Deformable mirror

Abstract

A deformable mirror includes a deformable section in which, a reflecting surface is formed, a fixing section which fixes an outer periphery of the deformable section, a GND electrode which is formed on the deformable section, a drive electrode which is provided facing the GND electrode, and a driving-signal source which deforms the deformable section by an electric voltage applied between the GND electrode and the drive electrode. The deformable mirror is sealed such that a pressure inside to be lower than an atmospheric pressure, and is provided with a capacitance detecting circuit which detects a change in response characteristics of the deformable section associated with a pressure change of a sealed-inside.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a basic structure of a deformable mirror according to a first embodiment;

FIG. 2 is a cross-sectional view of the basic structure of the deformable mirror according to the first embodiment;

FIG. 3 is a diagram showing an electrode substrate of the first embodiment;

FIG. 4 is a diagram showing a mirror substrate of the first embodiment;

FIG. 5 is a diagram of a basic circuit structure of the deformable mirror according to the first embodiment;

FIG. 6A and FIG. 6B are diagrams showing a change in a reflecting surface on a deformable section when a voltage is not applied;

FIG. 7A and FIG. 7B are diagrams showing a change in the reflecting surface on the deformable section when the voltage is applied;

FIG. 8 is a diagram showing a pressure in a sealed-inside, and frequency characteristics of the deformable section;

FIG. 9A to FIG. 9D are diagrams showing a signal applied to the drive electrode and an amount of deformation of the deformable section;

FIG. 10 is a top view of a basic structure of a deformable mirror according to a second embodiment;

FIG. 11 is a diagram showing an electrode substrate of the second embodiment;

FIG. 12 is a diagram showing a mirror substrate of the second embodiment;

FIG. 13 is a diagram showing a basic circuit structure of the deformable mirror according to the second embodiment;

FIG. 14 is a diagram showing a basic circuit structure of a deformable mirror according to a modified embodiment of the second embodiment;

FIG. 15 is a basic circuit structure of a deformable mirror according to another modified embodiment of the second embodiment;

FIG. 16A and FIG. 16B are diagrams showing a phase of the deformable section, and frequency characteristics of a deformable gain;

FIG. 17 is a diagram showing a relationship between the pressure in the sealed-inside, and a Q value;

FIG. 18 is a diagram showing an electrode substrate in a deformable mirror of a modified embodiment of the second embodiment;

FIG. 19 is a diagram showing a mirror substrate in the deformable mirror of the modified embodiment of the second embodiment;

FIG. 20 is a basic circuit structure diagram of the deformable mirror according to the modified embodiment of the second embodiment;

FIG. 21 is another basic circuit structure diagram of the deformable mirror according to the modified embodiment of the second embodiment;

FIG. 22 is a still another basic structure diagram of the deformable mirror according to the modified embodiment of the second embodiment;

FIG. 23A and FIG. 23B are external views of a conventional deformable mirror;

FIG. 24 is a diagram which describes a driving system of the conventional deformable mirror;

FIG. 25 is a basic circuit-structure diagram of a deformable mirror according to a third embodiment;

FIG. 26A to FIG. 26D are diagrams which describe a concept of detection of a resonance-frequency detecting circuit;

FIG. 27 is a diagram showing the pressure in the sealed-inside, and the frequency characteristics of the deformable section;

FIG. 28 is a diagram showing a relationship between the pressure in the sealed-inside and a resonance frequency;

FIG. 29 is a basic circuit structure diagram of a deformable mirror according to a modified embodiment of the third embodiment; and

FIG. 30 is a diagram showing the relationship between the pressure in the sealed-inside and the Q value.

Claims

1. A deformable mirror comprising: a deformable section on which, a reflecting surface is formed;a fixing section which fixes an outer periphery of the deformable section;a first electrode which is formed on the deformable section;a second electrode which is provided facing the first electrode; anda driving-signal source which deforms the deformable section by a voltage applied between the first electrode and the second electrode, whereinthe deformable mirror is sealed such that a pressure inside to be lower than an atmospheric pressure, and further comprising:a monitoring section which detects a change in response characteristics of the deformable section, associated with a pressure change in a sealed-inside.

2. The deformable mirror according to claim 1, wherein the monitoring section includes a vibration detector which detects a vibration waveform of the deformable section which vibrates, and at least a part of which is provided on the deformable section, anda change in an amplitude of deformation of the deformable section is detected by the vibration detector, andthe response characteristics of the deformable section are monitored based on a relationship between a pressure and the amplitude of deformation.

3. The deformable mirror according to claim 2, wherein the monitoring section includes a Q-value detector which detects a Q value when the deformable section undergoes resonant vibration, andthe response characteristics of the deformable section are monitored based on a relationship between the pressure and the Q value.

4. The deformable mirror according to claim 2, wherein the monitoring section includes a phase-difference detecting circuit which detects a phase difference between the vibration waveform of the deformable section obtained by the vibration detector, and a driving signal which is output from the driving-signal source, andthe response characteristics of the deformable section are monitored based on a relationship between the pressure and the phase difference.

5. The deformable mirror according to claim 2, wherein the monitoring section includes a resonance-frequency detector which detects a resonance frequency when the deformable section undergoes resonant vibration, andthe response characteristics of the deformable section are monitored based on a relationship between the pressure and the resonance frequency.

6. The deformable mirror according to one of claims 2 to 5, wherein the vibration detector is a capacitance detector which detects a capacitance between the first electrode and the second electrode.

7. The deformable mirror according to one of claims 2 to 5, wherein the vibration detector includes a third electrode which is provided facing the first electrode, andthe vibration detector is a capacitance detector which detects a capacitance between the first electrode and the third electrode.

8. A deformable mirror comprising: a deformable section on which, a reflecting surface is formed;a fixing section which fixes an outer periphery of the deformable section;a first electrode which is formed on the deformable section;a second electrode which is provided facing the first electrode; anda driving-signal source which deforms the deformable section by a voltage applied between the first electrode and the second electrode, whereinthe deformable mirror is sealed such that a pressure inside lower than an atmospheric pressure, and further comprising;a pressure sensor which detects a pressure in a sealed-inside.