JPS60111201A - Optical element - Google Patents

Abstract

PURPOSE:To obtain a variable focus lens of simple constitution which varies in focal length greatly by projecting an elastic body itself convexly from the opening of a member or recessing it concavely. CONSTITUTION:An optical element consists of a cylindrical container 1 with a circular opening part 2, transparent elastic body 3, and optically transparent parallel flat plate 4 as a moving part for pressing the elastic body. Figures show that no pressure is applied and that pressure is applied to the elastic body 3 through the movable part 4 and part of the elastic body projects convexly from the opening part according to the applied pressure. Further, the elastic body which applied with negative pressure through the movable part 4 forms a concave lens shape at the opening part. Thus, a desired optical surface shape is realized at the opening part by using part of the elastic body according to the external force applied to the movable part of the container.

Description

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

Conventionally, as a variable focus lens, Japanese Patent Application Laid-Open No. 55-3685
7, in which a liquid is filled in an elastic container and its shape is changed by the pressure of the liquid, and JP-A-56-1104.
03 and Japanese Patent Application Laid-Open No. 58-85415, a device using a piezoelectric material has been proposed.

However, the former's possession, liquid L.
#Noon Moshi F, +'l Lu Keisen Koyuki 17J? Power L7
However, there is a 6 in the 1F song, and the latter has the disadvantage that the variable amount is too wide (it cannot be adjusted).

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a variable focus lens with a thick focal length change cover (and a simple structure).

The optical element according to the present invention is characterized by comprising a member having an elastic body and an opening that allows the elastic body to protrude or sink to deform the optical surface. That is, the optical element according to the present invention deforms the optical surface formed by the elastic body at the opening by causing the bulk elastic body itself to protrude convexly or sink concavely from the opening of the member, thereby forming a desired shape. Optical properties 1, such as focal length, can be obtained.

Therefore, by simply applying an external force to the elastic body or changing the volume of the elastic body, the optical surface can be reversibly changed and the desired optical properties can be obtained, making it easy to configure and control the optical element. It is extremely easy to use, and the rate of change in optical properties can be set to an extremely high rate due to the change in optical properties based on the shape change of the optical surface. As long as the applied force is not too large (within the elastic limit), when the force is removed, the deformation returns to its original state (elasticity)
can be used.

In a normal solid, the maximum strain (limit strain) within its elastic limit is about 1 inch. In addition, vulcanized elastic rubber has a very large elastic limit, and its limit strain is 1oo
It will be close to o%.

In the optical element according to the present invention, an elastic modulus depending on the characteristics of the optical diagonal to be formed is used as appropriate, but in general, in order to easily obtain large elastic deformation, or the state after deformation is optical In order to make the material more homogeneous, it is preferable that the elastic modulus is small.

(one elastic strain). Further, elasticity that causes large deformation with small stress is called high elasticity or rubber elasticity, and therefore, in the present invention, this type of elastic body can be particularly preferably used. Natural rubbers known as ``, such as styrene-butadiene rubber (SBR), buta-renin rubber (CBR), isompre rubber (IR), ethylene propylene rubber (EL)
M.

E PDM ), butyl rubber (11 liters) 1, chloroprene rubber (CR), 7-crylonitrile-butadiene rubber (NBR), urethane rubber (U), silicone rubber (
Si), fluororubber (FPM), polysulfide rubber (polyether rubber (PO, CHR, CHC), etc.). All of these exhibit a rubber state at room temperature. However, generally Depending on the degree of Brownian motion of its molecules, polymeric substances take on either a glassy state, a rubbery state, or a molten state. Therefore, polymeric substances that exhibit a rubbery state at the operating temperature of optical elements have a wide range (the elastic material of the present invention). It can be used as

The modulus of elasticity in the rubber state 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.

It is desirable for the elastic body used in the present invention to exhibit large deformation with small stress, and adjustment of the crosslinking state is important for this purpose. On the other hand, this tendency leads to a decrease in strength, so it is necessary to appropriately select the elastic body to be used so that the strength can be maintained in accordance with the purpose of the optical element to be formed. In addition, the elastic modulus is measured by selecting a method such as tension, bending, or compression depending on the type of stress depending on the usage of the optical element. The elastic modulus of the rubber elastic body is preferably smaller than 1011 to 1018 dyne/cJ, preferably 108 dyne/Cml or less, preferably 10'dyne/cJ or less, particularly preferred when L<ti
5 x 10 SdyneArA or less, and the lower limit is when an elastic body constitutes an optical element, unlike a normal liquid, this! The smaller the elastic body, the better, as long as it has properties that do not deteriorate. Note that although optical elements are often used at room temperature, they may also be used at particularly high or low temperatures, so the range of elasticity described above is at the operating temperature of the optical element.

The hardness and softness of an elastic body depend to some extent on its elasticity. J
1, SK6301 stipulates a method of applying a minute strain to the sample light surface with a tin ring and evaluating the hardness of the rubber based on the degree of penetration, which can be easily determined.

However, if the elastic modulus is as low as 10 dyn/cffl or less, it cannot be measured using the above method, and in that case, the penetration can be measured using a 1/4 inch micro L consistency meter according to JIS K 2808. If the tsubo value is 0 or the elastic modulus is small, it is difficult to measure it by "tensile shear elongation" as a measurement method, so the value is determined by pressure &i (5 inch deformation).
It can be matched with the penetration of the tip.

In addition to the conventionally known vulcanization (crosslinking) rubber elastic bodies, ethylene-vinyl acetate copolymers and human-B-Ag
It can be obtained by appropriately gelling a material that does not require vulcanization, such as a butadiene-stine V block copolymer, or a chain polymer, etc. (by controlling the molecular chain length between cross-linking points).

In all of these, the elastic modulus is controlled by adjusting the crosslinking state, the combination of molecules in the block copolymer, the gel state, etc.

Also, depending on the structure of the elastic body, in addition to controlling the elastic body, it is also possible to change and adjust its properties by adding diluents and fillers.For example, silicone rubber (Shin-Etsu Chemical) Industrially manufactured; hardness and tensile strength decrease with KE dog, but conversely elongation increases.

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.

The member having an opening for forming the optical surface of the elastic body may be one in which the opening is provided in a flat plate, and when the elastic body is housed in a container and used, the member having an opening for forming the optical surface of the elastic body may be used. Both lenses may have an aperture in one wall.The aperture varies depending on the optical effect required, but it is generally circular to form a convex or concave lens with a variable focal length. It is true.

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 confectionery formed by these openings 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 EZO, and in this case, it is possible to realize a significantly more compact element.

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 using a feedback mechanism while detecting the optical effect, and for this purpose, a method that allows electrical control of electromagnets, stepping motors, piezoelectric elements, etc. is preferable. Further, the volume change due to heating can be achieved by using a heater provided outside or inside the elastic body. Next, a typical configuration of the optical element according to the present invention will be explained with reference to the drawings.

1 to 6 show cross sections of typical basic configurations of the optical element of the present invention, in which 1 is a cylindrical container having a circular opening 2, 3 is a transparent elastic body, and 4 is an elastic body. A movable part for pressurizing the body, consisting of optically transparent parallel flat plates. FIG. 1 shows a state in which no pressure is applied. Figure 2 shows the movable part 4
In this state, pressure is applied to the elastic body B through the opening, 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. 3 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 part of the container. I've allowed it (Kobeden 1----I'm 5-7 works of Shibita 1-T 4i system bookmo 41 Shiru-I-
2←f- Also, it is desirable that the aperture plate 2' having the aperture 2 is optically opaque, but if it is transparent,
It becomes possible to use it as a bifocal optical element.

Further, the movable part and the elastic body are bonded together using an adhesive or the like, if necessary. Further, if necessary, the elastic body and the inner wall surface of the container are entirely bonded. In addition, instead of the configuration shown in FIG. 1, an elastic body 6 placed in a container 5 having an optically transparent parallel plate at the bottom is used as a movable part 6 having a circular opening 7 as shown in FIG. It can also be configured to apply pressure. Furthermore, as shown in FIG. 5, it is also possible to provide a plurality of openings 7 and 9 and give each one a curvature by applying pressure.

Furthermore, by changing the size of the plurality of openings, different curvatures can be given to each one.Also, as shown in FIG.
3 may be housed in a container 10 in which a container 3 is formed inside the container. This opening 16 is formed by a circle @ 12 fixed to the optically transparent top 11 of one container, and by applying external pressure to the movable part 4, an optical surface made of an elastic body is formed in the opening 16. Ru.

Here, any method can be used to apply pressure to the elastic body 5 by driving the movable part 4 or 6, and a simple method is to cut a thread in the container and then screw the movable part into the container. , a method of controlling a movable part using an electromagnet, etc., but the present invention is not limited to these methods. Further, as an example of another optical element according to the present invention, as shown in FIG. 7, a cylindrical piezo element 14 is used.
By expanding and contracting in the radial direction, the elastic body 6 filled inside the piezo element can be made to protrude and sink from the cylindrical opening 15 to form an optical surface. The shape of the elastic body is not limited to a circle; for example, if a container 16 having a rectangular opening 17 is used as shown in FIG. It is possible to make it into a shape.

9 and 10 are specific examples of applying an external force to an elastic body, and in FIG. By applying a voltage through the disc-shaped movable part 20 and the driving part 19 having the opening 18, the opening 18 is moved closer to each other.
It deforms the optical surface of the Also, Figure 10 shows
The electromagnet 26 moves the movable part 25 made of ferromagnetic material to the container 2.
By moving the elastic body 6 in the depth direction, the optical surface at the opening 24 of the elastic body 6 can be deformed.

Example 1 FIG. 11 is a sectional view of an optical element manufactured in this example. First, silicone rubber (trade name "E104 Gel") was placed on a brass circular vJg device 29 (inner diameter 50 mm, depth 20 mm) with a transparent glass plate 28 at the bottom.

Shin-Etsu Chemical Co., Ltd.)
31yst 104 + manufactured by Shin-Etsu Chemical Co., Ltd.) was added in an amount of 12% by weight, and was left at 50°C for 48 hours.
A transparent elastic body 30 is used. The elastic modulus of this transparent elastic body is about 2 x 10 dYn/c-. Next, an aluminum plate 61 having an opening 32 with a diameter of about 15 mm is placed on this transparent column 60, and it is held down with a holding ring 66. Here, the holding ring 66 is screwed against the cylindrical container 29. The shape of the protruding and sinking portion at this time is a rotationally symmetrical aspherical surface with a large radius of curvature near the optical axis and a small radius of curvature at the periphery. The pressure applied by the rotation of the presser ring is O~200 g.
/cl+, the radius of curvature near the optical axis is c
It was possible to change it in the range of o to 60 strokes.

Example 2 In Example 1, the diameter of the opening 62 of the aluminum plate 61 was set to 1
When the pressure was set to 0 mm, the pressure was 0 to 200 gAn.

Example 6 (O In Example 1, the amount of catalyst added was set to 1=fL%^, and the elastic modulus of the obtained transparent elastic body was approximately 1×10
It was dyn/ctA. Pressure at this time 0-100g
/Ca, the radius of curvature near the optical axis is CK) ~ 62 m
111 focal length could be varied in the range of ω to 1.

Example 4 In Example 1, the surface of the aluminum plate 31 having the opening that will come into contact with the transparent elastic body 30 is subjected to primer treatment (product name Niprimer, manufactured by Shin-Etsu Chemical) in advance, and the aluminum plate 61 and the transparent elastic body 60 are Glued it. When the aluminum plate 31 was pulled up by rotation of the presser ring 66 and negative pressure was applied to the transparent elastic body 30, the transparent elastic body 30 settled in a concave shape at the opening 62 of the aluminum plate. It was confirmed that the convex-concave lens acts as a continuum by pushing down or pulling up the aluminum plate based on the applied negative pressure of 0 to 100 gArA.

[Brief explanation of the drawing]

1, 2, and 6 are cross-sectional views of the optical element according to the present invention, in which FIG. 1 shows a state in which no external force is applied, FIG. 2 shows a state in which an external force is applied upward, and FIG. indicates a state in which an external force is applied downward. FIG. 4, FIG. 5, FIG. 6, and FIG. 7 are sectional views of other embodiments of the optical element of the present invention, respectively. No. 80 is a sectional view illustrating the arrangement of means for applying an external force to the optical element of still another optical element according to the present invention. 6 and 30... Elastic body 2.7, 9, 13, 15. 17 and 62... Opening 4 and 6, #-H moving part 14φ Rivieso element 28... Glass plate 61, 0 aluminum plate 66.1111 Osaekan Applicant: Canon Co., Ltd.

Claims (1)

[Claims] (1) An optical element comprising an elastic body and a member having an opening capable of deforming an optical surface by protruding or sinking the elastic body.