JP2016167961A - Electrostatic comb-tooth actuator, and variable shape mirror using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of suppressing pull-in even when the drive voltage is increased for increasing the movable amount, in an actuator including a comb-tooth electrode or a variable shape mirror using the same.SOLUTION: An electrostatic comb-tooth actuator 101 has a plurality of fixed comb-tooth electrodes 108 extending from a support member 105, an elastic member 104 connecting a movable member 103 and the support member 105, and a plurality of movable comb-tooth electrodes 106 extending from the movable member 103 substantially in parallel with the fixed comb-tooth electrodes 108, and meshing therewith at intervals. A structure for applying individual potentials, respectively, to a portion of the support member 105 facing the outermost movable comb-tooth electrode in the arrangement direction of the plurality of movable comb-tooth electrodes 106, and a portion of the support member 105 from which the fixed comb-tooth electrodes extend is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrostatic comb actuator, a deformable mirror using the actuator, and an adaptive optics system using the mirror.

  A movable mirror or a deformable mirror of a type that is displaced by electrostatic attraction is expected to be applied to various fields using light. For example, it can be used as a wavefront correction device for adaptive optics such as a fundus inspection apparatus and an astronomical telescope. As a typical example of the movable mirror that displaces the reflecting surface by electrostatic attraction as described above, there is a method of making it movable by using two parallel plate electrodes, but the disadvantage of this parallel plate type is that the movable amount is small. Can be mentioned. On the other hand, a deformable mirror using a comb electrode that can obtain a larger movable amount has recently been proposed. An example thereof is disclosed in Patent Document 1. As shown in FIG. 6, in the deformable mirror 500, a support portion 530 that supports the movable comb electrode 520 and a support portion 570 that supports the fixed comb electrode 510 are respectively provided on the paper surface. Located vertically above and below. The movable comb electrode and the fixed comb electrode are arranged so as to face each other and be alternately spaced from each other. Thereby, since an electrode overlapping area larger than that of the parallel plate type is generated, the electrostatic attractive force generated between the comb electrodes is increased, and the movable amount can be increased.

US Pat. No. 6,384,952

  However, in the structure disclosed in Patent Document 1, the same voltage is applied to the outermost comb electrode and the outer wall 580, and different voltages are applied to the outermost comb electrode and the adjacent comb electrode. Applied. Therefore, an electrostatic attractive force acts between the outermost comb-tooth electrode and the adjacent comb-tooth electrode on the inner side, whereas no electrostatic attractive force acts between the outermost comb-tooth electrode and the outer wall 580. . Therefore, when the drive voltage is increased to increase the movable amount, the outermost comb electrode is affected by the electrostatic attractive force acting between the outermost comb electrode and the adjacent comb electrode side on the inner side. There is a case in which a phenomenon called pull-in (retraction) occurs in which collides with an adjacent comb electrode on the inside. Therefore, with this structure, it is not easy to obtain a larger movable amount.

  The present invention has been made in view of such problems. The purpose is to provide a structure in which pull-in does not easily occur even when the drive voltage is increased in order to increase the amount of movement in an actuator including a comb electrode or a deformable mirror using the same.

  The electrostatic comb actuator of the present invention for solving the above problems employs the following configuration. In other words, the electrostatic comb actuator includes a support member, a plurality of fixed comb electrodes supported by the support member and extending from the support member, a movable member, and an elastic connecting the movable member and the support member. A plurality of movable comb electrodes provided on the movable member, extending substantially parallel to the fixed comb electrodes from the movable member, and meshing with the fixed comb electrodes with a gap therebetween, A surface of the movable member on which the movable comb electrode is provided and a surface of the support member on which the fixed comb electrode is provided are arranged substantially parallel to the movable direction of the movable member. And each of the portion of the support member that faces the outermost movable comb electrode in the direction in which the plurality of movable comb electrodes are arranged and the portion of the support member that the fixed comb electrode extends from each other A structure for applying a potential is provided.

  Further, the deformable mirror of the present invention includes the electrostatic comb actuator and a mirror member having one surface as a reflection surface, and the movable member of the actuator is opposite to the reflection surface of the mirror member. Connected to the surface.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which can suppress generation | occurrence | production of a pull in can be provided even when it drives with a high drive voltage in the electrostatic comb actuator which has the above individual electric potential application structures.

FIG. 2 is a top view of the first embodiment. Sectional drawing of the manufacturing method of Embodiment 1. FIG. Sectional drawing of the manufacturing method of Embodiment 1. FIG. Sectional drawing explaining operation | movement of the deformable mirror of Embodiment 1. FIG. The graph which shows the area | region which satisfy | fills relational expressions (7) and (8). 1 is a schematic diagram of an optical compensation system according to the present invention and an ophthalmologic apparatus using the same. Sectional drawing which shows a prior art example.

  In the present invention, a structure in which an individual potential can be applied to a portion of the support member facing the outermost movable comb electrode in the direction in which the plurality of movable comb electrodes is arranged, independently of the other support member portions. It has in a support member. In this way, even if the drive voltage applied between the fixed comb electrode and the movable comb electrode in order to increase the movable amount is increased, the individual potential is adjusted appropriately, for example, the outermost movable comb. Pull-in can be suppressed by making the electrostatic attractive force acting on the tooth electrode symmetrical. In such a configuration, for example, in order to facilitate manufacture, the gap (A) between the movable comb electrode positioned on the inner side and the fixed comb electrode is formed on the outermost movable comb electrode and the portion of the support member facing the gap. It can be made smaller than the gap (B). When the gap (A) is smaller than the gap (B), there is an effect that the periphery of the structure from the comb electrode to the elastic member through the support member can be accurately and reliably manufactured. However, if there is a structure for applying the individual electric potential, the adjustment of the electric potential applied thereto can suppress the occurrence of pull-in even if A> B or A = B.

  Hereinafter, embodiments of a more specific structure will be described, but of course the present invention is not limited to these. Various modifications and changes may be made without departing from the scope of the invention.

(Embodiment 1)
A deformable mirror 100 including the electrostatic comb actuator according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2-1, 2-2, and 3. FIG. 1 is a top view of a deformable mirror 100 of the present embodiment. FIGS. 2-1 (a) to (g) and FIGS. 2-2 (h) to (j) are cross-sectional views of the manufacturing method. FIG. 3 is an A1-A2 cross-sectional view of the electrode pair of the comb-teeth structure of the electrostatic comb actuator of the deformable mirror 100 of the present embodiment in two different states.

  The actuator 101 is formed by processing the first substrate 102. The movable member 103 is supported on the support member 105 by two or more elastic bodies (elastic members) 104. Here, the elastic bodies 104 in the form of leaf springs are provided at equiangular intervals (here, 180 ° intervals) around the movable member 103 having a rotationally symmetric shape such as a square cross section. Thereby, the vertical movement of the movable member 103 in the direction perpendicular to the sheet of FIG. 1 is stably secured.

  Each of the movable comb electrodes 106 extends from the movable member 103 in a direction horizontal to the surface of the first substrate 102. A plurality of fixed comb electrodes 108 fixed to a portion of the support member 105 that is insulated via the insulating portion 107 and the electrode separation groove 127 with respect to the portion of the support member 105 to which the outer end of the elastic body 104 is coupled are supported. It extends in a direction parallel to the upper surface of the member 105. The insulating portion 107 is an insulating layer of an active layer described later, and an insulating layer on the handle layer side described later is formed in the electrode separation groove 127. The movable comb electrode 106 and the fixed comb electrode 108 are arranged so as to face each other, and the comb teeth are alternately arranged at equal intervals to constitute a comb electrode pair of the actuator. As described above, the actuator includes a plurality of fixed comb electrodes extending from the support member, an elastic member connecting the movable member and the support member, and extending substantially parallel to the fixed comb electrodes from the movable member. And a plurality of movable comb electrodes engaged with the tooth electrodes with a gap therebetween. The surface of the movable member on which the movable comb electrode is provided and the surface of the support member on which the fixed comb electrode is provided are arranged substantially parallel to the movable direction of the movable member.

  Further, the movable member 103 is joined to the reflecting member (mirror member) 109 by the gold bump 126, and the mirror 100 is deformed when the movable member 103 moves.

Next, a method for manufacturing the deformable mirror will be described. First, as shown in FIG. 2A, the first substrate 102 is prepared (S101). The first substrate 102 is an SOI substrate including a handle layer (Si) 110, a box layer (SiO ₂ ) 111, and an active layer (Si) 112.

Next, as shown in FIG. 2B, the pattern of the insulating layer 113 is formed on both surfaces of the first substrate 102 (S102). After forming silicon oxide (SiO ₂ ) by thermal oxidation as the insulating layer 113, a resist pattern (not shown) is formed. In this step, the insulating layer 113 is etched to form insulating layer patterns 113a and 113b using the resist pattern as a mask.

Next, as shown in FIG. 2-1 (c), through electrodes 114a to 114d are formed (S103). A resist pattern (not shown) is formed on the back surface of the first substrate 102. Using the resist pattern as a mask, the active layer (Si) 112 and the box layer (SiO ₂ ) 111 are etched to form a through hole. Further, after titanium and titanium (Ti) and gold (Au) as electrode materials are stacked, a resist pattern (not shown) is formed. Gold (Au) and titanium (Ti) are etched using the resist pattern as a mask. The through electrodes formed in this way are a through electrode 114a for a fixed comb electrode, a through electrode 114b for a movable comb electrode, and a through electrode 114c of a movable part (contact hole (electrode) for conducting the handle layer and the active layer). In addition, the through electrode 114d is used for supporting portion individual potential.

  Next, as shown in FIG. 2D, a bump bonding pad 115 is formed (S104). On the surface of the first substrate 102, titanium (Ti) and gold (Au), which are pad materials, are stacked and formed, and then a resist pattern (not shown) is formed. Gold (Au) and titanium (Ti) are etched using the resist pattern as a mask.

  Next, as shown in FIG. 2E, a mask for forming a comb-teeth shape is formed (S105). A resist pattern 116 is formed on the surface of the first substrate 102, and the insulating layer 113b on the surface of the first substrate 102 is etched.

  Next, as shown in FIG. 2-1 (f), from the surface of the first substrate 102, a comb electrode region 123 (a region including the movable comb electrode 106 and the fixed comb electrode 108), an elastic body opening region 122. (A region including the opening on the elastic body 104) and the electrode separation groove 127 are formed (S106). This is a step of etching the handle layer 110 (Si) using the resist pattern 116 formed in S105 and the insulating layer 113b as a mask. In order to form the desired comb-teeth shape by etching the handle layer (Si) 110, ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching) that can be etched with high cross-sectional perpendicularity is used. At this time, the comb electrode region 123 having a small mask opening area and the elastic body opening region 122 having a large mask opening area are simultaneously etched. Then, the support member 105 that is the fixed region, the outermost movable comb electrode 106 that is the movable region, and the movable member 103 are divided. The gap (B) 125 between the outermost movable comb electrode 106 and the support member (outer wall) is made wider than the central inter-gap electrode gap (A) 124 so that these manufacturing steps can be performed relatively easily and reliably. (See FIG. 1). Further, the formed electrode separation groove 127 allows the portion of the support member 105 facing the outermost movable comb electrode 106 in the direction (X direction in FIG. 1) in which the plurality of movable comb electrodes 106 are arranged, and the fixed comb. The portion of the support member 105 from which the tooth electrode 108 extends is electrically separated. Each of the electrically separated portions of the support member 105 can be independently applied with an individual potential. In order to apply individual potentials, electrode pads are formed on each of the electrically separated portions of the support member 105.

Next, as shown in FIG. 2-1 (g), comb-shaped steps are formed (S107). In order to form a step in the fixed comb electrode 108, the active layer (Si) 112 is etched using the insulating layer (SiO ₂ ) 113a on the back surface as a mask. Further, the box layer (SiO ₂ ) 111 is etched using the active layer 112 as a mask. Further, the silicon (Si) of the fixed comb electrode 108 is etched. In order to form a step on the movable comb electrode 106 side, the resist pattern 116 on the front surface and the resist pattern (not shown) on the back surface are peeled off, and then the movable comb is used with the insulating layer (SiO ₂ ) 113b on the front surface as a mask. The silicon (Si) of the tooth electrode 106 is etched.

Next, as shown in FIG. 2H, the box layer (SiO ₂ ) 111 is etched to release the movable comb electrode 106 and the fixed comb electrode 108 (S108). Etching of the box layer _(SiO 2) 111 is the 0.5% hydrofluoric acid (HF), selectively wet etching the box layer _(SiO 2) 111.

Next, as shown in FIG. 2-2 (i), the first substrate 102 and the second substrate 117 formed up to S108 are bonded (S108). The second substrate 117 is an SOI substrate including a handle layer (Si) 118, a box layer (SiO ₂ ) 119, and an active layer (Si) 120. Here, an insulating layer (not shown) of silicon oxide is formed on the surface of the handle layer 118 of the second substrate 117 by thermal oxidation. Next, a resist pattern (not shown) is formed, and wet etching is performed to form an insulating layer pattern (not shown) on the surface of the handle layer (Si) 118. Further, a pad portion 121 for forming a gold (Au) bump described later is formed on the surface of the active layer 120 of the second substrate 117. For this purpose, a resist pattern (not shown) is formed after laminating and forming titanium (Ti) and gold (Au). Gold (Au) and titanium (Ti) are etched using the resist pattern as a mask. Further, a gold (Au) bump 126 is formed on the pad portion 121. Then, the pad portion 115 of the first substrate 102 and the gold (Au) bump 126 of the second substrate 117 are accurately aligned and bump-bonded. The bonding method may be fusion bonding such as silicon-silicon (Si-Si), silicon oxide-silicon oxide (SiO ₂ -SiO ₂ ), and silicon-silicon oxide (Si-SiO ₂ ), or bonding with an adhesive. It is.

Next, as shown in FIGS. 2-2 (i) to (j), the handle layer (Si layer) 118 and the box layer (SiO ₂ ) 119 of the second substrate 117 are selectively etched (S110). In order to selectively etch the handle layer (Si) 118, a chemical solution such as tetramethylammonium hydroxide aqueous solution (TMAH) or potassium hydroxide (KOH) can be used. Further, the exposed box layer (SiO ₂ ) 119 is selectively wet-etched with 0.5% hydrofluoric acid (HF). By this step, the active layer (Si) 120 is exposed, the active layer (Si) 120 becomes a reflecting member, and the deformable mirror 100 is formed. Here, the movable member 103 of the actuator is connected to the surface of the mirror member 109 opposite to the reflecting surface.

  The operations of the actuator 101 and the deformable mirror 100 will be described with reference to FIG. There is a step in a direction perpendicular to the upper surface of the support member 105 between the movable comb electrode 106 and the fixed comb electrode 108. In other words, the movable and fixed comb electrodes have portions that do not overlap in the direction perpendicular to the upper surface of the support member 105. This is because the present embodiment employs a method (variable overlap type) that utilizes a phenomenon in which forces act in the overlapping direction and are displaced when the comb electrodes are pulled by electrostatic attraction. In this phenomenon, when all the comb electrodes overlap each other, they are not displaced any more. Therefore, it is necessary or preferable to reduce the overlapping portions at the initial position and increase the overlapping portions when a voltage is applied.

As shown in FIG. 1, the movable comb electrode 106 and the fixed comb electrode 108 are electrically separated by the insulating portion. Therefore, by applying a voltage between the movable comb electrode 106 and the fixed comb electrode 108, the movable member 103 is displaced in a direction perpendicular to the upper surface of the support member 105 while keeping the distance between the electrodes 106 and 108. To do. The electrostatic attraction force Fz in the Z direction that acts when a potential difference is applied to the movable comb electrode 106 and the fixed comb electrode 108 is expressed by the following relational expression 1.
Fz = [(ε ₀ · N · S) / (2 g)] · (Vm−Vf) ² (Relational Expression 1)
Where ε ₀ : dielectric constant of vacuum, N: number of gaps between comb electrodes, S: overlap area of movable comb electrodes and fixed comb electrodes (electrode area where electrostatic force is generated), Vm: movable comb The potential of the tooth electrode, Vf: the potential of the fixed comb electrode, and g: the gap width between the comb electrodes.

  First, as shown in FIG. 3A, immediately after voltage application, an electrostatic attraction is generated by applying a potential difference between the movable comb electrode 106 and the fixed comb electrode 108, and the comb electrodes attract each other. . As a result, the movable comb electrode 106 and the fixed comb electrode 108 attract each other, but since the electrostatic attraction force is received substantially evenly in the left and right directions in the direction in which the comb teeth face each other, it is displaced in the Z direction perpendicular to the reflecting member 109. become.

  Subsequently, a balanced state as shown in FIG. That is, the movable comb electrode 106 stops at a position where the restoring force of the elastic body 104 and the electrostatic attractive force that has displaced the movable member 103 are balanced. When the potential difference between the movable comb electrode 106 and the fixed comb electrode 108 is set to 0 V, the movable comb electrode 106 returns to the initial position by the restoring force of the elastic body 104.

  When driving the electrostatic comb actuator as described above, in the conventional electrostatic comb actuator, in order to increase the generated force, the movable comb electrode 106 and the fixed comb electrode 108 are formed with a small thickness. Densify the electrode part. In such a case, the rigidity of the movable comb electrode 106 and the fixed comb electrode 108 in the thickness direction (X direction) decreases. Further, as described in the step (S106) of the manufacturing method, when the comb electrode region 123 having a small mask opening area and the elastic body opening region 122 having a large mask opening area are simultaneously dry-etched, the following is necessary. That is, between the outermost movable comb electrode and the support member (outer wall) to suppress the pattern abnormality due to the loading effect and to divide the support member (fixed region) and the outermost movable comb electrode (movable region). It is necessary to make the gap (B) wider than the center inter-gap electrode gap (A).

Here, the electrostatic force in the X direction generated between the comb electrodes is expressed by the following relational expression (2).
Fx = [(ε ₀ · N · S) / (2g ² )] · (Vm−Vf) ² (Relational Expression 2)
Since the inner interdigital electrode gap (A) is the same on the left and right sides, the inner comb electrode has the same force acting in the X direction, so that the comb electrode does not pull in. However, since the gap (B) between the outermost movable comb electrode 106 and the support member (outer wall) is wider than the center inter-gap electrode gap (A), the following is likely to occur. That is, as drive voltage V increases, F _A (force toward the inner side) becomes greater than force F _B (force toward the outer side) generated on the outermost movable comb electrode, and the inner side (gap A side) increases. Deformation and finally a phenomenon called pull-in that contacts the inner fixed comb electrode 108 occurs.

  The loading effect will be described. If the elastic body opening 122, the gap (A), and the gap (B) have the same opening area, the etching rate becomes uniform and the loading effect is suppressed. However, as described above, it is necessary to narrow the gap (A) in order to increase the generated force, and if the gap (A) = gap (B), the opening of the elastic body opening 122 is large. In this case, the etching rate is increased, and pattern abnormality is likely to occur. Therefore, if A is made smaller than B as in the present embodiment, the gradient of the etching rate can be reduced, so that the pattern abnormality can be suppressed.

In view of the above circumstances, in the present embodiment, the pull-in phenomenon in order to solve a point where is likely to occur, to be able to control the electrostatic force F _B which is generated, the outermost of the movable comb electrode and the counter support member Individual potentials can be applied to these portions. Thus, stable driving can be realized without pulling in even with a large driving voltage.

A relational expression necessary for realizing stable driving from the generated electrostatic force and the rigidity of the comb teeth is shown. Generally, the spring constant k of the cantilever spring is represented by the relational expression (3). E is the Young's modulus of the movable comb electrode 106, w is the width of the movable comb electrode 106 (length in the Z direction) t is the thickness of the movable comb electrode 106 (length in the X direction) l is the movable comb electrode The length of 106 is shown.

The electrostatic force acting on the comb electrode is expressed by F _A (force toward the inner side) and F _B (force toward the outer side) in relational expressions (4) and (5). x is the amount of displacement of the comb electrode in the X direction (the inner direction is positive), g ₁ is the gap between the movable comb electrode and the fixed comb electrode, and g ₂ is between the comb electrode and the support member (outer wall). It is a gap. V _A is a potential difference between the movable comb electrode and the fixed comb electrode, V _B is a potential difference between the comb electrode and the support member (outer wall), and ε ₀ is a dielectric constant.

The electrostatic force ΔF applied to the outermost movable comb electrode 106 is represented by the relational expression (6).

In order for pull-in not to occur, it is necessary to satisfy the relational expression (7) and the relational expression (8) representing the relation between the restoring force kx and the electrostatic force F applied to the movable comb electrode 106.
_{δ = kx- (F A -F B} ) ≧ 0 ( equation _{7) x = 1 / 3g 1} ( equation 8)
Here, the reason why the right side of the relational expression (8) is 1/3 is that it is generally accepted that pull-in occurs when the displacement amount x increases.

Relational expression (6) and relational expression (8) are substituted into relational expression (7). Then, the structural parameters of the movable comb electrode 106 shown below are input, and the relationship between the individual potential V _B , the thickness t of the outermost comb electrode, and δ shown in the relational expression (7) is shown in FIG. . The input parameters are as follows: gap (A) between fixed comb electrode 108 and movable comb electrode 106: g ₁ = 7 μm, gap (B): g ₂ = 14 μm, length of movable comb electrode: l = 500 μm, The width of the movable comb electrode: w = 200 μm. The Young's modulus of the movable comb electrode is E = 130 GPa, and the dielectric constant of vacuum is ε ₀ = 8.85 × 10 ⁻¹² F / m.

Typically, the maximum drive voltage is driven at, for example, 150 V or more. However, if it is desired to drive at the maximum drive voltage of 150 V, the region satisfying the relational expressions (7) and (8) is the region A shown in FIG. is there. Therefore, when the thickness t of the movable comb electrode 106 is t = 11 μm and the individual potential V _B is smaller than 115 V, the movable comb electrode 106 does not satisfy the relational expressions (7) and (8), so that it is pulled in. Become. Therefore, by setting the individual potential V _B to 115 V or more and weakening the electrostatic force in the inner direction generated in the movable comb electrode 106, stable driving can be realized without pulling in even with a large driving voltage. Further, when the thickness of the movable comb electrode 10 is changed to 9 μm in order to increase the generated force, the individual potential V _B is set to 262 V or more. Thus, by weakening the electrostatic force in the inner direction generated in the movable comb electrode 106, stable driving can be realized without pulling in even with a large driving voltage.

  FIG. 1 shows a structure in which one actuator is connected to a reflecting member 109 having a continuous reflecting surface, but this is an example. By increasing the number of actuators connected to the reflecting member, a more complicated mirror surface shape can be realized with high accuracy. In addition, a type in which one reflection member 109 is connected to each of the plurality of actuators 101 via a connection portion is also possible. Thereby, since the optical path length of the light reflected by each reflecting member 109 can be changed, it can be used as a wavefront correction device.

(Embodiment 2: Ophthalmic apparatus)
The above-described deformable mirror will be described with respect to an adaptive optical system using a wavefront compensation device that compensates for optical aberration, taking a scanning laser opthalmoscope (hereinafter referred to as an SLO apparatus) as an example. The SLO device is an ophthalmic device that irradiates the fundus with light and enables observation of photoreceptor cells, retinal nerve fiber bundles, blood cell dynamics, and the like.

  FIG. 5 shows a schematic configuration of the SLO apparatus according to the present embodiment. The light emitted from the light source 301 propagates through the single mode optical fiber 302, passes through the collimator 303, and becomes a parallel light beam. The parallel light beam passes through the beam splitter 304 that is a light splitting unit as the measurement light 305 and is guided to the adaptive optics system 320. For example, the wavelength of the light source 301 that emits the laser light is not particularly limited, but is particularly about 800 to 1500 nm (for example, 850 nm band or less) in order to reduce the glare of the subject and maintain the resolution for fundus imaging. Are preferably used. The adaptive optics system 320 includes a beam splitter 306 that is a light splitting unit, a wavefront sensor (aberration measurement unit) 315, a deformable mirror (wavefront correction device) 308 that forms a reflective light modulation element, and a light guide for guiding them Reflecting mirrors 307-1 to 307-4 are included. Each reflecting mirror 307 is installed so that at least the pupil of the eye to be examined, the wavefront sensor 315, and the deformable mirror 308 are optically conjugate.

  The light that has passed through the adaptive optics system 320 is scanned one-dimensionally or two-dimensionally by the optical scanning unit 309. Measurement light scanned by the optical scanning system 309 is irradiated to the eye 311 through the eyepieces 310-1 and 310-2. By adjusting the positions of the eyepieces 310-1 and 310-2, optimal irradiation can be performed according to the diopter of the eye 311 to be examined. Here, a lens is used for the eyepiece, but it may be constituted by a spherical mirror or the like.

  The measurement light applied to the eye 311 is reflected or scattered by the fundus (retina). The light reflected and scattered by the fundus of the subject's eye 311 travels in the same direction as the incident light in the opposite direction, and is partially reflected by the beam splitter 306 and incident on the wavefront sensor 315 to be used for measuring the wavefront of the light beam. It is done. A known Shack-Hartmann sensor or the like can be used as the wavefront sensor 315. A part of the reflected scattered light that has passed through the beam splitter 306 is reflected by the beam splitter 304 and guided to the light intensity sensor 314 through the collimator 312 and the optical fiber 313. The light incident on the light intensity sensor 314 is converted into an electrical signal and processed into a fundus image by the image processing means 325.

  The wavefront sensor 315 is connected to the adaptive optics controller 316 that is a control unit, and transmits the wavefront of the received light beam to the adaptive optics controller 316. The adaptive optics controller 316 is connected to the deformable mirror 308 and deforms the mirror 308 into a shape designated by the adaptive optics controller 316. The adaptive optics controller 316 calculates a mirror shape that corrects the wavefront without aberration based on the measurement result of the wavefront acquired from the wavefront sensor 315. Then, the deformable mirror 308 calculates the applied voltage difference between the comb electrodes necessary to reproduce the shape and sends it to the deformable mirror 308. The deformable mirror 308 applies a potential difference sent from the adaptive optics controller 316 between the movable comb electrode and the fixed comb electrode, and deforms the mirror surface so as to have a predetermined shape.

  The measurement of the wavefront by the wavefront sensor 315, the transmission of the wavefront to the compensation optical controller 316, and the instruction to the deformable mirror 308 for correcting the aberration by the compensation optical controller 316 are repeatedly processed and are always optimal. Feedback control is performed so as to obtain a smooth wavefront. Note that the deformable mirror constituting the reflective light modulation element may be provided so as to correct the wavefront aberration of at least one of the measurement light and the return light.

  100: deformable mirror, 101: electrostatic comb actuator, 103: movable member, 104: elastic member, 105: support member, 106: movable comb electrode, 108: fixed comb electrode

Claims (10)

A support member; a plurality of fixed comb electrodes supported by and extending from the support member; a movable member; an elastic member connecting the movable member and the support member; and the movable member. A plurality of movable comb electrodes extending from the movable member substantially parallel to the fixed comb electrodes and meshing with the fixed comb electrodes with a gap therebetween, and the movable comb electrodes of the movable member An electrostatic comb actuator in which the surface provided with the surface of the support member provided with the fixed comb electrode is disposed substantially parallel to the movable direction of the movable member,
Individual potentials are respectively applied to the portion of the support member that faces the outermost movable comb electrode in the direction in which the plurality of movable comb electrodes are arranged and the portion of the support member from which the fixed comb electrode extends. An electrostatic comb actuator having a structure for applying.   The portion of the support member that faces the outermost movable comb electrode in the direction in which the plurality of movable comb electrodes are disposed, and the portion of the support member from which the fixed comb electrode extends are electrically connected. The electrostatic comb actuator according to claim 1, wherein the electrostatic comb actuator is separated.   The electrostatic comb actuator according to claim 1, wherein the structure is provided on the support member.   The gap between the movable comb electrode and the fixed comb electrode positioned inside is smaller than the gap between the outermost movable comb electrode and the portion of the support member facing the outermost movable comb electrode. The electrostatic comb actuator according to any one of claims 1 to 3.   5. The electrostatic comb tooth according to claim 1, wherein the outermost movable comb electrode has higher rigidity than the inner movable comb electrode and the fixed comb electrode. 6. Actuator.   The electrostatic comb actuator according to claim 1, wherein the driving voltage is driven at 150 V or more. The electrostatic comb actuator according to any one of claims 1 to 6,
A mirror member whose one surface is a reflecting surface,
The movable member of the actuator is connected to a surface of the mirror member that is opposite to the reflecting surface.   The deformable mirror according to claim 7, wherein the plurality of actuators are respectively connected to the plurality of mirror members. An ophthalmologic apparatus for acquiring an image of an eye to be examined,
A reflective light modulation element that corrects the wavefront aberration of at least one of the measurement light and the return light; and
An aberration measuring unit for measuring aberration generated in the eye to be examined;
A control unit for controlling the reflective light modulation element based on the measurement result of the aberration measurement unit,
An ophthalmologic apparatus, wherein the reflective light modulation element has the deformable mirror according to claim 7 or 8. An adaptive optics system for correcting wavefront aberrations,
A reflective light modulator for correcting wavefront aberration of incident light;
An aberration measuring unit for measuring the wavefront aberration of incident light;
A control unit for controlling the reflective light modulation element based on the measurement result of the aberration measurement unit,
An adaptive optics system, wherein the reflective light modulation element includes the deformable mirror according to claim 7 or 8.