the light source unit 100 is reflected by the object 900 to be measured, and the object light reflected by the measuring optical system 110 passes through the imaging optical system 110, and the reference light output from the light source unit 100 is a side surface wave. Caused by interference with the converted plane wave light,
Cosine wave Fresnel zone plate F on the imaging surface 410
(X, y, L) becomes F (x, y, L) = 1 + cos ((2π / λ) (x ² + y ² + L ² ) ^1/2 ) ... (9).

For simplicity, the distance L is approximated to an integral multiple of the wavelength λ, and the distance from the center of the image pickup surface 410 on the xy plane is r _xy.
Then, F (x, y, L) = 1 + cos ((2π / λ) (r _xy ² + L ² ) ^1/2 ) (10)

Therefore, the position r _xyb (n) of the nth bright part of the cosine wave Fresnel zone plate F (x, y, L) is r _xyb (n) = (2Lnλ + n ² λ ² ) ^1/2 (11) ), And the cosine wave Fresnel zone plate F (x,
The position r _xyd (n) of the n-th dark part of (y, L) is r _xyd (n) = ( _2Ln (λ + 1/2) + (n + ^1/2 ) ² λ ² ) ^1/2 (12).

Then, the cosine wave Fresnel zone plate F (x, y,
The condition for resolving L) is r _xyd (n) -r _xyb (n)> p (13).

In the equation (13), the right side and the left side are equal to n
_{Is the} maximum resolution order n _maxp , the maximum resolution order n _maxp is a function of the distance L, and is roughly inversely proportional to the distance L.

Further, when r _xyb (n) = (N / 2) p (14), that is, n at which the positions of the n-th bright parts are at both ends of the imaging surface 410 is the maximum imaging order n _maxd . Then,
The maximum imaging order n _maxd is a function of distance and is proportional to the distance L.

FIG. 10 is a graph showing the distance L dependence of the maximum resolution order n _maxp and the maximum imaging order n _maxd in this embodiment.

The distance L where n _maxp = n _maxd (15) is the optimum distance. By setting this optimal distance, the next light portion maximum resolution order n _{ma xp} becomes the opposite ends of the imaging surface 410 is greater than all the distance resolution p of the interference fringes therein. That is, the imaging surface 410 can be used with maximum efficiency.

From FIG. 10, in the present embodiment, (1
N satisfying the condition of the expression (5) is 64, and the optimum distance Loop
It can be seen that t is about 9.8 cm.

In the holographic imaging device of this embodiment,
The optimum distance Lopt may be set as the distance from the imaging point of the imaging optical system 110 to the imaging surface 410.

When the distance L is larger than 9.8 cm, information that can be originally captured cannot be received, but the stripe information that can be resolved on the entire image pickup surface remains the same.

That is, the distance L between the imaging point of the object 900 to be imaged and the imaging surface 410 is set to 10 by the moving means 440.
cm, that is, the imaging surface 410 is installed at a position separated from the imaging optical system 110 by 19.4 cm.

Next, from the light source section 100 to the image pickup object 9
The irradiation light of 00 and the reference light are output. Reflection occurs on the imaging target 900 irradiated with the irradiation light, and object light that is a spherical wave is generated.

Part of the object light is input to the image forming optical system 110 through the opening 211, is output toward the image forming point, and is input to the interference optical system 300. On the other hand, the reference light output from the light source unit 100 enters the interference optical system 300 and interferes with the object light.

With respect to the interference light output from the interference optical system 300, the object light and the reference light are selected by the analyzer 430 and received by the image pickup surface 410. The fringe image formed by the light received by the image pickup surface 410 is picked up by the image pickup device 420, and the image pickup result is stored in the storage means 710 together with the information of the distance L or is transmitted from the transmission means 720 to the holographic display device. Or

As the laser light source 611, a laser light source capable of sequentially outputting the three primary colors of light is prepared, and holographic imaging is sequentially performed for each color, whereby color reproducible imaging information can be acquired. As a laser light source capable of sequentially outputting the three primary colors of light, it is possible to prepare a laser element for respectively outputting light of each color and drive them sequentially.
A laser light source that outputs light including the three primary colors of light and a filter that selects one of the three primary colors of light may be sequentially used.

(Second Embodiment) FIG. 11 is a block diagram of a second embodiment of the holographic imaging device of the present invention. The holographic imaging device of this embodiment is a complex hologram recording type holographic imaging device. As shown in FIG. 11, this apparatus includes (a) a light source unit 610 for generating irradiation light and a reference light for irradiating an object to be imaged, and (b) a light source unit 61.
As a result of irradiating the imaging target 900 with the light output from 0, the diaphragm 210 having the aperture 211 through which the object light reflected by the imaging target 900 passes, and (c) the diaphragm 210 become the object-side focal plane. An image forming optical system 110 having a positive refractive index arranged at a position, and (d) an interference optical system 320 for causing the object light and the reference light via the image forming optical system 110 to interfere with each other.
(E) An image pickup unit 400 having an image pickup surface 410 perpendicular to the optical axis of the image forming optical system 110 and picking up an image formed by the interference light output from the interference optical system 310; and (f) an image pickup unit 40.
The imaging information output from 0 is input and processed to obtain the intensity and phase of the object light on the imaging surface 410, and
From the processing unit 800 that instructs the phase of the reference light to the interference optical system 320, (g) the storage unit 710 that stores the intensity information and the phase information obtained by the processing unit 800, and (h) the imaging unit 400. Transmission means 72 for inputting the output imaging information and transmitting the imaging information toward the holographic display device.
0.

When the wavelength of the object light = λ, the aperture diameter of the diaphragm means = a, the object-side focal length of the imaging optical system = f, and the spatial resolution of the image pickup means = p, then a ≦ λ · f / p (1) is satisfied.

The interference optical system 320 includes (i) optical system 616.
An optical system 311 for inputting the light through the light and converting it into a plane wave;
(Ii) The light is transmitted through the optical system 311, and the processing unit 800
A phase adjuster 321 that adjusts and outputs the phase of the output light by an amount instructed by, (iii) a half mirror 322 that sets the optical path of the light through the phase adjuster 321, and (iv) an imaging optical system. A half mirror 313 is provided, which receives the object light through 110 and the reference light through the half mirror 322, outputs both lights in substantially the same direction, and interferes with each other. In addition,
The phase adjuster 321 performs four-stage phase adjustment for each λ / 4.

The phase adjuster 321 comprises (i) a mirror 326 for reflecting incident light and (ii) a piezo element 327 for moving the mirror 326 in response to an instruction from the processing section 800.
And

FIG. 12 is a block diagram of the processing section 800.
As shown in FIG. 12, (i) frame memories 810 _{0 to} 810 ₃ for storing light intensity data of each pixel on the imaging surface 410 for each adjustment phase amount, and (ii) frame memory 8
10 _{0-810 3} based on the data of each pixel stored in the calculation unit 820 for calculating the object light amplitude and phase at each pixel location, (iii) a frame memory 810 _0-810
And a control unit 830 that issues a phase adjustment instruction signal to the phase adjuster 321.

In the holographic imaging device of this embodiment,
Imaging of a complex hologram is performed as follows.

First, similarly to the first embodiment, the diaphragm 2
While maintaining the positional relationship between 10 and the imaging optical system 110, the moving surface 440 sets the image pickup surface 410 at an appropriate distance L from the image pickup object 900 according to the resolution of the image pickup means.

From the processing section 800, the phase adjustment amount = 0
Is issued, and the phase adjuster 321 installs the mirror 326 at the position where the phase adjustment amount = 0.

Subsequently, from the light source section 100 to the image pickup object 9
The irradiation light of 00 and the reference light are output. Reflection occurs on the imaging target 900 irradiated with the irradiation light, and object light that is a spherical wave is generated.

A part of the object light is input to the image forming optical system 110 through the opening 211, is output toward the image forming point, and is input to the interference optical system 320. On the other hand, the reference light output from the light source unit 100 is input to the interference optical system 320 and interferes with the object light when the phase adjustment amount = 0.

The interference light output from the interference optical system 320 is received by the image pickup surface 410 after the object light and the reference light are selected by the analyzer 430. The fringe image formed by the light received by the image pickup surface 410 is picked up by the image pickup device 420, and the image pickup result is stored in the frame memory 810 ₀ as data (I ₀ ) with the phase adjustment amount = 0.

Next, the processing section 800 determines that the phase adjustment amount = π /
Phase adjustment instructions of 2, π, 3π / 2 are sequentially issued, and the imaging results (I ₁ , I ₂ , I ₃ ) for each case are issued to the frame memories 810 _1- .
The data is stored in 810 ₃ .

The phase adjustment amount is φΔ, and the object light is A _O ex
p [jφ _O ], reference light is A _R exp [j (φ _R + φΔ)]
Then, the light intensity I on the imaging surface 410 is I = A _O ² + A _R ² + 2A _O A _R (cos (φ _O −φ _R ) cos φΔ + sin (φ _O −φ _R ) sin φΔ) (16) Become.

Therefore, φΔ = 0, π / 2, π, 3π
I _{0 to} I ₃ that is / 2 are I ₀ = A _O ² + A _R ² + 2A _O A _R cos (φ _O −φ _R ) ... (17) I ₁ = A _O ² + A _R ² + 2A _O A _R sin (Φ _O −φ _R ) (18) I ₂ = A _O ² + A _R ² -2A _O A _R cos (φ _O −φ _R ) (19) I ₃ = A _O ² + A _R ² -2A _O A _R sin (φ _O −φ _R ) (20)

From the equations (17) to (20), I ₀ -I ₂ = 4A _O A _R cos (φ _O -φ _R ) (21) I ₁ -I ₃ = 4A _O A _R sin (φ _O − φ _R ) ... (22)

From equations (21) and (22), φ _O −φ _R = tan ⁻¹ ((I ₁ −I ₃ ) / (I ₀ −I ₂ )) (23) and the reference light of the object light The phase is obtained. Since the reference light is a plane wave, the phase φ _{R of the} reference light is constant at any point on the imaging surface 410, so φ _O − of each pixel obtained in (23).
From φ _R , the relative phase between each pixel is obtained.

From the expressions (21) and (23), the amplitude A _{O of the} object light is obtained as A _O = (I ₀ −I ₂ ) / (4A _R cos (φ _O −φ _R )) (24) .

The arithmetic operations (21) to (24) are performed in the arithmetic unit 820 under the sequence control of the control unit 830 as follows.

First, the frame memory 810i (i = 0,
The imaging results Ii are read out at the same video rate from 1, 2, and 3).

I ₀ and I ₂ are input to the difference calculator 821 to calculate (I ₀ −I ₂ ), and (I ₀ −I ₂ ) is input to the synchronization register 823 and the division calculator 824. Also,
I ₁ and I ₃ are input to the difference calculator 822 to calculate (I ₁ −I ₃ ), and (I ₁ −I ₃ ) is input to the division calculator 824. In the division calculator 824, (I ₁ −I ₃ ) / (I ₀ −I ₂ ).
Is calculated and the result is input to the arctangent calculator 825. The arctangent calculator 825 executes the calculation of Expression (23), the calculation result (φ _O −φ _R ) is input to the cosine calculator 826, and the calculator 820 is also supplied via the synchronization register 828.
Is output as the first calculation result of.

In the cosine calculator 826, 4A _R cos (φ _O −
φ _R ) is calculated, and the calculation result is input to the division calculator 827. In the division calculator 827, in addition to the calculation result of the cosine calculator 826, the data stored in the register 823 (I ₀ −I ₂ )
Is input to execute the calculation of Expression (24). Then, the amplitude A _O of the object light, which is the calculation result, is output as the second calculation result of the calculation unit 820.

The calculation result of the calculation unit 820 is stored in the storage means 710 or the transmission means 7 together with the information of the distance L.
20 to the holographic display device.

As in the case of the first embodiment, the laser light source 6
As 11, a laser light source that can sequentially output the three primary colors of light is prepared, and holographic imaging is sequentially performed for each color, whereby color reproducible imaging information can be acquired. As the laser light source capable of sequentially outputting the three primary colors of light, it is possible to prepare a laser element for respectively outputting light of each color and drive them sequentially, or a laser for outputting light including the three primary colors of light. A light source and a filter for selecting one of the three primary colors of light may be sequentially used.

[Embodiment of Holographic Display Device] (First Embodiment) FIG. 13 is a block diagram of the holographic display device according to the first embodiment of the present invention. The holographic display device according to the present embodiment is a device that reproduces an image of the imaging target 900 based on the intensity hologram imaged by the holographic imaging device in FIG. 9.

As shown in FIG. 13, this device has (a)
An information input unit 750 for inputting hologram information obtained by the holographic imaging device of FIG. 9 and (b) hologram information input via the information input unit 750, and a hologram forming unit 650 for forming a hologram 511 based on this hologram information. And (c) an image forming optical system 120 equivalent to the image forming optical system 110 of FIG. 9 for inputting and forming an image by inputting the light of the wavefront forming the hologram 511, and (d) the hologram 511 and the image forming optical system 110. Moving means 150 for changing the distance between
And (e) a zero-order light-shielding plate 250 arranged at the focal position on the side opposite to the hologram 511 side of the imaging optical system 110.

The information input section 750 includes (i) an information reading device 751 for reading the stored information from the storage medium of the imaging result of the holographic imaging device, and (ii) a receiver 752 for receiving the imaging result transmitted from the holographic imaging device. With.

The hologram forming section 650 writes (i) the display device 651 for displaying an image and (ii) the image displayed on the display device 651 based on the information notified from the information input section 750, and the space light. Modulator 652, and (iii)
A laser light source 653 that irradiates the spatial light modulator 652 to generate coherent light that is a plane wave, and (iv) laser light source 65
A relay optical system 654 that guides the light output from the light source 3 to the spatial light modulator 652, and (v) the space phase input by the spatial light modulator 652 is input and the space that matches the size on the image pickup surface at the time of image pickup The optical modulator 652 includes an afocal optical system 655 that forms the hologram 511.

Further, in order to prevent reflection by the protective glass of the spatial light modulator 652, it is preferable to use an optical fiber plate having a core diameter of not more than the imaging resolution in place of the ordinary protective glass.

A case where a convex lens having a focal length f = 18 cm and a wavelength λ of light to be used λ = 0.628 μm is adopted in the image forming optical system 120 will be described below as an example, in accordance with the holographic image pickup apparatus shown in FIG.

In this holographic display device, the image of the object to be imaged is reproduced and displayed from the image pickup result by the holographic image pickup device of FIG. 9 as follows.

First, the moving unit 150 adjusts the formation position of the hologram 511 and the imaging optical system 120 according to the condition of the expression (8). That is, in the holographic imaging device of FIG. 9, z = 1.4 cm, so 2.8 c from this position toward the imaging optical system 110 in FIG.
Move m (= 2z). As a result, the hologram 511 is formed at a position 16.6 cm from the imaging optical system 110.

Next, image information, which is hologram information, is input from the information input section 750, displayed on the display device 651, and the image information is written in the spatial light modulator 652. A small CRT is used as the display device 651, and the spatial light modulator 6 is used.
As 52, an optical writing type liquid crystal spatial light modulator can be preferably used. The image pickup result is displayed on the display device 651.
It is displayed by rotating 180 degrees around the optical axis (z axis).

Subsequently, the light emitted from the laser light source 653 passes through the relay optical system 654 and the spatial light modulator 652.
Is irradiated. Then, the light phase-modulated by the spatial light modulator 652 is passed through the afocal optical system 655 and has the same size as that at the time of image pickup, and the hologram 511 of the spatial light modulator 652 is used.
To form The magnification of the afocal optical system is the display device 6
It is determined by the ratio of the size of the pixel of 51 and the size of the pixel at the time of imaging. For example, when a 1.5-inch small CRT is used as the display device 651, the pixel size is about 40.
μm, and the pixel size at the time of imaging is 11
Since it is μm, an afocal optical system of about 4: 1 is used.

The real image RL2 reproduced by the hologram 511 is reproduced on the imaging optical system 120 side from the hologram 511 at a position of about 6.6 cm from the imaging optical system 120. The wavefront forming the real image RL2 is formed by the imaging optical system 12
A wavefront that forms a virtual image IM2 at 0 is set. Imaging optical system 12
The 0th-order light of the light output from 0 is converted into the imaging optical system 120.
The light is blocked by the 0th-order light shielding plate 250 arranged at the focal position of 1, and light of the 1st or higher order is transmitted.

Then, by observing the light not shielded by the 0th order light shielding plate 250 from the rear of the 0th order light shielding plate 250, a reproduced image of the image pickup object 900 without distortion is observed.

When holographic imaging is performed for each of the three primary colors of light, reproduction images for each color are combined, and when holographic imaging is performed for the three primary colors of light, the same procedure as above is performed. Image object 90
The image of 0 can be reproduced in color.

(Second Embodiment) FIG. 14 is a configuration diagram of a second embodiment of the holographic display device of the present invention. The holographic display device according to the present embodiment is a device that reproduces an image of the imaging target 900 based on the intensity hologram imaged by the holographic imaging device in FIG. 9.

As shown in FIG. 13, this device has (a)
An information input unit 750 for inputting hologram information of the holographic imaging device of FIG. 9 and (b) hologram information via the information input unit 750 are input, and a reproduced image of the imaging target 900 is calculated based on this hologram information. Operation unit 7
70 and (c) a display device 790 that displays the calculation result of the calculation unit 770.

As the arithmetic unit 770, a computer having a functional arithmetic capacity is used.

In this holographic display device, the image of the object to be imaged is reproduced and displayed from the image pickup result by the holographic image pickup device of FIG. 9 as follows. FIG. 15 is a flowchart of the arithmetic processing in the arithmetic unit 770 in this embodiment.

First, the calculation section 770 inputs hologram information from the information input section. Subsequently, either the amplitude or the phase is determined as the operation target, and the real number part and the imaginary number part are separated to obtain a complex number distribution H (x, y).

Next, for the calculation by the reproducing optical system model of FIG. 8, the position of the hologram is corrected according to the equation (8) and virtually arranged. In the holographic imaging device of FIG. 9, z =
Since it was 1.4 cm, the holography is virtually arranged at a position separated by 16.6 cm from the virtual imaging optical system equivalent to the imaging optical system 110, as in the first embodiment.

Next, the wavefront from the virtually arranged holography is subjected to Fresnel transformation, and the wavefront at the focal plane on the holography side (hereinafter also referred to as the front side) of the virtual imaging optical system is calculated.

As a method of such calculation, there are a spherical wave reproducing method and a fast Fourier transform method. Hereinafter, each of them will be described.

(1) Spherical wave reproduction method Transmission distance L (= 1.4 cm), pitch p (= 11 μ)
m), the number of pixels is N (= 512) × N, and the wavefronts from all of the hologram lattice points are added together for each point on the front focal plane of the virtual imaging optical system.

That is, assuming that the pitch at the front focal plane is h _P , the wavefront at the front focal plane is Of (h _P m, h _P n)
Is

[Equation 1] Here, m = -N / 2 to N / 2-1 integer n = -N / 2 to N / 2-1 integer j = -N / 2 to N / 2-1 integer i = -N / It is calculated by an integer of 2 to N / 2-1.

(2) Fast Fourier transform method Transmission distance L (= 1.4 cm), pitch p (= 11 μ)
m), the number of pixels N (= 512) × N, the pitch at the front focal plane is h _P, and the wavefront at the front focal plane is Of (h _P m, h _P
n) is Of (h _P m, h _P n) = F ⁻¹ [F [H (h _P m, h
_P n)] · F [f (h _P m, h _P n)]] where F: fast Fourier transform F ⁻¹ : fast Fourier inverse transform f (h _P m, h _P n) = (1 / r ) Exp [jkr] r = (h _P m ² + h _P n ² + L ² ) ^1/2 m = -N / 2 to N / 2-1 integer n = -N / 2 to N / 2-1 integer Calculate and obtain.

Depending on the size of the Fresnel propagation distance L, F [f (h _P m, h _P n)] = exp [2πL [(1 /
λ) ²⁻ (m / (h _P N)) ²⁻ (n / (h
_In some cases, it may be preferable to use _P N)) ² ] ^1/2 ].

As described above, after calculating the wavefront on the front focal plane, the sign of the Fresnel propagation direction is determined. The sign of the Fresnel propagation direction defines the direction from the hologram to the virtual imaging optical system as positive, and determines whether the direction of the front focal plane viewed from the hologram is positive or negative.

O when the sign of the Fresnel propagation direction is positive
f (h _P m, h _P n) is adopted as it is, and when negative, O
The complex conjugate of f (h _P m, h _P n) is adopted to match the wavefront propagation directions.

In the case of this embodiment, since the sign of the Fresnel propagation direction is negative, the complex conjugate is calculated.

Next, 2 is added to the wavefront at the adopted front focal plane.
A two-dimensional Fourier transform is performed to calculate a wavefront G (f _P m, f _P n) at the focal plane on the side opposite to the holography side of the virtual imaging optical system (hereinafter also referred to as the rear side). Here, f _P is the pixel pitch in the rear focal plane. G (f _P m, f _P n)
Is the pitch f _P = λf / (h _P N) (= 20.22 μm)
Then, one side is distributed at the lattice points in the range of λf / h _P.

Next, calculation is executed by setting the 0th-order light shielding to G (0,0) = 0. The range of the 0th-order light shielding operation for G (x, y) = 0 is adjusted appropriately.

Subsequently, the G (f _P
Inverse Fresnel transform is applied to m, f _P n) to calculate and obtain the wavefront distribution of the virtual image IM2.

In the present embodiment, the distance L _O between the rear focal point and the virtual image IM2 is 28.4 cm.

As a method of such calculation, there are a spherical wave reproducing method and a fast Fourier transform method. Hereinafter, each of them will be described.

[0162] (1) a spherical wave reproduction method transmission distance L _O (= 28.4cm), a pitch o _p (= 11μ
m), the number of pixels is N (= 512) × N, and the wavefronts from all the lattice points of the back focal plane of the virtual imaging optical system are added to each point of the virtual image IM2.

That is, the wavefront O (o in the virtual image IM2
_p m, o _p n) is

[Equation 2] Here, m = -N / 2 to N / 2-1 integer n = -N / 2 to N / 2-1 integer j = -N / 2 to N / 2-1 integer i = -N / It is calculated by an integer of 2 to N / 2-1. In the present embodiment was o _p = f _P.

[0164] (2) Fast Fourier Transform method the transmission distance L _O (= 28.4cm), a pitch o _p (= 11μ
m) and the number of pixels N (= 512) × N, and the wavefront O (f _p m, f _p n) in the virtual image IM2 is O (f _p m, f _p n) = F ⁻¹ [F [G ( h _P m, h _P n)]
_{· F [f (h P m} , h P n)]] where, F: Fast Fourier transform F ^-1: inverse fast Fourier transform _{f (h P m, h P} n) = (1 / r) exp [jkr ^{_{] r = (h P m 2}} + h P n 2 + L 2) 1/2 m = -N / 2~N / 2-1 integer n = calculates an integer -N / 2 to n / 2-1 Ask.

Depending on the size of the Fresnel propagation distance L, F [f (h _P m, h _P n)] = exp [2πL [(1 /
λ) ²⁻ (m / (h _P N)) ²⁻ (n / (h
_In some cases, it may be preferable to use _P N)) ² ] ^1/2 ].

Finally, O (o _p calculated above)
m, o _p n) or O (f _p m, f _p n) is converted to display a reproduced image of the imaging target on the display device 790.

In the above, the tomographic image of the virtual image IM2 is generally displayed.

If there is an image pickup result for each of the three primary colors of light, color reproduction can be performed by performing the above calculation for each color and synthesizing the final reproduced image.

(Third Embodiment) FIG. 16 is a block diagram of a holographic display device according to a third embodiment of the present invention. The holographic display device according to the present embodiment is a device that reproduces an image of the imaging target 900 based on the intensity hologram imaged by the holographic imaging device in FIG. 11.

As shown in FIG. 16, this apparatus has (a)
An information input unit 750 for inputting hologram information obtained by the holographic imaging device of FIG. 11, and (b) information input unit 750.
11, the hologram forming section 660 that forms the hologram 513 based on the hologram information and (c) the light of the wavefront that forms the hologram 513 are input to form the image. An imaging optical system 120 equivalent to the optical system 110, and (d) moving means 15 for changing the distance between the hologram 511 and the imaging optical system 110.
0, and (e) a zero-order light-shielding plate 250 arranged at the focal position on the opposite side of the hologram 511 side of the imaging optical system 110.

The hologram forming section 660 includes (i) a phase modulator 661 that modulates the phase of the input light and an amplitude modulator 662 that modulates the amplitude of the input light based on the phase information notified from the information input section 750. Phase amplitude modulator 66 including
3 and (ii) a laser light source 653 for irradiating the phase amplitude modulation unit 663 to generate coherent light that is a plane wave, and (ii)
i) The phase modulator 6 uses the light output from the laser light source 653.
61 and relay optical system 654 leading to the amplitude modulator 662
And (iv) input the light through the phase amplitude modulator 663,
Spatial light modulator 65 having the same size as that on the imaging surface at the time of imaging
Afocal optical system 6 for forming the second hologram 511
55.

Hereinafter, a case where a convex lens having a focal length f = 18 cm and a wavelength λ of light to be used λ = 0.628 μm is adopted in the image forming optical system 120 will be described as an example, in accordance with the holographic image pickup apparatus of FIG.

In this holographic display device, the image of the imaged object is reproduced and displayed from the image pickup result by the holographic image pickup device of FIG. 11 as follows.

First, similarly to the first embodiment, the moving means 15
By 0, the formation position of the hologram 511 and the imaging optical system 120 are adjusted according to the condition of the expression (8). That is, in the holographic imaging device of FIG. 9, z = 1.4 cm
Therefore, from this position, the imaging optical system 1 in FIG.
Move 2.8 cm (= 2z) in the direction to 10. As a result, the hologram 511 is formed at a position 16.6 cm from the imaging optical system 110.

Next, the light emitted from the laser light source 653 is applied to the phase amplitude modulation section 663 via the relay optical system 654. Further, phase information and amplitude information, which are hologram information, are input from the information input unit 750, and the phase modulator 661 executes the phase modulation operation and the amplitude modulator 662 executes the amplitude modulation operation. Phase modulator 661 and amplitude modulator 66
2 is Japanese Unexamined Patent Publication No. 5-127139 and Japanese Unexamined Patent Publication No. 5-11934.
It can be realized by using the technique disclosed in No. 1 and using a liquid crystal panel.

The light phase-modulated by the spatial light modulator 652 forms the hologram 511 of the spatial light modulator 652 through the afocal optical system 655 in the same size as that at the time of image pickup. The magnification of the afocal optical system is the display device 65.
It is determined by the ratio between the size of one pixel and the size of the pixel at the time of imaging.

The real image RL2 reproduced by the hologram 511 is reproduced on the imaging optical system 120 side of the hologram 511 at a position of about 6.6 cm from the imaging optical system 120. The wavefront forming the real image RL2 is formed by the imaging optical system 12
A wavefront that forms a virtual image IM2 at 0 is set. Imaging optical system 12
The 0th-order light of the light output from 0 is converted into the imaging optical system 120.
The light is blocked by the 0th-order light shielding plate 250 arranged at the focal position of 1, and light of the 1st or higher order is transmitted.

Then, by observing the light not shielded by the 0th order light shielding plate 250 from the rear of the 0th order light shielding plate 250, a reproduced image of the image pickup object 900 without distortion is observed.

If the phase and amplitude modulation is ideal, the 0th order light shielding plate 250 is not always necessary.

When holographic imaging is performed for each of the three primary colors of light, reproduction images for the respective colors are combined, and when holographic imaging is performed for the three primary colors of light, the same procedure as above is performed. Image object 90
The image of 0 can be reproduced in color.

(Fourth Embodiment) FIG. 17 is a block diagram of a holographic display device according to a fourth embodiment of the present invention. The holographic display device according to the present embodiment is based on the intensity hologram imaged by the holographic imaging device of FIG.
This is a device for reproducing an image of the imaging target 900.

As shown in FIG. 16, this apparatus has (a)
An information input unit 750 for inputting hologram information obtained by the holographic imaging device of FIG. 11, and (b) information input unit 750.
The calculation unit 780 which inputs the hologram information via the calculation unit and calculates the reproduced image of the imaging target 900 based on the hologram information, and (c) the display unit 790 which displays the calculation result of the calculation unit 770.

As the arithmetic unit 780, a computer having a functional arithmetic capacity is used.

In this holographic display device, the image of the object to be imaged is reproduced and displayed from the image pickup result of the holographic image pickup device of FIG. 11 as follows. FIG. 18 is a flowchart of the arithmetic processing in the arithmetic unit 780 in this embodiment.

First, the calculation section 780 inputs hologram information from the information input section. Subsequently, the calculation target is separated into a real number part and an imaginary number part in terms of amplitude and phase to obtain a complex number distribution H (x, y).

Thereafter, the same calculation as in the second embodiment is performed,
Finally calculated O (o _p m, o _p n) or O (f
_p m, f _p n) is converted and the reproduced image of the imaging target is displayed on the display device 790.

Note that, in the above, similarly to the second embodiment, a tomographic image of the virtual image IM2 is generally displayed.

[0188]

As described above in detail, according to the holographic image pickup device of the first aspect, the stop having the predetermined aperture is arranged at the object-side focal position of the image forming optical system, and
The object light that has passed through this opening is imaged by the imaging optical system, and the object light and the reference light that have passed through the imaging optical system are made to interfere
Since the interference fringes are imaged, the field of view can be varied, and a high quality hologram can be imaged by using an image sensor having a relatively low spatial resolution.

According to the holographic display device of the sixth aspect, an image forming optical system equivalent to the image forming optical system at the time of image pickup is adopted, and the positional relationship between the image forming optical system and the image pickup surface at the time of image pickup is adopted. Accordingly, the positional relationship between the formed hologram and the imaging optical system is set to reproduce the image of the imaged object, so that the distortion of the hologram imaged by the holographic imager according to claim 1 with respect to the original image is reduced and the imaged object is imaged. It becomes possible to reproduce and display the image of the object.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the principle of a holographic imaging device of the present invention.

FIG. 2 is an explanatory diagram of an incident angle of object light on an image formation point.

FIG. 3 is a configuration diagram of a reproduction optical system of a basic complex hologram (a hologram is arranged on a focal plane).

FIG. 4 is a configuration diagram of a reproduction optical system which is an improvement of the reproduction optical system of FIG.

FIG. 5 is a block diagram of a reproduction optical system for a basic intensity hologram (a hologram is arranged on a focal plane).

6 is a configuration diagram of a reproduction optical system which is an improvement of the reproduction optical system of FIG.

FIG. 7 is a configuration diagram of a basic reproduction optical system (a hologram is arranged on a surface other than the focal plane).

8 is a configuration diagram of a reproduction optical system which is an improvement of the reproduction optical system of FIG.

FIG. 9 is a configuration diagram of the first embodiment of the holographic imaging device of the present invention.

FIG. 10 is a graph showing changes in the maximum resolution order and the maximum imaging order with the distance L in the holographic imaging apparatus according to the first embodiment of the present invention.

FIG. 11 is a configuration diagram of a second embodiment of the holographic imaging device of the present invention.

FIG. 12 is a configuration diagram of a processing unit of a second embodiment of the holographic imaging device of the present invention.

FIG. 13 is a configuration diagram of the first embodiment of the holographic display device of the present invention.

FIG. 14 is a configuration diagram of a second embodiment of the holographic display device of the present invention.

FIG. 15 is a flowchart illustrating a calculation process in the second embodiment of the holographic display device of the present invention.

FIG. 16 is a configuration diagram of a holographic display device according to a third embodiment of the present invention.

FIG. 17 is a configuration diagram of a holographic display device according to a fourth embodiment of the present invention.

FIG. 18 is a flowchart illustrating a calculation process in the fourth embodiment of the holographic display device of the present invention.

[Explanation of symbols]

110, 120 ... Imaging optical system, 210, 220 ... Aperture,
211, 221 ... Aperture, 310, 320 ... Interference optical system,
410 ... Imaging surface, 420 ... Imaging device, 650, 660 ... Hologram forming section, 770, 780 ... Arithmetic section, 800 ... Processing section.

Claims (9)

[Claims] 1. A first device for generating light for irradiating an object to be imaged.
And a diaphragm unit having an opening for passing the object light reflected by the imaging target as a result of the light output from the first light source being applied to the imaging target, and the diaphragm unit. A first imaging optical system having a positive refractive index, disposed at a position serving as a side focal plane, a second light source for generating coherent light having the same wavelength as the object light, and the second The coherent light output from the light source as a reference light that is a plane wave, and an interference optical system that causes the object light and the reference light to pass through the first imaging optical system, and the first imaging The optical axis of the first imaging optical system is located at a position apart from the focal plane of the first imaging optical system on the side of the interference optical system in the traveling direction of the reference light output from the optical system. And an image pickup surface that is perpendicular to the And means, the wavelength of the object light beam = lambda, diameter of the opening of said throttle means =
a, the object-side focal length of the first imaging optical system = f, and the spatial resolution of the imaging means = p, the following relationship is satisfied: a ≦ λ · f / p Imaging device. 2. The holographic imaging device according to claim 1, wherein the first light source and the second light source are the same light source. 3. The holographic imaging device according to claim 1, further comprising a first moving unit that changes the first distance. 4. The holographic imaging device according to claim 1, wherein the imaging result of the imaging unit is the intensity of light on the imaging surface. 5. The holographic image pickup apparatus according to claim 1, wherein the image pickup result of the image pickup means is an amplitude of a light wave and a phase of a light wave on the image pickup surface. 6. A holographic display device for reproducing and displaying an image of an imaged object based on optical information imaged by the holographic image pickup device according to claim 1, wherein an image pickup result by the holographic image pickup device according to claim 1 is input. An information input unit for forming a hologram, a hologram forming unit that forms a hologram on an image pickup surface at the time of being picked up by the holographic image pickup device according to the information notified from the information input unit, and a focus on the hologram side. A second imaging optical system, the surface of which is separated from the position of the hologram in the average traveling direction of the hologram forming light by a first distance in the holographic imaging device according to claim 1, and the second imaging optical system. And a 0th-order light shielding unit arranged at the focal point on the side opposite to the hologram side. 7. The second moving means for changing the distance between the position of the hologram and the focal plane of the second imaging optical system on the hologram side is further provided. Holographic display device. 8. The hologram forming section writes a spatial light modulation image corresponding to the optical image displayed on the display means, the display means displaying an optical image of an imaging result notified from the information input section. Spatial light modulator, a light source for generating read light with which the spatial light modulator is irradiated, and phase or amplitude-modulated light in which the read light is phase- or amplitude-modulated by passing through the spatial light modulator. Then
The holographic display device according to claim 6, further comprising: a hologram forming optical system that forms a hologram having the same size as that of the image pickup element of the holographic image pickup device. 9. The imaging result obtained by the holographic imaging device according to claim 1 is amplitude information and phase information of incident light at each point on the imaging surface, and the hologram forming unit receives the amplitude notified from the information input unit. A phase-amplitude modulation unit that performs phase modulation and amplitude modulation on incident light and outputs the light according to the information and the phase information; a light source that generates read light with which the phase-amplitude modulation unit is irradiated; A holography forming optical system for inputting phase-amplitude modulated light, which is phase-amplitude-modulated by way of a modulator, and forming a hologram having the same size as that of the image pickup device of the holographic image pickup device. Display device.