JP2001337585A - Distortion image correcting method and distortion image corrector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously perform distortion image correction by optical deconvolution processing to a light receiving image which changes in terms of time, moreover can do so without changing a position of an optical element used for recording and readout of a hologram. SOLUTION: In the distortion image correcting method which corrects and restores the light receiving image with distortion recorded on the hologram 8, at the time of light wave mixing by using a photo refractive medium 14, light waves 24, 25 and 26 which contribute to the light wave mixing, and distortion reflection light wave 220 which does not have interference with the light waves 24, 25 and 26 contributing to the light wave mixing and reflecting the distortion component of the light receiving image are emitted to the photo refractive medium 14, the emitted light 270 generated by the light wave mixing is used as reading light 28 of the light receiving image with distortion recorded on the hologram 8 to remove the distortion from the light receiving image, and the light receiving image is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion image correction method and a distortion image correction apparatus for correcting and restoring a distorted received image recorded on a hologram.

[0002]

2. Description of the Related Art In an optical information communication process for measuring the shape of an object by receiving reflected light, scattered light from the object, or light generated from the object, and for optically transmitting and receiving image information,
When the received image is distorted due to the influence of wavefront disturbance in the light propagation path and the aberration in the light receiving system, use both a hologram that records the distortion component of the received image and an optical filter that is made using the distortion component of the received image. As a result, optical deconvolution processing is performed to restore a distorted received light image.

[0003] "Deconvolution" refers to the convolution of a certain function f and g.
Is a mathematical operation process for restoring g or f from the function h provided by the above. The optical deconvolution process here is a series of optical processes for restoring a received image by removing distortion. Is equivalent to

[0004]

However, in order to produce an optical filter using the distortion component of the received light image, exposure of the photosensitive material with the distortion component of the received light image and development processing of the exposed photosensitive material are performed. Therefore, a series of processes for producing an optical filter requires several minutes. For this reason, when the received light image changes in a shorter time than the manufacturing time of the optical filter, there is a problem that it is difficult to repair the distorted received light image by the optical deconvolution process to follow the temporal change of the received light image. Occurs.

[0005] In addition, since a series of processes for producing an optical filter is performed by removing the photosensitive material from the optical system used for exposing the photosensitive material, the optical filter produced is required to perform optical deconvolution processing. It has been required to relocate the photosensitive material at the exposure position with high precision, and this has been a time-consuming, complicated and difficult operation.

[0006] The present invention has been proposed in view of the above,
Distortion image correction by optical deconvolution processing,
An object of the present invention is to provide a distortion image correction method that can be performed continuously on a light-receiving image that changes with time and that can be performed without changing the position of an optical element used for recording and reading a hologram. And

[0007]

According to a first aspect of the present invention, there is provided a distortion image correction method for correcting and restoring a distorted light-receiving image recorded on a hologram. At the time of the light wave mixing used, the light wave contributing to the light wave mixing and the light wave contributing to the light wave mixing are irradiated to the photorefractive medium with a distortion reflected light wave that has no coherence and reflects the distortion component of the received image,
The emitted light generated by the light wave mixing is used as read light of a distorted light-receiving image recorded on a hologram, and distortion is removed from the light-receiving image to correct the light-receiving image.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the light wave mixing in the photorefractive medium is applied to the signal light of the light waves contributing to the light wave mixing. The phase conjugate light is emitted as readout light, and the phase conjugate light is controlled by the distortion reflected light wave so as to have a distribution inversely proportional to the power spectrum of the distortion component.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the present invention, a laser beam is branched by an optical switch, and a hologram is formed by using one of the laser beams. A distorted received light image is recorded, the other laser beam is used to generate readout light by light wave mixing in a photorefractive medium, and the two branched laser beams are alternately generated by an optical switch to generate a light beam from the received light image. Is continuously removed.

Further, the invention according to claim 4 is a distortion image correction apparatus for correcting and repairing a distorted received image recorded on a hologram, wherein the optical switch for alternately switching a laser beam emitted from a laser, A distorted light receiving image recording unit that records a distorted light receiving image on a hologram with one laser beam branched by a switch and the other laser beam branched by the optical switch contributes to light wave mixing in a photorefractive medium. The lightwave and the lightwave contributing to the lightwave mixing generate a distortion-reflected lightwave that has no coherence and reflects the distortion component of the received image, and irradiates each of these lightwaves to a photorefractive medium, and the lightwave mixture mixes the received lightwave. A reading light generation unit that generates reading light and irradiates the received light image recorded on the hologram; and the distortion is removed by the reading light. It is characterized by and a light receiving portion for forming receiving the received-light image.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of a distortion image correction device according to the present invention. In the figure, the distorted image correcting apparatus of the present invention uses a distorted received light image 29
(FIG. 2) is a device for correcting and restoring the light, and an optical switch 3 for alternately switching the laser beam 19 emitted from the laser light source 1, a distorted light receiving image recording unit 50, and a reading light generating unit 6
0 and a light receiving unit 70.

Laser beam 1 emitted from laser light source 1
Reference numeral 9 denotes a hologram recording beam 20 which is passed through the collimator lens 2 for shaping the beam diameter to a constant value,
And the readout light generating beam 21 are alternately switched, and the hologram recording beam 20 is guided to the above-described distorted light receiving image recording unit 50, and the readout light generation beam 21 is guided to the readout light generation unit 60. .

The distortion received light image recording section 50 includes a filter 5 through which the hologram recording beam 20 passes, and a filter 5
And a hologram 8 that records the hologram recording beam 20 that has passed through the lens 6.

The reading light generating section 60 splits the reading light generating beam 21 and divides it into a light wave mixing beam 23 and a distortion component irradiation beam 22 having no interference with the light wave mixing beam 23. A splitter 11, a filter 12 through which a distortion component irradiation beam 22 passes, and a filter 1
2 is a beam for irradiating the distortion component after passing through 2 (distortion reflected light wave) 220
13, a photorefractive medium (light-induced refractive index medium) 14, a beam splitter 16 for splitting the light wave mixing beam 23 into a signal light 24 and a first reference light 25, and a first reference light 25 Mirror 18 that reflects light
A mirror 15 that reflects the first reference light 25 after passing through the photorefractive medium 14, a second reference light 26 that is reflected by the mirror 15 and irradiates the photorefractive medium 14, and generated from the photorefractive medium 14. The light 27 includes the phase conjugate light 27, the beam splitter 17 that extracts the phase conjugate light 270 from the light 27, and the beam splitter 7 that reflects the phase conjugate light 270.

The light receiving section 70 includes a beam splitter 7.
The lens 9 includes a lens 9 that performs Fourier transform on the read light 28 reflected by the hologram 8 after passing through the hologram 8 and a light receiving device 10 that receives the read light 28 that has passed through the lens 9.

The optical switch 3 emits only the hologram recording beam 20 when recording the hologram 8, and blocks the readout light generation beam 21. On the other hand, when reading out the distorted received light image recorded on the hologram 8, the hologram recording beam 20 is cut off and only the readout light generating beam 21 is emitted. The light receiving device 10
Does not perform a light receiving operation during hologram recording, but performs a light receiving operation only during hologram reading.

As shown in FIG. 2, the received light image 29 and its distortion component 30 are spatially separated from each other and displayed on the filter 5. It is proportional to the intensity distribution of component 30. Note that the filter 5 is, for example, a liquid crystal display, and
9 and its distortion component 30 are images on the liquid crystal display obtained by imaging and processing the object with a CCD camera.

As shown in FIG. 3, only the distortion component 30 is disposed in the filter 12, and the amplitude transmittance of the filter 12 is proportional to the intensity distribution of the distortion component 30. Therefore, the distortion component irradiating beam 2 that has entered the filter 12
2 passes through the filter 12 and becomes a distortion reflected lightwave 220 reflecting the information of the distortion component 30 and enters the photorefractive medium 14. Note that this distortion component 30
Are transmitted from the filter 5, for example.

In the photorefractive medium 14 of the readout light generation section 60, the signal light 24, the first reference light 25, and the second reference light 26 are incident on the photorefractive medium 14, so that light wave mixing occurs. Phase conjugate light 270 is generated. When the signal light 24 is mathematically expressed, the mathematical expression of the generated light 27 is described as the phase conjugate amount of the mathematical expression of the signal light 24. Light including conjugate light). In particular,
When the signal light 24 is a plane wave, the phase conjugate light 27 is also generated as a plane wave.

When the distortion reflected light wave 220 is incident on the photorefractive medium 14, it acts to reduce the generation efficiency of the phase conjugate light 27. Therefore, the distortion reflected light wave 2
In FIG. 20, the amplitude of the phase conjugate light generated from the portion corresponding to the portion where the light intensity is high is greatly attenuated, and the amplitude of the phase conjugate light generated from the portion corresponding to the portion where the light intensity is low is not significantly attenuated. By utilizing this, a phenomenon that the amplitude component of the phase conjugate light has a distribution inversely proportional to the power spectrum of the distortion component 30 is obtained. Therefore, it is possible to generate the phase conjugate light 270 for optical deconvolution processing reflecting the information on the distortion component 30 by the distortion reflected lightwave 220 on which the information on the distortion component 30 is placed.

The phase conjugate light 270 is used as readout light of the distorted light-receiving image 29 recorded on the hologram 8, and by irradiating the readout light, an optical deconvolution process is performed. Image distortion correction for removing distortion is performed. As a result, distortion is removed, and the restored light-receiving image is displayed on the light-receiving device 10.

As described above, in the embodiment of the present invention, the light waves 24, 25, and 26 contributing to the light wave mixing and the light wave contributing to the light wave mixing reflect the distortion component 30 of the received light image 29 which has no coherence. The photorefractive medium 14 is irradiated with the strain-reflected light wave 220, and the phase conjugate light 270 generated by the light wave mixing is used as the readout light 28 to remove the distortion from the received light image 29. Distortion can be removed without changing the position, eliminating the need for high-precision rearrangement of the manufactured optical filter, which was required in the past. it can.

Further, since the readout light 28 can be supplied almost continuously by alternately branching the optical switch 3, the distortion image correction which conventionally required an interval of several minutes can be performed.
It can be performed almost continuously, so that it is possible to sufficiently cope with a light-receiving image that changes with time.

[0025]

Since the present invention has the above-described configuration,
The following effects can be obtained.

According to the first and fourth aspects of the present invention, the light wave contributing to the light wave mixing and the light wave contributing to the light wave mixing have a distorted light wave which has no coherence and reflects the distortion component of the received image. To a photorefractive medium,
The output light generated by the light wave mixing is used as the readout light, and the distortion is removed from the received image, so that the distortion can be removed without changing the position of each optical element.
There is no need to relocate the manufactured optical filter with high precision, which has been required conventionally, and the received light image can be restored instantaneously and easily.

According to the third and fourth aspects of the present invention, the reading light can be supplied almost continuously by alternately branching the optical switch, so that an interval of several minutes is conventionally required. The distortion image correction that has been performed can be performed almost continuously, and therefore, it is possible to sufficiently cope with a light-receiving image that changes with time.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a distortion image correction device according to the present invention.

FIG. 2 is an arrangement diagram of a received light image and a distortion component thereof in a filter 5;

FIG. 3 is an arrangement diagram of distortion components of a received light image in a filter 12;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser light source 2 collimating lens 3 optical switch 5 filter 6 lens 7 beam splitter 8 hologram 9 lens 10 light receiving device 11 beam splitter 12 filter 13 lens 14 photorefractive medium 15 mirror 16 beam splitter 17 beam splitter 18 mirror 19 laser beam 20 hologram recording Beam 21 light generating beam 22 distortion component irradiating beam 220 distortion reflecting light wave 23 light wave mixing beam 24 signal light 25 first reference light 26 second reference light 27 light including phase conjugate light 270 phase conjugate light 28 readout light 29 Reception image 30 Distortion component 50 Distortion reception image recording unit 60 Readout light generation unit 70 Light reception unit

Claims (4)

[Claims] 1. A distortion image correction method for correcting and restoring a distorted received image recorded on a hologram, wherein a light wave contributing to light wave mixing and a light wave contributing to the light wave mixing in light wave mixing using a photorefractive medium. A non-coherent and reflected light wave reflecting the distortion component of the received image is irradiated to the photorefractive medium, and the outgoing light generated by the light wave mixing is used as read light of the distorted received image recorded in the hologram. A distortion image correction method comprising: removing distortion from a received light image to correct the received light image. 2. The light wave mixing in the photorefractive medium emits, as readout light, phase conjugate light with respect to signal light among light waves contributing to light wave mixing, and the phase conjugate light has an amplitude distribution corresponding to the distortion reflected light wave. The distortion image correction method according to claim 1, wherein the distortion image is controlled so as to have a distribution inversely proportional to a power spectrum of the distortion component. 3. A laser beam is split by an optical switch, a distorted received image is recorded on a hologram using one of the laser beams, and the other laser beam is read out by light wave mixing in a photorefractive medium. Used for
The distortion image correction method according to claim 1 or 2, wherein distortion is removed from the received image continuously by alternately generating the two branched laser beams by an optical switch. 4. A distortion image correction device for correcting and restoring a distorted received image recorded on a hologram, comprising: an optical switch for alternately switching a laser beam emitted from a laser; and a laser beam branched by the optical switch. A distorted light receiving image recording unit for recording a distorted light receiving image on a hologram; and a light wave contributing to light wave mixing in a photorefractive medium and a light wave contributing to the light wave mixing from the other laser beam branched by the optical switch. Generates a reflected light wave that has no coherence and reflects the distortion component of the received image, irradiates each of these light waves to the photorefractive medium, generates the read light of the received image by mixing the light waves, and records it on the hologram A readout light generation unit for irradiating the readout light image with a readout light generating unit for receiving and forming an image of the light reception image from which distortion has been removed by the readout light; Distorted image correction apparatus characterized by comprising: a part, the.