JPH0323416A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain the small-sized, efficient optical switch and to simplify its operation by providing an optical member with >=1 folded part in parallel luminous flux and varying the angle of incidence of or the refracting index to light which is incident on parallel combined border surfaces. CONSTITUTION:The optical switch 1 consists of the optical member made of a freely expansive glass thin plate 2 which is bent in a triangular mountain shape and arranged in an optical system while having both end parts fixed to support members 3a and 3b. The total reflection and transmission of the incident light can be switched by varying the refractive index or incidence angle, so shutter operation for transmitting and cutting off a subject light beam can be performed by simple operation wherein the interval between the support members 3a and 3b holding the glass thin plate 2 is only varied. Consequently, the structure is simple and the operation quantity is small, so the switch is easily reduced in size and the energy-saving optical switch is realized.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an optical switch, more specifically, an optical switch that is disposed in an optical path in which the light beam of an imaging optical system becomes a substantially parallel light beam, and that transmits and totally reflects incident light. This invention relates to an optical switch that controls switching between

[Prior Art] As is well known, some stereoscopic televisions (3D-TV) and autofocus (AF) devices employ a method of selecting one of two light beams to form an image. be. In other words, in a 3D (three-dimensional) stereoscopic television, a stone image and a left image are output alternately on a cathode ray tube (CRT), and in synchronization with this, the shutter of viewing glasses is opened and closed alternately for the right and left eyes. However, the right image is formed on the retina of the right eye, and the left image is formed on the retina of the left eye.In addition, the AF device focuses on the right pupil and left pupil, which are divided on the imaging optical system. When the two pupils of the camera are imaged alternately in the same way as in the 3D TV, a relative shift occurs between the left and right images due to a shift in focus, so this shift in images is detected to perform the matching operation. ing.

These shutters, which alternately form images, are made of liquid crystal or PLZT (Pb,
La) (Zr, Ti) 03 Ceramics that utilize the property of rotating the direction of polarized light components, or a part of the rotating disk with a through hole that allows light to pass through, can be used to move the same disk at high speed. A device was used in which the transmission and blocking of light could be controlled by rotating it.

In addition, in the field of optical communication, there are devices that configure optical switches by changing the refractive index in the light guide path to switch between total reflection and transmission of light, and furthermore, by changing the refractive index in the light guide path, there are devices that configure optical switches that switch between total reflection and transmission of light. There is also a device that changes the optical axis of the imaging optical system by controlling the refractive index of the crystal and using a light polarizer that transmits and totally reflects light (Japanese Patent Laid-Open No. 5
7-128323).

[Problems to be Solved by the Invention] However, shutters that utilize the fact that the rotation angle of polarized light changes depending on voltage, such as the conventional liquid crystals and electro-optic ceramics described above, can only handle linearly polarized light components.
Orthogonal polarized light components cannot be transmitted, and the transmittance of the shutter section is usually 50% or less.

On the other hand, in the shirt evening style, which rotates the above-mentioned rotating disk with light transmission holes, all the light passes through, and the transmittance can be close to the maximum of 100%. As a result, as the equipment becomes larger, the timing of opening and closing the shutter is greatly affected by physical inertia. It will be subject to severe restrictions.

Furthermore, when the above-mentioned optical switch in the field of optical communication or the imaging optical axis switch using the optical polarization device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 57-128323 is arranged in the optical path of the imaging optical system, total reflection In order to satisfy the desired angle, the size of the changeover or switch must be extremely large.

An object of the present invention is to provide an optical switch that is compact, efficient, and easy to operate by changing the incident angle or refractive index of light incident on combined parallel rising surfaces in order to eliminate the above-mentioned drawbacks of the conventional art. It is in ltt Ig.

[Means and effects for solving the problems] The optical switch of the present invention is arranged at a position where the light rays of the imaging optical system form a substantially parallel high luminous flux, and the refractive index and the angle with respect to the incident light are adjusted by pressure, electromagnetic force, etc. The above-mentioned optical member has a variable optical member, and by changing the refractive index and the angle 21 to the incident light, the above-mentioned parallel light beam can be changed into a total reflection surface and a transmission surface by χ・I. In the optical switch in which the member is arranged, the optical member is characterized in that the optical member has one or more bent portions in the parallel light beam.

[Example] The present invention will be explained below with reference to illustrated embodiments.

First, before explaining the embodiments of the present invention, the principle of the optical switch of the present invention will be explained. When light passes through the boundary planes of two materials or spaces with different refractive indexes, it creates a plane of elevation in the same boundary. It emerges bent at an angle determined by the ratio of the refractive index of the material or space and the angle of incidence upon entering the interface.

That is, as shown in FIG. 8, the incident angle of light is l, the exit angle (
Assuming that the refractive index (refractive index) is L', and the refraction of the two spaces forming the boundary F are the human resource side Nr1 and the exit side N1, the light is transmitted in all other areas.

In addition, as shown in Fig. 9, two parallel boundary surfaces F1 and F
In the case of light incident on 2, if it is not totally reflected and the refractive index is N n , N 1 , N n , the incident light is only laterally shifted and exits at the same angle as the angle a=t angle i.

There are two types of angles for total reflection and transmission: positive and negative directions, and the two may be combined. In this case, a double image occurs due to image shift, but Jii
If the width of the space with the refractive index N1 is narrowed, it will fall within the allowable value. Further, by using this fact, it can also be used as an optical LPF (C low pass filter).

In this way, light changes the refractive index or the angle of incidence,
Since it is possible to switch between full-reflection #1 and transmission, this can be skillfully used to create an optical switch that can change the incident angle or refractive index of light, and install this in the optical system. If provided, the shutter can be easily constructed.

The above is the principle of the optical switch of the present invention.

Next, an optical switch according to a first embodiment of the present invention is shown in FIG. 1 and FIGS. 2A and 2B. The optical switch 1 of this first embodiment is designed to change the incident angle of light. This optical switch 1 is composed of an optical member consisting of a telescopic thin glass plate 2 bent into a triangular mountain shape, and its both ends are fixed to support members 3a and 3b and arranged in an optical system. be done.

The optical system is composed of a lens 4 and an imaging lens 5, and when a ray of light from an object 6 or a virtual object such as an image is incident, the ray is turned into substantially parallel light by the lens 4, and the same The light passes through the thin glass plate 2 disposed between the lens 4 and the lens 5, enters the lens 5, and forms an image 7 on the optical axis O.

The glass thin plate 2, whose both ends are fixed to the supporting members 3a and 3b, is arranged between the lenses 4 and 5 so that the apex angle of the bent portion of the triangular mountain shape is located on the optical axis O. By changing the distance between the supporting members 3a and 3b, the angle of the bent portion changes and the light ftio of the straight portion (flat portion) changes.
The structure is such that the angle of inclination relative to the surface changes.

In the optical switch 1 of the 17A embodiment constructed in this manner, when the shutter is opened to allow light to pass through, the flat part (straight part) of the thin glass plate 2 shown in FIG. 1 is inclined. . Then, when the light rays from the object 6 that have been made substantially parallel by the lens 4 are incident on the thin glass plate 2, they are refracted at a certain angle and proceed through the thin glass plate 2, and
When the light ray exits into the air, it is refracted once again in the opposite direction to that when it was incident on a person, and exits at the same angle as the incident angle, and an image 7 is formed by the lens 5.

Next, when closing the shutter to block the passage of light, move both support members 3g and 3b in the direction of the arrow in the figure as shown in FIG. Shrink the thin plate 2. Then, since the slope of the flat part (straight part) of the thin glass plate 2 becomes steep, the light beam that has become substantially parallel light at the lens 4 is reflected by the thin glass plate 2 and cannot pass through, as shown in FIG. 2B. Therefore, the image formation 7 as shown in FIG. 1 does not occur.

As described above, according to the optical switch 1 of the first embodiment,
It is easy to change the distance between the supporting parts 44 3 a and 3 b that hold the thin glass plate 2.
Can perform shut-off shutter operation. In addition, this optical switch 1 has a simple structure and has a small amount of operation, so it can be easily miniaturized and an energy-saving optical switch can be realized.

Note that the triangular mountain shape of the thin glass plate 2 is not limited to this, but may include a flat part (
It goes without saying that, for example, the bent shape of the thin glass plate may be formed into a sawtooth shape or the like.

3A and 3B show a second length embodiment of the present invention. The optical switch top 1 of this second length embodiment is constructed so that a refractive index changing member 8 is used in place of the glass thin plate 2 to transmit and cross light. That is, this optical switch 11 has two supports 9 made of transparent materials.
a, 9b, a refractive index changing member 8 supported between both supports 9a, 9b, and electrodes 10a, 1 to which an electric field is applied.
0b.

The refractive index changing member 8 is a material such as ceramics such as PLZT, which changes the refractive index of light rays in the same direction as the electric field when a voltage is applied, and a relatively thin plate member made of this material is shaped into a triangular 111 shape. Continuously fold both supports 9
It is supported between a and 9b. This optical switch 11 is disposed between the lens 4 and the imaging lens 5 as in the first embodiment.

In this example, the refractive index of the refractive index change member 8 is determined by applying an electric field E such that the C axis of the crystal (hexagonal product) is parallel to the Z axis.
(0,0,E3), the refraction ``11'' for light coming in that direction is 12 n 10 ( 1 7 l3n 11 E
s)11 II. 2 is floating in the river. This is the first-order electro-optic effect expressed by [n11: refractive index before voltage application, γ: constant, n22' = nll'' [For details, see Ceramics Science Series 3 Obtoceramics Visit Yamaguchi/Yanagi ml! (Refer to 2, 2. 1 Refractive index and birefringence, edited by Katsumi Miyauchi and To, written by Kozo H, Gihodo Publishing, p. 14).Other electro-optic effects may of course be used.

Next, the operation of the optical switch 11 of the second embodiment configured in this way will be described. First, when filtering out the transmission of the light rays that have passed through the lens 4 from the subject 6, the two poles 10a , 10b. Here, the refractive index is 9
If the refractive index of a and 9b is N■, and the refractive index of the refractive index changing member 8 is N1, then when NII is N1, the refractive index changing member 8
The incident light is totally reflected. That is, as in the case of the glass thin plate 2 of the first embodiment, the refractive index changing member 8 is connected to the support body 9.
As shown in FIG. 3B, when moving to step A. jl)<
The frame image 7 does not occur because it prevents the transmission of light rays.

When transmitting light, both electrodes 10a, 10
Apply voltage between b. Then, the hli refractive index changing member 8
As the refractive index of , decreases, the condition for total reflection is no longer satisfied, and the light is transmitted and an image 7 is formed.

Furthermore, in this second cusp embodiment, a case has been described in which a refractive 4S changing member 8 whose refractive index decreases when a voltage is applied is used, but this is different from a type in which the refractive index increases when a voltage is applied or an NII
>N may be used. In this case, when N■>NI, the surface that causes total reflection becomes the surface that enters the refractive index historicizing member 8.

In addition, in the above embodiment, the refractive index changing member 8 is formed into a triangular mountain-shaped continuous shape, but this is also a sawtooth-shaped refractive index changing member like the optical switch IIA shown in FIG. The member 8A may be supported between the support Fjj bodies 9a and 9b. Further, although it may not be good to apply voltage only in one direction, depending on the case, pressure may be applied to the AC 7, or a clear voltage may be applied in the opposite direction after use.

According to the optical switch 11, IIA of this second embodiment,
Since it uses the electro-optic effect, there is no physical movement at all, allowing for static and quick operation.Also, by narrowing the width of the reflecting surface, the electric field can be directed in approximately the same direction as the direction of light. Since it is possible to apply voltage, it can be driven at a low voltage, and it can be set at a position where drag refraction is less likely to occur.

FIG. 5 shows an example in which the optical switch 11 of the second embodiment is applied to an autofocus device of a camera. The reflected light from the object 6 is formed into a mirror image 14 near the condenser lens 13 by the photographing lens 12 . Since this image formation can be handled optically in the same way as an object, the structure is the same as that of the second embodiment shown in FIGS. 3A and 3B above, that is, the lens 4 and the optical switch 11.
, is imaged again as an image 7 on the image sensor 15 by the image lens 5. However, optical switch 11
are arranged in two parts between the lens 4 and the image lens 5 in the pupil transmission area of the photographic lens 12, and are arranged so that the images of the subject can be formed alternately. With this configuration, the image sensor 15 can receive separate images of the pupil in y, so that automatic focus adjustment can be performed by known means based on the difference in these images.

Next, FIGS. 6A and 6B show a third embodiment of the present invention. The optical switch 11B of the third embodiment differs from the optical switch 1 in the second length embodiment in that the interface between the supports 9a, 9b and the refractive index changing member 8 must be parallel to each other. In this example, the 6th A
As shown in the figure, the refractive index changing member 8B is formed into a continuous rectangular prism shape so that one side is flat and the other side is sawnout, so that they do not need to be parallel. It is. Further, because of this structure, the refractive index changing member 8B has the same function as a prism, so the optical axis O' of the frame 13I lens 5 is also shifted by the amount that the optical axis O is shifted. The other configurations are the same as those of the second embodiment. The refractive index of the supports 9a and 9b is N n 1
If the refractive index of the refractive index changing part 8B is N, total reflection ■
, r, NII>N1.

Optical switch of the third embodiment configured in this way 1.
1B, the light incident on the lens 4 from the subject 6 is turned into a substantially parallel beam by the lens 4, and is incident on the optical switch 11B. At the point where the light enters the refractive index changing portion +A'8B from the photographic body 9a, total reflection occurs as shown in FIG. 6B, and the light does not enter the image lens 5. Both mI here!
! When the refractive index of the refractive index changing member 8B is changed by changing the voltage between Oa and 10b, the above condition for total reflection NU>N1 is no longer satisfied, so the incident light is refracted and transmitted. Light enters the image lens 5, and the image 7
begins to form.

According to this third embodiment, the boundaries between the supports 9a, 9b and the refractive index changing member 8B do not have to be made parallel to each other, so there is an effect that the influence of manufacturing errors is less likely to occur, and the light In the transmitting state, the position of the image can be controlled by adjusting the refractive index of the refractive index changing member 8B. This image position control means in the second embodiment can also be used when the boundary surfaces are not parallel due to manufacturing errors, or when the entire module is aligned for other applications.

FIG. 7 shows an example in which the optical switch IIB of the third embodiment is applied to an autofocus device of a camera. In this example, as in the case of the example shown in FIG. Then, this imaged image is the optical switch 1.1B of the third embodiment, which is arranged in two parts on the pupil transmission plane of the lens 4 and the photographing lens 12.
1. Imaging lenses 5a and 5b arranged correspondingly to each other
, 1.6a and 1.6b to form an image 7 on the image sensor 15 again. In this case, on the output side of the optical switches IIB, 11B2, the optical axis O is shifted and becomes the optical axis O' as explained in FIG. I'm trying to change it back to .

Even with this configuration, images of different pupils can be received separately on the image sensor 15, thereby allowing automatic salt point adjustment by known means. You can perform verse 21.

Also in this application example, the image position can be moved by the voltage applied to the optical switch, so even if the two image positions change due to manufacturing errors of the module, they can be adjusted by the electrode voltage. Furthermore, this fact can be actively utilized to shift the image position slightly.

[Effects of the Invention] As described above, according to the present invention, there is no large physical movement such as movement of the shutter film, so the on/off switch operation of the square image is much faster than that of the conventional one. , the energy saving effect is increased. Also, compared to devices that use a single beam of light, such as liquid crystals, which do not physically move, since polarized light is not used, the transmittance will not be halved like in the case of devices that use polarized light, resulting in a very high transmittance. . Historically, the overall length can be made shorter than that of a similar type using a total anti-reflection J]=l, so the entire optical system, including the lens design, can be made smaller, and in this regard, the electrode Since the distance between the electrodes can be narrowed, the direction of the electric field in the crystal and the direction of the light beam can be brought closer to ideal directions, and the voltage between the electrodes can also be lowered. Further, depending on the configuration, it can also serve as an optical low-pass filter for the image. Therefore, in addition to these effects, when applied to an autofocus device of a camera, for example, effects such as being able to shorten the overall length of the module and other parts can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an optical switch according to a first embodiment of the present invention, showing the state of light transmission. FIG. 2A is a cross-sectional view of an optical switch according to a first embodiment of the invention.
This is a cross-sectional view of the main part showing the blocking state due to total reflection of light.
The figures are a partially enlarged view of FIG. 2A, FIG. 3A is a sectional view of a main part of an optical switch showing a second embodiment of the present invention, FIG. 3B is a partially enlarged view of FIG. 3A, and FIG. 4 is a partially enlarged view of FIG. , FIG. 5 is a schematic configuration diagram of essential parts when the optical switch of the second embodiment is applied to an autofocus device, and FIG. 6A 6B is a partially enlarged view of FIG. 6A, and FIG. 7 is a sectional view of a main part of an optical switch showing a third embodiment of the present invention. FIG. 7 shows an optical switch of the third embodiment as an autofocus device. The schematic configuration diagrams of the main parts when applied, Figures 8 and 9, are for explaining the entrance angle and exit angle 1 and 1, respectively, when light passes through the interface between substances with different refractive indexes. It is a line diagram. 1. Upper Yu, ■ included, IIB, IIB, ++B2
l

Claims (1)

[Claims] (1) The imaging optical system is placed in a position where the light rays are approximately parallel and have a high luminous flux, and has an optical member whose refractive index and angle with respect to the incident light can be changed by pressure, electromagnetic force, etc. By changing the angle to the parallel light beam, the total reflection surface and the transmission surface can be switched for the parallel light beam.
An optical switch in which the optical member is arranged, wherein the optical member has one or more bent portions in the parallel light beam.