JPS63153512A - Image forming optical device - Google Patents

Abstract

PURPOSE:To attain rapid focusing by arranging a light branching device and a focus variable mirror so that incident light on the light branching device is transmitted through the branching face of the light branching device (or reflected on the branching face), reflected by the focus variable mirror and then reflected on the branching face again (or transmitted through the branching face). CONSTITUTION:Since light (circularly polarized light) reflected by a mirror face material 11 is passed through a 1/4 wavelength plate 2 again, the light is converted into the linearly polarized light of a component (s). The linearly polarized light of the component (s) is reflected by a joint face 12 of a polarized light beam splitter 1 and reached to a two-dimensional image sensor 6 to be an image pickup device. Input image information to the image sensor 6 is transmitted to a control device 8 through an image sensor drive 7. The control device 8 decides whether the image inputted to the sensor 6 is focused or not, and when the image is defocused, feeds back a mirror face driver 4 to change the curvature, i.e. a focal distance, of the focus variable mirror 3 and focus the image. Thus, the incident light forms its image on the image sensor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an imaging optical device for focusing and enlarging/reducing an image.

[Conventional technology]

In recent years, the number of devices that operate using visual information as input information has rapidly increased. For example, when considering a television camera that automatically tracks the eyes of a robot or a moving object, a camera that can focus quickly and enlarge or reduce the image as necessary is required. Furthermore, when writing and reading data at high speed in an optical disk storage device or the like, an imaging optical system that can focus the laser beam on the disk at high speed is required.

Conventionally, optical systems in which a lens system is moved by an electromagnet, a motor, etc. have been mainly used for these applications.

[Problem that the invention seeks to solve]

However, with such conventional optical systems, it is difficult to downsize due to the need to secure movement space for the lens system, and
There was a limit to how quickly the lens system could be moved.

[Means for solving problems]

The imaging optical device of the present invention was made in view of the above problems, and after the light incident on the optical demultiplexer passes through the demultiplexing surface of the optical demultiplexer (or is reflected by the demultiplexing surface), An optical demultiplexer and a variable focus mirror are arranged so that the light is reflected by the variable focus mirror and then reflected again by the demultiplexing surface of the optical demultiplexer (or transmitted through the demultiplexing surface).

In addition, after the light incident on the first optical demultiplexer passes through the demultiplexing surface (or is reflected on the demultiplexing surface), it is reflected by the first variable focus mirror and returns to the first optical demultiplexer. After the light is reflected by the demultiplexing surface (or transmitted through the demultiplexing surface), and then the light incident on the second optical demultiplexer is transmitted through the demultiplexing surface (or reflected by the demultiplexing surface), the second focal point is changed. the first and second optical demultiplexers and the first and second variable focal points so as to be reflected by a mirror and reflected again at the demultiplexing surface of the second optical demultiplexer (or transmitted through the demultiplexing surface); It has a mirror placed in it.

[Effect]

Simply changing the curvature of the mirror surface of the variable focus mirror changes the position of the imaging point. Furthermore, by independently changing the curvatures of the mirror surfaces of the two variable focus mirrors, not only the position of the imaging point but also the size of the image can be changed.

〔Example〕

Hereinafter, the present invention will be described in detail along with examples.

FIG. 1 is a block diagram showing an embodiment of the present invention, and shows an example in which the present invention is applied to an autofocus camera. In the figure, the polarizing beam splitter 12 which splits a polarized beam with a wide spectrum width is a quarter-wave plate, and the reference numeral 3 is a variable focus mirror whose mirror surface can be freely changed to a flat, convex, or concave surface. The variable focus mirror 3 is composed of an opening type actuator section 10 and a mirror material 11. 4 is a mirror drive device that changes the curvature of the mirror surface of the variable focus mirror 3; 5 is a convex lens; 6 is a two-dimensional image sensor (CCD array); 7
8 is an image sensor driving device, 8 is a control device, and 9 is a housing. Further, the dashed dotted line at 50.51 indicates the optical axis.

The light incident from the left side of the convex lens 5 is a light wave such as natural light, and the vibration direction is an S component in a direction perpendicular to the plane of the paper in FIG. It can be divided into a vertical p component. On the other hand, the polarizing beam splitter 1 is a cube made by using two right-angle prisms, depositing a dielectric multilayer film on one of the hypotenuses, and joining the hypotenuses, which transmits the p component and transmits the s component. Joint surface 12
It is designed to reflect. Therefore, convex lens 5
Of the light that has passed through, the S component is reflected by the bonding surface 12, travels upward, and is absorbed, for example, by the housing 9 whose inner wall is painted black. On the other hand, the p component passes through the bonding surface 12 and enters the quarter-wave plate 2. In this embodiment, a cubic structure is used as the polarizing beam splitter 1, but a plate-type polarizing beam splitter in which one side of parallel plane glass is coated with a multilayer may also be used. In this case, the multilayer coated surface corresponds to the bonding surface 12 of this embodiment.

The quarter-wave plate 2 is an element that converts linearly polarized light and circularly polarized light, and is made of a polyvinyl alcohol (PVA) film, mica foil, or the like. In order to convert linearly polarized light into circularly polarized light using this two-wavelength plate 2, it is sufficient to arrange the plate so that the vibration direction of the light inside the plate is 45 degrees with respect to the vibration direction of the incident light. In the embodiment, the 1/4 wavelength plate 2 is arranged so that the direction of vibration of light inside it is 456 with respect to the direction of vibration of the p component. Therefore, the light that has passed through the quarter-wave plate 2 becomes circularly polarized light and is reflected by the variable focus mirror 3.

The variable focus mirror 3 includes a 7-opening type actuator 10 made of two stacked piezoelectric plates with electrodes on both sides, and a forward deformation actuator 1.
0 and a mirror material 11 provided on one side of the mirror. Opening type 7
The cutuator 10 is driven by the mirror driving device 4 so that one plate extends in the surface direction and the other plate contracts as necessary, so that the mirror material 11 changes its curvature to form a convex mirror or a concave mirror. form. Details of the configuration and driving method of this variable focus mirror 3 will be described later.

The light (circularly polarized light) reflected by the mirror material 11 is again 1/4
Since it passes through the wave plate 2, it is converted into linearly polarized light of the S component. This S-component linearly polarized light is sent to the polarizing beam splitter.
1 and reaches a two-dimensional image sensor 6, which is an imaging device.

Input image information from the two-dimensional image sensor 6 is transmitted to the control device 8 via the image sensor driving device 7. The control device 8 determines whether or not the image input to the two-dimensional image sensor 6 is focused. If it is not focused, it applies a feed hack to the mirror driving device 4 to move the variable focus mirror 3.
Focus is adjusted by changing the zero curvature, that is, the focal length. In this way, the incident light forms an image on the two-dimensional image sensor 6.

FIG. 2 shows how an image is formed in the optical system of FIG. 1 by showing the optical path.

In the figure, a solid line 21 indicates the lens surface of the lens 5,
A solid line 22 indicates the mirror surface of the variable focus mirror 3. Also, arrow 23
indicates an object to be visually recognized, and arrows 24 and 25 indicate images, respectively. Note that the quarter wavelength plate 2 is not shown in the figure.

The light from infinity passes through the lens surface 21 as shown in the optical path ■.
The light beam is refracted at the mirror surface 22 and the bonding surface 12, and an image is formed at a point 27 where the surface of the two-dimensional image sensor 6 intersects the optical axis 51, that is, approximately at the center of the two-dimensional image sensor 6.

At this time, the mirror surface 22 is a flat surface.

Next, a case where there is an object 23 as shown in the figure on the optical axis 50 will be described. When the mirror surface 22 is flat, the light (2) parallel to the optical axis 50 and the light (2) passing through the intersection of the lens surface 21 and the optical axis 50 are reflected by the mirror surface 22 and the cemented surface 12, respectively, as shown by solid lines, and the light (2) parallel to the optical axis 50 An image 25 is formed on top. Therefore, the image on the two-dimensional image sensor 6 is blurred. Here, the mirror surface 22 is a predetermined concave surface 22 as shown by a broken line.
When the light is changed to ゛, the lights ① and ② are reflected as shown by the broken line and are formed on the two-dimensional image sensor 6 as an image 24. In this way, by changing the uneven shape of the mirror surface 22 of the variable focus mirror 3, an image can be formed on the two-dimensional image sensor 6 without moving any other elements in the optical path. can.

In the embodiment shown in the figure, when the mirror surface 22 of the variable focus mirror 3 is flat, light from an infinite distance is set to form an image, but when the mirror surface 22 is a convex mirror with a predetermined curvature, light from an infinite distance forms an image. The mirror surface 22 may be set to form an image on the two-dimensional image sensor 6'', and as the object 23 approaches the lens surface 2, the mirror surface 22 may be changed to a plane mirror or even a convex mirror.

In this embodiment, the variable focus mirror 3 and the 1/4 wavelength plate 2 are arranged on the right side of the polarizing beat splitter 1, but the positions of the % wavelength plate 2 and the variable focus mirror 3 are centered on the polarizing beam splitter 1. The polarizing beam splitter 1 may be rotated 906 times counterclockwise and placed above the polarizing beam splitter 1. In this case, S reflected on the junction surface 12 of the polarizing beam splitter 1
The component passes through the two-wavelength plate 2, reaches the variable focus mirror 3, is reflected by the variable focus mirror 3, and passes through the quarter-wave plate 2 and the bonding surface 12.
and reaches the two-dimensional image sensor 6. In other words, in this case, the S component of the incident light becomes the signal.

Furthermore, this embodiment does not preclude the addition of other optical elements. For example, for the purpose of shortening the optical path length, a polarizing beam splitter 1 and a two-dimensional image sensor 6 are used.
It is also possible to insert another lens system or the like into the optical path between the two.

The above is a case where the method is applied to a black and white camera, but it can also be applied to a color camera. In color cameras, the color is basically red (
Three primary colors are required: R), green (G), and blue (B). Therefore, it is necessary to separate the light into the three primary colors before the image is formed on the two-dimensional image sensor 6. The methods for this are: (1) Separating into RGB using a color separation prism and providing two-dimensional image sensors for each to obtain three color signals in parallel; (2)
A possible method is to simultaneously obtain color signals in a multiplexed form from one two-dimensional image sensor, as shown in the cross-sectional view of FIG. In FIG. 3, 31 is a two-dimensional image sensor 6
This is a color filter array provided above, in which three types of color filter elements that selectively transmit each color of RGB are arranged in a checkered pattern at high density. Each of the color filter elements corresponds to an individual light receiving element 41 of the two-dimensional image sensor 6, as shown in FIG. The incident light is divided into three colors by passing through this color filter array 31 and detected by each light receiving element 41.

The color of a minute area on the two-dimensional image sensor 6 is obtained by combining the output signals of three light receiving elements corresponding to the three color filter elements within that area.

By the way, in the present invention, the optical axis 50 of the incident light is adjusted using polarized light.
In order to form an image on an optical axis 51 different from the optical axis 51, it is preferable that the incident light has a wavelength equal to that of the optical axis. This is because polarizing beam splitter 1, etc., can be selected from a broadband type, but the two-wavelength plate 2 has wavelength dependence, so if it is not selected according to the wavelength of the light to be used, linearly polarized light and circularly polarized light can be used. This is because it is not possible to perform a clean conversion of . Therefore, when forming a color image of natural light as described above, the two-wavelength plate 2 is
When tuned to the wavelength of , the R and B components cannot be converted into linearly polarized light and circularly polarized light and become elliptically polarized light. This results in
The light intensity of the imaging plane is lower for R and B than for G.

Therefore, when receiving color light, it is necessary to correct the RGB light intensities to be approximately uniform. To achieve this, the selective transmittance of G in the 0-color filter array 31 is slightly lowered than that of the others, so that the light intensity of each component is about the same.
There is a value such as 0 where the light intensity is slightly higher than the light receiving element output of , and the light intensity is made to be the same level through image processing, and if such a method is used, sufficient color light reception is possible.

FIG. 5 is a configuration diagram showing a second embodiment of the present invention,
In place of the polarizing beam splitter 1 in FIG. 1, a semi-transparent film is used as an optical demultiplexer. In the figure, reference numeral 102 is a semi-transparent film that functions as an optical demultiplexer.

The light that has passed through the lens 5 enters the semi-transparent film 102, about half of which is transmitted as shown by ■, and the rest is reflected and travels upwards as shown by ■, where it is absorbed by the casing (not shown). The light (2) is reflected by the variable focus mirror 3 and enters the semi-transparent film 102 again.

Approximately half of this light is reflected by the semitransparent film 102 and is imaged on the two-dimensional image sensor 6. Although this embodiment has a larger amount of attenuation of light than the embodiment shown in FIG. 1, it has the advantage that a quarter-wave plate is not required and it is easy to reduce the size and weight.

FIG. 6 is a block diagram showing a third embodiment of the present invention, and shows an example of application to an autofocus camera capable of scaling. That is, this embodiment has an image enlargement/reduction function in addition to the focusing function as in the first embodiment described above. In this figure, the same elements as in FIG. 1 or elements having similar functions are given the same reference numerals, and their explanations will be omitted. Reference numeral 52 denotes a second variable focus mirror, which, like the variable focus mirror 3, is composed of a piezoelectric expansion surface deforming actuator 53 and a mirror material 54. The curvature of the mirror surface of the variable focus mirror 52 is adjusted by a mirror drive device 57. 55 is a polarizing plate, and 56 is a second quarter wavelength plate.

In this camera, the incident light is divided into two variable focus mirrors 3.5
2 and form an image on a two-dimensional image sensor 6.

The light incident from the left side of the convex lens 5 is a light wave such as natural light, and the vibration direction is p as in the embodiment shown in FIG.
It is divided into component and S component. When this light passes through the polarizing plate 55, the S component is absorbed, so that it becomes linearly polarized light with only the p component. In this way, since the light incident on the polarizing beam splitter 1 does not contain the S component, it is completely transmitted through the junction surface 12 without being reflected at all, and is converted into circularly polarized light by the quarter-wave plate 2, making the focus variable. Reach mirror 3. This light is reflected by the variable focus mirror 3, passes through the two-wavelength plate 2 again, and becomes linearly polarized light of the S component. Therefore, this light is reflected by the bonding surface 12 and transmitted through the second wavelength plate 56. Here, the linearly polarized light of the S component is converted into circularly polarized light and reaches the variable focus mirror 52. The light reflected by the variable focus mirror 52 becomes linearly polarized light of the p component by passing through the second 1/4 wavelength plate 56 again. and reaches the two-dimensional image sensor 6.

Input image information to the two-dimensional image sensor 6 is transmitted to the control device 8 via the image sensor driving device 7. Here, if the image on the two-dimensional image sensor surface 6 is out of focus, or if the size of the image is different from the expected one, the control device 8 sends feedback to the mirror drive devices 4 and 57. This changes the curvature of the mirror surfaces of the variable focus mirrors 3 and 52. In this way, the image is enlarged or reduced, and the two-dimensional image sensor 6-
1-, l images.

FIG. 7 shows in detail how the image is formed in the embodiment of FIG. 6 by not showing the optical path, and the same symbols are used for the same or corresponding parts as in FIG. Detailed explanation will be omitted. In the figure, 61 is a mirror surface of the variable focus mirror 52.

Light from infinity passes through the lens surface 2, as shown by the solid line in ■.
1 , is reflected by the mirror surface 22 , the joint surface 12 , and the mirror surface 61 , and is imaged at a point 27 where the surface of the two-dimensional image sensor 6 intersects with the optical axis 51 , that is, approximately at the center of the two-dimensional image sensor 6 . At this time, mirror surfaces 22 and 61 are flat.

Next, the case where the object 23 is on the optical axis 50 will be described.

When the mirror surface 22 is a flat surface, the light (2) parallel to the optical axis 5o and the light (2) passing through the intersection of the lens surface 21 and the optical axis 50 are reflected as shown by solid lines, and an image 25 is formed on the optical axis 51. The image is formed like this. Therefore, the image on the two-dimensional image sensor 6 is blurred.

Here, if the mirror surface 22 of the variable-focus mirror 3 is changed to a predetermined concave surface 22', the light of ■ and ■ will be reflected by the mirror surface 22' and the mirror surface 61 as shown by the broken line, and an image will be formed on the two-dimensional image sensor 6. do.

FIG. 8 is a table showing the shapes of the variable focus mirror 3 (mirror surface 22) and the variable focus mirror 52 (mirror surface 61) when enlarging or reducing an image using the apparatus shown in FIG. Same figure (a)
shows the state shown in FIG.

If the mirror surface 61 is made a concave mirror and the focal length of the mirror surface 22 as a concave mirror is lengthened, the image becomes smaller as shown in (2) compared to the case (A). When the radius of curvature of the mirror surface 61 is reduced and the mirror surface 22 is changed from a plane mirror to a convex mirror, (1
) becomes even smaller like (e). In addition, the mirror surface 61
When is made into a convex mirror and the focal length of the mirror surface 22 as a concave mirror is made small, the image becomes large as shown in (A).

In this way, by changing the uneven shape of the surface of the variable focus mirror 3.52, the size of the image can be changed and the image can be formed on the two-dimensional image sensor 6.

In addition, in FIG. 7, when the variable focus mirror 3.52 is a plane mirror, it is set so that an object at infinity is imaged on the two-dimensional image sensor 6-A. When the object at a predetermined distance from the convex lens 5 is 2
The image may be set to be formed on the dimensional image sensor 6.

In addition, in this embodiment, the 1/4 wavelength plate 2 and the variable focus mirror 3 are placed on the right side of the polarizing beam splitter 1, and the two-dimensional image sensor 6 is placed above the polarizing beam splitter l. The plate 2 and the variable focus arm 3 are placed above the polarizing beam splitter 1, the two-dimensional image sensor 6 is placed on the right side of the polarizing beam splitter 1, and the polarizing plate 55 is rotated by 90 degrees to transmit only the S component. You may also do so. In this case, the incident light is transmitted to the joining surface 12 of the polarizing beam splitter 1, the variable focus arm 3, and the variable focus arm 52.
, from the junction surface 12 of the polarizing beam splitter 1, and finally enters the two-dimensional image sensor 6 on the right side of the polarizing beam splitter 1.

In the third embodiment shown in FIG. 6, the polarized light Fi55 is
Although we have described an ideal case in which the components are completely absorbed, if the light wavelength band is wide, the components may not be completely absorbed and may pass through.

Since this light is reflected by the cemented surface 12 and enters the image sensor 6, it may overlap with the intended image of this optical system.

The fourth embodiment shown in the perspective view of FIG. 9 solves this problem. In this embodiment, the polarizing beam splitter 20
0 has two joining surfaces 201 and 202. FIG. 10 is a front view of this embodiment, and the dashed line in the figure is the imaging optical path.

As shown by (2), the incident natural light is separated at the joint surface 201 as shown by a dashed line and a dashed double dotted line.

Here, since the two-dot chain line is unnecessary in this imaging optical system, it is absorbed by a housing or the like which is not shown. The S-component linearly polarized light reflected by the joint surface 201 is converted into circularly polarized light by the quarter-wave plate 2 and reaches the variable focus arm 3. This light is reflected by the variable focus arm 3 and becomes a p-component linearly polarized light that passes through the quarter-wave plate 2 again.

Therefore, this light passes through the bonding surfaces 201 and 202 and the second quarter wavelength plate 56. Here, the p-component linearly polarized light is converted into circularly polarized light and reaches the variable focus arm 52. The light reflected by the variable focus arm 52 becomes S-component linearly polarized light by passing through the second 1/4 wavelength plate 56 again, so it is reflected by the joint surface 202 of the polarizing beam splitter 200 and becomes 2
It reaches the dimensional image sensor 6. After that, the process is similar to the embodiment shown in FIG.

FIG. 11 shows a fifth embodiment of the present invention, which is an example applied to an optical disc writing/reproducing mechanism.

In this figure, the same or corresponding parts as in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted.

81 is a semiconductor laser, 82 and 83 are convex lens systems, and 84 is an information storage surface on the optical disk.

The light emitted from the laser 81 is
As shown, the light becomes parallel and enters the polarizing beam splitter l. Of the incident light, the S component is reflected by the bonding surface 12 and passes upward in the figure, and only the p component is reflected by the bonding surface 12.
pass through. This light passes through the wavelength plate 2 and becomes circularly polarized light, is reflected by the variable focus arm 3, and when it passes through the two-wavelength plate 2 again, becomes linearly polarized light with an S component. Therefore, this light is reflected by the cemented surface 12 and formed into an image on the information storage surface 84 by the lens 83. Here, since the information storage surface 84 moves slightly up and down during rotation during writing and reproduction, it is necessary to change the imaging position in accordance with the movement of this surface. In this embodiment, this is achieved by changing the mirror surface 22 of the variable focus arm 3 into a concave or convex surface. When the mirror surface is made concave like the broken NlA 22', the light is imaged slightly above the information storage surface 84 as shown in ■, and on the other hand, when it is made convex, it is imaged downward as shown in ■. The image formation position may be recognized and determined in the same manner as in the case of moving a conventional lens system. For example, by detecting the reflected light from the information storage surface 84 and applying a feedbank to change the curvature of the mirror surface 22 of the variable focus arm 3 when blurring occurs, the information storage surface 84 can be moved. It is possible to form an image according to the

Next, the configuration of the variable focus arm used in all the above embodiments will be explained.

FIG. 12 is a configuration diagram showing an embodiment of the variable focus arm.

In the figure, 91 is a disc-shaped piezoelectric element or an electrostrictive element, and electrodes 92 and 93 are provided on both surfaces to constitute a surface deformation actuator.

Piezoelectric plate 91 is polarized in the direction of arrow 94.

A disk 95 made of a rigid body such as glass is bonded to one side of this surface deformation actuator, and a mirror surface 96 (similar to the mirror surface 22 of the above embodiment) formed by silver vapor deposition, sputtering, plating, etc. is attached to the surface facing the adhesive surface. corresponding) is formed.

Here, the deformation operation of the mirror surface 96 will be described.

When a voltage is applied in the same direction as the polarization 94 formed on the piezoelectric plate 91, the piezoelectric plate 91 contracts in the entire surface direction as shown by an arrow 97, so that the mirror surface 96 becomes a concave mirror. Conversely, when a voltage in the opposite direction to the polarization 94 is applied to the piezoelectric plate 91, the piezoelectric plate 91 extends in the entire surface direction, so that the mirror surface 96 becomes a concave mirror. In this way, a mirror surface with an arbitrary curvature can be created depending on the polarity and magnitude of the voltage applied to the piezoelectric plate 91.

Although the same figure shows the case where the electrodes 92 and 93 are uniformly applied to each surface of the piezoelectric plate 91, as shown in FIG. It is also possible to divide the electrode into a plate-shaped electrode 93b and change the voltage applied to each electrode. That is, a voltage v1 is applied between the electrode 92 and the electrode 93a, and a voltage v2 is applied between the electrode 92 and the electrode 93b.
can be added. By doing so, if the curvature of the mirror surface is not uniform, it can be corrected, or a mirror surface whose curvature is not uniform can be intentionally created.

Further, as shown in FIG. 14, the curvature can also be corrected by making the thickness of the cross section of the piezoelectric plate 91 non-uniform.

FIG. 15 is a configuration diagram showing another embodiment of the variable focus mirror 3. In the figure, 91a, 91. b are circular ceramic piezoelectric plates or electrostrictive plates, and electrodes 92,
93.98 are provided to constitute a rotary actuator. These are manufactured by integral sintering, and in the case of piezoelectric plates, they are polarized (↓) as shown in the same figure. A flexible resin 99 is applied thereon, and a mirror surface 100 is formed thereon by silver vapor deposition, sputtering, plating, or the like.

The deformation operation of the mirror surface 100 will be described. A voltage is applied to the piezoelectric plate 91a in the same direction as the polarization, and a voltage is applied to the piezoelectric plate 91b in the opposite direction to the polarization. As shown in the figure, the piezoelectric plate 91a contracts in the plane direction, and the piezoelectric plate 91b expands, so that the two piezoelectric plates are deformed so that their upper portions are depressed. Therefore, the resin 99 coated on this, and the mirror surface 1 on it
00 similarly forms a depression. Moreover, conversely, the piezoelectric plate 91a
When a voltage is applied to the piezoelectric plate 91b in the opposite direction to the polarization and to the piezoelectric plate 91b in the same direction as the polarization, the piezoelectric plate 91a expands in the plane direction and the piezoelectric plate 91b contracts in the plane direction, so the upper part of the two piezoelectric plates It transforms so that it sticks out. Therefore, a concave mirror is formed.

Further, in the case of an electrostrictive plate, since it has the property of shrinking in the surface direction regardless of the polarity when a voltage is applied, a concave or convex surface can be created by applying a voltage to either 91a or 91b.

Note that in this embodiment, a case is shown in which piezoelectric plates or electrostrictive plates 91a and 91b in which electrodes are uniformly formed are used;
By dividing the electrode into multiple parts and changing the voltage applied to each electrode as shown in Fig. 13, or by stacking piezoelectric plates with uneven thickness as shown in Fig. 14, mirror surface 10
0 curvature can be modified.

The manufacturing method for forming the flat surface of the flexible resin 99 on the rotary actuator is to place ultraviolet-effect resin on the center of the electrode 93 and rotate the rotary actuator horizontally to reduce centrifugal force. There is a method in which the resin is uniformly deposited on the open position actuator and then cured by applying ultraviolet rays from above. Alternatively, a resin film may be bonded onto the opening type actuator.

Next, a description will be given of the structure and operation of the drive device for the rotary type actuator for the variable focus mirror, that is, the mirror surface drive devices 4 and 57 of the above-described embodiment. If you apply a voltage in the same direction as the polarization to the piezoelectric plate of a rotary actuator, you can apply a high voltage, but if you apply a voltage in the opposite direction to the polarization, the polarization may deteriorate. It is desirable to apply a voltage obtained by subtracting a predetermined voltage from the voltage applied to . Regarding such a driving method, there is Japanese Patent Application No. 1988-196058, which was invented by Inventor Mokura and filed by the applicant of the present application.

FIG. 16 shows its driving circuit. A constant voltage diode ZDI is connected in series to the piezoelectric plate 91a, and a power supply 200 is connected to this circuit. Then, while the voltage applied to the piezoelectric plate is applied in an unrestricted direction, that is, while the anode of the constant voltage diode ZD1 is positive, the phototransistor PTI that operates to short-circuit the constant voltage diode ZDI is constant. It is connected in parallel to the voltage diode ZDI.

The phototransistor PTI is operated by light emission from the photodiode LEDI.

On the other hand, a constant voltage diode z02 is connected in series to the piezoelectric plate 91b, and a power source 200 is connected to this circuit. Then, while the voltage applied to the piezoelectric plate 91b is applied in an unrestricted direction, that is, while the electrode 98 is positive, the phototransistor PT2, which operates to short-circuit the constant voltage diode ZD2, short-circuits the constant voltage diode ZD.
2 are connected in parallel. The phototransistor PT2 is operated by light emission from the photodiode LED2.

The voltages applied to the piezoelectric plates 91a and 91b are shown by solid lines in FIGS. 17(a) and 17(b), respectively. The operation of the circuit that applies voltage to the piezoelectric plate 91a will be explained using FIG. On the other hand, without the phototransistor PTI, if the power supply voltage is as shown by the dashed line, the voltage applied to the piezoelectric plate 91a will be as shown by the broken line. That is, as the power supply voltage increases, the voltage applied to the piezoelectric plate 91a in the polarization direction also increases, but even if the power supply voltage begins to decrease after time tP, the voltage of the piezoelectric plate 91a does not decrease for a while. This is because the constant voltage diode ZDI is connected, and the voltage ■ charged to the piezoelectric plate 91a.

This is because the charge charged in the piezoelectric plate 91a is not discharged until the difference between the voltage and the power supply voltage becomes 2.1.

The reason why this problem is solved by adding the phototransistor PTI is as follows. While the point A in FIG. 16 is positive, the photodiode LEDI emits light, so the phototransistor P
TI is working. Therefore, when the power supply voltage begins to decrease after time tP, the charge on the piezoelectric plate 91a is discharged via the phototransistor PTI, so that the same voltage as the power supply voltage is applied to the piezoelectric plate 91a as shown by the solid line. . When the polarity changes and point A becomes negative, the phototransistor PT
I is turned off. When the voltage at point A becomes -V2DI or less, voltage begins to be applied in the opposite polarization direction, as shown in the figure.

When this circuit is used in this way, it can be applied to any power supply voltage.
- A power supply voltage is applied in the polarization direction, and a voltage obtained by subtracting VZDI from the power supply voltage is applied in the reverse polarization direction. Note that the piezoelectric plate 91b operates in the same manner as the piezoelectric plate 91a, so a description thereof will be omitted.

FIG. 18 shows a Darlington transistor DT instead of the phototransistor used as a short circuit in FIG.
11. This is an example using DT21. The operation of the circuit for charging the piezoelectric plate 91a will be explained.

When the voltage at point A is positive and rising, a forward current flows through the constant voltage diode zDl, and the piezoelectric plate 91a is charged in the polarization direction. When the voltage at point A starts to drop, the voltage at electrode 93 tries to become higher than point A, but at this time Darlington transistor DTII turns on, so piezoelectric plate 91
The charge at a is discharged and eventually becomes equal to the voltage at point A. When the point A becomes negative, a current flows to the base of the Darlington transistor DT12 and turns it on, so that the base voltage of the Darlington transistor DT11 becomes equal to the emitter voltage and the base current is cut off, so the Darlington transistor DT11 turns off. Therefore, piezoelectric plate 91a=2
A voltage of VVZDI is applied to 8- in the reverse polarization direction. Here, since the Darlington transistor DT12 is in an on state while a voltage is applied to the piezoelectric plate 91a in the reverse polarization direction, the charging current in the reverse polarization direction is generated at 8 points - electrode 98 - piezoelectric plate 91a → electrode 93 → resistance The current flows through a path from point R11 to Darlington transistor DT12-A, and a voltage of VVZDI is applied to the piezoelectric plate 91A in the reverse polarization direction. Piezoelectric plate 9
The same applies to 1b.

〔Effect of the invention〕

As explained below, according to the imaging optical device of the present invention,
Simply changing the curvature of the mirror surface of the variable focus mirror changes the position of the imaging point. Therefore, focusing can be performed extremely quickly, and the structure is simple, small, and lightweight. In addition, by independently changing the curvature of the mirror surfaces of the two variable focus mirrors, it is possible to change not only the position of the imaging point but also the size of the image. For example, by moving the mirror surfaces with a sine wave, the imaging position can be changed. By scanning back and forth, applications such as use as a television camera with a three-dimensional effect are possible.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing its optical path, FIG. 3 is a sectional view showing a color filter array, and FIG. 4 is a perspective view showing a two-dimensional image sensor. Fig. 5 is a block diagram showing the second embodiment of the present invention, Fig. 6 is a block diagram showing the third embodiment of the invention, Fig. 7 is a diagram showing the optical path, and Fig. 8 is a variable focus diagram. 9 is a perspective view showing the fourth embodiment of the present invention, FIG. 10 is a plan configuration diagram thereof, and FIG. 11 is a diagram showing the fifth embodiment of the present invention. 12 to 15 are configuration diagrams each showing an example of a variable focus mirror, FIG. 16 is a circuit diagram showing an example of a mirror drive device, FIG. 17 is an operation waveform diagram thereof, and FIG. FIG. 3 is a circuit diagram showing another example of a mirror drive device. 1.200...Polarizing beam splitter, 2.56.
... Wavelength plate, 3,52... Variable focus mirror, 4,57.
... Mirror drive device, 5... Convex lens, 6... Two-dimensional image sensor, 7... Image sensor drive device, 8
...control device, 10...rotary actuator, 1
1°54...Mirror surface material, 12,201,202...Joining surface, 55...Polarizing plate, 102...Semi-transparent film.

Claims (8)

[Claims] (1) An optical demultiplexer and a variable focus mirror are provided, and after the light incident on the optical demultiplexer passes through a demultiplexing surface of the optical demultiplexer (or is reflected by the demultiplexing surface), An imaging optical device characterized in that the optical demultiplexer and a variable focus mirror are arranged so that the optical demultiplexer and the variable focus mirror are reflected at the demultiplexer and then reflected again at the demultiplexing surface of the optical demultiplexer (or transmitted through the demultiplexing surface). (2) A variable focus mirror consists of at least two plates pasted together, at least one of which is distorted in the plane direction of the plates, thereby changing the curvature of the outer surface of the bonded plates and making the outer surface a mirror surface. An imaging optical device according to claim 1. (3) The imaging optical device according to claim 2, wherein the plate that is distorted in the plane direction is a piezoelectric element or an electrostrictive element. (4) An optical demultiplexer is composed of a polarizing beam splitter and a 1/4 wavelength plate, each having a bonded surface for splitting light.The light incident on the polarizing beam splitter is transmitted through the bonded surface (or 2. The imaging optical device according to claim 1, wherein the quarter-wave plate is disposed after the light is reflected by the variable focus mirror. (5) Two sets of optical demultiplexers and variable focus mirrors are provided, and after the light incident on the first optical demultiplexer passes through the demultiplexing surface (or is reflected by the demultiplexing surface), the first variable focus mirror is provided. The light is reflected by a mirror, is reflected again at the branching surface of the first optical demultiplexer (or is transmitted through the demultiplexing surface), and then the light incident on the second optical demultiplexer is transmitted through the demultiplexing surface ( or after reflection on the wavefront),
The first and second optical demultiplexers and the first and An imaging optical device characterized in that a second variable focus mirror is arranged. (6) A variable focus mirror has at least two plates pasted together, and at least one of them is distorted in the direction of the plane of the plates, thereby changing the curvature of the outer surface of the bonded plates, and the outer surface has a mirror surface. An imaging optical device according to claim 5. (7) The imaging optical device according to claim 5, wherein the plate that is distorted in the plane direction is a piezoelectric element or an electrostrictive element. (8) An optical demultiplexer is composed of a polarizing beam splitter and a quarter-wave plate, each having a bonded surface that separates light.The light incident on the polarizing beam splitter is transmitted through the bonded surface (or the bonded surface 6. The imaging optical device according to claim 5, wherein the quarter-wave plate is disposed between the time when the light is reflected by the variable focus mirror and the time when the light is reflected by the variable focus mirror.