JPS634165B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging device, which is characterized by using a shutter element made of a solid electro-optic material, and which is capable of high-speed imaging with a relatively simple configuration. The purpose of the present invention is to provide a device that can perform the following steps.

Conventionally, shutter elements have generally been constructed mechanically using mechanical parts, but this increases the number of parts, requires relatively many man-hours for assembly and adjustment, and makes it difficult to achieve high-speed operation. There is a drawback. on the other hand,
When analyzing high-speed phenomena, high-speed photography is performed using a rotating prism, and objects are visualized using a TV camera combined with a strobe. However, according to the former method, the mechanism is complicated because it includes rotating elements, and it takes a considerable amount of processing time to visualize it. Furthermore, according to the latter method, the background of the subject must be darkened, and it is difficult to observe the luminescent phenomenon. In order to solve these drawbacks, an imaging device has been proposed that combines an image tube that performs high-speed electronic shutter operation and a low-resistance image pickup tube.
The device becomes complicated and it is difficult to miniaturize it. Also,
It also changes significantly over time and is susceptible to mechanical shock.

The present invention solves these drawbacks and is characterized by using a shutter element of an imaging device made of a solid electro-optic material.

FIG. 1 is a configuration explanatory diagram showing one embodiment of the present invention, and shows an example of a high-speed TV imaging device.
In Figure 1, LS is a condenser lens, ST is an optical shutter, IS is an image sensor, VM is an image memory,
CTL is a control circuit and MT is a monitor. The object image is focused by a condensing lens LS, inputted to an optical shutter ST, and focused on an image sensor IS. The object information imaged on the image sensor IS is sent to the control circuit.
It is stored in the image memory VM via the CTL and is also sent to the monitor MT. Condensing lens LS,
The optical shutter ST and the image sensor IS constitute a camera head CH. The control circuit CTL centrally controls the operations of the camera head CH, image memory VM, and monitor MT.

The optical shutter ST is constructed of a solid electro-optic material (for example, PLZT) and performs high-speed shutter operation with a relatively low driving voltage. FIG. 2 is a configuration explanatory diagram showing an example of the configuration of such an optical shutter ST, in which M1 to M3 are electro-optic plates, and P1 to P4 are polarizing plates. Each of the electro-optic plates M1 to M3 has a plurality of electrodes arranged along a one-dimensional direction, and when driven by applying a voltage between the electrodes, birefringence changes due to the electro-optic effect between the electrodes. is configured to produce. FIG. 3 is a structural explanatory diagram showing a specific example of such electro-optical plates M1 to M2.
In FIG. 3, a is a perspective view, and b is an explanatory diagram of the operation. The electro-optic plate shown in FIG. 3 has a plurality of grooves 4 provided along one-dimensional direction on one surface of an electro-optic substrate 3 (for example, PLZT), and an electrode 5 provided on the surface of each groove 4. It is. In addition, although the example of FIG. 3 shows an example in which the cross-sectional shape of the kerf 4 is rectangular, it may be triangular, arcuate, or linear. By applying a voltage with a polarity as shown in b to each electrode 5 of the electro-optic plate configured in this way, an electro-optical voltage is created between the electrode to which positive polarity is applied and the electrode to which negative polarity is applied. This results in a change in birefringence due to the effect. In the electro-optic board configured in this way, each electrode 5 is provided along the thickness direction of the electro-optic substrate 3 as described above, so when electrodes are provided only on the surface of the electro-optic substrate Compared to this, the internal electric field component perpendicular to the traveling direction of light can be made larger when compared with the same applied voltage, and operation can be performed at a lower voltage. Again in Figure 2,
Each of the electro-optical plates M1 to M3 has half-wavelength voltage characteristics that are equal to each other. Each of the polarizing plates P1 to P4 has a predetermined plane of polarization. These electro-optical plates M1 to M3 and polarizing plates P1 to P4 have electrodes arranged in the same direction, and are orthogonal to both surfaces of each electro-optic plate M1 to M3, and each electro-optic plate is The plates M1 to M3 are sequentially overlapped to form a plane of polarization inclined at 45 degrees with respect to the electrodes. a shows an example in which the electro-optic plate M1 and polarizing plates P1 and P2 are superimposed, b shows an example in which the electro-optic plates M1 and M2 and polarizing plates P1 to P3 are superimposed, and c shows an example in which the electro-optic plates M1 to M3 are superimposed. An example is shown in which polarizing plates P1 to P4 are stacked on top of each other. For example, in the configuration a, when a predetermined voltage is applied to each electrode of the electro-optic plate MM1 and unpolarized light is input from the polarizing plate P1 side, linearly polarized light is output from the polarizing plate P1. Then, this linearly polarized light is input to the electro-optic plate M1, and undergoes birefringence change due to the electro-optic effect depending on the magnitude of the applied voltage. The light passing through the electro-optic plate M1 is polarized by the polarizing plate P2.
, and linearly polarized light corresponding to the polarization plane of the polarizing plate P2 is output. Therefore, by controlling the magnitude of birefringence change in the electro-optic plate M1, it is possible to control the amount of linearly polarized light output from the polarizing plate P2. In configuration b, the same operation as in a is performed twice by simultaneously applying a predetermined voltage to each electrode of each electro-optical plate M1, M2, and in configuration c, each electro-optical plate M1 to M2
By simultaneously applying a predetermined voltage to each electrode of No. 3, the same operation as a is performed three times. FIG. 4 is a characteristic diagram showing the relationship between the applied voltage V and the light transmittance T in each of the configuration examples in FIG. 2, and curves a to c are for each of the configuration examples in FIG. It shows the characteristics. As is clear from Fig. 4, the transmittance of each configuration example at a certain applied voltage V ₁
Ta~Tc becomes Ta>Tb>Tc, which decreases as the number of polarizing plates and electro-optic plates to be stacked increases, and the transmission characteristics reach a sharp turning point. By the way, since the electro-optical plates M1 to M3 are dielectrics sandwiched between electrodes, they become capacitive loads when viewed from the power source side.
As a result, even if a voltage is applied in a pulsed manner, the voltage will rise with a certain time delay, and the electro-optic effect will occur with a certain time delay. The rise time of the electro-optic effect can be changed depending on the number of plates and electro-optic plates. FIG. 5 is a characteristic diagram showing the rise characteristics of the electro-optic effect in each of the configuration examples in FIG. 2, and curves a to c indicate the characteristics of each of the configuration examples in FIG. . As is clear from FIG. 6, the rise time is a>b>c.
That is, the rise time can be shortened as the number of polarizing plates and electro-optical plates to be stacked increases.

Referring again to FIG. 1, a charge coupled device (CCD), for example, is used as the image sensor IS. As a result, the camera head CH is entirely composed of solid-state elements, making it possible to simplify and downsize the structure, reduce deterioration over time, and increase the strength against mechanical shock and the like. Note that known image memory VM and monitor MT are used. As mentioned above, the control circuit CTL connects the camera head CH,
It centrally controls the operations of the image memory VM and monitor MT, transmits and receives image signals between each component, and sends control signals to each component.

FIG. 6 is an explanatory diagram of the operation of the apparatus shown in FIG. 1, in which a indicates an image signal waveform, and b indicates an optical shutter.
The operating waveform of ST is shown, and c shows the operating waveform when the optical shutter ST is operated multiple times. The optical shutter ST is driven to open and close once or multiple times during the blanking period Tb of the image signal a, as shown in b or c. The light passing through the optical shutter ST forms a subject image on the image sensor IS, and this subject image is read out within the next frame period T _f and sent to the image memory VM and monitor MT. This allows real-time analysis of high-speed phenomena. Note that, if necessary, a scan converter, digital frame memory, etc. can be added to perform advanced image calculation processing.

By the way, in FIG. 2, each electro-optical plate M1 to M
Since the optical shutter ST is constructed by overlapping the electrodes 3 with their electrodes aligned in the same direction, there is a risk that the amount of light transmitted will be non-uniform. In order to solve this drawback, for example, as shown in FIG. 7, the electro-optical plates M1 and M2 may be arranged so that the electrode arrangement directions are perpendicular to each other. Note that the polarizing plates P1 to P3 are arranged so as to form polarizing plates parallel to each other on both sides of each electro-optical plate M1 and M2. Thereby, non-uniformity in the amount of light transmitted can be improved. Note that even in the configuration shown in FIG. 8, the same effects as in FIGS. 4 and 5 can be obtained by increasing the number of electro-optical plates and polarizing plates to be superposed.

In the above embodiment, an example of a high-speed TV imaging device has been described, but a normal optical camera can be realized by using a photosensitive film as an image sensor. In addition, by advancing the photosensitive film frame by frame according to the opening and closing operations of the optical shutter,
A high-speed camera can be realized.

As described above, according to the present invention, it is possible to realize an imaging device that can perform high-speed photography with a relatively simple configuration, and the practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram showing a configuration example of the optical shutter used in FIG. 1, FIG. 3 is an explanatory diagram showing a part of a specific example of the electro-optic plate in FIG. Figure 5 is a characteristic diagram showing the relationship between applied voltage and light transmittance in the optical shutter of Figure 2.
This figure is an explanatory diagram of the operation of the apparatus shown in FIG. 1, and FIG. 7 is a configuration explanatory diagram showing another example of the configuration of the optical shutter. LS...Condensing lens, ST...Optical shutter, IS...
...Image sensor.

Claims (1)

[Claims] 1. A lens for condensing a subject image, a plurality of polarizing plates having a predetermined plane of polarization, and a plurality of kerfs provided along a one-dimensional direction on one surface, each of which has a plurality of kerf grooves. It consists of a plurality of electro-optic plates, each having an electrode formed on its surface, which causes a change in birefringence due to the electro-optic effect by simultaneously applying a voltage between these electrodes and driving them. an optical shutter which is sequentially superimposed on the image sensor and which selectively passes the object image focused by the condenser lens according to the drive of the electro-optic plate; and an image sensor which converts the object image that has passed through the optical shutter into an electrical signal. An imaging device comprising: , and.