JPS60120303A - Optical element - Google Patents

Abstract

PURPOSE:To facilitate the constitution and control of an optical element and to set the variation rate of optical characteristics large by forming a cured surface as the whole or part of a surface except a surface forming an optical surface which constitutes an optical element. CONSTITUTION:The optical element consists of the cured surface 1 of a cylindrical elastic body, a transparent elastic body 3, and an opening plate 4 with an opening part 2 serving as a movable part for applying pressure to the elastic body. When pressure is applied to the elastic body 3 through the opening plate 4, part of the elastic body 3 projects in a convex lens shape from the opening part 2 according to the applied pressure. When negative pressure is applied to the elastic body 3 through the opening plate 4, the elastic body 3 becomes concave at the opening part 2. The opening plate 4 having the opening part 2 is preferably opaque, but when it is transparent, this is utilized as a doublefocus optical element.

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 equipment that uses laser discs, and in particular, by changing the optical surface shape. The present invention relates to a variable focus optical element whose focal length can be changed.

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, JP-A-58-85415 has proposed a lens using a piezoelectric material.0 However, the former so-called liquid lens requires a liquid reservoir, a pressurizing device, etc., and there are problems in making the element compact. However, the latter has the disadvantage that the amount of variation cannot be made very large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and provide a variable focus lens that has a large change in focal length and is simple in construction.

The optical element according to the present invention consists of an elastic body and an opening capable of protruding or sinking the elastic body to deform the optical surface, and includes all or part of the other surfaces excluding the surface forming the optical surface. It is characterized by having a hardened 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. It is possible to obtain optical properties such as focal length. 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. This is extremely easy, and the rate of change in the optical characteristics can be set extremely large since the optical characteristics do not change due to changes in the shape of the optical surface.

The elastic body used in the present invention is one that has the property (elasticity) that it deforms when force is applied to the object, and that the deformation returns to its original state when the force is removed, as long as the applied force is not too large (within the elastic limit). can be used.

In a normal solid, the maximum strain (critical strain) within its elastic limit is about les. In addition, vulcanized elastic rubber has a very large elastic limit, with a limit strain of 10
It will be close to 00%.

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

Note that the elastic modulus (G) is expressed as G=ρ/γ (ρ=stress, γ=elastic strain). Elasticity that causes large deformation with small stress is called high elasticity or rubber elasticity.
Therefore, in the present invention, this type of elastic body can be particularly preferably used.

Such rubber elastic bodies include natural rubber, generally known as 6-rubber, and styrene-butadiene rubber (SBR).
, butadiene rubber (BR), inpre rubber (IR), ethylene propylene rubber (EPM, EPDM), butyl rubber (IIR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), urethane rubber (
U), silicone rubber (Si), fluororubber (F'PM)
), polysulfide rubber (T), polyether rubber (POR.), polysulfide rubber (T), polyether rubber (POR.

Examples include synthetic rubbers such as CHR and CHC. All of these exhibit a rubbery state at room temperature. However, in general, polymeric substances vary depending on the degree of Brownian motion of the molecules.
It can be either glassy, rubbery or molten.

Therefore, polymeric substances that exhibit a rubbery state at the operating temperature of optical elements can be widely used as the elastic body of the present invention.

The elastic modulus in the rubber state is mainly determined by the crosslinking state of the polymer chains constituting the elastic body, and is therefore nothing but a process that determines the vulcanized linear elastic modulus of natural rubber, for example.

In the present invention, it is desirable that the elastic body used be capable of large deformation with small stress, and for this purpose, adjustment of the crosslinking state is important.

However, a decrease in the elastic modulus (a tendency for large deformations to occur with small stress) also leads to a decrease in strength. It is necessary to select the body appropriately.

The elastic modulus is also measured by, for example, tensile, bending, or compression methods, depending on the type of stress depending on the usage of the optical confectionery.

For the elastic body used in the present invention, the elastic modulus of a normal solid is smaller than 1011 to 10 udyne/c/, and the elastic modulus of a rubber elastic body is suitably 10" d7neΔ or less, preferably 10' d7neΔ or less, particularly preferably 10' d7neΔ or less. 5×10'
dyneΔi or less, and the smaller the lower limit is, the more preferable the lower limit is if the elastic body has a property that it will not spill, unlike a normal liquid, when the elastic body constitutes an optical element. Note that although optical elements are often used at room temperature, they may also be used at particularly high or low temperatures, so the above range of elastic modulus is at the operating temperature of the optical element.

The hardness and softening of an elastic body depend on its elasticity. J
ISK 6301 stipulates a method of applying a small strain to the surface of a sample using a spring and evaluating the hardness of rubber based on the degree of penetration9, which can be easily understood.

However, if the modulus of elasticity is as low as I O' dyne/i or less, it cannot be measured using the above method, and in that case, a 1/4-inch micro-consistency meter according to J I SK 2808 is used to measure the penetration. Evaluate〇Also, if the modulus of elasticity is small, it is difficult to measure it with 1 tension 9 - elongation, so find the value by compression (5% deformation) and compare it with the penetration of the tip. Can be done.

Rubber elastic materials do not require vulcanization, such as ethylene-acetate Bigol copolymer and A-B-A type butadiene-styrene block copolymer, in addition to the conventional vulcanization (crosslinking) method. It can be obtained by appropriately gelling a substance or a chain polymer by controlling the molecular chain length between the bridge 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.In addition, the elastic modulus is controlled by the structure of the elastic body itself. In this case, it is also possible to change and adjust the properties by adding diluents and fillers.

For example, silicone rubber (manufactured by M-Etsu Kagaku Kogyo; KE104 (
When a diluent (trade name: RTV thinner manufactured by Shin-Etsu Chemical) is added to a catalyst (trade name: AT-104゜ manufactured by Shin-Etsu Chemical), the hardness increases as the amount added increases.
Tensile strength decreases and elongation increases.

Further, the elastic body according to the present invention is preferably a highly elastic body so as to obtain a large deformation with a small stress, but such an elastic body is soft and has a problem in its self-retention ability.

The present invention improves this point by maintaining elasticity in the necessary parts of the elastic body and hardening the external part that does not have any influence.

As mentioned above, the woodcutter type of elastic body is known,
Many materials exhibit their elasticity through "cross-linking" such as vulcanization, and in this case, the behavior of the elasticity depends on the "cross-linking" state.

When 9-crosslinking is 0, it is a solution or a viscous liquid, and when it is 100-3-dimensionally crosslinked, it becomes a rigid body, as seen in thermosetting resins.

Various crosslinking agents are used depending on the structure of the target polymer; for unsaturated polymers (natural rubber, butadiene rubber, etc.), sulfur, sulfur compounds such as sulfur chloride and dithiol, benzoyl peroxide, amino These include substances that generate radicals through thermal decomposition such as azobenzene, oxidizing substances with resonance structures such as quinone and polynitrobenzene, and compounds that generate radicals when used in combination with an appropriate oxidizing agent such as aromatic amines, phenols, and mercaptans.

In addition, divinyl or diallyl compounds such as divinylbenzene, ethylene dimethacrylate, methacrylic anhydride, and diaryl phthalate are used as vinyl compounds, mono-, di-, and polyamines are used as epoxy resins, and alkaline resins are used as di- and polyisocyanates. Polyamides, polyurethanes, etc. are excellent crosslinking agents.

In addition, this catalyst absorbs light in the visible or ultraviolet region and easily decomposes into radicals, and the generated radicals promote the crosslinking reaction, or when excited by light and collide with monomers, the radicals are easily decomposed into radicals. It is also possible to use a substance that activates the 7-mer and performs a crosslinking reaction.These include carbonyl compounds such as diacetyl, benzyl, benzophenone, benzaldehyde, and cyclohexane, azo compounds such as azobisisobutyronitrile and azomethane, and tetracarbonyl compounds such as azobisisobutyronitrile and azomethane. Methylthiuram disulfide, benzothiazolyl disulfide,
The following dyes are used: carbon tetrachloride, organic peroxides, ranyl nitrate, and eosin, erythrosin, and neutral red nanotonos.

Furthermore, the crosslinking reaction can be carried out by irradiation with radiation without using a crosslinking agent. Polymers that can be crosslinked by radiation include natural rubber, polybutadiene rubber, silicone rubber,
In addition to neoprene rubber, other materials include polyethylene, polypropylene, polystyrene, and polyvinyl chloride.

Further, any crosslinked state can also be obtained as an intermediate state during curing of the thermosetting resin.

The present invention is achieved by controlling the crosslinking state of a part of the elastic body, that is, all or a part of the surface other than the surface forming the optical surface, by the above-mentioned method and crosslinking three-dimensionally to form a network structure. , the periphery of an elastic body is hardened to form a container.

That is, it is made into a container by hardening only the peripheral portion while maintaining elasticity such that the inside of the elastic body protrudes or sinks from the opening and can be deformed to exhibit its optical effect.

This makes it possible to integrate the elastic body and the container,
This greatly contributes to the miniaturization of devices.

The member having openings for forming the optical surface of the elastic body may be a flat plate with openings, or the parts other than the openings may be cured by a crosslinking reaction as described above.

In addition, as a method for curing only the surface of the elastic body, the above-mentioned crosslinking agent is dispersed, adsorbed, and diffused only on the surface, heated,
A reaction occurs only on the surface by light irradiation. Further, this hard film on the surface is not necessarily made of rubber, but may be made of a general hardening type resin. Although the shape of this aperture varies depending on the required optical effect, it is generally a circular aperture to form a convex or concave lens with a variable focal length.

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 openings can change its shape arbitrarily by external force applied to the elastic body or by volume change of the elastic body due to thermal expansion/contraction, sol-gel change, etc. It is possible to control by feedback while detecting the effect.

Furthermore, it is also possible to provide this opening with a piezoelectric element such as a cylindrical piezo, which allows the element to 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 use a feedback mechanism without 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 3 show cross-sections of the basic configuration of the optical element of the present invention, in which 1 is a hardened surface of a cylindrical elastic body, 3 is a transparent elastic body, and 4 is an opening. Figure 1 shows a state in which no pressure is applied. FIG. 2 shows a state in which pressure is applied to the elastic body 3 through the aperture plate 4, and in this case, a portion of the elastic body protrudes from the aperture 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 aperture plate 4, and in this case, the elastic body has a concave lens shape at the aperture.

In this way, a desired optical surface shape can be realized at the p-opening by a portion of the elastic body depending on the magnitude of the external force applied to the movable part of the container. In addition, opening 2
It is desirable that the aperture plate 4 is optically opaque, but if it is transparent, it can be used as a bifocal optical element. Also, instead of the configuration shown in Fig. 1, the elastic body itself can be hardened to form an aperture plate as shown in Fig. 4.
It is also possible to configure the elastic body 3 to be pressurized by the movable part 6. 5 is a hardened surface. Furthermore, as shown in FIG. 5, it is also possible to provide a plurality of openings 7 and 8 and give each one a curvature by applying pressure. Further, by changing the sizes of the plurality of openings, different curvatures can be given to each of the openings.

Here, any method can be used to apply pressure to the elastic body 3 by driving the opening plate or the movable part, and a simple method is to cut a thread in the container and screw the movable part into it. , a method of controlling a movable part using an electromagnet, etc., but the present invention is not limited to these methods. Further, examples of other optical elements according to the present invention include:
As shown in FIG. 6, using a cylindrical Viezo element 9,
By expanding and contracting in the radial direction, the elastic body 3 filled inside the piezo element can be caused to protrude and sink from the cylindrical opening lO, thereby forming an optical surface. Furthermore, the aperture of the optical element according to the present invention is not limited to a circular shape;
As shown in the figure, when the opening 11 is rectangular, the elastic body that protrudes and settles under pressure can have a 7-lindrical or toric shape.

8 and 9 are specific examples of applying an external force to an elastic body. In FIG. 8, an elastic body 3 whose periphery is hardened is housed in a cylindrical piezoelectric body 12, By applying a voltage through the switch 17, the disk-shaped movable portion 14 and the driving portion 16 having the opening 15 are brought closer together, thereby deforming the optical surface of the opening 15. FIG. 9 shows a movable part 1 made of ferromagnetic material by an electromagnet 18.
9 in the depth direction, the optical surface at the opening 20 of the elastic body 3 whose periphery is hardened can be deformed.

Example 1 Elastic body (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE 104GE
L) When preparing the catalyst (trade name: CAT-10
4. Add 14 g of (manufactured by Shin-Etsu Chemical Co., Ltd.) to form an outer container. An elastic body containing 9% catalyst is housed in the inner part, and the outside is hard (penetration is 30 using a 1/4-inch micro-consistency meter according to JIS K2808) and the inside is soft (penetration is also 8).
0) An elastic body was prepared. FIG. 10 shows this state. By combining a member 19 made of a ferromagnetic material having a circular opening and an electromagnet 18 in an elastic body 3 whose periphery is hardened, a very compact optical element can be made. did it. 4
Figure 11 shows how an elastic body is compressed by an electromagnet to make the optical surface protrude in a convex shape.

Example 2 An example of the piezo element explained in FIG. 6 was manufactured as a prototype.

First, one end of the piezo (10~φX15WX,) was covered with a Teflon plate with a polished surface, and the same KE1 as in Example 1 was placed on top.
04GEL to which 14 grams of catalyst CAT-104 was added was poured to a thickness of 3% and cured.

Then, on top of this, KE104 containing 9% CAT 104
Filled with GEL elastic material and hardened.

As a result, it was possible to create a convex lens at the other end without blocking one end with a glass plate, etc., and to create a compact element.

[Brief explanation of drawings]

1, 2, and 3 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;
Figure 2 shows a state in which a Hirogai force is applied upward, and Figure 3 shows a good state in which an external force is applied downward. FIG. 4, FIG. I@5, and FIG. 6 are sectional views of other embodiments of the optical element of the present invention, respectively. FIG. 7 is a perspective view of yet another optical element according to the present invention. 8, 9, 10 and 11 are cross-sectional views of an optical element according to the invention in which means for applying an external force are arranged, respectively. l and 5 ... hardened surface 2, 7.8.10.11.15 and 20 ... opening 3 ... elastic body 6.14 and 19 ... movable part 9 ... piezo element 12 ...Piezoelectric body 13 ...Power supply 16 ...Driver 17 ...Switch 18 ...Electromagnet applicant Canon Co., Ltd.

Claims (1)

[Claims] (1) In an optical element comprising an elastic body and a member having an opening capable of protruding or sinking the elastic body to deform the optical surface, the surface of the other surface other than the surface forming the optical surface is An optical element characterized by having a hardened surface in whole or in part.