JPS60114803A - Optical element - Google Patents

Abstract

PURPOSE:To enable a reflective face to change its focal distance by forming a reflective face on the interface between a transparent medium and a reflective medium, and rendering its form variable. CONSTITUTION:An optical element comprises a cylindrical vessel 11 having a circular opening 12, a transparent elastic medium 13, an optically transparent flat plate 14 mobile in parallel for pressurizing the elastic member 13, mercury 15 as a reflective medium, an elastic member 16 made of rubber or the like, and a vessel for storing said mercury. When pressure is applied to the elastic member 13 by moving the mobile plate 14, a part 13a of the elastic member 13 is protruded out of the opening 12 like a convex lens, and the protruded part 13a is in contact with the mercury 15, forming a contact face 18 between the member 13 and the mercury 15 serviceable as a reflective face for reflecting a luminous flux 19 incident from the side of the elastic member 13. This reflective face 18 can be utilized as a concave mirror, and this concave mirror can be changed in focal distance by changing the pressure to be applied to the plate 14 to change the protrusion length of this member 13a like a concave lens and the radius of curvature of the reflective face 18.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical elements used in optical devices such as cameras and videos, optical communications, and electro-optical devices such as laser discs, and particularly relates to optical elements used in optical devices such as cameras and videos, and electro-optical devices such as laser discs. This invention relates to a variable focus optical element that changes the distance.

Conventionally, as a variable focus lens, Japanese Patent Application Laid-open No. 55. -368
57, in which liquid is filled in an elastic container and its shape is changed by the pressure of the liquid, and JP-A-56-110.
403 and Japanese Patent Application Laid-open No. 58-85415, a device using a piezoelectric material has been proposed.

In addition, apart from these methods, the present method deforms the optical surface formed by the elastic body at the opening by causing the elastic body itself to protrude convexly or sink concavely from the opening of the member. Therefore, we proposed an elastic lens, which is an optical element that can obtain desired optical characteristics, such as focal length. This optical element can achieve optical properties by simply applying an external force to the elastic body or changing the volume of the elastic body (reversibly changing the surface to obtain desired optical characteristics). It is extremely easy to configure and control, and because the optical characteristics change based on changes in the shape of the optical surface, the rate of change in the optical characteristics can be set to an extremely high rate.

When the above-mentioned optical element is used as a reflecting mirror, it is necessary to provide a reflective surface of a metal such as aluminum or copper on the formed optical surface by means of vapor deposition or the like.

However, when such vapor deposition is performed on the surface of an elastic body filled with liquid, or an elastic body that protrudes or settles from an opening, the surface of the elastic body becomes thick due to a change in shape (because it expands and contracts, it becomes thicker than before). The elastic modulus of the metal thin film does not match that of the elastic body, which has the drawback that the metal thin film peels off or inhibits the shape change of the elastic body.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective variable-focus optical element that eliminates the drawbacks of the prior art.

In the optical element according to the present invention, a transparent first medium whose shape can be changed depending on factors such as pressure change and temperature change and a light-reflective second medium are brought into contact with each other, and the second medium The shape of the reflective surface of the second medium is changed by changing the shape of the surface of the first medium that is in contact with the second medium.

The first medium contains a liquid or gas,
The second medium is something like an elastic body whose shape changes depending on liquid or gas, or an elastic body that protrudes or settles from an opening, and the second medium is something like a liquid such as mercury.

In the following embodiments of the present invention, an elastic lens is used as a light-transmitting first medium and mercury is used as a second medium. (This is an analysis plane of a typical basic configuration of an optical element called a lens.)
1 is a cylindrical container with a circular opening 2, 6 is a transparent elastic body, and 4 is a movable part for pressurizing the elastic body, which is an optically transparent parallel flat plate. It is ℃・l ℃・state kQ. 32 shows a state in which pressure is applied to the elastic body 6 through the movable part 4, and in this case, a part of the elastic body protrudes from the opening in the shape of a convex lens according to the magnitude of the applied pressure. FIG. 6 shows a state in which negative pressure is applied to the elastic body through the movable part 4, and in this case, the elastic body has a concave lens shape at the opening.

In this way, a desired optical surface shape can be realized at the opening by a portion of the elastic body depending on the magnitude of the external force applied to the movable portion of the container.

The elastic body 6 used here has the property of causing deformation when force is applied to the object, and as long as the applied force is not too large (within the elastic limit), the deformation returns to its original state when the force is removed (elasticity). can be used.

In a normal solid, the maximum strain (critical strain) within its elastic limit is about 1 inch. In addition, vulcanized elastic rubber has a very large elastic limit (the limit strain is 1o
oos is coming.

Examples of such elastic materials include natural rubber, which is generally known as 6-rubber, and styrene-butadiene rubber (SBR).
), butadiene rubber (B it ), inbre rubber (1
), ethylene propylene rubber (EPM, EPDM),
Butyl rubber (11B), chloroprene rubber (C1()) acrylonitrile-butadiene rubber (NBR), urethane rubber (U), silicone rubber (8i), fluorine rubber (E)
Examples include synthetic rubbers such as poly(jft-1'A (T)), polyether rubber (POIIJCHR, CHC), etc. All of these exhibit a rubber state at room temperature.

However, in general, polymeric substances take either a glassy state, a rubbery state, or a molten state depending on the degree of Brownian motion of the molecules. Therefore, polymeric substances that exhibit a rubbery state at the operating temperature of optical elements are widely used as elastic bodies. The modulus of elasticity in the zero rubber state that can be created is mainly determined by the crosslinking state of the polymer chains that make up the elastic body, and therefore, for example, vulcanization of natural rubber is nothing but a process that determines the modulus of elasticity.

The elastic body used here has an elastic modulus of 1 for a normal solid.
0" to 10" dyne/cffl, suitably 76 ffl or less of 10 Bdyne of the rubber elastic body, preferably 10' dyne, 4J or less, particularly preferably 5 X iQ dyne/CIII,
The lower limit is preferably as small as possible when the elastic body constitutes an optical element and the elastic body has properties such as spillage, unlike ordinary liquids.

As a method for deforming the optical surface at the opening of the elastic body, in addition to external force, it is also possible to use the volume change due to thermal expansion/contraction, sol-gel change, etc. using the above-mentioned materials.

Further, by providing an opening in the shape of a rectangular slit, a cylindrical lens and a toric lens can also be formed.

The optical element formed by these apertures can change its shape arbitrarily by applying an external force to the elastic body or by changing the volume of the elastic body, and the degree of change can be controlled by feedback while detecting the effect. It is possible.

Further, it is also possible to provide this opening with a piezoelectric element such as a cylindrical piezo, and thereby the confectionery can be made significantly more compact.

All the conventionally known methods can be used to apply an external force to the elastic body, but the deformation of the elastic body can be
It is desirable to perform this with a feedback mechanism while detecting the magnetic effect, and for this purpose, electromagnets, stepping motors, etc.
A method that allows electrical control of a piezoelectric element or the like is preferred. Further, the volume change due to heating can be performed using a heater provided outside or inside the elastic body.

FIG. 4 and FIG. 5 are diagrams each showing an embodiment of the optical element of the present invention.

In the figure, 11 is FJ+4F#-M having a circular opening 12
44 is a cylindrical container, 16 is the above-mentioned transparent elastic body, 14 is a movable part for pressurizing the elastic body 16 and is an optically transparent parallel flat plate, and 15 is mercury as a reflective medium. , 16 is an elastic member such as rubber, and 17 is a container for storing mercury. FIG. 4 shows a state in which pressure is applied to the elastic body 16 through the parallel plate movable portion 14, and in this case, a portion 15a of the elastic body 16 protrudes from the opening 12 in the shape of a convex lens due to the magnitude of the applied pressure. At this time, the convex lens-shaped protruding portion 13a comes into contact with the mercury 15 and forms a contact surface 18 between the elastic body 16 and the water bottle 15. This surface 18 serves as a reflective surface for the light beam 19 entering from the elastic body 16 side. As the elastic body 13 is pressurized, its protruding portion 16a will contact the contact surface 18.
Push mercury 15 away while changing the shape of (0
The displaced mercury 15 is an elastic part 1 that is easily deformed.
Since the water gas deforms the elastic member 16 and escapes, the water gas cannot block the elastic member 16 that projects like a convex lens.

This reflecting surface 18 can be used as a concave mirror, and the parallel plate 14
By changing the amount of pressure applied, the leaves protruding into a convex lens shape will change and the curvature of the reflecting surface 18 will change, resulting in a concave mirror with a variable focus. Under negative pressure, that is, when the elastic body 13 is pulled by the parallel plate 14, the elastic body 16 becomes concave lens-shaped at the opening 12. At this time as well, the mercury 15 forms a surface 18 in contact with the deformed elastic body 16, and this surface 18 is used to change the magnitude of the negative pressure applied to the zero-parallel flat plate 14, which is a convex mirror. However, it is possible to continuously change the curvature of the convex mirror 18. Instead of mercury, which forms the reflective surface described above, other liquid substances capable of forming the reflective surface can be used, for example, aluminum powder in a solvent such as Kijiroru. A liquid in which powder is suspended may also be used. Further, instead of mercury, an easily deformable elastic body that can form a reflective surface, such as silicone rubber mixed with fine aluminum powder, may be used.

In the above nine reflective variable focus optical elements according to the present invention, the reflective surface is formed by the surface where the transparent medium and the reflective medium are in contact with each other, and the reflective surface is formed by applying a physical action to the transparent medium. It is possible to change the shape of the reflector to change its focal length, and a reflecting surface with variable power can be obtained with a simple configuration.

[Brief explanation of drawings]

1, 2, and 6 are views showing an elastic lens applied to the optical element according to the present invention, and FIGS. 4 and 5 each show an embodiment of the optical element according to the present invention. Figure shown. 11... Container, 12... Circular opening, 16.0 elastic body, 14... Parallel flat plate, 15... Mercury, 16...
Elastic member, 17... Container, 18... Reflective surface, 19.
... Luminous flux. Applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] (1) It is characterized by having a reflective surface whose shape is variable, which is formed by contacting a first medium having a light transmitting property and an M2 medium having a light reflective property. optical element. (2) The optical element according to claim 1, wherein the change in the surface shape is a change in the shape of the first medium. (6) The first medium is an elastic body, and the second medium is an optical element. Claim f: The optical element according to claim A1, which is a reflective liquid.