JP2011221402A - Deformable mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary the shape of a light reflection surface with high accuracy.SOLUTION: A deformable mirror 1 comprises a mirror 10 having a light reflection surface 10a, an actuator 20 for varying the shape of the mirror 10, a back plate 30 for holding the actuator 20, a temperature sensor 50 for measuring each temperature of the mirror 10, the actuator 20 and the back plate 30, a temperature compensation operation part 60 for calculating an adjustment value to adjust the deformation amount of the mirror based on each temperature measurement value inputted from the temperature sensor 50 and preset linear expansion coefficients of the mirror 10, the actuator 20, and the back plate 30, and an actuator control part 40 for adjusting a given drive command value based on the adjustment value calculated by the temperature compensation operation part 60 to drive the actuator 20.

Description

  The present invention relates to a deformable mirror that changes the shape of a light reflecting surface that reflects incident light into a desired shape.

  The deformable mirror is used for wavefront control and optical path length control of incident light by changing the shape of the light reflecting surface to a desired shape. For example, according to Patent Document 1, the deformable mirror includes a mirror having a light reflecting surface, a plurality of actuators, and a back plate connected to the actuator. By changing the shape, the shape of the light reflecting surface is made variable.

JP 05-333274 A

  However, in Patent Document 1 described above, when used for wavefront control of a high power laser, the temperature of the mirror, the actuator, and the back plate rises due to the laser incident heat and the heat generated by the actuator drive, causing thermal expansion, and light reflection. There was a problem that the surface was distorted from the desired shape and the accuracy was poor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a deformable mirror that can vary the shape of the light reflecting surface with high accuracy.

  A deformable mirror according to the present invention includes a mirror having a light reflecting surface, an actuator that deforms the mirror, a back plate that holds the actuator, a temperature sensor that measures each temperature of the mirror, the actuator, and the back plate, and a temperature sensor A temperature compensation calculation unit for calculating an adjustment value for adjusting the deformation amount of the mirror based on each temperature measurement value inputted from the linear expansion coefficient of the mirror, actuator, and back plate set in advance, and a temperature compensation calculation unit And an actuator control unit that adjusts a given drive command value to drive the actuator based on the adjustment value calculated in (1).

  The deformable mirror according to the present invention includes a mirror having a light reflecting surface, an actuator for deforming the mirror, a back plate for holding the actuator, a temperature sensor for measuring each temperature of the mirror and the back plate, and a temperature sensor. A temperature compensation calculation unit for calculating an adjustment value for adjusting the deformation amount of the mirror based on each temperature measurement value input from the preset mirror and the linear expansion coefficient of the back plate, and between the mirror and the back plate A relative displacement measurement unit that measures the displacement of the actuator, and an actuator that drives the actuator by adjusting a given drive command value based on the adjustment value calculated by the temperature compensation calculation unit and the relative displacement measurement value from the relative displacement measurement unit And a control unit.

  The deformable mirror according to the present invention is configured to calculate the adjustment value for adjusting the deformation amount of the mirror based on the temperature measurement values of the mirror, the actuator, and the back plate, so that the distortion of the light reflecting surface of the mirror is compensated. can do. As a result, the deformable mirror can change the shape of the light reflecting surface with high accuracy.

  In addition, the deformable mirror is configured to calculate an adjustment value for adjusting the deformation amount of the mirror based on the measured temperature values of the mirror and the back plate and the displacement amount of the actuator. Can be compensated for. As a result, the deformable mirror can change the shape of the light reflecting surface with high accuracy.

It is a figure which shows the structure of the variable shape mirror which concerns on Embodiment 1 of this invention. It is a flowchart which shows the processing operation in the deformable mirror which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the deformable mirror which concerns on Embodiment 2 of this invention. It is a flowchart which shows the processing operation in the deformable mirror which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the deformable mirror which concerns on Embodiment 3 of this invention. It is a flowchart which shows the processing operation in the deformable mirror which concerns on Embodiment 3 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 shows the configuration of a deformable mirror 1 according to Embodiment 1 of the present invention.
As shown in FIG. 1, the deformable mirror 1 includes a mirror 10, an actuator 20, a back plate 30, an actuator control unit 40, a temperature sensor 50, and a temperature compensation calculation unit 60.

  The mirror 10 has a light reflecting surface 10a on one surface (mirror surface), and a plurality of actuators 20 are connected to the other surface (mirror back surface) 10b. The mirror 10 functions so that incident light is received and reflected by the light reflecting surface 10a.

  The actuator 20 has a movable end 20 a that is driven in the axial direction connected to the mirror back surface 10 b, the other end with respect to the movable end 20 a is held by the back plate 30, and is disposed between the mirror 10 and the back plate 30. Each of the plurality of actuators 20 is driven and controlled by each actuator control unit 40, and when the movable end 20a is driven, the mirror 10 is deformed by pressing in the normal direction of the mirror 10 from the mirror back surface 10b, and the light reflecting surface 10a. It functions to change the shape of.

  The back plate 30 is provided close to the mirror back surface 10b so as to hold the actuator 20.

The actuator control unit 40 includes a drive command unit 41, a drive circuit 42, and a regulator 43, and functions to drive and control the actuator 20.
The drive command unit 41 outputs a drive command value A given by an external drive instruction or a drive instruction from a preset program. The drive command value A is given based on, for example, a drive instruction from the user, and indicates the amount of displacement of the movable end 20a of the actuator 20.

  The adjuster 43 inputs a drive command value A from the drive command unit 41 and an adjustment value ΔZ from a temperature compensation calculation unit 60 described later, and functions to adjust the drive command value A by the adjustment value ΔZ. For example, the adjuster 43 subtracts the adjustment value ΔZ from the drive command value A to adjust the drive command value A, and outputs the adjusted drive command value A ′.

  The drive circuit 42 functions to input the drive command value A ′ adjusted by the adjuster 43 and give a drive command to the actuator 20 based on the input drive command value A ′.

  A temperature sensor 50 is attached to the mirror 10, the actuator 20, and the back plate 30. The temperature sensor 50 functions to measure the temperature in the mirror 10, the actuator 20, and the back plate 30. The temperature sensor 50 includes a temperature sensor 50 m attached to the mirror 10, a temperature sensor 50 a attached to the actuator 20, and a temperature sensor 50 b attached to the back plate 30.

  The temperature sensor 50m measures the temperature of the mirror 10 near the actuator 20, the temperature sensor 50a measures the temperature of the actuator 20, and the temperature sensor 50b measures the temperature of the back plate 30 near the actuator 20. . The temperature sensors 50m, 50a, and 50b output the measured temperature values to the temperature compensation calculation unit 60, respectively.

  The temperature compensation calculation unit 60 calculates the thermal expansion amount based on the linear expansion coefficients of the mirror 10, the actuator 20, and the back plate 30 set in advance and the input temperature measurement values, and totals the thermal expansion amounts. It functions to calculate the adjustment value ΔZ. The temperature compensation calculation unit 60 calculates, for example, a temperature change amount indicating a value obtained by changing a temperature measurement value from the temperature sensor 50m at a predetermined time, and multiplies the linear expansion coefficient of the mirror 10 by the temperature change amount to generate the mirror 10. The amount of thermal expansion of is calculated. The temperature compensation calculation unit 60 calculates a temperature change amount indicating a value obtained by changing the temperature measurement value from the temperature sensor 50 a at a predetermined time, and multiplies the linear expansion coefficient of the actuator 20 by the temperature change amount to thereby calculate the heat of the actuator 20. Calculate the amount of expansion. The temperature compensation calculation unit 60 calculates a temperature change amount indicating a value obtained by changing the temperature measurement value from the temperature sensor 50b at a predetermined time, and multiplies the linear expansion coefficient of the back plate 30 by the temperature change amount. The amount of thermal expansion of is calculated.

  The temperature compensation calculation unit 60 calculates the adjustment value ΔZ by adding the thermal expansion amount of the mirror 10, the thermal expansion amount of the actuator 20, and the thermal expansion amount of the back plate 30.

Here, the adjustment value ΔZ calculated by the temperature compensation calculation unit 60 will be described.
Generally, the amount of thermal expansion when an object changes in temperature is proportional to the linear expansion coefficient and the amount of temperature change. The linear expansion coefficient of the mirror 10 is CTEm, the linear expansion coefficient of the actuator 20 is CTEa, the linear expansion coefficient of the back plate 30 is CTEb, the temperature change amount in the mirror 10 is ΔTm, the temperature change amount in the actuator 20 is ΔTa, and the back plate 30 When the temperature change amount is expressed by ΔTb, the thermal expansion amount ΔZm of the mirror 10 in the vicinity of the actuator 20, the thermal expansion amount ΔZa of the actuator 20, and the thermal expansion amount ΔZb of the back plate 30 in the vicinity of the actuator 20 are expressed by the following equation (1): It is represented by (3).

ΔZm = CTEm × ΔTm (1)
ΔZa = CTEa × ΔTa (2)
ΔZb = CTEb × ΔTb (3)

The adjustment value ΔZ is the sum of the thermal expansion amounts ΔZm, ΔZa, ΔZb calculated by the equations (1) to (3) as shown in the following equation (4). The total thermal expansion amount of the plate 30 is shown.

ΔZ = ΔZm + ΔZa + ΔZb (4)

  The deformable mirror 1 adjusts the drive command value A with this adjustment value ΔZ, and drives and controls the actuator 20 with the adjusted drive command value A ′, thereby compensating for distortion generated on the light reflecting surface 10a in the vicinity of the actuator 20. Thus, the deformation amount of the mirror 10 can be adjusted.

  Next, the processing operation in the deformable mirror 1 will be described using the flowchart of FIG. The deformable mirror 1 starts a processing operation in response to an external driving instruction or a driving instruction from a preset program (start).

  The drive command unit 41 outputs a drive command value A given by an external drive instruction or a drive instruction from a preset program (step ST101).

  Here, the temperature compensation calculation unit 60 receives temperature measurement values from the temperature sensors 50m, 50a, and 50b, calculates the temperature change ΔTm based on the temperature measurement values from the temperature sensor 50m, and outputs the temperature change amount ΔTm from the temperature sensor 50a. A temperature change amount ΔTa is calculated based on the temperature measurement value, and a temperature change amount ΔTb is calculated based on the temperature measurement value from the temperature sensor 50b.

  Subsequently, the temperature compensation calculation unit 60 calculates the thermal expansion amount ΔZm of the mirror 10 by multiplying the linear expansion coefficient CTEm of the mirror 10 by the temperature change amount ΔTm, and calculates the linear expansion coefficient CTEa and the temperature change amount ΔTa of the actuator 20. The thermal expansion amount ΔZa of the actuator 20 is calculated by multiplication, and the thermal expansion amount ΔZb of the back plate 30 is calculated by multiplying the linear expansion coefficient CTEb of the back plate 30 by the temperature change amount ΔTb.

  The temperature compensation calculation unit 60 adds the thermal expansion amounts ΔZm, ΔZa, ΔZb to calculate the adjustment value ΔZ, and outputs it to the adjuster 43 (step ST102).

  When the controller 43 of the actuator control unit 40 receives the drive command value A from the drive command unit 41, the controller 43 receives the adjustment value ΔZ from the temperature compensation calculation unit 60. The adjuster 43 subtracts the adjustment value ΔZ from the drive command value A for adjustment, and outputs the adjusted drive command value A ′ to the drive circuit 42 (step ST103).

  When the drive command value A ′ is input from the regulator 43, the drive circuit 42 outputs a drive command to the actuator 20 based on the drive command value A ′ (step ST104). The actuator 20 presses the mirror back surface 10b by displacing the movable end 20a in accordance with the drive command input from the drive circuit 42.

  The mirror 10 is pressed from the mirror back surface 10b to the movable end 20a, and is deformed in the normal direction of the mirror 10 (step ST105).

  As described above, according to the first embodiment, the deformable mirror 1 includes the mirror 10 having the light reflecting surface 10a on one surface and the actuator that is connected to the other surface 10b of the mirror 10 and deforms the mirror 10. 20, a back plate 30 that holds the actuator 20 and is opposed to the other surface of the mirror 10, and temperature sensors 50m, 50a, and 50b that measure the temperatures of the mirror 10, the actuator 20, and the back plate 30, respectively. The thermal expansion amounts ΔZm, ΔZa, ΔZb are calculated based on the measured temperature values input from the temperature sensors 50m, 50a, 50b and the linear expansion coefficients of the mirror 10, the actuator 20, and the back plate 30 set in advance. A temperature compensation calculation unit 60 that calculates an adjustment value ΔZ that is a sum of the thermal expansion amounts ΔZm, ΔZa, and ΔZb, and a temperature compensation calculation unit 60 Based on the calculated adjustment value ΔZ, the drive command value A given by the drive instruction is adjusted, and the actuator control unit 40 that drives the actuator 20 with the adjusted drive command value A ′ is provided. The drive command value A for driving the actuator can be adjusted based on the thermal expansion amounts of the actuator 20 and the back plate 30, and the distortion of the light reflecting surface 10a of the mirror 10 can be compensated with the adjusted drive command value A ′. As a result, the deformable mirror can change the shape of the light reflecting surface with high accuracy.

  In addition, the mirror 10 of the deformable mirror 1 is generally made of low expansion glass having a small deformation due to temperature change, and has superior strength, thermal conductivity, heat resistance, and the like compared to general glass. ing. On the other hand, with the configuration described above, the deformable mirror 1 is configured to reflect light from the mirror 10 when the material of the mirror 10 is a metal, ceramic, semiconductor, or the like that has a large linear expansion coefficient and a large thermal expansion due to laser incident heat. The distortion of the surface 10a can be compensated, and the structure can be used at high strength and high temperature.

Embodiment 2. FIG.
In the first embodiment, the configuration for calculating the thermal expansion amount ΔZa of the actuator 20 based on the linear expansion coefficient CTEa and the temperature change amount ΔTa has been described. However, the second embodiment describes the configuration for actually measuring the thermal expansion amount ΔZa. To do.

FIG. 3 shows the configuration of the deformable mirror 1 of the second embodiment. In FIG. 3, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in FIG. 3, the deformable mirror 1 has a configuration in which a relative displacement measuring unit 70 is provided instead of the temperature sensor 50 a of the first embodiment, and a regulator 44 is added.

  The configurations of the mirror 10, the actuator 20, the back plate 30, the temperature sensors 50m and 50b, and the temperature compensation calculation unit 60 have the same functions as those in the first embodiment and will not be described.

  The relative displacement measuring unit 70 includes a relative displacement sensor 70m and a relative displacement sensor 70b. The relative displacement sensor 70m is attached to the vicinity of the actuator 20 on the mirror back surface 10b of the mirror 10, and the relative displacement sensor 70b is attached to the back plate 30 at a position facing the mirror back surface 10b. The relative displacement sensors 70 m and 70 b function to measure the displacement between the mirror 10 and the back plate 30, and output the relative displacement measurement value to the adjuster 44 of the actuator control unit 40 and feed back to the drive circuit 42.

  The adjuster 44 is provided in the actuator controller 40 and is disposed between the adjuster 43 and the drive circuit 42. The adjuster 44 functions to adjust the drive command value B ′ from the adjuster 43 based on the relative displacement measurement value from the relative displacement measurement unit 70. For example, the adjuster 44 subtracts the relative displacement measurement value from the drive command value B ′ to adjust the drive command value B ′, and outputs the adjusted drive command value B ″ to the drive circuit 42. The adjuster 44 may be replaced with the adjuster 43.

  Here, the relative displacement between the mirror 10 and the back plate 30 in the vicinity of the actuator 20 is substantially equal to the thermal expansion amount of the actuator 20. Therefore, the actuator control unit 40 inputs a relative displacement measurement value indicating an actual measurement value of the thermal expansion amount of the actuator 20 from the relative displacement measurement unit 70, and adjusts the drive command value B ′ based on the relative displacement measurement value. .

  Next, the processing operation in the deformable mirror 1 of the second embodiment will be described using the flowchart of FIG. The deformable mirror 1 according to the second embodiment performs processing in which the processing operations of Step ST201 and Step ST202 are added between Step ST103 and Step ST104 of the processing operation shown in FIG.

  The deformable mirror 1 starts a processing operation in response to an external driving instruction or a driving instruction from a preset program (start). The drive command unit 41 outputs a drive command value B given by an external drive instruction or a drive instruction from a preset program (step ST101).

  The temperature compensation calculation unit 60 receives temperature measurement values from the temperature sensors 50m and 50b, calculates a temperature change amount ΔTm based on the temperature measurement values from the temperature sensor 50m, and based on the temperature measurement values from the temperature sensor 50b. A temperature change amount ΔTb is calculated.

  Subsequently, the temperature compensation calculation unit 60 calculates the thermal expansion amount ΔZm of the mirror 10 by multiplying the linear expansion coefficient CTEm of the mirror 10 and the temperature change amount ΔTm, and the linear expansion coefficient CTEb of the back plate 30 and the temperature change amount ΔTb. To calculate the thermal expansion amount ΔZb of the back plate 30.

  The temperature compensation calculation unit 60 adds the thermal expansion amounts ΔZm and ΔZb, calculates the adjustment value ΔZ ′, and outputs it to the adjuster 43 (step ST102).

  When the controller 43 receives the drive command value B from the drive command unit 41, the adjuster 43 receives the adjustment value ΔZ ′ from the temperature compensation calculation unit 60. The adjuster 43 subtracts the adjustment value ΔZ ′ from the drive command value B for adjustment, and outputs the adjusted drive command value B ′ to the adjuster 44 (step ST103).

  Here, the relative displacement measuring unit 70 measures the displacement between the mirror 10 and the back plate 30 by using the relative displacement sensor 70m and the relative displacement sensor 70b, and outputs the relative displacement measurement value to the adjuster 44.

  When the drive command value B ′ is input from the adjuster 43 (step ST201), the adjuster 44 of the actuator control unit 40 inputs the relative displacement measurement value from the relative displacement measurement unit 70, and measures the relative displacement from the drive command value B ′. The drive command value B ′ is adjusted by subtracting the value, and the adjusted drive command value B ″ is output to the drive circuit 42 (step ST202).

  When the drive command value B ″ is input from the adjuster 44, the drive circuit 42 outputs a drive command to the actuator 20 based on the drive command value B ″ (step ST104). The actuator 20 presses the mirror back surface 10b by displacing the movable end 20a in accordance with the drive command input from the drive circuit 42.

  The mirror 10 is pressed from the mirror back surface 10b to the movable end 20a, and is deformed in the normal direction of the mirror 10 (step ST105).

  As described above, according to the second embodiment, the deformable mirror 1 is arranged between the mirror 10 and the back plate 30 by using the relative displacement sensor 70m and the relative displacement sensor 70b instead of the temperature sensor 50a of the first embodiment. Based on the relative displacement measurement unit 70 for measuring the displacement and the relative displacement measurement value from the relative displacement measurement unit 70, the drive command value B ′ from the adjuster 43 is adjusted by the adjuster 44 and output to the drive circuit 42. Since the actuator control unit 40 is provided, the mirror 10 having the light reflecting surface 10a on one surface, the actuator 20 connected to the other surface 10b of the mirror 10 to deform the mirror 10, and the actuator 20 are held. The back plate 30 provided opposite to the other surface of the mirror 10 and a temperature sensor for measuring each temperature of the mirror 10 and the back plate 30 The thermal expansion amounts ΔZm and ΔZb are calculated based on 0 m and 50 b, the respective temperature measurement values input from the temperature sensors 50 m and 50 b, and the linear expansion coefficients of the mirror 10 and the back plate 30 set in advance. The displacement of the actuator 20 disposed between the mirror 10 and the back plate 30 is detected by the temperature compensation calculation unit 60 that calculates the adjustment value ΔZ ′ obtained by adding the expansion amounts ΔZm and ΔZb, and the relative displacement sensor 70 m and the relative displacement sensor 70 b. Based on the relative displacement measurement unit 70 to be measured, the adjustment value ΔZ ′ calculated by the temperature compensation calculation unit 60 and the relative displacement measurement value from the relative displacement measurement unit 70, the drive command value B given by the drive instruction is adjusted. The actuator control unit 40 that drives the actuator 20 with the adjusted drive command value B ″ is provided with the relative displacement measurement unit 70. The thermal expansion amount ΔZa of the actuator 20 is measured, the drive command value B ′ is adjusted based on the measured value of the thermal expansion amount ΔZa, and the distortion of the light reflecting surface 10a of the mirror 10 is adjusted with the adjusted drive command value B ″. Can be compensated. As a result, the deformable mirror 1 can obtain the same effects as those of the first embodiment.

Embodiment 3 FIG.
In the first and second embodiments, the configuration in which the drive command value is adjusted based on the thermal expansion amounts of the mirror 10, the actuator 20, and the back plate 30 has been described. In the third embodiment, the mirror 10, the actuator 20, the back A configuration using a cooling command value for cooling the plate 30 will be described.

  FIG. 5 shows a configuration of the deformable mirror 1 in the third embodiment. In FIG. 5, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 5, the deformable mirror 1 includes a mirror 10, an actuator 20, a back plate 30, an actuator control unit 40, a temperature sensor 50, a temperature compensation calculation unit 60, a cooling element 80, and a cooling control unit 90. Yes. The configurations of the mirror 10, the actuator 20, the back plate 30, the actuator control unit 40, and the temperature sensor 50 are the same as those in FIG.

  The cooling element 80 includes cooling elements 80m, 80a, and 80b, and is controlled by the cooling control unit 90. The cooling element 80 is, for example, a Peltier element that is cooled by being supplied with external electric energy and whose amount of cooling heat is controlled in accordance with the supply amount (cooling command value) of the electric energy.

  The cooling element 80m is attached to the mirror 10, and the amount of cooling heat is controlled by the cooling command value Qm from the cooling control unit 90. The cooling element 80 a is attached to the actuator 20, and the amount of cooling heat is controlled by the cooling command value Qa from the cooling control unit 90. The cooling element 80 b is attached to the back plate 30, and the amount of cooling heat is controlled by the cooling command value Qb from the cooling control unit 90.

  The cooling control unit 90 functions to supply electric energy to the cooling element 80 and control the cooling heat amount of each of the cooling elements 80m, 80a, and 80b based on the supply amount (cooling command value) of the electric energy. For example, the cooling control unit 90 supplies electric energy to the cooling elements 80m, 80a, and 80b with cooling command values Qm, Qa, and Qb based on an external cooling instruction. The cooling control unit 90 controls the amount of cooling heat of each cooling element 80m, 80a, 80b in this way.

  Further, the cooling control unit 90 functions to output the cooling command values Qm, Qa, Qb to the temperature compensation calculation unit 60 when supplying electric energy to the cooling element 80.

  In the deformable mirror 1, when a high-power laser is incident, the temperature rises due to laser incident heat, so that each component of the deformable mirror 1 is damaged or the light reflecting surface 10 a of the mirror 10 is thermally deformed. To do. Therefore, in order to prevent each component of the deformable mirror 1 from being damaged or thermally deformed, the cooling element 80m, 80a, 80b and the cooling control unit 90 are used to cool the mirror 10, the actuator 20, and the back plate 30. ing.

  However, even when the deformable mirror 1 is cooled in this way, when it is applied to the wavefront control of a laser beam in which the laser is intermittently turned on and off, or the laser power changes suddenly, Cooling by the cooling element is not in time for the temperature change due to the change. In addition, a temperature gradient due to a difference between the position where the laser incident heat is transmitted and the position of the cooling portion or a transient change in temperature occurs.

  Therefore, the temperature measurement values of the temperature sensors 50m, 50a, and 50b attached to the mirror 10, the actuator 20, and the back plate 30 respectively do not indicate typical temperatures of the mirror 10, the actuator 20, and the back plate 30, respectively. When the thermal expansion amount ΔZ is calculated based on the temperature change amounts ΔTm, ΔTa, ΔTb obtained by the temperature sensors 50m, 50a, 50b, a deviation from the actual thermal expansion amount occurs.

  Therefore, in the deformable mirror 1 of the third embodiment, in addition to the temperature change amounts ΔTm, ΔTa, ΔTb, the cooling command values Qm, Qa of the electric energy supplied from the cooling control unit 90 to the cooling elements 80m, 80a, 80b. , Qb, the drive command value C for driving the actuator 20 is adjusted.

  The temperature compensation calculation unit 60 is based on preset linear expansion coefficients of the mirror 10, the actuator 20, and the back plate 30, and temperature measurement values from the temperature sensors 50m, 50a, and 50b, and thermal expansion amounts ΔZm, ΔZa, and ΔZb. And the thermal expansion amounts f (Qm), f (Qa), and f (Qb) function based on the cooling command values Qm, Qa, and Qb from the cooling control unit 90.

  The temperature compensation calculation unit 60 calculates, for example, a temperature change amount ΔTm in which a temperature measurement value from the temperature sensor 50m has changed at a predetermined time, and multiplies the linear expansion coefficient CTEm of the mirror 10 by the temperature change amount ΔTm. The thermal expansion amount ΔZm is calculated. The temperature compensation calculation unit 60 calculates a temperature change amount ΔTa in which the temperature measurement value from the temperature sensor 50 a has changed at a predetermined time, and multiplies the linear expansion coefficient CTEa of the actuator 20 by the temperature change amount ΔTa to heat the actuator 20. An expansion amount ΔZa is calculated. The temperature compensation calculation unit 60 calculates a temperature change amount ΔTb in which the temperature measurement value from the temperature sensor 50b has changed at a predetermined time, and multiplies the linear expansion coefficient CTEb of the back plate 30 by the temperature change amount ΔTb to thereby calculate the back plate 30. The amount of thermal expansion ΔZb is calculated.

  The temperature compensation calculation unit 60 receives, for example, the cooling command values Qm, Qa, Qb from the cooling control unit 90, and the input cooling command values Qm, Qa, Qb and the heat capacities of the mirror 10, the actuator 20, and the back plate 30. Then, heat calculation is performed based on the laser incident heat and the heat transport amount of cooling, and the temperature distribution for each of the mirror 10, the actuator 20, and the back plate 30 is calculated. The temperature compensation calculation unit 60 calculates thermal expansion amounts f (Qm), f (Qa), and f (Qb) based on the temperature distribution for each of the mirror 10, the actuator 20, and the back plate 30.

Further, as shown in the following equation (5), the temperature compensation calculation unit 60 adjusts the amount of thermal expansion ΔZm, ΔZa, ΔZb, f (Qm), f (Qa), and f (Qb) as a total adjustment value ΔZ. It functions to calculate ″.

ΔZ ″ = ΔZm + f (Qm) +, ΔZa + f (Qa) + ΔZb + f (Qb) (5)

  Thus, the deformable mirror 1 cools the mirror 10, the actuator 20, and the back plate 30 to an appropriate temperature range by controlling the cooling command values Qm, Qa, and Qb for each by the cooling control unit 90. It is configured to

Next, the processing operation of the deformable mirror 1 of Embodiment 3 will be described using the flowchart of FIG. The deformable mirror 1 according to the third embodiment performs the processing operation of Step ST301 instead of Step ST102 of the processing operation shown in FIG.
In FIG. 6, the process in step ST101 is the same as that in FIG.

  When the drive command unit 41 of the actuator control unit 40 outputs the drive command value C in step ST101, the temperature compensation calculation unit 60 calculates the temperature change amount ΔTm based on the temperature measurement value from the temperature sensor 50m, and from the temperature sensor 50a. The temperature change amount ΔTa is calculated based on the temperature measurement value of, and the temperature change amount ΔTb is calculated based on the temperature measurement value from the temperature sensor 50b.

  Subsequently, the temperature compensation calculation unit 60 calculates the thermal expansion amount ΔZm of the mirror 10 by multiplying the linear expansion coefficient CTEm of the mirror 10 by the temperature change amount ΔTm, and calculates the linear expansion coefficient CTEa and the temperature change amount ΔTa of the actuator 20. The thermal expansion amount ΔZa of the actuator 20 is calculated by multiplication, and the thermal expansion amount ΔZb of the back plate 30 is calculated by multiplying the linear expansion coefficient CTEb of the back plate 30 by the temperature change amount ΔTb.

  Further, the temperature compensation calculation unit 60 inputs the cooling command values Qm, Qa, Qb for cooling the mirror 10, the actuator 20, and the back plate 30 from the cooling control unit 90, and the cooling command values Qm, Qa, Qb Then, heat calculation is performed based on the heat capacities of the mirror 10, the actuator 20, and the back plate 30, the laser incident heat, and the cooling heat transport amount, and the temperature distribution for each of the mirror 10, the actuator 20, and the back plate 30 is calculated. The temperature compensation calculation unit 60 calculates thermal expansion amounts f (Qm), f (Qa), and f (Qb) based on the temperature distribution for each of the mirror 10, the actuator 20, and the back plate 30.

  The temperature compensation calculation unit 60 calculates an adjustment value ΔZ ″ obtained by adding the respective thermal expansion amounts ΔZm, ΔZa, ΔZb, f (Qm), f (Qa), and f (Qb) to the actuator control unit 40 (step ST301). ). When the process of step ST301 ends, the deformable mirror 1 proceeds to step ST103. The processing from step ST103 to step ST105 is the same as that in FIG.

  As described above, according to the third embodiment, the deformable mirror 1 supplies the cooling elements 80m, 80a, and 80b that cool the mirror 10, the actuator 20, and the back plate 30, and the cooling elements 80m, 80a, and 80b. A cooling control unit 90 that outputs cooling command values Qm, Qa, and Qb, and a temperature compensation calculation unit 60 that calculates an adjustment value ΔZ ″ based on the cooling command values Qm, Qa, and Qb from the cooling control unit 90 are provided. Since it comprised in this way, even if it is the case of the deformable mirror 1 which cools the mirror 10, the actuator 20, and the backplate 30 with the cooling element 80, the distortion of the light reflection surface 10a of the mirror 10 can be compensated. As a result, the same effect as in the first embodiment can be obtained.

  In the first to third embodiments, the case where the temperature of the deformable mirror rises due to laser incident heat has been described. However, the present invention can be applied to the case where the deformable mirror 1 is operated in a wide temperature range of a high temperature environment or a low temperature environment. .

  In the first to third embodiments described above, the case where the present invention is used for a deformable mirror useful for light wavefront control, optical path length control, and the like has been described. It may be configured by applying.

  DESCRIPTION OF SYMBOLS 1 Variable shape mirror, 10 mirror, 10a Light reflecting surface, 10b Mirror back surface, 20 Actuator, 20a Moving end, 30 Back plate, 40 Actuator control part, 41 Drive command part, 42 Drive circuit, 43,44 Adjuster, 50m Temperature Sensor (for mirror), 50a Temperature sensor (for actuator), 50b Temperature sensor (for back plate), 60 Temperature compensation calculation unit, 70 Relative displacement measurement unit, 70m Relative displacement sensor (mirror side), 70b Relative displacement sensor (back) Plate side), 80 cooling element, 80m cooling element (for mirror), 80a cooling element (for actuator), 80b cooling element (for back plate), 90 cooling control unit.

Claims (3)

A mirror having a light reflecting surface;
An actuator for deforming the mirror;
A back plate for holding the actuator;
A temperature sensor for measuring each temperature of the mirror, the actuator, and the back plate;
Temperature compensation calculation for calculating an adjustment value for adjusting the amount of deformation of the mirror based on each temperature measurement value input from the temperature sensor and a preset linear expansion coefficient of the mirror, the actuator, and the back plate And
An actuator controller that drives the actuator by adjusting a given drive command value based on the adjustment value calculated by the temperature compensation calculator;
Deformable mirror with A mirror having a light reflecting surface;
An actuator for deforming the mirror;
A back plate for holding the actuator;
A temperature sensor for measuring each temperature of the mirror and the back plate;
A temperature compensation calculation unit that calculates an adjustment value for adjusting the deformation amount of the mirror based on each temperature measurement value input from the temperature sensor, the mirror set in advance, and the linear expansion coefficient of the back plate;
A relative displacement measuring unit for measuring a displacement between the mirror and the back plate;
An actuator control unit that adjusts a given drive command value to drive the actuator based on the adjustment value calculated by the temperature compensation calculation unit and the relative displacement measurement value from the relative displacement measurement unit;
Deformable mirror with A cooling element for cooling the mirror, the actuator, and the back plate;
The deformable mirror according to claim 1, wherein the temperature compensation calculation unit calculates an adjustment value based on a cooling command value supplied to the cooling element.

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