JP2005221579A - Variable shape mirror control device and eye fundus observing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable shape mirror control device for improving response characteristics, by devising a control state even in a variable shape mirror with a large time constant, as compared with the response speed needed for applications, such as eye fundus camera. <P>SOLUTION: The variable shape mirror device comprises the variable shape mirror 10 changing the reflection face shape by impressing a voltage, and a voltage control circuit 20 for controlling the impressed voltage impressed on the variable shape mirror 10. The voltage control circuit 20, generating working voltage being a desired shape in a working state by the reflection face shape of the variable shape mirror 10, generates transition voltage to make the reflection face shape of the variable shape mirror 10 deformed into a desired shape side, and generates the transition voltage shifting the reflected face shape of the variable shape mirror 10 by the transition voltage into a desired shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a deformable mirror device suitable for use in a fundus camera, a head-up display, an astronomical telescope, a laser irradiation device, and the like. The present invention also relates to a fundus oculi observation device that records a fundus image of a subject's eye by irradiating a subject's eye with a light beam emitted from a photographing light source and recording a reflected light beam reflected by the fundus as photographing light.

  In a fundus observation device such as a fundus camera, a fundus image is taken, and an ophthalmologist or an optometrist examines the state of the retina, fundus bleeding, and the like. By the way, the human eye optical system is composed of an eyeball composed of a cornea, a crystalline lens, a glass body, etc., but compared with a perfect optical system assumed in geometrical optics, the human eye optical system has There is distortion. In particular, in the field of ophthalmology, since the degree to which the subject's eye deviates from the normal eye is used as diagnostic information, a clear fundus image with little aberration is required. However, since the eye optical system constituting the object to be imaged is incomplete, there are cases where sufficient resolution cannot be obtained. Therefore, in order to correct the collapse of the wavefront in the eye optical system, for example, a deformable mirror using a piezoelectric effect as shown in Patent Documents 1 and 2 is used.

Japanese Patent Laid-Open No. 11-137522 [0031], FIG. US Pat. No. 6,042,223, column 3, lines 51-65, FIG.

  However, since the deformable mirror disclosed in Patent Documents 1 and 2 described above uses a piezoelectric element, the applied voltage of the piezoelectric element increases, and the high-voltage resistant element that is expensive as an electronic control circuit It was necessary to use. Therefore, in a commercial fundus camera, a deformable mirror using electrostatic attraction that requires a lower driving voltage than a piezoelectric type is used.

  However, the electrostatic deformable mirror has a low natural frequency (for example, about 10 Hz) and a response speed, for example, has a time constant of about 100 milliseconds. Therefore, since the electrostatic variable shape mirror has a slow response to a change in shape, it is difficult to perform real-time processing (for example, a response speed of about 30 milliseconds) required for ophthalmic examination. was there.

  In addition, the deformable mirror has a problem that the shape of the deformable mirror is determined due to restrictions on the product specifications to be incorporated, and the thickness, size, and material of the deformable mirror cannot be freely changed. Further, the deformable mirror has a problem that the dynamic range related to the amount of change is determined on the specifications of the product to be incorporated, and the distance between the electrodes of the electrostatic deformable mirror is also determined. Therefore, the response characteristic of the electrostatic variable shape mirror is uniquely determined with respect to the applied voltage. In order to shorten the time constant of the variable shape mirror, the variable shape mirror can be used as a structural design change measure. There is a problem that measures such as adopting a hard material, increasing the thickness of the deformable member, and reducing the size of the deformable member cannot be adopted.

  The present invention solves the above-mentioned problems, and even with a deformable mirror having a large time constant compared to the response speed required for applications such as fundus images, response characteristics can be improved by devising the control mode. An object is to provide an improved deformable mirror device. Another object of the present invention is to provide a fundus oculi observation device capable of real-time processing as required in ophthalmic examinations.

  The deformable mirror device of the present invention that achieves the above object controls the deformable mirror 10 whose reflecting surface shape changes and the applied voltage applied to the deformable mirror 10 according to the applied voltage, for example, as shown in FIG. A variable shape mirror device including a voltage control circuit 20. Here, the voltage control circuit 20 generates a steady voltage in which the shape of the reflecting surface of the deformable mirror 10 becomes a desired shape in a steady state, and the transient voltage that deforms the shape of the reflecting surface of the deformable mirror 10 to the desired shape side. And a transient voltage that quickly shifts the reflecting surface shape of the deformable mirror 10 to a desired shape is generated by the transient voltage.

  In the apparatus configured as described above, at the moment of deforming the shape of the deformable mirror 10 (immediately after voltage application), a transient voltage is applied by the voltage control circuit 20 to improve the rise of the shape change of the deformable mirror 10. doing. When the desired shape change is obtained, the voltage applied to the deformable mirror 10 of the voltage control circuit 20 is changed from a transient voltage to a steady voltage, so that the response characteristic of the deformable mirror 10 is changed as the entire deformable mirror device. Improve.

  Preferably, for example, as shown in FIG. 1, in the deformable mirror device of the present invention, the voltage control circuit 20 is a control circuit that controls the applied voltage with a DC voltage, and the applied voltage when generating a steady voltage is used. In comparison, the transient voltage may be configured so that the amount of change in the shape of the reflecting surface of the deformable mirror 10 increases toward the desired shape. With this configuration, the voltage control circuit 20 needs only to directly control the output DC voltage, so the relationship between the applied voltage and the shape change of the deformable mirror 10 can be easily understood intuitively.

  Preferably, for example, as shown in FIG. 5, in the deformable mirror device of the present invention, the voltage control circuit 20 is a control circuit that performs pulse width control (PWM), and generates a steady voltage. It is preferable that the transient voltage is generated by a duty ratio in such a direction that the amount of change of the reflecting surface of the deformable mirror 10 is increased toward the desired shape. If comprised in this way, since the voltage control circuit 20 should just carry out pulse width control of the DC voltage to output, it can change an average applied voltage, without performing control of a voltage level.

  Preferably, for example, as shown in FIG. 8, in the deformable mirror device of the present invention, the voltage control circuit 20 is an electric circuit having a switching circuit 26 that switches the applied voltage between positive and negative and outputs it to the load side. The transient voltage is a direction in which the amount of change in the shape of the reflecting surface of the deformable mirror 10 increases toward the desired shape as compared with the applied voltage when generating a steady voltage. It may be configured. With this configuration, the polarity of the applied voltage applied to the deformable mirror 10 by the voltage control circuit 20 is constantly changed by the switching circuit 26, so that the deformable mirror 10 is charged to either positive or negative polarity. The deformed shape of the deformable mirror 10 is stable.

  Preferably, for example, as shown in FIG. 10, in the deformable mirror device of the present invention, the voltage control circuit 20 is an inverting circuit 28 that inverts and drives the polarity of the deformable mirror, and a control circuit that performs pulse width control. Thus, the transient voltage is generated with an on-time ratio in which the reflection surface shape of the deformable mirror 10 tends to increase the amount of change toward the desired shape as compared to the on-time ratio when the steady voltage is generated. Good. With this configuration, the polarity of the voltage applied to the deformable mirror 10 by the voltage control circuit 20 changes without using two types of positive and negative high voltage power supplies. Either one of the polarities is not charged, and the deformed shape of the deformable mirror 10 is stabilized. Further, since the voltage control circuit 20 only needs to control the output DC voltage by pulse width control, the average applied voltage can be changed without controlling the voltage level.

  Preferably, in the deformable mirror device of the present invention, the transient voltage is defined as a time for applying a voltage in a direction in which the reflection surface shape of the deformable mirror 10 increases in amount toward the desired shape. Using the time determined from the time constant, the shape of the reflecting surface of the deformable mirror 10 is shifted to a state close to the desired shape, and then the voltage control by the steady voltage is shifted to the transient voltage in the voltage control circuit 20. Can be smoothly switched to a steady voltage.

  The fundus oculi observation device of the present invention that achieves the above object uses the deformable mirror device according to any one of claims 1 to 6 as shown in FIG. 13, for example.

  According to the deformable mirror device of the present invention, the voltage control circuit generates a transient voltage in a direction that increases the amount of change of the reflecting surface shape of the deformable mirror 10 toward the desired shape, and then the reflecting surface shape of the deformable mirror 10 is changed. Since a steady voltage having a desired shape is generated in a steady state, it can be moved to a target steady state more quickly than a time constant determined by the size, material, thickness, etc. of the deformable mirror. it can.

  According to the fundus oculi observation device of the present invention, the measurement result from the subject eye can be reflected in the mirror shape in real time, so that it can be used for automatic correction of the fundus camera.

[principle]
1A and 1B are configuration diagrams showing an example of an electrostatic deformable mirror, in which FIG. 1A is a plan view, FIG. 1B is a sectional view taken along line BB in FIG. Show. In the figure, the electrostatic deformable mirror 10 includes a glass substrate 11, a silicon substrate 12, a membrane 13, a spacer 14, a reflective film 15, and an electrode 16. The membrane 13 is manufactured by a selective etching process on the silicon substrate 12 and has flexibility, for example, a thickness of about 4 μm. The reflective film 15 is formed by vapor-depositing a material having a high reflectance on the membrane 13, and for example, a metal film having a high reflectance such as aluminum is used. The spacer 14 is used to maintain the gap length between the membrane 13 and the electrode 16 at a predetermined value. For example, a highly rigid sphere is used. A predetermined number of electrodes 16 are formed on the glass substrate 11. The electrodes 16a, 16b, 16c, 16d, and 16e are individually voltage-driven by the voltage control circuit 20.

FIG. 2 is a waveform diagram showing a response curve of the reflective film when an applied voltage is applied to the deformable mirror in a stepped manner. (A) is a waveform 1 corresponding to the applied voltage, and (B) is a displacement amount. Waveform 2 is shown. In FIG. 2A, the applied voltage Vi is applied as the applied voltage X [V] stepwise from time 0. FIG. 2B is a curve obtained by measuring a temporal change in the displacement amount Di of the membrane 13 and shows a first-order lag response curve of the time constant τ. The time t is measured based on the time when the applied voltage is applied stepwise. In the response curve of the first order lag system, the displacement amount Di of the membrane 13 reaches about 10% of the total displacement amount Dtotal of the membrane 13 when t = τ / 10, and the displacement amount of the membrane 13 when t = τ. Di reaches about 63% of the total displacement Dtotal of the membrane 13. Here, the total displacement amount Dtotal of the membrane 13 is the total displacement amount A [of the reflective film in an equilibrium state with respect to the applied voltage when a sufficient time has elapsed with reference to the time constant τ (for example, after the settling time t _{set has} elapsed). μm].

FIG. 3 is a waveform diagram showing a response curve of the reflective film when a transient voltage and a steady voltage are sequentially applied to the deformable mirror. (A) is a waveform 4 corresponding to the applied voltage, and (B) is a displacement amount. Corresponding waveforms 3 and 5 are shown. In FIG. 3 (A), the applied voltage Vi is between high voltage V _high at time t _high from time 0, after time t _high and has a constant voltage V _stable. In FIG. 3B, the waveform 3 shows the step response to the high voltage V _high by a one-dot chain line, and the waveform 5 shows the step response to the steady voltage V _stable by a thin line. The displacement amount Di of the membrane 13 is a curve indicated by the waveform 3 from the time 0 to the time t _high , a curve connecting the waveform 3 and the waveform 5 from the time t _high to the settling time t _set, and a waveform after the settling time t _set. Indicated by 5.

In the apparatus configured as described above, the high voltage V _high as a transient voltage is applied to the membrane 13 by the voltage control circuit 20 at time 0 when the shape deformation of the membrane 13 is started. Then, the rise of the shape change of the membrane 13 becomes abrupt compared to the steady voltage V _stable , and a desired shape change can be obtained as the response time t _high elapses. Next, the voltage control circuit 20 resets the applied voltage to the steady voltage V _stable at time t _high . As a result, the response of the deformable mirror 10 becomes quick and the response characteristics are improved. Here, the response time t _high is determined at the time when the response displacement amount Di of the membrane 13 reaches the total displacement amount Dtotal of the membrane 13 at the steady voltage V _stable by the high voltage V _high . The response time t _high is, for example, 80% to 90% of the theoretical response time in order to prevent the response displacement amount Di of the membrane 13 from overshooting the target total displacement amount Dtotal. You may set to the time of a grade.

Next, the relationship between the applied voltage Vi and the displacement amount Di of the membrane 13 will be described. The applied voltage Vi and the displacement amount Di are expressed by equation (1).
^{k · Di = εo · S ·} Vi 2/2 · (dg-Di) 2 ... (1)
Here, dg represents a gap length, k represents a spring constant, Di represents a displacement amount of the membrane 13, S represents a surface area, Vi represents an applied voltage, and εo represents a vacuum dielectric constant. For example, when the gap length dg is 40 μm and the displacement amount Di is increased from 5 μm to 10 μm as the total displacement amount Dtotal of the membrane 13 in the steady state, the applied voltage V ₁₀ for 10 μm is ₅ to 10 μm for the applied voltage V ₅ for ₅ μm. It is necessary to satisfy the following relationship.
V ₁₀ / V ₅ = 1.21 (2)

For example, the deformable mirror 10 is made of single crystal silicon, has a shape of 15 mmφ, has a thickness of 4 μm, and is driven by the voltage control circuit 20 with an applied voltage X [V] of 50 [V]. Then, the total displacement amount Dtotal of the membrane 13 is 5 μm, the response waveform is as shown in FIG. 2B, and the settling time for the total displacement amount Dtotal is about 200 milliseconds. Therefore, in order to set the total displacement amount Dtotal of the membrane 13 to 10 μm, which is twice 5 μm, 60.5 [V] is applied as the applied voltage X [V] by the voltage control circuit 20 according to the equation (2). The response time t _high is about 30 milliseconds, for example, and the response becomes very short.

  FIG. 4 is a plan view for explaining the electrode arrangement of the deformable mirror. The electrode of the deformable mirror is, for example, a hexagonal honeycomb. 1-No. For example, an electrostatic voltage is applied so that deformation corresponding to each electrode occurs.

  In the first embodiment, it has been described that the response characteristics can be improved by controlling the applied voltage. However, in order to control the applied voltage level of the voltage control circuit 20, it is necessary to perform linear voltage control of several hundred volts, and there is a problem that an advanced voltage control technique is required. Further, in order to increase the shaping resolution of the shape of the deformable mirror 10, it is necessary to increase the number of electrodes, but voltage control must be performed independently for each electrode (channel) shown in FIG. In order to perform multi-channel voltage control equally, there is a problem that the circuit configuration becomes complicated.

  Accordingly, in the second embodiment, the voltage control is not performed by directly controlling the level of the applied voltage of the voltage control circuit 20 but by applying the pulse width control technique to control the pulse width of the switching element and changing the average voltage. Adopt the configuration to do. FIG. 5 is a block diagram illustrating a second embodiment of the present invention. 6A and 6B are waveform diagrams for explaining the operation of the apparatus shown in FIG. 5, wherein FIG. 6A is a sawtooth input signal in1 and a rectangular wave signal in2, FIG. 6B is an output signal out1 of the comparator 22, and FIG. 24 output signals out2 are shown.

  The voltage control circuit 20 includes a comparator 22 and a high voltage buffer circuit 24. The comparator 22 receives a sawtooth input signal in1 and a rectangular wave signal in2 as a duty ratio control signal. Then, the sawtooth input signal in1 is sliced by the comparator 22 based on the signal level of the rectangular wave signal in2, and the output signal out1 having a high duty ratio is output during a period in which the signal level of the rectangular wave signal in2 is high (transition period). During a period when the signal level is low, the output signal out1 having a low duty ratio is output to the high voltage buffer circuit 24. In the high voltage buffer circuit 24, a high voltage HV is supplied from a high voltage source (not shown), and an output signal out2 obtained by amplifying the output signal out1 is output and applied to the deformable mirror 10. For example, when the output signal out1 is 5V, the output signal out2 is amplified to a drive voltage several tens of times higher than the logical voltage level, for example, 300V.

FIG. 7 is a waveform diagram showing a response curve of the reflective film when a transient voltage and a steady voltage are sequentially applied to the deformable mirror in the second embodiment. FIG. 7A is a waveform 4 ^* , (B ) Shows the waveform 5 ^* corresponding to the displacement, and (C) shows the waveforms 6 and 6 ^* corresponding to the switching voltage. In FIG. 7 (A), the applied voltage Vi is between high voltage V _high at time t _high from time 0, after time t _high and has a constant voltage V _stable. In FIG. 7B, the displacement amount Di of the membrane 13 is a curve indicating a step response to the high voltage V _high from time 0 to time t _high , and the total displacement amount Dtotal from time t _high to settling time t _set . After the straight line, the settling time t _set is indicated by a step response to the steady voltage V _stable . In FIG. 7C, the switching signal indicated by the waveform 6 has a high duty ratio from time 0 to time t _high and has a low duty ratio after time t _high . When the duty ratio with respect to the steady voltage V _stable is, for example, 1: 1, the duty ratio with respect to the high voltage V _high is, for example, 1.21: 1. A waveform 6 ^* indicates an output voltage signal obtained by rectifying and smoothing the switching signal indicated by the waveform 6, and corresponds to the waveform 4 ^* .

  FIG. 8 is a configuration block diagram of a voltage control circuit for explaining the third embodiment of the present invention. In the figure, the voltage control circuit 20 includes a switching circuit 26 that switches the applied voltage between positive and negative and outputs it to the load side, and a high-voltage buffer circuit 24. The high voltage buffer circuit 24 has a positive voltage DC power supply unit and a negative voltage DC power supply unit as a high voltage source for supplying the high voltage HV. The switching circuit 26 is a control circuit that controls positive and negative applied voltages, and the transient voltage is the amount of change in the shape of the reflecting surface of the deformable mirror 10 to the desired shape side compared to the applied voltage when generating a steady voltage. It is preferable to adopt a configuration in which the direction is increased. With this configuration, the polarity of the applied voltage applied to the deformable mirror 10 by the voltage control circuit 20 is constantly changed by the switching circuit 26, so that the deformable mirror 10 is charged to either positive or negative polarity. The deformed shape of the deformable mirror 10 is stable.

In such a configuration, when the applied voltage is switched between the electrode 16 and the membrane 13 with a period sufficiently fast with respect to the response time of the deformable mirror 10 and applied between the two without causing charge-up. An electrostatic attractive force is generated, and the membrane 13 is deformed into a concave shape. 9A and 9B are switching voltage waveform diagrams in the case where an applied voltage is applied to the deformable mirror in a stepwise manner. FIG. 9A is a waveform 6, 6 ^* corresponding to the switching voltage in FIG. FIG. 7 is a diagram illustrating a waveform 7 of the applied DC voltage of the circuit 24, and the period of the waveform 7 is enlarged compared with the period of the waveform 6. That is, as shown in the waveform 7, by performing high voltage control of forward and reverse polarity by pulse drive, it is possible to drive the deformable mirror 10 with a charge-up countermeasure.

  In the third embodiment shown in FIG. 8, a case where both the positive voltage DC power supply unit and the negative voltage DC power supply unit are used as the high voltage source of the high voltage buffer circuit 24 is described as an example. If a countermeasure for charging up the deformable mirror 10 is realized only by the power supply unit, the circuit configuration is simplified.

  FIG. 10 is a configuration block diagram of a voltage control circuit for explaining a modification of the third embodiment of the present invention. In the figure, the voltage control circuit 20 includes a PWM (pulse width modulation) circuit 22, a high voltage buffer circuit 24, and an inversion circuit 28 that inverts and drives the polarity of the deformable mirror 10. The inversion circuit 28 has four transistors Tr1, Tr2, Tr3, Tr4, and the polarity of the drive voltage of the deformable mirror 10 is inverted by a timing signal supplied from the outside. Here, the transistors Tr1 and Tr4 operate on the positive side, and the transistors Tr2 and Tr3 operate on the negative side. As the PWM (pulse width modulation) circuit 22, for example, a comparator to which a sawtooth input signal in1 and a rectangular wave signal in2 as a duty ratio control signal are input as shown in FIG. 5 is used.

  According to such a configuration, even if only the positive voltage DC power supply unit is used as the high voltage source of the high-voltage buffer circuit 24, the inverting circuit 28 can implement a charge-up countermeasure for the deformable mirror 10.

FIG. 11 is a waveform diagram showing the response curve of the reflective film when an applied voltage is applied to the deformable mirror in a stepped manner. (A) is a waveform 8 corresponding to the applied voltage, and (B) is a displacement amount. Waveform 9 is shown. In FIG. 11A, the applied voltage Vi was initially a high applied voltage X _h [V], but is applied as a steady voltage V _stable stepwise from time 0. FIG. 11B is a curve obtained by measuring a temporal change in the displacement amount Di of the membrane 13, and shows a response curve of a first-order lag system of the time constant τ. The time t is measured based on the time when the low applied voltage X ₁ [V] is applied in a stepped manner. Here, due to the change from the high applied voltage X _h [V] to the low steady voltage V _stable , the total displacement Dtotal generated in the membrane 13 has passed a sufficient time with respect to the time constant τ (for example, the settling time t the _set elapsed after) the time, represented by the total displacement of the reflective film at equilibrium with respect to the change with applied voltage.

FIG. 12 is a waveform diagram showing the response curve of the reflective film when a transient voltage and a steady voltage are sequentially applied to the deformable mirror. (A) shows the waveform 11 corresponding to the applied voltage, and (B) shows the displacement amount. Corresponding waveforms 10 and 12 are shown. In FIG. 12A, the applied voltage Vi was initially a high applied voltage X _h [V], but is a low transient applied voltage X _tr from time 0 to time τ, and after time τ, the transient applied voltage X _tr The steady voltage V _stable is higher than that. In FIG. 12B, a waveform 10 indicates a step response to a low transient applied voltage _Xtr by a one-dot chain line, and a waveform 12 indicates a step response to a steady voltage V _stable by a thin line. Displacement Di of the membrane 13, curve while the shown by waveform 10 from time 0 time tau, the curve from time tau to settling time t _set to contact waveform 10 and waveform 12, the settling time t _set later by the waveform 12 Indicated.

In the apparatus configured as described above, a low transient applied voltage _Xtr is applied to the membrane 13 by the transient voltage control function provided in the voltage control circuit 20 at time 0 when the deformation of the membrane 13 is started. Then, the shape change speed of the membrane 13 becomes abrupt compared to the steady voltage V _stable , and a desired shape change is obtained as the response time τ elapses. Next, the applied voltage is reset to the steady voltage V _stable at time τ by the steady voltage control function provided in the voltage control circuit 20. Then, the displacement amount of the deformable mirror 10 is quickly moved to the reflecting surface shape in a steady state and stabilized. As a result, the response of the deformable mirror 10 becomes quick and the response characteristics are improved. Here, the response time t _tr is determined at the time when the response displacement Di of the membrane 13 reaches the total displacement D total of the membrane 13 at the steady voltage V _stable by the low transient applied voltage X _tr . The response time t _tr is, for example, 80% to 90% of the theoretical response time in order to prevent the response displacement amount Di of the membrane 13 from overshooting the target total displacement amount Dtotal. You may set to the time of a grade.

  Next, a fundus oculi observation device using the deformable mirror 10 will be described. FIG. 13 is a block diagram illustrating the entire fundus oculi observation device. In the figure, the fundus oculi observation device includes a wavefront correction system 8, a fundus illumination system 2, a fundus oculi observation system 3, an alignment system 4, a fixation system 5, and an adaptive optics unit 70. The wavefront correction system 8 includes a wavefront measurement system 80 including a point image projection optical system 81, a point image light reception optical system 82, and a point image light reception unit 83 (CCD), a computer 84, and a control unit 85. The computer 84 includes an optical characteristic measuring unit 841, an image data forming unit 842, a compensation amount determining unit 843, a memory 844, and a display unit 845.

  The fundus illumination system 2 includes a second light source unit, a condensing lens, and a beam spiriter, and illuminates a predetermined region on the eye retina with the second light flux from the second light source unit. The fundus oculi observation system 3 includes a fundus image forming optical system 36 and a fundus image light receiving unit 38 (CCD). The fundus image forming optical system 36 includes, for example, an afocal lens 88, an compensation optical unit 70, a condensing lens, and a beam spiriter. Light reflected from the fundus 61 is transmitted to the fundus image light receiving unit 38 via the compensation optical unit 70. Lead. The compensation optical unit 70 includes a deformable mirror 10 that compensates for the aberration of the measurement light, a moving prism that moves in the optical axis direction and corrects the spherical component, and a spherical lens. The compensation optical unit 70 is disposed in the point image projection optical system 81 and the fundus image forming optical system 36, and compensates for aberrations of a reflected light beam reflected and returned from the eye 60, for example.

  The alignment system 4 includes a condenser lens and an alignment light receiving unit, and guides a light beam emitted from the light source unit and reflected back from the cornea 62 of the eye 60 to be examined to the alignment light receiving unit. The fixation system 5 includes, for example, an optical path for projecting a visual target for causing fixation or clouding of the eye 60 to be examined, and includes a third light source unit 51, a fixation target 52, and a relay lens. The fixation target 52 can be irradiated onto the fundus 61 with the light flux from the third light source unit 51, and the eye 60 is observed by the eye 60 to be examined.

  The optical characteristic measurement unit 841 obtains optical characteristics including high-order aberrations of the eye 60 based on the output from the point image light receiving unit 83. The image data forming unit 842 performs the simulation of the visual appearance of the target based on the optical characteristics, and calculates the eye image data such as the simulation image data or the MTF indicating the visual appearance. The memory 844 stores a plurality of voltage change templates for adjusting the deformable mirror 10. The compensation amount determination unit 843 selects the voltage change template stored in the memory 844, determines the correction amount of the deformable mirror 10 based on the selected voltage change template, and outputs the correction amount to the control unit 85. To do. The control unit 85 deforms the deformable mirror 10 based on the output from the compensation amount determination unit 843. Further details of the fundus oculi observation device are described in, for example, the specification of Japanese Patent Application No. 2003-125279 applied to the applicant's proposal.

  In the above-described embodiment, the fundus oculi observation device is shown as a device using a deformable mirror, but various devices such as a head-up display, an astronomical telescope, and a laser irradiation device can be used as a device for mounting the deformable mirror. Exists.

It is a cross-sectional block diagram which shows an example of an electrostatic variable shape mirror, and has shown the voltage generation circuit and the voltage control circuit collectively. FIG. 6 is a waveform diagram showing a response curve of a reflective film when an applied voltage is applied to a deformable mirror in a stepped manner, where (A) shows a waveform 1 corresponding to the applied voltage, and (B) shows a waveform 2 corresponding to a displacement amount. ing. FIG. 4 is a waveform diagram showing a response curve of a reflection film when a transient voltage and a steady voltage are sequentially applied to a deformable mirror, where (A) shows a waveform 4 corresponding to the applied voltage, and (B) shows a waveform 3 corresponding to the displacement amount. 5 is shown. It is a top view explaining the electrode arrangement | sequence of a deformable mirror. It is a block diagram explaining a second embodiment of the present invention. It is a wave form diagram explaining operation | movement of the apparatus of FIG. It is a wave form diagram which shows the response curve of a reflecting film at the time of applying a transient voltage and a steady voltage to the deformable mirror in Example 2 in order. It is a block diagram of the configuration of a voltage control circuit for explaining a third embodiment of the present invention. It is a switching voltage waveform figure in the case of applying an applied voltage to the deformable mirror in Example 3 in steps. It is a block diagram of the configuration of a voltage control circuit for explaining a modification of the third embodiment of the present invention. It is a wave form diagram which shows the response curve of a reflecting film at the time of applying an applied voltage to the deformable mirror in Example 4 in steps. It is a wave form diagram which shows the response curve of a reflecting film at the time of applying a transient voltage and a steady voltage to the deformable mirror in Example 4 in order. It is a block diagram explaining the entire fundus oculi observation device.

Explanation of symbols

10 Deformable mirror 20 Voltage control circuit 22 Comparator (PWM circuit)
24 high voltage buffer circuit 26 switching circuit 28 inverting circuit

Claims (9)

A deformable mirror whose reflecting surface shape changes according to the applied voltage;
A voltage control circuit for controlling the applied voltage;
A deformable mirror device comprising:
The voltage control circuit generates a steady voltage in which a reflecting surface of the deformable mirror has a desired shape in a steady state, and the variable shape mirror is in a transient state until the deformable mirror is deformed to a desired shape. A variable shape mirror device having a function of changing an applied voltage as a transient voltage for quickly shifting the reflecting surface shape of the mirror to the desired shape side.   The variable shape mirror device according to claim 1, wherein the voltage control circuit is a control circuit that controls an applied voltage of the variable shape mirror with a DC voltage. The voltage control circuit is a control circuit for controlling a voltage applied to the deformable mirror by a DC voltage, and includes a switching element for turning on and off the DC voltage;
A control circuit that applies pulse width control by applying an on / off control signal to the switching element, and the transient voltage has a reflecting surface shape of the deformable mirror as compared with a duty ratio when the steady voltage is generated. The deformable mirror device according to claim 1, wherein the deformable mirror device is generated by a duty ratio that increases the amount of change toward the desired shape. The voltage control circuit is a control circuit that controls the deformable mirror with positive and negative applied voltages, and includes a switching circuit that switches the applied voltage between positive and negative and outputs it to the load side;
2. The deformable mirror device according to claim 1, wherein the transient voltage has a direction in which the amount of change in the shape of the reflecting surface of the deformable mirror increases toward the desired shape as compared with an applied voltage when generating the steady voltage. . The voltage control circuit is a control circuit that controls the deformable mirror with positive and negative applied voltages, a switching circuit that switches the applied voltage between positive and negative and outputs it to the load side, and positive and negative switching that turns on and off the positive and negative applied voltages. Having an element;
A control circuit that applies an on / off control signal to the positive and negative switching elements to perform pulse width control, wherein the transient voltage is reflected by the mirror of the deformable mirror as compared to an on-time ratio when the steady voltage is generated; The deformable mirror device according to claim 1, wherein the surface shape is generated by an on-time ratio in a direction of increasing the amount of change toward the desired shape. The voltage control circuit is a control circuit for controlling a voltage applied to the deformable mirror by a DC voltage, and includes an inverting circuit capable of inverting the polarity of a load;
2. The variable shape mirror according to claim 1, wherein the transient voltage has a direction in which a change amount of a reflection surface shape of the variable shape mirror increases toward the desired shape side as compared with an applied DC voltage when generating the steady voltage. apparatus. The voltage control circuit is a control circuit that controls the voltage applied to the deformable mirror by a DC voltage, and includes an inverting circuit that inverts the polarity of a load and a switching element that turns on and off the DC voltage;
A control circuit that applies an on / off control signal to the positive and negative switching elements to perform pulse width control, wherein the transient voltage is reflected by the mirror of the deformable mirror as compared to an on-time ratio when the steady voltage is generated; The deformable mirror device according to claim 1, wherein the surface shape is generated by an on-time ratio in a direction of increasing the amount of change toward the desired shape. The transient voltage is a time determined from a time constant of the reflecting surface shape of the deformable mirror as a time for applying a voltage in a direction in which the reflecting surface shape of the deformable mirror increases the amount of change on the desired shape side. Shifting the shape of the reflecting surface of the deformable mirror to a state close to the desired shape, and then shifting to voltage control by the steady voltage;
The deformable mirror device according to any one of claims 1 to 7. 9. A fundus oculi observation device using the deformable mirror device according to any one of claims 1 to 8.

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