Optical: systems and elements – Mirror – Including specified control or retention of the shape of a...
Reexamination Certificate
2002-04-15
2003-12-23
Sikder, Mohammad (Department: 2872)
Optical: systems and elements
Mirror
Including specified control or retention of the shape of a...
C359S847000, C359S848000
Reexamination Certificate
active
06666559
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-118640, filed Apr. 17, 2001; and No. 2001-133435, filed Apr. 27, 2001, the entire contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a variable-profile optical device and optical element in which a curvature can continuously be changed, particularly to a small-sized variable-profile optical device and optical element to which a semiconductor technique is applied.
Moreover, the present invention relates to a variable-profile mirror and variable-profile optical element, particularly to a small-sized variable-profile mirror and variable-profile optical element to which a semiconductor technique is applied in a variable-profile optical device having a curvature able to be continuously varied.
2. Description of the Related Art
In micro optics such as an optical pickup, for the purpose of simplifying a mechanism related with focusing in which an electromagnetic actuator is used, there has heretofore been proposed a micro variable focus mirror in which the curvature of a reflective surface can be changed.
Moreover, also in small-sized optics for camera, application of the variable focus mirror can largely contribute to miniaturization.
In a variable focus mirror, when a so-called micro electromechanical system (MEMS) technique with a semiconductor manufacturing technique applied thereto is used, low-cost high-precision production can be expected.
Known driving methods for this type of variable-profile mirror include using an electrostatic attractive force, as described in Jpn. Pat. Appln. KOKAI Publication No. 2-101402, a piezoelectric effect, as described in Jpn. Pat. Appln. KOKOKU Publication No. 3-81132, fluid pressure, as described in Jpn. Pat. Appln. KOKAI Publication No. 1-219801, and the like.
These methods have advantages and disadvantages, but the method of using fluid pressure is suitable for use in which a relatively large displacement to a convex surface from a concave surface is required.
As an example of a variable-profile mirror driven by fluid pressure, the method described in Jpn. Pat. Appln. KOKAI Publication No. 1-219801 will briefly be described with reference to FIG.
26
.
A variable focus mirror
1
is constituted of a shell
2
, chamber pressure adjustment apparatus
3
, and reflective mirror
4
.
A pressure chamber
5
is formed in the shell
2
, and a holder
7
for holding the reflective mirror
4
in an airtight manner by O rings
6
is formed in an opening of the shell.
The pressure chamber
5
is connected to a pressure gauge
8
and piping
9
of the chamber pressure adjustment apparatus
3
.
The piping
9
is branched into a compressor piping
9
a
and vacuum pump piping
9
b
, and the piping can appropriately be switched to a compressor
11
a
or a vacuum pump
11
b
by electromagnetic operation valves
10
a
,
10
b.
In the constitution, the switching is performed, when a controller
12
opens/closes the electromagnetic operation valves
10
a
,
10
b.
The reflective mirror
4
is formed of a thin plate, and a reflective surface
13
is coated with a reflective material such as aluminum.
In the variable focus mirror
1
constituted as described above, to obtain a concave reflective surface
13
a
, the electromagnetic operation valve
10
a
is closed, and the electromagnetic operation valve
10
b
is opened by the controller
12
.
In this case, when the pressure chamber
5
is connected to the vacuum pump piping
9
b
, a negative pressure is produced by the vacuum pump
11
b.
Therefore, in this case, the reflective mirror
4
is deflected toward the pressure chamber
5
, and the concave reflective surface
13
a
is formed.
On the other hand, to form a convex reflective surface
13
b
of the reflective mirror
4
, the electromagnetic operation valve
10
a
is opened, and the electromagnetic operation valve
10
b
is closed by the controller
12
.
In this case, when the pressure chamber
5
is connected to the compressor piping
9
a
, a positive pressure is produced by the compressor
11
a.
Therefore, in this case, the reflective mirror
4
is deflected away from the pressure chamber, and the convex reflective surface
13
b
is formed.
Furthermore, when the pressure of the pressure chamber
5
is controlled to be the same as an external pressure, the reflective surface
13
has a flat reflective surface
13
c
due to the elasticity thereof.
For the shape of the reflective surface
13
, when the controller
12
is controlled based on a measured value of the pressure gauge
8
, the reflective mirror
4
can continuously be set at an optional focal distance.
As compared with the electrostatic attractive force driving method in which the displacement amount is limited by the distance between electrodes, or the piezoelectric driving method in which it is difficult to obtain a large deflection because of limitation of the materials of the reflective surface, the variable-profile mirror whose driving source is fluid pressure is preferable particularly for use in which a broad range of focal distances are required.
The variable focus mirror of the above-described fluid pressure system has a problem that a pump or compressor is necessary and therefore it is very difficult to miniaturize the mirror.
Moreover, the above-described variable focus mirror of the fluid pressure system has complicated mechanisms such as a valve, and has a problem that efficiency or response is deteriorated due to the pump and pressure chamber channel.
Furthermore, since a uniform force is exerted on a deformable portion of the variable focus mirror in principle in the method of using fluid pressure, the deformed shape has rotational symmetry. However, since light is generally incident from an oblique direction in relation to a light path in the reflective optics, a large aberration is generated.
In this respect, the transmission type variable-profile optical device (i.e., a variable-profile lens) is advantageous. For example, in the conventional variable focus lens described in Jpn. Pat. Appln. KOKOKU Publication No. 3-27090 (corresponding to Jpn. Pat. KOKAI Publication No. 60-114802), as the deformable member needs to be sealed in a container, there is a problem that assembly is complicated, and the lens is not suitable for miniaturization.
Moreover, for the above-described variable focus mirror of the fluid pressure system, because the mechanism is complicated, it is difficult to miniaturize the mirror, and there is a problem that the efficiency and response are deteriorated.
Furthermore, the above-described variable focus mirror of the fluid pressure system is applied particularly to the optics in which the light is obliquely incident. In this case, the aberration is generated in principle, and this may cause serious problems, depending on the use.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a low-cost variable-profile optical device and optical element which have a quick response, and which can obtain a sufficient displacement with a small size.
Another object of the present invention is to provide a transmission-type variable-profile optical device and optical element which are small-sized and highly efficient.
A further object of the present invention is to provide a low-cost variable-profile mirror and variable-profile optical element which has a quick response, and which can obtain a sufficient displacement with a small size.
Another object of the present invention is to provide large-displacement variable-profile optical device in which fluid pressure is used, and a composite variable-profile optical element in which aberration correction is also achieved.
To achieve the above-described objects, according to a first aspect of the present invention, there is provided a variable-profile optical device comprising:
a light-transmission elastic member in which an elasticity of a first surfac
Frishauf, Holtz, Hoodman & Chick, P.C.
Olympus Optical Co,. Ltd.
Sikder Mohammad
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