Deformable mirror

Abstract

A deformable mirror includes a deformable section on which a reflecting surface and a COM electrode are formed, a fixing section which fixes the deformable section, a driving and sensing electrode (driving force generating unit) which has a plurality of driving and sensing electrodes provided facing the COM electrode, and which drives the deformable section by applying an electric potential difference between the COM electrode and the driving and sensing electrode, and a capacitance detecting circuit which detects simultaneously a plurality of capacitances between the COM electrode and the driving and sensing electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a deformable mirror of a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of the deformable mirror of the first embodiment of the present invention;

FIG. 3 is a diagram depicting an electrode substrate of the deformable mirror of the first embodiment of the present invention;

FIG. 4 is a diagram depicting a mirror substrate of the deformable mirror of the first embodiment of the present invention;

FIG. 5 is a diagram showing an arrangement for driving an electrode in a central portion of the first embodiment of the present invention;

FIG. 6 is a top view showing a deformation of a reflecting surface when the electrode in the central portion is driven;

FIG. 7 is a cross-sectional view showing the deformation of the reflecting mirror when the electrode in the central portion is driven;

FIG. 8 is a diagram showing an arrangement for driving the other electrode of the first embodiment;

FIG. 9 is a diagram showing the deformation of the reflecting surface when the other electrode is driven;

FIG. 10 is a cross-sectional view showing the deformation of the reflecting surface when the other electrode is driven;

FIG. 11 is a diagram showing an equivalent circuit of a deformable mirror;

FIG. 12 is a block diagram describing a capacitance detecting circuit of the first embodiment;

FIG. 13 is a diagram showing a reference signal;

FIG. 14 is another diagram showing the reference signal;

FIG. 15 is a diagram showing a schematic structure of a signal superimposing unit;

FIG. 16 is a diagram showing a schematic structure of a capacitance detecting circuit and a detection signal separating unit;

FIG. 17 is a block diagram describing a capacitance detecting circuit of a second embodiment;

FIG. 18 is a diagram showing a schematic structure of an output signal separating unit and the capacitance detecting circuit;

FIG. 19 is a diagram showing a structure of a conventional deformable mirror; and

FIG. 20 is a diagram showing a structure of a capacitance detecting circuit of the conventional deformable mirror.

Claims

1. A deformable mirror comprising: a deformable section on which a reflecting surface and a first electrode are formed;a fixing section which fixes the deformable section;a plurality of second electrodes which are provided facing the first electrode;a driving force generating unit which drives the deformable section by applying an electric potential difference between the first electrode and the second electrode; anda capacitance detecting unit which detects simultaneously a plurality of capacitances between the first electrode and the second electrode.

2. The deformable mirror according to claim 1, wherein the capacitance detecting unit includesa reference signal applying unit which applies individually to the second electrode, a reference signal having different identifying factors necessary for operation of the capacitance detecting unit,a capacitance detecting unit connected to the first electrode, which detects a full capacitance detection signal in which, a capacitance between the first electrode and the plurality of second electrodes is superimposed, by using the plurality of reference signals, anda detection signal separating unit which separates the full capacitance detection signal into capacitance detection signals corresponding to each of the second electrodes, based on the identifying factors.

3. The deformable mirror according to claim 2, wherein the identifying factor is a frequency, andthe detection signal separating unit separates the signal based on the frequency.

4. The deformable mirror according to claim 2, wherein the identifying factor is a phase, andthe detection signal separating unit separates the signal based on the phase.

5. The deformable mirror according to claim 1, wherein the capacitance detecting unit includesa reference signal generating unit which applies to the first electrode, a reference signal necessary for an operation of the capacitance detecting unit, anda capacitance detecting circuit, which is connected to each of the second electrodes, and which detects the capacitance between the first electrode and the second electrode.