JPH01312505A - Mirror and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an electrical real-time system that can be widely used as a mirror in laser processing machines used for cutting and welding, laser discs, compact discs, and other electronic devices. The present invention relates to a mirror whose optical axis can be changed in a single direction, and a method for manufacturing the mirror.

[Prior art] Figure 5 shows the optical axis and curvature when a conventional optical element is used, for example, as shown on pages 56-57 of the Laser Application Technology Handbook (edited by the Laser Association, published by Asakura Shoten in 1984). FIG. 3 is a characteristic diagram showing the relationship with radius. As shown in the figure,
If the mirrors have radii of curvature bl and b2 and the distance between them is d, and one of the mirrors is rotated by θ, then the line connecting the centers of curvature of the mirrors is rotated by an angle φ. When the angle is small, the following equation holds.

b1θ=(b++b2 d)φ X= [b+ (b2 d)/ (b+b2 d)]
BY=[b+b2/(b++b2 d)]θ where X and Y are the deviations of the mode center on the mirror.

From the above equation, for example, in the case of a parallel plane type (b+, b2→oo), X, Y, cause a very large deviation even for a slight θ. Conversely, in order to utilize light effectively, the positioning accuracy of the mirror is required to be extremely high. In conventional mirrors, the radius of curvature is constant, and the optical axis is adjusted by mechanical positioning.

[Problems to be Solved by the Invention] As is clear from the above explanation, when constructing an optical system using a conventional mirror with a constant radius of curvature, first, the optical axis is statically adjusted at room temperature during light irradiation. Adjusting the dynamic optical axis deviation due to temperature changes caused by irradiation of light requires the high level of skill of a skilled technician, and is extremely difficult. The problem was that it was difficult to

The present invention was made to solve the above-mentioned problems, and it is possible to adjust the radius of curvature by applying electric power to easily adjust the optical system without requiring a skilled engineer. The aim is to obtain a mirror that can be changed, which was not possible with conventional mirrors.
By dynamically controlling the radius of curvature in real time, we aim to create a mirror that can greatly expand the applications of various optical instruments.

Furthermore, another object of the present invention is to provide a method for manufacturing a mirror in which a reflective film can be formed with high adhesion.

[Means for Solving the Problems] The mirror of the present invention includes a first electrostrictive element having a reflective film on one surface, a first electrostrictive element whose strain direction is shifted from the first electrostrictive element, and a first electrostrictive element joined to the other surface of the first electrostrictive element. 2 electrostrictive elements, a first electric field applying means for applying an electric field to the first electrostrictive element to distort the first electrostrictive element, and a second electrostrictive element;
A second device that applies an electric field to the electrostrictive element to distort the second electrostrictive element.
It is equipped with an electric field applying means.

Further, in another method of manufacturing a mirror according to the present invention, a reflective film is formed on one surface of the first electrostrictive element by ion beam evaporation.

[Function] The mirror of the present invention has a structure in which electrostrictive elements that can be distorted, expanded and contracted by applying an electric field are bonded together, so it is possible to realize a bimetallic effect by electrical control. It is possible to create irregularities on the mirror surface (reflection film) with extremely high precision. That is, the radius of curvature can be changed.

In the method for manufacturing a mirror according to another aspect of the present invention, the reflective film (mirror surface) is formed by the ion beam evaporation method, so that the reflective film adheres to the first ta strain element with high adhesion force, resulting in the above-mentioned A mirror with high reliability can be formed without fear of the film peeling off even when unevenness changes.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a configuration diagram showing the configuration of a mirror according to an embodiment of the present invention. In the figure, (1) is a flat plate-shaped first electrostrictive element, on one surface of which a reflective film (4) serving as a mirror surface is formed, in this case an Au vapor-deposited film with a film thickness of 0.3 μI. (2) is a flat second electrostrictive element, which is bonded to the other surface of the first electrostrictive element (1) so that its strain direction is orthogonal to the strain direction of the first electrostrictive element (1). . (3) is a bonding layer, in this case an epoxy adhesive; (5) is a first electric field applying means for applying an electric field to the first electrostrictive element (1) to distort the first electrostrictive element (1); (6) is a second electric field applying means that applies an electric field to the second electrostrictive element (2) to distort the second electrostrictive element (2).

The principle by which the axis of light hitting the mirror surface of a mirror configured in this way can be varied will be explained.

Variable optical axis control, that is, controlling the shape of the mirror to make it concave and convex, is based on the principle of applying the bimetal effect.
An example of this will be explained below based on FIGS. 1 and 2. Incidentally, FIG. 2 is an explanatory diagram of the operation of the mirror to facilitate understanding of the operation of the embodiment shown in FIG. 1. As is well known, an electrostrictive element has the property of changing its dimensions (distorting, expanding, contracting) by applying an electric field. For example, inorganic materials include P Z T (Pt+
-Ti-Zr-0 compounds), and organic materials such as polyvinylidene fluoride have already been put into practical use. In this case, PZT was used. At the start when no electric field is applied, a first electric field is applied to the first and second electrostrictive elements (1) and (2), which are flat as shown in (A) or (A') in Fig. 2, respectively. By applying an electric field using the means (5) and the second electric field applying means (6), it can be deformed as shown in (B) or (8°) in FIG. By combining these deformations, it becomes possible to deform the mirror surface into a concave shape as shown in (C). Note that in order to deform the mirror surface into a convex shape, it is clear that the direction of application of the electric field can be reversed.
By controlling the electric field output from the electric field applying means (6), the degree of unevenness and degree of deformation can be adjusted to adjust the mirror surface to a desired curvature. Therefore, there is no need for skilled technicians to determine the optical axis of the mirror with high precision, and positioning can be performed easily in real time, and by dynamic control of the radius of curvature,
The applications of various optical instruments can be greatly expanded.

Note that the thickness of the reflective film (4) should be 500 Å or more since reflective properties are obtained, and if it is 5000 Å or more, cracks may occur due to repeated strain in the first electrostrictive element (1). 5,000 people is appropriate.

Next, an embodiment of a mirror manufacturing method according to another invention will be described. A method for forming a reflective film (mirror surface) mainly by ion beam evaporation will be described.

FIG. 3 is a configuration diagram showing an example of a cluster ion beam evaporation apparatus according to this embodiment. In the figure, (20
) are the first electrostrictive element (1) and the second electrostrictive element (2) of the material to be deposited.
) is bonded to the mirror substrate, (4) is the reflective film (deposited film)
, (8) is an accelerating electrode, (9) is a vapor deposition material, (10) is a crucible, (12) is an ionization electrode, (13) is a vacuum chamber.

First, a mirror substrate is formed by bonding a first electrostrictive element (1) and a second electrostrictive element (2) with an epoxy adhesive such that their strain directions are perpendicular to each other. Next, a reflective film, in this case an Au film, is formed on the surface of the first electrostrictive element (1) of the mirror substrate by ion beam evaporation. First, the vacuum [(13) is
After exhausting the air to about 0-6 Torr, the crucible (10) is heated by the crucible heating heater (11), and the crucible (10)
It is heated to about 1700° C. (for example, about 1600° C. in the case of A1) so that the vapor pressure of the material Au inside becomes about I Torr. In this state, Au is removed from the crucible (10).
Clusters of steam erupt. When this cluster is showered with electrons from an ionizing electrode (12), a portion of the cluster is ionized. The Au vapor (7), which has become cluster ions, is given kinetic energy by the accelerating electrode (8), collides with the mirror substrate (20), and participates in film formation together with neutral clusters that have not been ionized. At this time, if the accelerating voltage is set to at least 3 V or higher during the initial stage of film formation (up to a film thickness of about 50), the cluster ions will be given a large kinetic energy and the mirror substrate (2
0) to form a mixing (surface layer ion implantation) layer with the surface layer of the mirror substrate (20). Therefore, the adhesion to the mirror substrate (20) is strong, and a good mirror surface can be formed without fear of peeling even when the curvature of the mirror changes. In addition, by setting the acceleration voltage to 3 V or higher,
For example, in the case of an Au reflective film (film thickness 0.3 μm), as can be seen from the characteristic diagram showing the experimental results of investigating the dependence of reflectance on accelerating voltage in Figure 4, CO2 laser light (wavelength 10.6 μm)
), it has been confirmed through experiments that it has an extremely high reflectance of 99.3%. The vertical axis of the figure is the reflectance (
%), and the horizontal axis is the acceleration voltage (Kv).

By the way, in the vacuum evaporation method, it is 99.0% or less (usually 98.
8%). The acceleration voltage is the adhesion force of the film,
3 from the viewpoint of reflectance, and 3 from the point of view that if it exceeds V, the substrate will become rough and the film adhesion efficiency will decrease.
~7Kv is desirable. In this case, the acceleration voltage is 5Kv until the film thickness reaches 50 people, and after that, the acceleration voltage is 3Kv, and the A of 0.3μm is applied.
A u reflective film was formed. In addition, in order to further increase the adhesion force, irradiation with inert gas ions such as Ar and No is performed before vapor deposition to remove adsorbed matter on the substrate surface and create an activated and clean mirror substrate surface. It is also effective to form a film thereon.

Although the above embodiments have been explained using a plane mirror, it is clear that the same effect can be achieved using a concave mirror or a convex mirror.

[Effects of the Invention] As described above, according to the present invention, the first electrostrictive element has a reflective film on one surface, and the first electrostrictive element is bonded to the other surface of the first electrostrictive element with the strain direction shifted. a second electrostrictive element that applies an electric field to the first electrostrictive element to distort the first electrostrictive element; and a first electric field applying means that applies an electric field to the second electrostrictive element to distort the first electrostrictive element; By using a mirror equipped with a means for applying a second electric field for distortion, there is an effect that the curvature of the mirror can be easily changed in real time.

According to another aspect of the present invention, by forming a reflective film on one surface of the first electrostrictive element by ion beam evaporation, the mirror has a sufficiently strong adhesion force that can cope with changes in the curvature of the mirror. This has the effect of providing a variable optical axis mirror with excellent long-term reliability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a mirror according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the mirror in FIG. 1, and FIG. 3 is a block diagram showing a cluster ion beam evaporation apparatus according to the present invention.
FIG. 4 is a characteristic diagram showing the dependence of reflectance on accelerating voltage according to the present invention, and FIG. 5 is an explanatory diagram showing the relationship between the optical axis and the radius of curvature in a conventional optical element. (1) is the first electrostrictive element, (2) is the second electrostrictive element, (3) is the bonding layer, (4) is the reflective film, and (5) is the first electrostrictive element.
The electric field applying means (6) is a second electric field applying means. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A first electrostrictive element having a reflective film on one surface, a second electrostrictive element joined to the other surface of the first electrostrictive element with the strain direction shifted from the first electrostrictive element, and an electric field applied to the first electrostrictive element. A mirror comprising a first electric field applying means for applying an electric field to distort the first electrostrictive element, and a second electric field applying means for applying an electric field to the second electrostrictive element to distort the second electrostrictive element. (2) The method for manufacturing a mirror according to claim 1, wherein a reflective film is formed on one surface of the first electrostrictive element by ion beam evaporation.