JPH052198A - Light moving picture detection device - Google Patents

Abstract

PURPOSE:To detect only a part which is in motion in an input light image as a light image. CONSTITUTION:This detection device consists of a display means 10 which displays an image of an object, a light moving picture selecting means which has a light selection member 14 made of a nonlinear optical medium, and a two-dimensional light position detection means 16 which detects the position of the light output of the moving picture selecting means and outputs a light moving picture signal. Consequently, the position of an image of the part in motion can optically be detected, and the motion of the object can accurately be discriminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical moving image detecting apparatus, and more particularly to an optical moving image detecting apparatus which selectively outputs only a moving portion in an input optical image.

[0002]

2. Description of the Related Art Generally, in an information processing system such as a workstation, the intention of the user such as moving the position of a cursor displayed on a display means as a user interface or selecting an icon is controlled by operating the mouse or cursor keys. Has been transmitted to. On the other hand, it is conceivable to use the movement of the face or the movement of the eyes of the user, that is, the operator, as a means for transmitting the above-mentioned user's intention to the workstation. For that purpose, a means for detecting a moving part (face area of the user) and its moving direction in the optical image obtained by capturing the subject including the face of the user is required. Further, such a motion detecting means is not limited to the above workstation,
Conveyance of work tools and products arranged on the production line,
Alternatively, as a means for detecting the movement of the product in the inspection process, the moving portion in the optical image as described above is detected and the portion is selectively output, or as a monitoring means in the crime prevention system or the disaster prevention system. It becomes an effective means.

As a means for optically detecting the movement in an optical image, there is known a technique of detecting a changing optical image by utilizing a photorefractive effect (photorefractive effect). Regarding the above technology, the following materials have been published. Anderson et al., “Optical Engineering” (Anderson et. Al., Opt. Eng.) 26, 434 (1987)) Material 1: Anderson et al., “Optical Letters” (Anderson et. Al., Opt. Lett.). 12, 123 (1987)) Material 2: Anderson et al., “IE EJ Journal of Quantum Electron” (Anderson et. Al., IEEE J. Quant. Electron.) 25, 635 (1989)).・ Material 3 Cronin-Gollon et al., "Optical Letters" (Cronin-Go romb et. Al., Opt. Lett.) 12, 1029 (1987)) ... Material 4 Kudney et al., "Cudney et al." al., Nature 332, 424 (1988)) ... Material 5 Ford et al., “Optical Letters” (Ford et. al., Opt. Lett.) 13,856 (1988)) ... Material 6 Won Others, "Journal of Optical Society of America" (Kwong et. Al., J. Opt. Soc. Am.) B5, 1788 (1988) ... Material 7 Bucks et al., "Applied Optics" (Vachss et. al., Appl. Opt.) 27, 2887 (1988)) ... Material 8 In the above material, a means for detecting a changing light image by using a photorefractive effect is described in "Optical Tracking Novelty Filter (OpticalTrac)".
"King Novelty Filter)". The "novelty filter" generally means signal processing that selects only information of a moving object from information obtained by a radar, and in the above literature,
This meaning is based on the process of detecting a moving part in an optical image.

FIG. 12 is an explanatory view of a moving object detection system using the two-wave coupling disclosed in the above-mentioned document, in which 121 is a beam splitter, 122 is an object to be observed, 123 is a mirror,
Reference numeral 124 denotes a photorefractive crystal plate (BaTi
O ₃ ), 125 is an output optical system, and 126, 127 are magnifying optical systems. This figure shows a structure for observing the movement of microorganisms placed on a slide glass. A laser beam from a laser light source (not shown) is split into two by a beam splitter 121, and one of them is a magnifying optical system 126, 1 as a microscope.
The signal light passing through the observation object 122 via 27 is projected onto the photorefractive crystal plate 124, and the other is projected as reference light (pump light) by the mirror 123 and projected onto the photorefractive crystal plate 124. At this time, on the photorefractive crystal plate 124, the laser light on the pump light side is a stationary light that does not fluctuate in intensity and phase with time, and so-called two-wave coupling is established in a state where the signal light does not change. There is. The two-wave coupling condition is configured so that the photorefractive crystal plate 124 does not output an optical image in a normal state where there is no movement, by utilizing the delay in response time between the signal light and the pump light. When the intensity or the phase of the laser light (signal light) passing through the observation object 122 changes according to the change of the optical image of the observation object 122, the two-wave coupling is broken and the photorefractive crystal plate 124 changes its intensity. An optical image (optical image of only changed portion: optical moving image selection image) corresponding to the change (movement) is output.

FIG. 13 is an explanatory view of an object to be observed,
(A) is a microscopic image of a microorganism as an observation target, (b)
Is a light moving image selection output image obtained by motion processing by the system of FIG. As shown in the figure, by obtaining an optical image of only the moving microorganisms in the image of (a), the moving state of the microorganisms can be observed more clearly.

[0006]

After the moving image is detected by the moving object detecting system as described above, the moving direction, moving speed, or the shape of the part where the moving occurs is used as information. In order to effectively use the image, conventionally, an output light image of the photorefractive crystal plate is picked up by an image pickup means such as a CCD and taken in as an image signal, and the taken image signal is calculated by a difference calculation between frames (or in a frame). Image processing calculation was performed. However, this kind of image processing requires a considerably high-level arithmetic processing means, the arithmetic load of a computer for executing the arithmetic becomes large, an optical image to be observed is captured, and the captured image signal (video Signal) is directly taken into the calculation processing type of a computer or the like to perform the motion detection processing, there is no difference in the magnitude of the calculation load of the computer, and it makes sense to use the optical moving image detection device as described above. There was a problem of disappearing. An object of the present invention is to provide an optical moving image detection device for detecting a moving position of an optical moving image portion by combining an optical moving image selecting means and an optical position detecting means, and a moving portion of the optical moving image. By extracting a limited area containing
An object of the present invention is to provide an optical moving image detection device that reduces the load on the image processing means and can recognize an image such as the shape of a moving portion in an optical image.

[0007]

In order to achieve the above object, the present invention provides an optical moving image detecting apparatus which selectively outputs only an optical image of a portion of an input image having a change in movement. A light moving image selecting unit that includes a light selecting member made of a non-linear optical medium having a refraction effect, outputs a portion of an input light image that is changed by optical interaction, and a light output of the moving image selecting unit. And a light position detecting means for detecting a position and outputting a light moving image signal, wherein an image of a moving portion of the light image is detected by a detection output of the light position detecting means. Further, the present invention, in an optical moving image detection device for selectively outputting only an image of a part in which the movement is changed in an input image, including a light selection member made of a nonlinear optical medium having a photorefractive effect, A light moving image selecting unit that outputs a portion of the input light image that changes due to optical interaction, and a light position that detects a light output position of the light moving image selecting unit and outputs a light moving image signal. Detection means, image pickup means for picking up the light output of the light moving image selection means, and detection output of the light position detection means extract the image pickup area of the image pickup means to recognize the shape of the moving portion of the input light image. And a region processing means.

[0008]

According to the invention of claim 1, the optical moving image selecting means for outputting the portion which changes due to the optical interaction displays the image of only the portion of the optical moving image which is the portion in the input optical image where the motion has occurred. The image is output and the output image is detected by the light position detecting means. The light position detecting means outputs a signal indicating the center of gravity of the light intensity of the moving image, and detects a moving portion in the input light image based on this output signal. In the invention of claim 2,
The light moving image selection means for outputting a portion that changes due to optical interaction outputs an image of only a portion of the light moving image which is a portion in the input light image where a motion has occurred, and detects the light position of this output image. It is detected by means. The light position detecting means outputs a signal indicating the center of gravity of the light intensity of the moving image, the moving signal in the input light image is detected by the output signal, and the area processing means images the light output of the moving image selecting means. The image pickup area for the center of gravity of the moving image is extracted from the image signal of the light moving image selecting means picked up by the image pickup means based on the detection output of the light position detecting means, and image processing is performed only on the image of the extracted area. Then, image processing such as shape recognition of a moving portion of the input light image is performed.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the principle of moving image selection using two-wave coupling according to the embodiments of the present invention will be described.

FIG. 14 is a schematic diagram for explaining the operation of the moving image selector using the two-wave coupling used in the present invention, in which 141 is a signal light pattern, 142 is a signal light output pattern, and 143 is a pump light. 144 is a photorefractive crystal plate. In the figure, the photorefractive crystal plate 144 is, for example, a crystal plate of titanium titanate (BaTiO ₃ ) or gallium arsenide. (Signal light 141 and pump light 143) are made incident. The pump light 133 which is one of the laser lights is a stationary light whose intensity and phase do not change temporally, and the signal light 141 which is the other laser light uses an image display means such as a liquid crystal display plate (liquid crystal television). Then, the image pattern displayed thereon is displayed as a light moving image to be subjected to motion detection, and is projected on the photorefractive crystal plate 144 as a display light image of this display image. The image pattern displayed on the image display means may be intensity distribution or phase distribution.

In a steady state in which the intensity or phase of the input image does not change, a refractive index grating is written in the crystal of the photorefractive crystal plate 144, and two-wave coupling occurs. At this time, if the signal light intensity is moved to the side of the pump light 143, the signal light output becomes substantially 0, and the output surface of the photorefractive crystal plate 144 is entirely dark. When the input image suddenly changes at a certain point in time, the intensity (or phase) pattern of the signal light changes according to the change. Therefore,
At this time, the interference fringes formed in the photorefractive crystal plate 144 change, but when the change of the interference fringe occurs faster than the response time of the photorefractive effect, the refractive index grating written in the photorefractive crystal plate 144 interferes. I cannot follow the change in stripes. This breaks the condition of two-wave coupling, so that the output on the signal light side (142)
, A pattern of an optical image corresponding to the above change appears. After that, when a time about the response time of the photorefractive effect of the photorefractive crystal plate 144 elapses, the refractive index grating becomes a steady state corresponding to the pattern of the interference fringes.
At this stage, the output 142 of the signal light again becomes approximately 0, and the entire surface again becomes dark. That is, as a result, the pattern of the optical image of only the changed portion of the input image is output at the output of the photorefractive crystal plate 144. Hereinafter, an embodiment of the present invention using the above operation principle will be described.

FIG. 1 is a block diagram of an optical system for explaining an embodiment of the optical moving image detecting apparatus according to the present invention, in which 1 is a laser light source (Ar-ion Laser) and 2 is a first 1/1 /
2 wavelength plate (W.P. 1), 3 is a beam splitter (G.
P: Grand prism), 4 is a first mirror, 5 is a second half-wave plate (W.P.2), 6 is a second mirror, 7 is a first condenser lens, and 8 is a first condenser lens. 1 aperture, 9 first
Condenser lens, 10 is a liquid crystal display (LCTV),
11 is a polarizing plate, 12 is a second condenser lens, 13 is a photorefractive crystal plate (BaTiO _3, etc.), 14
Is a second aperture, 15 is an imaging lens, 16 is a two-dimensional PSD, 17 is a third mirror, 18 is a third half-wave plate (W.P.3), 19 is a video signal circuit, 20 Is an image pickup means (CCD camera or the like), and 21 is a subject (object). In the figure, the laser light source 1 has an oscillation wavelength of 514
in nm argon laser, ethacrylic in order to maintain the coherence
I'm wearing Ron . A laser beam emitted from this laser light source 1 passes through a first half-wave plate 2 and is split into two by a beam splitter 3, one beam of which is a first mirror 4 and a second half-wave plate 5. , Second mirror 6, first
The light is collimated by the first condenser lens 9 through the condenser lens 7 and the first aperture 8 and is projected onto the liquid crystal display panel 10.

The liquid crystal display board 10 constitutes a liquid crystal television display device and displays an image of a subject 21 which is a motion detection target imaged by the image pickup means 20. The video signal circuit 19
Is a means for performing signal processing for displaying the output video signal of the image pickup means 20 on the liquid crystal display panel 10. The laser beam from the first condenser lens 9 is intensity-modulated according to the display image on the liquid crystal display panel 10 to become signal light, enters the second condenser lens 12 through the polarizing plate 11, and enters the photorefractive crystal plate 13. Is incident on. On the other hand, the other laser beam split by the beam splitter 3 is rerouted by the third mirror 17,
Pump light projected onto the photorefractive crystal plate 13 through the third half-wave plate 18 is formed. The photorefractive crystal plate 13 couples the signal light and the pump light under the two-wave coupling condition. As long as the image displayed on the liquid crystal display plate 10 does not move, its output side is in the dark state, No image output (no detection output in the two-dimensional PSD 16).

When a change occurs in the image displayed on the liquid crystal display panel 10, that is, when a subject 21 imaged by the camera 20 moves, a change in the intensity of the signal light occurs, and as a result, An optical image corresponding to the moving part is output to the output side of the photorefractive crystal plate 13 according to the principle described above, and this optical image is incident on the two-dimensional PSD 16 via the second aperture 14 and the condenser lens 15. The two-dimensional PSD 16 is a photoelectric conversion element (optical position detection element, for example, a large screen PSD manufactured by Hamamatsu Photonics) capable of detecting the light input position in the two-dimensional plane, and is incident on the detection surface of the two-dimensional PSD. The position of the emitted light is output as an electric signal representing, for example, (X, Y) coordinate values regardless of the energy thereof. The signal light and the pump light are p-wave polarization whose polarization planes are both within the plane of incidence as shown by the double-headed arrow in the figure, and the crystal axis of the photorefractive crystal plate is also as shown by the single-headed arrow in the figure. Orientation lies in the plane of incidence. The crossing angle and the incident position of the signal light and the pump light incident on the photorefractive crystal plate 13 are
The angle dependence of the two-wave coupling gain is taken into consideration, and the output image is set so that the influence of scattered light that becomes noise is reduced. The crossing angle in this embodiment is 37.8 degrees, that is, the clockwise direction is positive with respect to the normal line of the crystal incident surface of the photorefractive crystal plate 13, and the signal light is 20.degree.
8 degrees, pump light is 58.6 degrees.

As for the amount of light incident on the photorefractive crystal plate 13, the maximum value of the signal light is 119 μW and the minimum value is 2 μW. The maximum value is a value when the image signal (video signal) input to the liquid crystal display panel 10 is in the full screen saturated input state, and the minimum value is a full screen dark state, that is, a value in the black level. The light quantity of the pump light at this time is 11
It is constant at 5 mW. In such an arrangement, the pump light is strongly anisotropically scattered (Beam Fanning). Therefore, the second aperture 14 is installed immediately after the photorefractive crystal plate 13 on the emission surface side to suppress the scattered light noise. There is.

In the configuration of FIG. 1, when the subject 21 moves, the image pickup means (CCD) for picking up this image.
A change occurs in the display image on the liquid crystal display panel 10 that displays the output of the camera 20. As a result, the two-light wave coupling condition in the photorefractive crystal plate 13 is broken, and the optical image of only the portion where the movement occurs through the aperture 14 becomes the second image.
It is input to the two-dimensional PSD 16 via the condensing lens 15. The two-dimensional PSD 16 outputs the center of gravity of the input optical image as a coordinate signal. That is, according to the present embodiment, the movement of the entire moving object within the imaging visual field of the camera including the subject 21 can be converted into the movement of the center of gravity of the light intensity, and can be detected as the movement of the coordinates of the center of gravity. For example, when the input image displayed on the liquid crystal display panel 10 is the entire head of the operator, the vertical and horizontal movements of the face are reflected in the movement of the center of gravity. The motion can be easily detected. Therefore, by utilizing this, it is possible to execute a dialogue (user interface) with a workstation or the like by the movement of the head, and it is possible to widen the width of the dialogue.

FIG. 2 is a block diagram of an optical system for explaining another embodiment of the optical moving image detecting apparatus according to the present invention. Not only the detection of the moving portion but also the shape of the image portion in which the moving has occurred is detected. The recognition (image recognition) is also made possible. In the figure, the half mirror 2 is added to the configuration shown in FIG.
2, screen 23, CCD camera 2 as an image pickup means
4. By adding the area processing circuit 25 and the computer 26 to perform the image processing only on the optical image of the part in which the motion has occurred, the area to be subjected to the image processing is reduced and the load of the computer 26 responsible for the image processing is reduced. It is a reduced one. The optical image of the moving portion output from the photorefractive crystal plate 13 is output to the two-dimensional PSD 16 via the half mirror 22 installed in the subsequent stage of the second imaging lens 15. On the other hand, the optical image of the photorefractive crystal plate 13 transmitted through the half mirror 22 is projected on the screen 23, and the optical image projected on the screen is captured by the CCD camera 24. The captured image signal is transferred to the area processing device 25.
Region processing is executed based on the output of the dimension PSD 16,
Set the area for image processing. The computer 26 performs image processing for image recognition only on the set area.

FIG. 3 is an explanatory view of the image physical area setting executed by the area processing means 25 based on the output of the two-dimensional PSD and the output of the CCD camera 24. FIG. (B) is an explanatory view of the image processing area. The two-dimensional PSD 16 outputs the coordinates indicating the position of the center of gravity of the intensity pattern of the irradiated optical image as a current value. Therefore, the output image A of the camera shown in FIG.
Intensity signal (optical image) corresponding to the change (movement) part d in
On the other hand, the coordinate signal B indicating the center of gravity of the movement as shown in (b) is output. The area processing means 25 uses the coordinate signal B
The optical image area including the moving portion d is set centering on, and the set area is given to the computer 26 as the image processing target area C. As described above, by processing only the optical image of the necessary portion of the visual field imaged by the camera 20 (FIG. 1) as the target of the image processing, it is not necessary to process the unnecessary portion. Therefore, the load required for the image processing of the computer. Can be reduced and efficient image recognition can be achieved. For example, when configuring a so-called eye camera application user interface that detects the movement of the user's eyes and transmits the point of gaze to the workstation, this device is used to detect the position of the point of gaze of the user. By using this for processing, it is possible to efficiently execute the image processing for detecting the point of gaze. In addition, it is effective in shortening the processing speed when applied to image processing in object recognition of moving objects, and recognizes the position or shape of products in the inspection process of the production line, crime prevention, intruding objects, abnormalities in disaster prevention management systems. It can be applied to object recognition to obtain a great effect. Next, the measurement and analysis of various characteristics of the optical image selecting means in each of the above embodiments will be described in detail.

FIG. 4 is a layout diagram of a measuring optical system for measuring the response characteristics of the photorefractive crystal plate.
1 is a laser light source, 202 is a first half-wave plate, 20
3 is a beam splitter, 204 is a second half-wave plate,
205 is the first acousto-optic modulator, 206 is a condenser lens,
207 is a half mirror, 208 is a first PSD (for input monitor), 209 is a first mirror, 210 is a photorefractive crystal plate (BaTiO ₃ ), 211 is a second acousto-optic modulator, and 212 is a second. Mirror 213 is second
Is a PSD (for output monitor). PSD 208,2
The output of 13 is connected to an observation device such as an oscilloscope. With this configuration, the characteristics of the two-light wave coupling were measured with respect to the rising time (or the falling time) of the signal light, which is considered to contribute to the characteristics of the optical moving image selection apparatus using the two-light wave coupling, and the intensity thereof. By this measurement,
The characteristics required for a liquid crystal television (liquid crystal display element) that is an input device become clear.

In the figure, two acousto-optic modulators (AOM) having the same carrier frequency are used, one of which (211) is used for frequency shifting of pump light and the other (205) of which is signal light. Used for modulation of. Thereby, coherence of two waves (signal light and pump light) is obtained.
The polarization planes of the signal light and the pump light are both p-wave polarization in the incident plane, and the crystal axis of the photorefractive crystal plate 210 is also in the incident plane in the direction of the arrow shown. The beam diameter of the incident light on the photorefractive crystal plate 210 was 0.3 mm for signal light and 1.3 mm for pump light.
The signal light is transmitted through the half mirror 207 to the first PSD.
At 208, the pump light is detected at the second PSD 213.

Various response characteristics measured by the measuring optical system shown in FIG. 4 will be described below. [Response to Rise (Fall) Time] FIG. 5 is an input / output waveform diagram showing the measurement results of the response characteristics of the liquid crystal display element. The rising (falling) of a rectangular pulse as a drive signal for the liquid crystal display element.
Shows the measured waveforms of the input and output intensities when the slope of is changed. (A) is the whole waveform, (b) is an enlarged view of the rising part, (c) is an enlarged view of the falling part. is there.
In this measurement, the crossing angle of the signal light and the pump light on the incident surface of the photorefractive crystal plate 210 was 37.8 degrees (signal clockwise with respect to the normal to the crystal incident surface of the photorefractive crystal plate). Light is 2
0.8 degree, pump light is 58.6 degrees), and the light intensity incident on the crystal is 0.048 W / c when the signal light is on.
m ² , and the pump light was 4.4 W / cm ² .

FIG. 6 shows the time when the input of the signal light rises (falls) from off to on (on to off), that is, the time of the slope of the waveform shown in the lower side of FIGS. FIG. 6 is a measurement diagram in which the relationship with the output peak intensity at that time is plotted, and the response time (the time at which the intensity decays to 1 / e) obtained by exponential function fitting from the decaying output waveform is 0.02 seconds. It was This reduces the peak intensity of the output for long rise (fall) times. Furthermore, saturation of the peak intensity is seen at about 1/2 of the response time. Therefore, in order to use under good conditions, it is desirable that the intensity change of the image displayed on the liquid crystal display element is sufficiently faster than the response time. [Response to intensity change]
In order to evaluate how the contrast of the liquid crystal display device affects the operating characteristics of the system of the present invention, the input intensity of the rectangular wave pulse applied to the liquid crystal display device was changed,
The output intensity was measured. The rising (falling) of the pulse was measured in a state faster than 1 msec. The crossing angle of the signal light and the pump light at this time is 38.9 degrees (the signal light is 19.7 degrees with the clockwise direction being positive with respect to the normal to the crystal incident surface, and the pump light is 58.6 degrees), and the photorefractive light intensity entering the crystal plate, the maximum 48W / cm ² when the signal light on the pump light 4.4 W / cm ²
Met.

FIG. 7 is an explanatory view showing the relationship between the input intensity and the output intensity measured under the above-mentioned conditions. FIG. 7A shows the case where the intensity of the input light is changed while the intensity of the input light is kept constant. b) shows the peak intensity of each output light when the intensity of the input light in the off state is set to 0 and the intensity of the input light in the on state is changed. Next, the numerical analysis in the above measurement will be described. First, let the intensity of the pump light be I _P ,
When the intensity of the signal light is I _S , the two-wave coupling gain is as follows using the input light intensity I _S (O) and the output light intensity I _S (I) when I _P >> I _S Described.

[Equation 1] However,

[Equation 2] In equations (1) and (2), Γ is the coupling coefficient, α is the absorption coefficient, I is the light intensity, λ is the wavelength of the laser light, φ is the phase shift angle, n ₀ is the refractive index of the medium, and n ₁ is Refractive index change due to electro-optic effect, r _eff is the effective electro-optic constant, E
_sc is a space electric field.

Since the spatial electric field E _sc is proportional to the degree of modulation of the interference fringes by the incident light,

[Equation 3] Becomes In the equation (3), m is the degree of modulation of interference fringes, E _D is the diffusion electric field, and E _q is the space charge limited electric field.
When the photorefractive crystal plate is BaTiO ₃ , the spatial electric field E _sc is a pure imaginary number, so the phase shift φ = π / 2.
Becomes Therefore, the equation (1) is as follows.

[Equation 4] However, k is a proportional coefficient. Since this system uses an attenuation type two-wave coupling, k has a negative value. When the input waveform rises, it is considered that the grating in the off state is written. Therefore, if the intensity of the on state of the input light of the rectangular wave pulse is I _on and the intensity of the off state is I _off , the peak output light I after the change is generated. _out is

[Equation 5] Becomes

Focusing on the amount of change from the off state to the on state, substituting I _on = I _off + ΔI _out into the equation (5),

[Equation 6] However, the first item on the right side is not limited to the steady state output immediately before the change, and the second item appears as the output. Therefore, in the case of FIG.

[Equation 7] Contributes to the change in the peak intensity of the output light, and in the case of FIG. 7B, since the grating contributing to the two-wave coupling is not written in the off state,

[Equation 8] And is proportional to the input light intensity in the ON state. The same can be said when changing from the on state to the off state, but the output light is supplied from the pump light by two-wave coupling and appears at the output without being canceled by the signal light in the off state.

FIG. 8 is an explanatory view of the measurement result of FIG. 7A, showing a change in peak intensity when the off-state intensity is used as a parameter. On-off ratio (On Off R
atio: Intens-OFF / Intens-O
N) on the horizontal axis, peak intensity (absolute value (Peak Int
The energy (Arb. Unit)) is shown on the vertical axis. The solid line in the figure is fitting (approximated) to the measured data using the equation (13). Two curves are obtained at the rising edge and the falling edge.
_{This is because on} and I _off are different.

FIG. 9 is an explanatory view of the measurement result of FIG. 7B, showing the change of the peak intensity when the intensity in the ON state is used as a parameter, and the horizontal axis (Normalized I).
nput Intensity) is standardized by the maximum input strength in the ON state. Also in this measurement result, FIG.
For the same reason as above, two straight lines are obtained. [Evaluation of frequency response] Considering that the input / output characteristics of the video image selection device act as a high-pass filter for fluctuations in the input light amplitude, the Laplace transform is used by linearly approximating the differential equation of the photorefractive effect. The frequency response can be described. The measurement arrangement of the frequency response is the same as that shown in FIG. 4, and the crossing angle is 45.4 degrees (the signal light is 18.1 degrees and the pump light is 63.5 degrees with the clockwise direction being positive with respect to the normal to the crystal incident surface) in the light intensity incident on the photorefractive crystal plate, the pump light 7.08W / cm ^2, it was the peak intensity of the signal light 126mW / cm ^2. The response time at this time was 10 msec. In addition, the signal light intensity due to the attenuation type two-wave coupling in the steady state is 2.
Decay by 2%. The pump light is the acousto-optic modulator 21 of FIG.
A steady light intensity is obtained with the first-order diffracted light of 1. The signal light is modulated with a sine wave using the acousto-optic modulator 205.

FIG. 10 is a waveform diagram showing an example of the measured waveform of the input / output signal. FIG. 10A shows the case where the input signal is 1H _Z , and FIG. 10B shows the case where the input signal is 20H _Z. The scale of the vertical axis (output) is arbitrary, but the same scale is used for both (a) and (b). In (a), an output intensity sufficiently attenuated by two-wave coupling is obtained, while in (b), an output similar to a waveform obtained by differentiating an input waveform and taking an absolute value is obtained. The output waveform in (a) has spike-like noise, which is considered to be due to vibration and air fluctuations. In (b), noise is reduced by integrating.
In Document 5, it is pointed out that the frequency characteristic of the optical moving image selection device can be theoretically expressed as follows using the Laplace transform. That is, if the amplitude component of the incident light is described using the Laplace transform,

[Equation 9]

[Equation 10] Becomes

Here, s is the complex frequency s = σ + iω. When the incident end face of the photorefractive crystal is z = 0 and the emitting end face is z = 1 (ell), the output c (l, s) ≡e ′ (s) is calculated using the transfer function h (s).

[Equation 11] Becomes This transfer function h (s) can describe the characteristics of the optical moving image selection device. Using this, the amplitude of the output electric field can be written as That is,

[Equation 12] The transfer function showing the characteristics as a selector is

[Equation 13] Becomes However, γ is a time constant and Γ is a coupling constant. Here, the amplitude of the input light is sine wave shaped ε (0, t)
To

[Equation 14] Becomes Substituting this into equation (12) and solving it yields the following.

[Equation 15]

FIG. 11 is an explanatory diagram in which the measured frequency and output light peak intensity are plotted, and the vertical axis is standardized by the intensity of output light (crystal transmitted light) when pump light is not incident. Heretofore, the measurement of various characteristics of the optical image selecting means in each of the embodiments has been described. By this measurement,
The characteristics required for liquid crystal televisions (liquid crystal display elements) that are input devices have become clear.

[0031]

As described above, according to the present invention,
By combining the optical moving image selecting means and the light position detecting means, it is possible to detect the image of the portion where the motion has occurred, that is, the position of the light moving image portion, and to limit the light moving image portion from the target image. By extracting only the
It is possible to provide a light moving image detection apparatus that reduces the load on the image processing means and enables image recognition such as determining the shape of a moving portion in a light moving image.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical system for explaining an embodiment of an optical moving image detection device according to the present invention.

FIG. 2 is a configuration diagram of an optical system for explaining another embodiment of the optical moving image detection device according to the present invention.

FIG. 3 is an explanatory diagram of image physical area setting executed by an area processing unit based on an output of a two-dimensional PSD and an output of a CCD camera.

FIG. 4 is a layout diagram of a measurement optical system for measuring response characteristics of a photorefractive crystal plate.

FIG. 5 is an input / output waveform diagram showing measurement results of response characteristics of a liquid crystal display element.

FIG. 6 is a measurement diagram plotting the relationship with the time output peak intensity when the input of signal light rises (falls) from on to on (on to off).

FIG. 7 is an explanatory diagram showing a relationship between measured input intensity and output intensity.

FIG. 8 is an explanatory diagram of measurement results showing changes in peak intensity when the off-state intensity is used as a parameter.

FIG. 9 is an explanatory diagram of measurement results showing changes in peak intensity when the intensity in the ON state is used as a parameter.

FIG. 10 is a waveform diagram showing an example of measured waveforms of input / output signals.

FIG. 11 is an explanatory diagram in which measured frequencies and output light peak intensities are plotted.

FIG. 12 is an explanatory diagram of a moving object detection system using two-wave coupling.

FIG. 13 is an explanatory diagram of an observation object and a light moving image selection output image obtained by performing a movement process of the observation object.

FIG. 14 is a schematic diagram illustrating the operation of a moving image selector using two-wave coupling.

[Explanation of symbols]

1 ... laser light source, 2 ... first half-wave plate,
3 ... Beam splitter, 4 is first mirror, 5 ...
・ Second half-wave plate, 6 ... Second mirror, 7 ...
・ First condenser lens, 8 ... First aperture, 9
・ ・ ・ First condenser lens, 10 ・ ・ ・ Liquid crystal display plate (LCTV), 11 ・ ・ ・ Polarizing plate, 12 ・ ・ ・ Second condenser lens, 13 ・ ・ ・ Photorefractive crystal plate, 14 ・ ・ ・2nd aperture, 15 ... 2nd condensing lens, 16 ... 2D PSD, 17 ... 3rd
Mirror, 18 ... third half-wave plate, 19 ...
Video signal circuit, 20 ... Imaging means (CCD camera),
21 ... Subject.

Claims (2)

[Claims] 1. An optical moving image detection device for selectively outputting only an image of a part of an input light image having a change in motion, comprising a light selection member made of a non-linear optical medium having a photorefractive effect, Of the input optical image, optical moving image selection means for outputting only a portion that changes due to optical interaction,
A light output of the light moving image selecting means, a position of the received light is detected, and a light position detecting means for outputting a light moving image detection signal, and a detection output of the light position detecting means. An optical moving image detection device, characterized by detecting an image of a moving portion of an input optical image by means of. 2. An optical moving image detection device for selectively outputting only an image of a portion having a change in movement in an input optical image, comprising a light selection member made of a non-linear optical medium having a photorefractive effect, Of the input optical image, optical moving image selection means for outputting only a portion that changes due to optical interaction,
The light output of the moving image selecting means is received, the position of the received light is detected, and the light position detecting means for outputting a light moving image detection signal and the light output of the moving image selecting means are imaged. An image processing unit, and a region processing unit for extracting a limited region including the center of gravity of the optical moving image from the image captured by the image capturing unit by the detection output of the optical position detecting unit to recognize the shape of the moving portion of the input optical image. An optical moving image detection device comprising: