JPS60151603A - Optical element - Google Patents

Abstract

PURPOSE:To enable a considerable change of the focal length by a simple structure by projecting or sinking an elastic body so as to deform the optical surface. CONSTITUTION:A container 1 is packed with an elastic body 4, and a member 3 having an opening 2 is placed on the elastic body 4. When pressure is applied to the elastic body 4, the elastic body 4 projects from the opening 2. Since pressure is applied to the elastic body 4 even in an ordinary state, the surface 5 of the elastic body 4 in the opening 2 is provided with a gently convex shape to form an optical surface. The bottom plate 1a is made of a piezoelectric element, and the convex shape of the optical surface can be changed by applying voltage to the plate 1a so as to deform it.

Description

[Detailed Description of the Invention] Misfire 8/J relates to optical elements used in optical equipment such as cameras and videos, optical communications, laser discs, and other electronic optical devices, and in particular, by changing the optical surface shape. , relates to an optical element whose focal length and direction or position of an optical axis can be changed.

Conventionally, as a variable pointless lens, Japanese Patent Application Laid-Open No. 55-5685
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 so-called liquid lens requires a liquid reservoir, a pressurizing device, etc., and has a problem in making the element compact, while the latter has the disadvantage that its variable amount cannot be made very large.

Also, if you try to use conventional optical elements to create a device that has a variable focal length and can change the position of the optical axis,
The entire device is complicated and large, which leads to high costs.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide an optical element that has a simple configuration, has a large amount of change in focal length, and can also change the position of the optical axis. be.

The optical structure of the present invention is characterized in that it comprises an aperture member having an elastic body and an aperture capable of protruding or sinking the elastic body to deform the optical surface, and is configured to dance with the aperture member. There is a patent.

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 changing its curvature. By this, a desired focal length can be obtained, and by changing the direction or position of the aperture, the direction or position of the optical axis of the optical surface can be varied.

The elastic body used in the present invention has the property (elasticity) that it deforms 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. can be used. - For a normal solid, the maximum strain (critical strain) within its elastic limit is about 1%. In addition, vulcanized elastic rubber has a very large elastic limit, with a limit strain of 100
becomes close to 0.

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

Note that the elasticity height (G) is expressed as G=ρ/γ (ρ=stress, γ=elastic strain). In addition, 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, such as styrene butane (1!: PM, I
PDM), butyl rubber (TTR), aoprene rubber (OR), acrylonitrile-butadiene rubber (NBR)
), +7 urethane rubber (U), silicone rubber (Sl)
Synthetic rubbers such as , fluororubber (PM), polysulfide rubber (T), and polyethergol (POR, OHR, OHO) can be mentioned. All of these exhibit a rubbery state at room temperature. However, polymeric substances generally take one of a glass state, a rubber state, or a molten state depending on the Brownian motion of the molecules. 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 modulus of elasticity in the rubber state is determined primarily by the crosslinking of the polymer chains that make up the elastic body, and therefore, for example, vulcanization of natural rubber VC is nothing but a process that determines the modulus of elasticity.

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

However, a decrease in the elastic modulus (large deformation caused by a small stress) also leads to a decrease in strength, so it is necessary to use It is necessary to select an appropriate elastic body.

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 element.

The elastic body used in the present invention preferably has an elastic modulus smaller than that of a normal solid from 10" to 10"yne/cm" and 1 o' ayne/cpF or less of a rubber elastic body,
Preferably 10'ayne/cm' or less, particularly preferably 5X'10' dyne/crtF or less, the lower limit is such that when the elastic body constitutes an optical element, unlike a normal liquid, it will not spill. The smaller the elastic body, the better. Although optical elements are often used at room temperature, they may also be used at particularly high or low temperatures.
The above elastic modulus range is at the operating temperature of the optical element.

The hardness and softness of an elastic body depend to some extent on its elasticity.

JIS K6501 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 penetration, which can be easily determined.

However, if the elastic modulus is as low as 10'ayn/cm" or less, it cannot be measured using the above method, and in that case, it is evaluated by the penetration using a 1.4 inch micro-consistency meter according to JTSK2808. debt.

In addition, when the elastic modulus is small, it is difficult to obtain a constant value of 1 when using ``tensile and elongation'' as a measurement method, so it is possible to find the value by compression (deformation to 5) and to compare it with the penetration of the tip. can.

Rubber elastic materials include those that do not require vulcanization, such as ethylene-vinyl acetate copolymers and AB-A type getadiene-styrene block copolymers, in addition to those that require vulcanization (crosslinking), which are conventionally known. It can also be obtained by appropriately gelling a hook-shaped polymer or the like (by controlling the molecular chain length between the bridge points).

In all of these, the modulus of elasticity is determined by determining the crosslinked state, the combination of molecules in the σ-block copolymer, the gel state, etc.

Further, in addition to controlling the elastic body depending on the structure of the elastic body itself, it is also possible to change and adjust its properties by adding a diluent or a filler.

For example, silicone rubber (manufactured by Shin-Etsu Chemical; Km104 (
When a catalyst (trade name)) and a catalyst (trade name: Iru'I'-104, manufactured by Shin-Etsu Chemical Co., Ltd.) are added, as the amount added increases, the hardness and tensile strength decrease, and conversely, the 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.

Although the shape of the aperture provided in the aperture plate varies depending on the required optical effect, it is generally circular to form a convex or four-concave lens with a variable focal length.

Moreover, by providing an opening in the shape of a rectangular slit, a 7-lindrical lens and a toric lens can be formed, and by providing a large number of openings, an array 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 the change can be determined by feeding the element while detecting the effect. It is possible to control it.

The means for applying an external force to the elastic body can be performed using any of the conventionally known methods751, but it is desirable to deform the elastic body using a feedback mechanism while detecting the optical effect. For this purpose, a method that allows direct control of electromagnets, stepping motors, piezoelectric elements, etc. is preferable.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing a row of optical elements according to the present invention, in which a container 1 is filled with an elastic body 4 and an opening member 6 is arranged above the elastic body 4. As shown in FIG. An opening 2 is formed in the opening member 3.

When pressure is applied to the elastic body 4 in this state, the elastic body 4 protrudes from the opening 2. In the optical element of the present invention shown in FIG. 1, pressure is applied to the elastic body 4 even in a normal state.

Therefore, the surface 5 of the elastic body within the opening 2 (hereinafter, the inner surface 1j of the opening has a gently convex shape) forms an optical surface.

In the optical element of the present invention shown in FIG.
is made of a piezoelectric element, and when voltage is applied to the bottom plate 1a,
The bottom plate 1a shown in FIG. 2 is raised inside the container 1 and applies pressure to the elastic body 4. Then, the opening inner surface 5 is @1
It has a convex shape with a smaller radius of curvature than the shape shown in the figure.

As a result, the optical element of the invention has a shorter focal length than that of FIG. In the illustrated example, pressure is applied to the elastic body 4 by the bottom plate 1a, but
It may be configured such that pressure is applied to the elastic body 4 by the opening member 6 or the side surface of the container 1.

Now, in the optical element of the present invention, the aperture member 6 can be moved arbitrarily. In the optical element of the present invention shown in FIG. 3, the opening 2 of the opening member 3 is moved toward the side surface 1b of the container 1. Therefore, the optical axis of the optical element of the present invention moves in parallel with the movement of the aperture member 3. On the other hand, the inner surface of the opening 5
9 The surface shape does not change unless the pressure (tension) applied to the elastic body 4 is changed.

In FIGS. 1 to 3, a transparent material was used as the elastic body 4, and the optical element according to the present invention was used as a lens.

In the figure, when a point light source is placed at point P, in the state shown in Figure 1, the inner surface of the aperture 50 has a weak positive refractive power. The imaging position can be changed arbitrarily by changing the voltage applied to 1a and the position of the aperture 3. 1. The optical element according to the present invention has a five-dimensional optical scanning function. The inner surface 5 of the opening can be used not only as a refractive surface but also as a reflective surface.

FIG. 4 shows another example of the optical element according to the present invention, in which an aperture member 7 having an aperture 9 has a spherical shape. Therefore, the opening member 7 moves on a spherical surface. In the optical element of the present invention shown in FIG. 4, the bottom plate 8IL of the container 8
is configured to be movable up and down, and the elastic body 6 includes a bottom plate 8a.
Pressure (tension) is applied by.

FIG. 4 shows a state where no force is applied to the bottom plate aaVCtE. In FIG. 5, the opening 9 moves to the left, the bottom plate 8a rises, and pressure is applied to the elastic body 6. Therefore, the aperture inner surface 16 has a convex shape, and the optical axis t rotates as the aperture member 7 moves. In FIG. 6, the opening 9 moves to the right, the bottom plate 8a descends, and negative pressure is applied to the elastic body 6. Therefore, the opening inner surface 16
It has a concave shape, and the optical axis t rotates as the aperture member 7 moves.

In this example, which is different from the example shown in FIG. 1, FIG.
1' is placed.

18 is an elastic body, and 19 is a bottom plate made of parallel flat glass. Two electromagnets 12 and 12' are arranged below the bottom plate 19. , by independently controlling the amount of current of the two electromagnets 12, 12'! Changing the attractive or repulsive force acting between the magnet 12.12' and the permanent magnet 11.11',
The shape of the inner surface 20 of the opening and the position of the optical axis can be freely changed.

Figure 7 shows the case where no current is passed through the electromagnets 12 and 12'. Figure 8 shows the strong attraction between the permanent magnet 11 and the electromagnet 12, and the permanent magnet 11'! t so that a weak attractive force acts between the magnets 12'.
When a current is applied, FIG. 9 shows the permanent magnet 11 and the magnet 12.
The case is shown in which a current is passed so that a strong repulsive force acts between the permanent magnet 11' and the electromagnet 12', and a weak repulsive force acts between the permanent magnet 11' and the electromagnet 12'.

Next, an example in which the optical element of the present invention is used in an actual lens system will be shown.

The optical element of the present invention can be used, for example, in an objective lens system for pinking up an optical disc. 10 and 11 show examples of the configuration of an objective lens system for picking up an optical disk using the optical element of the present invention, where 13 is the optical element of the present invention shown in FIG. 7, 14 is an objective lens, and 15 is the recording surface of the optical disc.

The parallel laser beam incident on the left side of the drawing is imaged onto the recording surface 15 of the optical disk by the optical element 13 and objective lens 14 of the present invention. The focused laser beam undergoes a change in polarization state according to the information written at the focused point and is reflected. The reflected laser beam travels back along the same optical path as when it was incident, its polarization state is detected by a detector, and the report is read out.

In such an optical system, it is necessary to focus the laser beam as a small spot on a predetermined position on the optical disk, and it is necessary to eliminate the effects of vibration, eccentricity of the optical disk, surface waviness, and the like. Therefore, the big amplifier VC of the optical disk has an automatic adjustment mechanism, that is, even if the recording surface 15 moves in the direction of the light J47g of the objective lens system, the recording surface 15 is always
A tracking mechanism is used to image the beam on the same circumference even if the recording surface 15 moves in a direction perpendicular to the optical axis m. A mechanism is necessary.

For this reason, in conventional optical disc pink-up, these mechanisms were provided by mechanically moving the entire objective lens or by using means such as optical deflection of a galvanometer, but these mechanisms were difficult to achieve in terms of device miniaturization and response speed. There was a problem.

However, as shown in FIGS. 10 and 11, if the optical element 13 of the present invention is used, the focal length of the entire accessory lens system can be changed by moving the aperture member 10'Jk in the direction of the optical axis m. It can be changed. In addition, opening member 1
By changing the angle of 0 with respect to the bottom plate 19,
A single prism can deflect a laser beam f.

According to the optical element of the present invention, an automatic focusing mechanism and a tracking mechanism can be obtained at the same time.

That is, a specific 1. 'J R is the optical axis m
The optical element 13 according to the invention makes it possible for the laser beam to always be focused on the point R, even if the laser beam is moved perpendicularly to the direction of illumination.

Other applications of the optical element according to the present invention include various types of illumination such as laser processing machines and condensing lenses for Redemes, etc., light projection optical systems, and three-dimensional shape reading devices.

The optical element of the present invention is very effective because it can greatly change the focal length and also freely change the position of the optical axis due to the highly modular configuration described above. Therefore, by using the optical element of the present invention, the entire optical device can be made simple and have a small wall.

[Brief explanation of drawings]

- Figure 1 is a sectional view showing an example of the optical element of the present invention, Figure 2 is a sectional view showing an example of the optical element of the present invention.
The figure is a sectional view showing an example in which the focal length is changed using the optical element shown in Fig. 1, Fig. 3 is a sectional view showing an example in which the optical axis is moved in parallel with the optical element shown in Fig. 2, and Fig. 4. 5 is a sectional view showing another example of the optical element according to the invention; FIG. 5 is a sectional view showing an example in which the inner surface of the opening of the optical element shown in FIG. 4 is made convex and the direction of the optical axis is changed; FIG. 6 is a sectional view showing an example in which the inner surface of the aperture of the optical element shown in FIG. 4 is made concave and the direction of the optical axis is changed, and FIG. A cross-sectional view showing an example, Fig. 8 is a cross-sectional view showing an example in which the inner surface of the aperture of the optical element shown in Fig. 7 is made convex and the direction of the optical axis is changed, Fig. 9 #-i
FIG. 7 is a sectional view showing an example in which the inner surface of the opening of the optical element is made concave and the direction of the optical axis is changed, and FIGS. 10 and 11 are cross-sectional views of the optical element of the present invention shown in FIG. 7. FIG. 3 is a cross-sectional view showing an example of use in an objective lens system for picking up an optical disc. 1.8... Container 2.9.17... Opening 5.7.10... Opening member 4.6.18... Elastic body 5.1S, 20... Opening Inner surface 11.11'...Permanent magnet 12, 12'...Electromagnet 13...Optical element 14,...Objective lens 15...Recording surface 19...Bottom plate Applicant Canon Co., Ltd. Figure 7 Figure 2 Haze Figure 2 Figure 11

Claims (1)

[Claims] It consists of an aperture member having an elastic body and an aperture capable of deforming the optical surface by protruding or sinking the elastic body, and the position of the aperture member can be freely changed to adjust the focal length and optical axis position of the optical surface. An optical element characterized in that it has a configuration that allows it to change arbitrarily.