JP2009205005A - Deformable mirror system and deformable mirror drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deformable mirror system and a deformable mirror drive device by which a deformable mirror can be driven with sufficient accuracy. <P>SOLUTION: The deformable mirror drive device includes: a deformation part 22 with a reflection surface 24 formed thereon; an electrode substrate 11 for fixing the deformation part 22; an amplifier 29 for generating driving force so as to deform the deformation part 22 of the deformable mirror 10 equipped with a first electrode 23 and a second electrode 14 provided facing the deformation part 22 and the electrode substrate 11 respectively; a capacitance detector 32 for detecting binding capacitance 31 which is connected in series with electrostatic capacitance between the first electrode 23 and the second electrode 14 and synthetic capacity of the electrostatic capacitance between the first electrode 23 and the second electrode 14 and the binding capacitance 31 and outputting a displacement signal showing deformation amount of the deformation part 22 corresponding to the synthetic capacity based on the relationship between the capacity amount and the deformation amount of the deformation part 22; a comparator 33 and an integrator 34 for determining driving force generated from the amplifier 29 so that a target deformation quantity signal may coincide with output from the capacitance detector 32. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a deformable mirror system including a deformable mirror that can change the shape of a reflecting surface using electrostatic driving and a deformable mirror driving device that drives the deformable mirror, and a variable shape mirror driving device used therefor.

  2. Description of the Related Art In recent years, attention has been paid to a deformable mirror that can change the shape of a reflecting surface using electrostatic drive by applying a so-called MEMS (Micro Electro-Mechanical System) technology using semiconductor manufacturing technology.

  In such a deformable mirror, it is required to measure the deformation amount of the reflecting surface so as to obtain a desired reflection. As a method for measuring the amount of deformation, for example, Patent Document 1 discloses a method for measuring a change in capacitance.

  FIG. 10A is a diagram showing a configuration of a conventional deformable mirror 1 disclosed in Patent Document 1. The deformable mirror 1 serves as a flexible thin film 3 having a reflective surface deformed by electrostatic attraction and an upper electrode 2, and for control and capacitance detection disposed opposite the flexible thin film 3. And a control electrode 4. The reflection surface is deformed by an electrostatic driving force generated by applying a voltage between the upper electrode 2 and the control electrode 4, and the deformation amount of the reflection surface is controlled by the capacitance detection circuit 5 with the upper electrode 2. The calculation is performed by measuring the capacitance between the electrodes 4.

That is, Patent Document 1 discloses a configuration as shown in FIG. 10B as a detection method. When a high voltage is applied to the control electrode 4 via the resistor 6 from the constant voltage source 7 and a high frequency voltage is applied to the capacitance detection electrode 4 ′ from the high frequency power source 8, the potential of the control electrode 4 changes. To do. This change is monitored as a current change by the capacitance detection circuit 5 through the upper electrode 2. The capacitance, that is, the amount of deformation of the reflecting surface is detected by the phase and amplitude of the current.
JP 2002-228813 A

  In the above-mentioned Patent Document 1, a method for detecting the deformation amount of the reflecting surface is disclosed, but how is the voltage value applied between the upper electrode 2 and the control electrode 4 of the deformable mirror 1 using the detected value? There is no mention of what to control.

  The present invention has been made in view of the above points, and by detecting the deformation amount of the reflecting surface and controlling the voltage applied between the electrodes using the value, the deformable mirror can be driven with high accuracy. An object is to provide a deformable mirror system and a deformable mirror driving apparatus.

One aspect of the deformable mirror system of the present invention is:
A deformable part including a deformed part formed with a reflection surface, a fixed part for fixing the deformed part, and a pair of electrodes provided to face the deformed part and the fixed part,
A driving circuit for generating a driving force to deform the deforming portion;
A correction capacitor connected in series with the capacitance between the pair of electrodes;
The combined capacitance of the capacitance between the pair of electrodes and the correction capacitance is detected, and the deformation amount of the deformation portion corresponding to the combined capacitance is determined based on the relationship between the capacitance value and the deformation amount of the deformation portion. A capacitance detection circuit that outputs a displacement signal indicating;
A controller for determining a driving force generated in the driving circuit so that a target deformation amount signal and an output of the capacitance detecting circuit match;
It is characterized by comprising.

Also, one aspect of the deformable mirror driving device of the present invention is:
The deformable portion of the deformable mirror, comprising: a deformable portion having a reflecting surface; a fixed portion that fixes the deformable portion; and a pair of electrodes provided to face the deformable portion and the fixed portion, respectively. A driving circuit for generating a driving force to deform,
A correction capacitor connected in series with the capacitance between the pair of electrodes;
The combined capacitance of the capacitance between the pair of electrodes and the correction capacitance is detected, and the deformation amount of the deformation portion corresponding to the combined capacitance is determined based on the relationship between the capacitance value and the deformation amount of the deformation portion. A capacitance detection circuit that outputs a displacement signal indicating;
A controller for determining a driving force generated in the driving circuit so that a target deformation amount signal and an output of the capacitance detecting circuit match;
It is characterized by comprising.

  According to the present invention, a deformable mirror system and a variable shape mirror drive capable of accurately driving a deformable mirror by detecting the deformation amount of the reflecting surface and controlling the voltage applied between the electrodes using the value. An apparatus can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[First Embodiment]
(Explanation of device structure)
First, the device structure of the deformable mirror in the deformable mirror system according to the first embodiment of the present invention will be described.

  FIG. 1A is a top view of the deformable mirror 10 of the present embodiment, and FIG. 1B is a cross-sectional view taken along the line A-A ′ in FIG. FIG. 1C is an exploded view of the deformable mirror 10.

  As shown in these drawings, the deformable mirror 10 includes an electrode substrate 11 and a mirror substrate 12, and the electrode substrate 11 and the mirror substrate 12 are fixed via a spacer 13.

  A second electrode 14 and a third electrode 15 are disposed on the electrode substrate 11 and are electrically connected to the second extraction electrode 19 and the third extraction electrode 20 by wirings 16 and 17, respectively. Yes.

  The mirror substrate 12 includes a support portion 21 and a deformation portion 22. The support portion 21 supports the deformation portion 22 and is used as a fixing portion when being fixed to the electrode substrate 11 via the spacer 13. In this case, the deformed portion 22 formed on the mirror substrate 12 is fixed so as to come to a position facing the second and third electrodes 14 and 15.

  Further, a conductive material such as metal is formed on the entire surface of the mirror substrate 12 facing the second and third electrodes 14 and 15 and is used as the first electrode 23. . With the surface on which the first electrode 23 is formed as the back surface, a reflective surface 24 in which a metal or the like is formed on the deformed portion 22 is formed on the surface of the mirror substrate 12. The material deposited as the reflecting surface 24 varies depending on the specifications of the deformable mirror 10, but aluminum, gold, or a dielectric multilayer film is often used. The surface of an oxidizing metal such as aluminum is further coated with silicon oxide or the like.

  The spacer 13 is used for fixing the electrode substrate 11 and the mirror substrate 12 while determining the distance between them. In many cases, the spacer 13 is made of an inorganic material such as glass or a silicon substrate, a metal, or the like, but an organic adhesive including beads for determining the interval may be used.

  In order to electrically connect the first electrode 23 of the mirror substrate 12 to the first extraction electrode 25 formed on the electrode substrate 11, the first electrode 23 provided on the support portion 21 of the mirror substrate 12. A part of the connection part 26 is used as a connection part 26, and when the mirror substrate 12 is fixed, the connection part 26 is electrically connected to a conductive material 27 for electrical connection formed on the electrode substrate 11. This may be connected by metal pressure welding, or may be connected by a conductive paste or the like. As a result, the first electrode 23 on the mirror substrate 12 and the first extraction electrode 25 on the electrode substrate 11 are electrically connected.

  The electrical connection from the first extraction electrode 25, the second extraction electrode 19, and the third extraction electrode 20 to the external deformable mirror driving device is not shown, but is usually performed by wire bonding.

(Explanation of driving principle)
Next, the deformable mirror driving device 28 for driving the deformable mirror 10 configured as described above will be described with reference to FIG.

  The deformable mirror 10 having the above configuration employs an electrostatic drive system in which the reflecting surface 24 on the deforming portion 22 is deformed by an electrostatic force. As shown in FIG. 2, the deformable mirror driving device 28 applies a voltage to the third electrode 15 of the deformable mirror 10 by an amplifier 29, and the first electrode 23, the third electrode 15, A potential difference is given between the two. As a result, an attractive force due to electrostatic force is generated, and in the deformable mirror 10, the reflecting surface 24 is deformed toward the electrode substrate 11 together with the deforming portion 22.

  The deformation amount of the reflecting surface 24 can be changed by the potential difference applied between the first electrode 23 and the third electrode 15.

  The distance between the electrode substrate 11 and the mirror substrate 12 determined by the height of the spacer 13 can be determined from the maximum deformation amount of the reflecting surface 24, and is generally about three times or more the maximum deformation amount. Substrate spacing is required.

(Description of capacitance detection)
When the deformation portion 22 is deformed by applying a potential difference between the first electrode 23 and the third electrode 15, the distance between the first electrode 23 and the second electrode 14 (hereinafter, this distance). (Referred to as “electrostatic gap”). As the electrostatic gap decreases, the capacitances of the first electrode 23 and the second electrode 14 (hereinafter, the capacitances of the first electrode 23 and the second electrode 14 are “variable”. Increases the "capacitance of the shape mirror 10").

The relationship between the deformation amount Δd of the reflecting surface 24 and the capacitance value C ₁ of the deformable mirror 10 is in an inversely proportional relationship as expressed by the following [Equation 1] and is relative to the deformation amount Δd. the value of the electrostatic capacitance value C ₁ of the deformable mirror 10 has a non-linearity Te.

Where ε is the dielectric constant, A is the area of the electrodes, d ₀ is the initial value of the spacing between the electrodes, and Δd is the amount of deformation of the reflecting surface 24.

  In the deformable mirror driving device 28 according to the present embodiment, as shown in FIG. 2, the first electrode 23 generates a reference signal generator 30 that generates a reference signal necessary for detecting capacitance. Is connected. The reference signal applied from the reference signal generator 30 to the first electrode 23 is a signal having periodicity. For example, a sine wave, a rectangular wave, a triangular wave, or a periodic arbitrary waveform may be used. It is done.

In addition, a capacitance detector 32 is connected to the second electrode 14 via a coupling capacitance 31 that is a capacitor. Here, the capacitance value C ₂ of the coupling capacitor 31, the deformation amount of the deformable mirror 10 is the capacitance value of 0, i.e.,

If it is set so as to satisfy, the capacitance detector 32 seems to be in a state where the capacitance value C ₂ of the coupling capacitance 31 and the capacitance value C ₁ between the electrodes of the deformable mirror 10 are connected in series. , The detected composite capacitance value _CT is

It becomes.

When the electrostatic capacitance value C _{1 of the} deformable mirror 10 and the combined capacitance value C _T in a state where the coupling capacitor 31 is connected in series are expanded in series with respect to the deformation amount Δd,

Next, higher order terms from the secondary deformation amount Δd underlined that, towards the deformable mirror 10 combined capacitance value C _T as compared with the electrostatic capacitance value C ₁ of it can be seen that smaller. Therefore, compared with the case where the detection circuit is directly connected to the second electrode 14 without using the coupling capacitor 31, the terms higher than the second order are reduced when the coupling circuit 31 is used. Therefore, displacement detection with good linearity can be performed.

  Although the initial values of the capacitances of the coupling capacitor 31 and the deformable mirror 10 are used here, it is possible to reduce nonlinearity by using other capacitance values.

Thus, the reference signal as described above is applied from the reference signal generator 31 to the combined capacitor, and the impedance of the combined capacitor is detected by the capacitance detector 32, or the charge charged in the combined capacitor is by detected by the capacitance detector 32 can detect the combined capacitance value C _T. Then, the capacitance detector 32, based on the relationship between the deformation amount of the capacitance value and the deformation portion 22 stored in advance, the amount of deformation of the deformable portion 22 corresponding to the combined capacitance value C _T described above detected The indicated displacement signal is output.

  Note that the reference signal from the reference signal generator 31 is used not only for detection of the combined capacitance but also generates driving force, so that the frequency of the reference signal is higher than the frequency band that can be driven by the deformation unit 22. It is necessary to make it sufficiently high, and it is desirable that the high-order resonance frequency of the deformable portion 22 is set to be avoided.

(Explanation of control part)
The displacement signal output from the capacitance detector 32 is compared with a target displacement signal input from the outside by the comparator 33, and the difference is output to the integrator 34 as a displacement error. The integrator 34 integrates the displacement error, amplifies the integrated result by the amplifier 29, and outputs it to the third electrode 15.

  With the configuration of the deformable mirror driving device 28 as described above, the variable shape mirror is output so that the capacitance value error output from the comparator 33 becomes zero when a sufficient time has elapsed for the integrator 34 to operate. The voltage of the third electrode 15 of the mirror 10 is determined. In other words, the voltage value of the third electrode 15 is determined so that the deformation amount corresponding to the target displacement signal is obtained by the deformation amount of the deformable mirror 10 in a state where the target capacitance signal and the displacement signal coincide with each other. .

  With the above configuration, according to the deformable mirror system according to the present embodiment, by using the coupling capacitor 31 that is a capacitor having substantially the same capacitance as the capacitance of the deformable mirror 10 in the deformable mirror 10, Since the non-linearity of the capacitance of the deformable mirror 10 is reduced, the non-linearity can be corrected with a simple circuit configuration, control with good linearity can be performed. Can be driven with high accuracy.

  In addition, a plurality of second electrodes 14 are installed on the electrode substrate 11, and a capacitance detector 32 is connected to each through a coupling capacitor 31, thereby detecting deformation amounts at a plurality of points of the deformable mirror 10. Is possible. Furthermore, the deformed shape of the deformable portion 22 of the deformable mirror 10 can be changed by installing a plurality of third electrodes 15 on the electrode substrate 11 and connecting an amplifier 29 to each of them.

(Modification)
In this embodiment, the coupling capacitor 31 is installed between the second electrode 14 and the capacitance detector 32. However, as shown in FIG. 3, the coupling capacitor 31 is connected to the reference signal generator 30 and the first signal generator 30. It is also possible to connect between the electrode 23, place the second electrode 14 on the deformable portion 22, and place the first electrode 23 and the third electrode 15 on the electrode substrate 11. In this case, electrostatic attraction is generated by the electric field generated between the second electrode 14 and the voltage applied to the third electrode 15 by the amplifier 29, and the deforming portion 22 is deformed. Further, the coupling capacitor 31 and the electrostatic capacitance of the deformable mirror 10 are connected in series between the capacitance detector 32 and the reference signal generator 30 and are detected by the capacitance detector 32. that capacitance is a combined capacitance value C _T. Therefore, as in the first embodiment, since the higher-order terms than the second-order capacitance of the deformable mirror 10 are reduced, the nonlinearity can be corrected with a simple circuit configuration, and the linearity is good. As a result, the deformable mirror 10 can be driven with high accuracy.

In the embodiment and the modification described above, it is also possible to adopt a configuration in which the electrode arrangements of the deforming portion 22 and the electrode substrate 11 are interchanged. As an example, FIGS. 4 and 5 show configurations in which the electrode arrangements in FIGS. 2 and 3 are interchanged, respectively. In the configuration of FIG. 4, the deformed portion 22 is deformed by the voltage applied to the third electrode 15, and the second electrode 14 and the third electrode 15 move together. Therefore, the first electrode 23 and the second electrode by detecting the combined capacitance value C _T of capacitance and coupling capacitance 31 between the 14, it can detect the amount of deformation of the deformable portion 22. In the configuration of FIG. 5, the deformed portion 22 is deformed by the voltage applied to the third electrode 15, and the first electrode 23 and the third electrode 15 move together. by the electrode 23 and the detecting combined capacitance value C _T of capacitance and coupling capacitance 31 between the second electrode 14 can be detected deformation amount of the deformable section 22. Other operations in the configurations of FIGS. 4 and 5 are as described above.

[Second Embodiment]
Next, the deformable mirror system according to the second embodiment of the present invention will be described, but the description of the same parts as those in the first embodiment will be omitted.

  In the deformable mirror system according to the second embodiment, the deformable mirror 10 has the second electrode 14 disposed on the deformable portion 22 as shown in FIG. One electrode 23 is arranged.

  In the deformable mirror driving device 28, the output of the amplifier 29 is connected to the first electrode 23 of the deformable mirror 10 via the coupling resistor 35, and the reference signal generator is connected via the coupling capacitor 31. 30 is connected. A capacitance detector 32 is connected to the second electrode 14 of the deformable mirror 10, and the second electrode 14 is fixed to a zero potential or a fixed potential by the capacitance detector 32.

  The coupling resistor 35 and the coupling capacitor 31 apply a signal obtained by superimposing the reference signal, which is the output of the reference signal generator 30, to the drive signal output from the amplifier 29, to the first electrode 23. In the low frequency band where the drive signal generated by the amplifier 29 is present, the coupling capacitor 31 can be regarded as being almost open, so that the drive signal is applied to the first electrode 23. In the high frequency band where the reference signal exists, the impedance of the coupling capacitor 31 is sufficiently lower than the resistance value of the coupling resistor 35, so that the reference signal is applied to the first electrode 23. When the above is considered and the entire frequency band is considered, it is equivalent to a case where a low-frequency drive signal and a high-frequency reference signal are superimposed and applied to the first electrode 23.

Therefore, in the deformable mirror system having the configuration shown in FIG. 6, in the low frequency band, a potential difference is generated between the first electrode 23 and the second electrode 14 by the drive signal output from the amplifier 29, and is variable by electrostatic force. The deformation part 22 of the shape mirror 10 is deformed. In the high frequency band, a reference signal is applied to the first electrode 23, and the impedance of the combined capacitor is detected by the capacitance detector 32, or the charge charged in the combined capacitor is detected by the capacitance detector 32. by detecting it can detect the combined capacitance value C _T of capacitance and coupling capacitance 31 between the first electrode 23 and the second electrode 14.

  As described above, by using the coupling resistor 35, it is possible to easily apply a high voltage to the first electrode 23 without using a high-voltage operational amplifier as the amplifier 29.

When the deformed portion 22 is deformed by applying a potential difference between the first electrode 23 and the second electrode 14, the distance (electrostatic gap) between the first electrode 23 and the second electrode 14 decreases. However, the capacitances of the first electrode 23 and the second electrode 14 increase. The relationship between the deformation amount Δd of the reflecting surface 24 and the capacitance value C ₁ of the deformable mirror 10 is an inversely proportional relationship as expressed by [Equation 1] described in the first embodiment, and the deformation amount variable capacitance value C ₁ of the deformable mirror 10 has a non-linearity, but by the action similar to the above first embodiment, an electrostatic of the deformable mirror 10 by the influence of the coupling capacitor 31 connected in series for Since terms higher than the second order of the capacitance are reduced, displacement detection with good linearity can be performed.

  The displacement signal output from the capacitance detector 32 is compared with a target displacement signal input from the outside by the comparator 33, and the difference is output to the integrator 34 as a displacement error. The integrator 34 integrates the displacement error, amplifies the integrated result by the amplifier 29, and outputs it to the first electrode 23 via the coupling resistor 35.

  With the above configuration, according to the deformable mirror system according to the second embodiment, in the deformable mirror 10, the coupling capacitor 31 that is a capacitor having substantially the same capacitance as the capacitance of the deformable mirror 10 is used. Thus, the non-linearity of the capacitance of the deformable mirror 10 is reduced, so that the non-linearity can be corrected with a simple circuit configuration, and control with good linearity can be performed. The mirror 10 can be driven with high accuracy.

(Modification)
Note that, as shown in FIG. 7, the same effect can be obtained by a configuration in which the second electrode 14 is disposed on the electrode substrate 11 and the first electrode 23 is disposed on the deformation portion 22.

  In addition, as shown in FIG. 8, a reference signal generator 30 is connected to the first electrode 23 arranged in the deforming portion 22, and an amplifier 29 is connected to the second electrode 14 arranged on the electrode substrate 11 via a coupling resistor 35. The same effect can be obtained with the configuration in which the capacitance detector 32 is connected via the coupling capacitor 31 as well as the output of the capacitor. In the case of this configuration, in the low frequency band where the drive signal generated by the amplifier 29 exists, the coupling capacitor 31 can be regarded as being almost open, so that the drive signal is not applied to the capacitance detector 32 and the second electrode 14. Applied to Since the impedance of the coupling capacitor 31 is sufficiently lower than the resistance value of the coupling resistor 35 in the high frequency band where the reference signal generated by the reference signal generator 30 exists, the capacitance that the capacitance detector 32 is to detect. A current signal flowing through the capacitor is input to the capacitance detector 32 via the coupling capacitor 31. Considering all the frequency bands collectively, the low frequency drive signal is applied to the second electrode 14 without being applied to the capacitance detector 32, and the current signal output from the second electrode 14 is an amplifier. Since it is input to the capacitance detector 32 without flowing to 29, it is possible to apply a high voltage and detect the capacitance to the same electrode (in this case, the second electrode 14).

  Further, as shown in FIG. 9, the same effect can be obtained by a configuration in which the second electrode 14 is installed on the electrode substrate 11 and the first electrode 23 is installed on the deforming portion 22.

  Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are naturally possible within the scope of the gist of the present invention.

(Appendix)
The invention having the following configuration can be extracted from the specific embodiment.

(1) A deformable mirror including a deformable portion having a reflecting surface, a fixed portion that fixes the deformable portion, and a pair of electrodes provided to face the deformable portion and the fixed portion, respectively.
A driving circuit for generating a driving force to deform the deforming portion;
A correction capacitor connected in series with the capacitance between the pair of electrodes;
The combined capacitance of the capacitance between the pair of electrodes and the correction capacitance is detected, and the deformation amount of the deformation portion corresponding to the combined capacitance is determined based on the relationship between the capacitance value and the deformation amount of the deformation portion. A capacitance detection circuit that outputs a displacement signal indicating;
A controller for determining a driving force generated in the driving circuit so that a target deformation amount signal and an output of the capacitance detecting circuit match;
A deformable mirror system comprising:

(Corresponding embodiment)
The first and second embodiments correspond to the embodiment of the deformable mirror system described in (1). In these embodiments, for example, the reflective surface 24 is the reflective surface, the deformable portion 22 is the deformable portion, the electrode substrate 11 is the fixed portion, and the first electrode 23 and the second electrode 14 are the pair of pairs. In the electrodes, the deformable mirror 10 is in the deformable mirror, the amplifier 29 is in the drive circuit, the coupling capacitor 31 is in the correction capacitor, the capacitance detector 32 is in the capacitance detection circuit, the comparator 33 and the integrator 34 are Each corresponds to the upper controller.

(Function and effect)
According to the deformable mirror system described in (1), the deformation amount is detected using the capacitance value, and the non-linearity existing in the relationship between the capacitance and the deformation amount is corrected. Good control can be performed, and, in turn, the deformable mirror can be driven with high accuracy.

  In addition, since the nonlinearity of the capacitance of the deformable mirror is reduced by using the correction capacitance, control with good linearity can be performed.

(2) The pair of electrodes includes a first electrode installed in the deformed portion and a second electrode installed in the fixed portion facing the first electrode,
The deformable mirror system further includes a reference signal generator that is connected to the first electrode via the correction capacitor and generates a reference signal used for capacitance detection.
The capacitance detection circuit is connected to the second electrode and detects a combined capacitance of a capacitance between the first electrode and the second electrode and the correction capacitance. Item 2. The deformable mirror system according to Item 1.

(Corresponding embodiment)
The embodiment related to the deformable mirror system described in (2) corresponds to the first and second embodiments, and particularly corresponds to, for example, the configurations of FIGS. 3 and 7. In these embodiments, for example, the first electrode 23 corresponds to the first electrode, the second electrode 14 corresponds to the second electrode, and the reference signal generator 30 corresponds to the reference signal generator. .

(Function and effect)
According to the deformable mirror system described in (2), when the deforming portion is deformed, the first electrode moves together with the deformation of the deforming portion, so that the electrostatic capacitance between the first electrode and the second electrode is changed. By detecting the combined capacity of the capacity and the correction capacity, the deformation amount of the deformation portion can be detected.

(3) The pair of electrodes includes a first electrode installed in the deformed portion and a second electrode installed in the fixed portion facing the first electrode,
The deformable mirror system further includes a reference signal generator connected to the first electrode for generating a reference signal used for capacitance detection,
The capacitance detection circuit is connected to the second electrode via the correction capacitance, and detects a combined capacitance of the capacitance between the first electrode and the second electrode and the correction capacitance. (3) The deformable mirror system according to (1).

(Corresponding embodiment)
The embodiment relating to the deformable mirror system described in (3) corresponds to the first and second embodiments, and particularly corresponds to, for example, the configurations of FIGS. 2 and 8. In these embodiments, for example, the first electrode 23 corresponds to the first electrode, the second electrode 14 corresponds to the second electrode, and the reference signal generator 30 corresponds to the reference signal generator. .

(Function and effect)
According to the deformable mirror system described in (3), when the deforming portion is deformed, the first electrode moves together with the deformation of the deforming portion, so that the electrostatic capacitance between the first electrode and the second electrode is changed. By detecting the combined capacity of the capacity and the correction capacity, the deformation amount of the deformation portion can be detected.

(4) The pair of electrodes includes a first electrode placed on the fixed portion and a second electrode placed on the deformable portion so as to face the first electrode,
The deformable mirror system further includes a reference signal generator that is connected to the first electrode via the correction capacitor and generates a reference signal used for capacitance detection.
The capacitance detection circuit is connected to the second electrode and detects a combined capacitance of a capacitance between the first electrode and the second electrode and the correction capacitance ( The deformable mirror system according to 1).

(Corresponding embodiment)
The embodiment relating to the deformable mirror system described in (4) corresponds to the first and second embodiments, and particularly corresponds to, for example, the configurations of FIGS. 3 and 6. In these embodiments, for example, the first electrode 23 corresponds to the first electrode, the second electrode 14 corresponds to the second electrode, and the reference signal generator 30 corresponds to the reference signal generator. .

(Function and effect)
According to the deformable mirror system described in (4), when the deforming portion is deformed, the second electrode moves together with the deformation of the deforming portion, so that the electrostatic capacitance between the first electrode and the second electrode is changed. By detecting the combined capacity of the capacity and the correction capacity, the deformation amount of the deformation portion can be detected.

(5) The pair of electrodes includes a first electrode placed on the fixed portion and a second electrode placed on the deformable portion so as to face the first electrode,
The deformable mirror system further includes a reference signal generator connected to the first electrode for generating a reference signal used for capacitance detection,
The capacitance detection circuit is connected to the second electrode via the correction capacitance, and detects a combined capacitance of the capacitance between the first electrode and the second electrode and the correction capacitance. (3) The deformable mirror system according to (1).

(Corresponding embodiment)
The embodiment relating to the deformable mirror system described in (5) corresponds to the first and second embodiments, and particularly corresponds to, for example, the configurations of FIGS. 4 and 9. In these embodiments, for example, the first electrode 23 corresponds to the first electrode, the second electrode 14 corresponds to the second electrode, and the reference signal generator 30 corresponds to the reference signal generator. .

(Function and effect)
According to the deformable mirror system described in (5), when the deforming portion is deformed, the second electrode moves together with the deformation of the deforming portion, so that the electrostatic capacitance between the first electrode and the second electrode is changed. By detecting the combined capacity of the capacity and the correction capacity, the deformation amount of the deformation portion can be detected.

(6) The deformable mirror further includes a third electrode disposed on the fixed portion or the deformable portion so as to face the first electrode,
The deformable mirror system according to (3) or (5), wherein the driving circuit drives the deforming portion by applying a potential to the third electrode.

(Corresponding embodiment)
The embodiment related to the deformable mirror system described in (6) corresponds to the first embodiment, and particularly corresponds to, for example, the configurations of FIGS. 2 and 4. In the embodiment, for example, the third electrode 15 corresponds to the third electrode.

(Function and effect)
According to the deformable mirror system described in (6), the deformed portion is deformed by the voltage applied to the third electrode, and the first or second electrode moves together with the deformation of the deformed portion. By detecting the combined capacitance of the capacitance between the first electrode and the second electrode and the correction capacitance, the deformation amount of the deformation portion can be detected.

(7) The deformable mirror further includes a third electrode disposed on the fixed portion or the deformable portion so as to face the second electrode,
The deformable mirror system according to (2) or (4), wherein the driving circuit drives the deforming portion by applying a potential to the third electrode.

(Corresponding embodiment)
The embodiment related to the deformable mirror system described in (7) corresponds to the first embodiment, and particularly corresponds to, for example, the configurations of FIGS. 3 and 5. In the embodiment, for example, the third electrode 15 corresponds to the third electrode.

(Function and effect)
According to the deformable mirror system described in (7), the deformed portion is deformed by the voltage applied to the third electrode, and the first or second electrode moves together with the deformation of the deformed portion. By detecting the combined capacitance of the capacitance between the first electrode and the second electrode and the correction capacitance, the deformation amount of the deformation portion can be detected.

  (8) The drive circuit is connected to the first electrode via a resistor, and drives the deformed portion by applying a potential to the first electrode (2) or ( The deformable mirror system according to 4).

(Corresponding embodiment)
The embodiment relating to the deformable mirror system described in (8) corresponds to the second embodiment, and particularly corresponds to, for example, the configurations of FIGS. 6 and 7. In the embodiment, for example, the coupling resistor 35 corresponds to the resistor.

(Function and effect)
According to the deformable mirror system described in (8), it is possible to easily apply a high voltage by using a resistor and a correction capacitor.

  (9) The drive circuit is connected to the second electrode via a resistor, and drives the deformed portion by applying a potential to the second electrode (3) or ( The deformable mirror system according to 5).

(Corresponding embodiment)
The embodiment relating to the deformable mirror system described in (9) corresponds to the second embodiment, and particularly corresponds to, for example, the configurations of FIGS. 8 and 9. In the embodiment, for example, the coupling resistor 35 corresponds to the resistor.

(Function and effect)
According to the deformable mirror system described in (9), it is possible to easily apply a high voltage and detect a capacitance to the same electrode by using a resistor and a correction capacitor. Become.

  (10) The variable according to any one of (1) to (9), wherein the correction capacitor is a capacitor having substantially the same capacitance as the capacitance between the deforming portion and the fixed portion. Shape mirror system.

(Corresponding embodiment)
The first and second embodiments correspond to the embodiment relating to the deformable mirror system described in (10).

(Function and effect)
According to the deformable mirror system described in (10), the detection circuit is directly connected to the electrode without using the correction capacitor by making the capacitance value of the correction capacitor substantially the same as the capacitance value of the deformable mirror. Compared to the case where the correction capacitor is connected, the higher-order term than the second-order is reduced when the connection is made through the correction capacitor, so that it is possible to detect the displacement with good linearity.

(11) The deformable mirror including the deformable portion on which the reflecting surface is formed, a fixed portion that fixes the deformable portion, and a pair of electrodes provided to face the deformable portion and the fixed portion, respectively. A drive circuit that generates a drive force to deform the deformable portion;
A correction capacitor connected in series with the capacitance between the pair of electrodes;
The combined capacitance of the capacitance between the pair of electrodes and the correction capacitance is detected, and the deformation amount of the deformation portion corresponding to the combined capacitance is determined based on the relationship between the capacitance value and the deformation amount of the deformation portion. A capacitance detection circuit that outputs a displacement signal indicating;
A controller for determining a driving force generated in the driving circuit so that a target deformation amount signal and an output of the capacitance detecting circuit match;
A deformable mirror driving device comprising:

(Corresponding embodiment)
The embodiment relating to the deformable mirror driving device described in (11) corresponds to the first and second embodiments. In these embodiments, for example, the reflective surface 24 is the reflective surface, the deformable portion 22 is the deformable portion, the electrode substrate 11 is the fixed portion, and the first electrode 23 and the second electrode 14 are the pair of pairs. In the electrodes, the deformable mirror 10 is in the deformable mirror, the amplifier 29 is in the drive circuit, the coupling capacitor 31 is in the correction capacitor, the capacitance detector 32 is in the capacitance detection circuit, the comparator 33 and the integrator 34 are Each corresponds to the upper controller.

(Function and effect)
According to the deformable mirror driving device described in (11), the deformation amount is detected using the capacitance value, and the non-linearity existing in the relationship between the capacitance and the deformation amount is corrected. Therefore, it becomes possible to drive the deformable mirror with high accuracy.

  In addition, since the nonlinearity of the capacitance of the deformable mirror is reduced by using the correction capacitance, control with good linearity can be performed.

FIG. 1A is a top view of a deformable mirror in the deformable mirror system according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA ′ in FIG. FIG. 1C is an exploded view of the deformable mirror. FIG. 2 is a diagram illustrating a configuration of the deformable mirror system according to the first embodiment. FIG. 3 is a diagram illustrating a configuration of a modified example of the deformable mirror system according to the first embodiment. FIG. 4 is a diagram illustrating a configuration of another modification of the deformable mirror system according to the first embodiment. FIG. 5 is a diagram illustrating a configuration of still another modified example of the deformable mirror system according to the first embodiment. FIG. 6 is a diagram showing a configuration of a deformable mirror system according to the second embodiment of the present invention. FIG. 7 is a diagram illustrating a configuration of a modified example of the deformable mirror system according to the second embodiment. FIG. 8 is a diagram showing a configuration of another modified example of the deformable mirror system according to the second embodiment. FIG. 9 is a diagram illustrating a configuration of still another modified example of the deformable mirror system according to the second embodiment. FIG. 10A is a diagram illustrating a configuration of a conventional deformable mirror, and FIG. 10B is a diagram illustrating a configuration of a conventional capacitance detection circuit.

Explanation of symbols

    DESCRIPTION OF SYMBOLS 10 ... Deformable mirror, 11 ... Electrode substrate, 12 ... Mirror substrate, 13 ... Spacer, 14 ... Second electrode, 15 ... Third electrode, 17, 18 ... Wiring, 19 ... Second extraction electrode, 20 ... 3rd extraction electrode, 21 ... support part, 22 ... deformation part, 23 ... 1st electrode, 24 ... reflective surface, 25 ... 1st extraction electrode, 26 ... connection part, 27 ... electrically conductive material for electrical connection, 28 DESCRIPTION OF SYMBOLS ... Variable shape mirror drive device, 29 ... Amplifier, 30 ... Reference signal generator, 31 ... Coupling capacitance, 32 ... Capacitance detector, 33 ... Comparator, 34 ... Integrator, 35 ... Coupling resistance.

Claims (11)

A deformable part including a deformed part formed with a reflection surface, a fixed part for fixing the deformed part, and a pair of electrodes provided to face the deformed part and the fixed part,
A driving circuit for generating a driving force to deform the deforming portion;
A correction capacitor connected in series with the capacitance between the pair of electrodes;
The combined capacitance of the capacitance between the pair of electrodes and the correction capacitance is detected, and the deformation amount of the deformation portion corresponding to the combined capacitance is determined based on the relationship between the capacitance value and the deformation amount of the deformation portion. A capacitance detection circuit that outputs a displacement signal indicating;
A controller for determining a driving force generated in the driving circuit so that a target deformation amount signal and an output of the capacitance detecting circuit match;
A deformable mirror system comprising: The pair of electrodes includes a first electrode placed on the deforming portion and a second electrode placed on the fixed portion facing the first electrode,
The deformable mirror system further includes a reference signal generator that is connected to the first electrode via the correction capacitor and generates a reference signal used for capacitance detection.
The capacitance detection circuit is connected to the second electrode and detects a combined capacitance of a capacitance between the first electrode and the second electrode and the correction capacitance. Item 2. The deformable mirror system according to Item 1. The pair of electrodes includes a first electrode placed on the deforming portion and a second electrode placed on the fixed portion facing the first electrode,
The deformable mirror system further includes a reference signal generator connected to the first electrode for generating a reference signal used for capacitance detection,
The capacitance detection circuit is connected to the second electrode via the correction capacitance, and detects a combined capacitance of the capacitance between the first electrode and the second electrode and the correction capacitance. The deformable mirror system according to claim 1. The pair of electrodes includes a first electrode installed on the fixed portion, and a second electrode installed on the deformable portion so as to face the first electrode,
The deformable mirror system further includes a reference signal generator that is connected to the first electrode via the correction capacitor and generates a reference signal used for capacitance detection.
The capacitance detection circuit is connected to the second electrode and detects a combined capacitance of a capacitance between the first electrode and the second electrode and the correction capacitance. Item 2. The deformable mirror system according to Item 1. The pair of electrodes includes a first electrode installed on the fixed portion, and a second electrode installed on the deformable portion so as to face the first electrode,
The deformable mirror system further includes a reference signal generator connected to the first electrode for generating a reference signal used for capacitance detection,
The capacitance detection circuit is connected to the second electrode via the correction capacitance, and detects a combined capacitance of the capacitance between the first electrode and the second electrode and the correction capacitance. The deformable mirror system according to claim 1. The deformable mirror further includes a third electrode disposed on the fixed portion or the deformable portion so as to face the first electrode,
6. The deformable mirror system according to claim 3, wherein the driving circuit drives the deforming portion by applying a potential to the third electrode. The deformable mirror further includes a third electrode disposed on the fixed portion or the deformable portion so as to face the second electrode,
5. The deformable mirror system according to claim 2, wherein the driving circuit drives the deforming portion by applying a potential to the third electrode. 6.   5. The drive circuit according to claim 2, wherein the drive circuit is connected to the first electrode via a resistor, and drives the deformed portion by applying a potential to the first electrode. Deformable mirror system.   The said drive circuit is connected to the said 2nd electrode through a resistor, The said deformation | transformation part is driven by applying an electric potential to the said 2nd electrode, The Claim 3 or 5 characterized by the above-mentioned. Deformable mirror system.   10. The deformable mirror system according to claim 1, wherein the correction capacitor is a capacitor having a capacitance that is substantially the same as a capacitance between the deforming portion and the fixed portion. The deformable portion of the deformable mirror, comprising: a deformable portion having a reflecting surface; a fixed portion that fixes the deformable portion; and a pair of electrodes provided to face the deformable portion and the fixed portion, respectively. A driving circuit for generating a driving force to deform,
A correction capacitor connected in series with the capacitance between the pair of electrodes;
The combined capacitance of the capacitance between the pair of electrodes and the correction capacitance is detected, and the deformation amount of the deformation portion corresponding to the combined capacitance is determined based on the relationship between the capacitance value and the deformation amount of the deformation portion. A capacitance detection circuit that outputs a displacement signal indicating;
A controller for determining a driving force generated in the driving circuit so that a target deformation amount signal and an output of the capacitance detecting circuit match;
A deformable mirror driving device comprising:

Images