JPH09178922A - Reflection mirror antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the spread of image by correcting thermal deformation generated at a reflection mirror antenna by driving an actuator provided on the rear side of reflection mirror antenna. SOLUTION: Concerning a reflection mirror antenna 3, plural partial mirror members are arranged according to the levels of their average linear expansion coefficients or the respective partial mirror members are arranged in the order of change rate levels of their linear expansion coefficients in thickness direction. An actuator 5 impresses force to the partial mirror members by stretching and compressing its driving shaft 6 through a driving part 7 while fixing one end of that driving shaft 6 on the rear surface of the reflection mirror antenna 3. Concerning a processing part 8, the temperature ΔT of the reflection mirror antenna 3 is inputted from a temperature sensor 4, temperature difference ΔT from a reference temperature is calculated and while using this temperature difference ΔT, a command value Δf of correction force for each actuator 5 is operated and outputted to an actuator controller 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector antenna device used for a large reflecting telescope or the like.

[0002]

2. Description of the Related Art FIG. 19 is an explanatory view showing a conventional reflector antenna device. In the figure, reference numeral 1 denotes a boule as a unit for manufacturing a mirror material, and reference numeral 2 denotes a stack as a partial mirror material formed by stacking and bonding a plurality of the boules 1.
Reference numeral 3 is a reflector antenna in which a plurality of the stacks 2 are arranged in a predetermined concave shape such as a paraboloid or a hyperboloid, and adjacent stacks 2 are bonded to each other and joined.

Next, the operation will be described. The surface of the reflector antenna 3 is polished with a very high precision to a predetermined concave shape such as the above-mentioned paraboloid or hyperboloid, and reflects electromagnetic waves such as visible rays and infrared rays coming from celestial bodies, and focuses on the focus. Form an image of a celestial body.

Here, since the linear expansion coefficient of the boule 1 is not zero, when the temperature changes, the reflector antenna 3 undergoes thermal deformation. If the linear expansion coefficient of the entire reflector antenna 3 is uniform, the reflector antenna 3 is deformed into a similar shape, so that the electromagnetic waves from the celestial body are collected at a position similar to the original focal point, and an image of the celestial body is formed. Form an image. However, in reality, there is non-uniformity in the linear expansion coefficient, and the thermal deformation due to the non-uniformity causes the surface of the reflector antenna 3 to be distorted, and causes deterioration in imaging performance.

Therefore, when the stack 2 is prepared, the boules 1 are combined based on the data of the rate of change of the coefficient of linear expansion in the thickness direction of the boules 1 measured in advance, and the average rate of change is made close to zero. That is, the stack 2 is configured by combining the Booleans 1 that are considered to cancel each other. Thereby, the thermal deformation of each stack 2 is reduced. The reflector antenna 3 is configured by arranging such stacks 2 at random.

[0006]

Since the conventional reflector antenna device is configured as described above, the nonuniformity of the remaining rate of change of the linear expansion coefficient in the thickness direction among the stacks 2 and Due to the non-uniformity of the average linear expansion coefficient of each stack 2, there is a problem that non-uniform thermal deformation occurs in the entire reflector antenna 3.

The present invention has been made to solve the above problems, and controls the thermal deformation of the reflector antenna so that it is a relatively simple pattern that is easy to correct, and the thermal deformation that occurs is an actuator. Corrected by
It is an object to obtain a reflector antenna device that reduces the spread of an image.

[0008]

In the reflector antenna device according to the invention described in claim 1, the magnitude of the average linear expansion coefficient of a plurality of partial mirror materials is measured in advance, and the average linear expansion coefficient of these average linear expansion coefficients is calculated. Adjacent to each other in the descending order, the partial mirror materials are arranged in a spiral shape or in a line shape from one end to the other end, and are arranged in the order of the average linear expansion coefficient between the adjacent lines in order of the reflector mirror antenna. Is configured to correct the thermal deformation generated in the reflecting mirror antenna by driving an actuator provided on the back surface side of the reflecting mirror antenna.

In the reflecting mirror antenna device according to the second aspect of the present invention, the rate of change is measured in advance from the linear expansion coefficient distribution in the thickness direction of the plurality of partial mirror materials.
Adjacent to each other in the order of magnitude of the rate of change, the partial mirror materials are arranged in a spiral shape or a line shape from one end to the other end, and are arranged in the order of magnitude of the rate of change between adjacent lines. Then, a reflecting mirror antenna is configured to correct the thermal deformation generated in the reflecting mirror antenna by driving a plurality of actuators provided on the back surface side of the reflecting mirror antenna.

According to another aspect of the present invention, there is provided a reflector antenna device, wherein a plurality of partial mirror materials are arranged based on their linear expansion coefficients to form a reflector antenna, and the reflector antenna has a predetermined shape. And a correction force to be applied to a plurality of actuators provided on the back side of the reflector antenna when the difference between the predetermined temperature and the temperature of the reflector antenna is a unit temperature. And a temperature difference between the temperature of the reflecting mirror antenna measured by the temperature measuring means and the predetermined temperature from the memory means, and a correction for the temperature difference based on the correction force from the memory means. The force is calculated by the calculation means, the correction force is applied to the corresponding actuator to drive each actuator, and the thermal deformation of the reflector antenna is corrected.

According to a fourth aspect of the present invention, there is provided a reflector antenna device, wherein deformation measuring means for measuring the deformation of the surface of the reflector antenna and a plurality of actuators for correcting the deformation are provided, and the calculating means is provided. , Mode expansion of the deformation of the surface of the reflector antenna is performed from the measured deformation amount, and the correction force is calculated by selecting the mode to be corrected in a predetermined order in order to make the residual deformation equal to or less than the predetermined deformation amount. The correction force is applied to the corresponding actuator to drive each actuator to correct the deformation of the reflector antenna.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. 1 is a perspective view showing a reflection antenna portion of a reflection mirror antenna device according to a first embodiment of the present invention. In the figure, 1 is a boule, 2 is a stack as a partial mirror material, and 3 is a reflector antenna device in which 37 stacks 2 are arranged and adjacent ones are bonded and bonded to each other. The numbers "1" to "37" given to each of these stacks 2 indicate the order of magnitude of the respective average linear expansion coefficients. Although not shown in the figure, a plurality of actuators are attached to the back surface of the reflector antenna 3 so that the deformation of the reflector antenna 3 can be corrected by pushing and pulling the actuators.

Next, the operation will be described. The stack 2 is composed of a combination of the Boolean 1 that cancels out the thermal deformation, in that the operation of the reflector antenna 3 as an imaging mirror and the thermal deformation due to the non-uniformity of the linear expansion coefficient cause the deterioration of the imaging performance. This is the same as in the case of the conventional reflector antenna 3, and a description thereof will be omitted.

Although the stack 2 is composed of the combination of the boule 1 which cancels out the thermal deformation, some change rate of the linear expansion coefficient in the thickness direction remains, and this change rate is obtained for each stack 2. Vary between. There is also non-uniformity between the average linear expansion coefficients of the stacks 2.

Now, even if the surface of the reflector antenna 3 is correctly set to a predetermined concave shape, the star image of the celestial body does not become a point due to the diffraction phenomenon of light, and the theoretical limit based on the aperture diameter D and the wavelength λ. FWHM (Full Width at Half Maxim
um). This FWHM is generally expressed by the following equation.

[0016]

[Equation 1]

This theoretical limit FWHM has a light intensity of 1 in the light intensity distribution of the star image at the focal plane as shown in FIG.
It is the width when it becomes / 2. For example, visible light (λ = 0.5
.mu.m), the diameter of the reflector antenna 1 is 7.5 m, and the focal point of the F ratio of 2 is 1.02 .mu.m.

Thus, the theoretical limit FWH of the size of the star image
M is determined by the aperture diameter D and the wavelength λ, and becomes smaller as the aperture diameter D becomes larger, and the condensing power increases. Therefore, conventionally, as an improvement of the reflector antenna device, the reflector antenna 3 has been increased in diameter.

That is, increasing the diameter of the reflector antenna 3 reduces the size of the star image, and has important significance for improving the resolution, detecting limit, and shortening the exposure time. However, in reality, the shape of the reflector antenna 3 is, for example, as shown in FIG.
Thermal deformation occurs as shown in. When such thermal deformation occurs, the light incident from the star is scattered and the star image is shown in Fig. 3.
As shown in (b), the intensity distribution is widened, resulting in a blurred image.

Here, the focus intensity I is approximately expressed by the following equation using the wavelength λ and the RMS value (σ) of the mirror surface deformation.

[0021]

[Equation 2]

However, the focal intensity when there is no mirror surface deformation of the reflector antenna 3 is 1.0. This relationship is as shown in FIG. As a result, in order not to deteriorate the imaging performance, it is necessary to suppress the mirror surface deformation to about one tenth of the wavelength, that is, 0.01 μm in the case of visible light (λ = 0.5 μm).

However, even if the diameter of the reflector antenna 3 is increased, if the heat deformation of the reflector antenna 3 is large, the advantage of increasing the diameter cannot be fully utilized, and if the diameter of the reflector antenna 3 is increased, each stack is increased. The thermal deformation of the reflector antenna 3 tends to increase due to the variation in the linear expansion coefficient of 2.

Here, the coefficient of linear expansion CTE of the stack 2 is
(Coefficient of Thermal Expansion) is defined by the following equation.

[0025]

(Equation 3)

However, L ₀ Is the length at 0 ° C, L is T
The length in ° C. From this, the temperature is from 0 ℃ to T ℃
The amount of change in length ΔL when it changes to
₀ ) and ΔT are set to (T-0), the following equation is obtained, and the expansion is made in this direction in any direction.

[0027]

(Equation 4)

Therefore, regarding the thermal deformation of the reflector antenna 3, when the CTE is uniform, (1 + CT
Expands by E × ΔT) times. This is a similar deformation, and the property that the focal position moves to a similar position and converges to one point does not change. However, in reality, the reflector antenna 3
There is a non-uniformity of the coefficient of linear expansion CTE between the stacks 2 constituting the. For this reason, the reflector antenna 3 partially expands or contracts to cause distortion on the mirror surface, and the star image does not converge to one point.

Next, a case where the linear expansion coefficient CTE varies between the stacks 2 of the reflector antennas 3 will be described. Here, variations in the linear expansion coefficient between the stacks 2 of the reflector antenna 3 are classified into the following two types.

(1) The case where the average linear expansion coefficient of each stack 2 varies among the stacks 2. Reflector antenna 3
The difference between the average of the linear expansion coefficients of all of the stacks 2 and the average linear expansion coefficient of the predetermined stack 2 is defined as Δα of that stack. If this Δα varies for each stack 2, the manner of change in curvature differs for each stack 2, and as a result, mirror surface deformation of the reflector antenna 3 occurs.

(2) This is a case where the rate of change of the linear expansion coefficient of each stack 2 in the thickness direction varies among the stacks 2. In the stack thickness direction, the linear expansion coefficient CT as shown in FIG.
There is a distribution of E. When the linear expansion coefficient distribution is linearly approximated, the rate of change of the straight line is defined as Δβ. This deformation due to Δβ is a bimetallic deformation, and the curvature of each stack 2 changes. Actually, since the change in the curvature is different for each stack 2, the mirror surface deformation results.

As described above, the deformation of the stack 2 has Δα and Δβ. By the way, since Δα and Δβ of each stack 2 have different values, for example, when performing a certain arrangement in descending order of the value of Δβ by paying attention to the value of Δβ of each stack, the value of Δα is random. It becomes an array. However, when the amount of mirror surface deformation due to Δα is sufficiently smaller than that due to Δβ, the reflecting mirror antenna 3 is controlled by controlling the arrangement method in descending order of the value of Δβ.
Can be produced in a desired pattern.

6 (a) and 6 (b), the reflecting mirror antenna 3 is constructed by sequentially arranging in a line from the one end to the other end in the descending order of the value of Δβ. FIG.
The numbers shown in (a) and (b) are shown in descending order of the value of Δβ of each stack.

FIGS. 6C and 6D show the stacks arranged in descending order of the value of dβ from the peripheral portion to the central portion and from the central portion to the peripheral portion. In addition, an arrangement method as shown in FIG.

As described above, when the reflector antenna 3 is constructed by the arrangements shown in FIGS. 6A to 6E in the descending order of the value of Δβ of each stack 2, the adjacent stacks 2 push and pull each other. Force is applied to cause thermal deformation, which is a very gentle and relatively simple pattern.

For example, in the case of the array as shown in FIG.
The deformation pattern is as shown in FIG.
In the case of the arrangement as shown in (c), the deformation pattern is shown in FIG.
(B). FIGS. 7A and 7B are contour maps that connect points at which the deformation amount ΔZ is equal at each point of the reflector antenna 3.

In FIG. 7A, the contour line has a high density at one peripheral edge and a low density at the peripheral edge in the opposite direction.
Further, in FIG. 7B, the density of the peripheral portion of the reflector antenna 3 is high and the density of the central portion thereof is low. For example, the cross-sectional shape of the reflector antenna 3 when cut along XX in FIG. 7A is as shown in FIG.

As described above, the arrangement of the stacks 2 as shown in FIGS. 6A to 6E makes the thermal deformation of the entire reflector antenna 3 a relatively simple pattern. This means that when the thermal deformation of the reflector antenna 3 is used as an actuator and a force is applied to each stack 2 to correct it, the number of actuators can be reduced.

That is, the thermal deformation of the reflector antenna 3 is shown in FIG.
As is clear from a comparison between the case of the relatively simple pattern shown in FIG. 9A and the case not shown in FIG. 9B, the number of actuators required increases as the thermal deformation pattern becomes more complicated. Become. Note that FIG.
(B) shows the sectional shape of the entire reflector antenna 3.

The above is a description of the case where the deformation caused by Δβ is larger than the deformation caused by Δα, but the same applies when the deformation caused by Δα is larger than the deformation caused by Δβ. Also, for some of the plurality of stacks 2, Δ
When the deformation due to β is larger than the deformation due to Δα and the remaining deformation is due to Δα is larger than the deformation due to Δβ, it is sufficient to pay attention to either Δα or Δβ, depending on which stack 2 is larger. .

As described above, according to the first embodiment, a plurality of partial mirror materials are used according to the magnitude of the average linear expansion coefficient, or each partial mirror material is changed in the rate of change of the linear expansion coefficient in the thickness direction. By arranging in order of size, the thermal deformation pattern of the entire reflector antenna becomes a relatively simple pattern, and a reflector antenna device capable of correcting the thermal deformation with a small number of actuators is realized. To do.

Embodiment 2. 10 is a configuration diagram showing a reflector antenna device according to a second embodiment of the present invention.
In the figure, 3 is a reflector antenna, focusing on the rate of change Δβ when the linear expansion coefficient distribution in the thickness direction of a plurality of stacks 2 is linearly approximated. ) To (e) are arranged to form a predetermined concave surface shape. Reference numeral 4 denotes a temperature sensor as a temperature measuring means provided on or near the back side of the reflector antenna 3. 5 is an actuator, one end of the drive shaft 6 of which is fixed to the back surface of the reflector antenna 3,
The drive shaft 6 is expanded and contracted by the drive unit 7 to form the stack 2
The force is applied to. Reference numeral 8 is a processing unit, and 9 is an actuator controller as a control unit that supplies the correction force from the processing unit 8 to the corresponding actuator 5 to drive the actuator 5.

FIG. 11 is a block diagram including a processing unit 8 used in the reflector antenna device according to the second embodiment of the present invention, and FIG. 12 is a flowchart thereof. 11 and 12, 10 is a memory as a storage unit, 11 is a CPU as an arithmetic unit, and the processing unit 8 includes the memory 10 and the CPU 11. The memory 10 stores a reference temperature T ₀ that is a reference when the reflector antenna 3 has a predetermined concave shape, that is, an ideal parabolic shape or a hyperboloid shape, and the reference temperature obtained in advance is stored. When the temperature difference ΔT between T ₀ and the temperature of the reflector antenna 3 is 1 ° C., the correction force to be applied to each actuator 5 when correcting the thermally deformed reflector antenna 3 into a predetermined concave shape. Is stored in correspondence with each actuator 5.

That is, for the correction forces f ₁ , f ₂ , ..., F _n corresponding to each actuator 5, Δβ of each stack 2 is measured at the time of manufacturing a plurality of stacks, and based on the data of these Δβ. A reflector antenna model is created with the above arrangement, and the correction force to be applied to each actuator 2 is obtained in advance by the finite element method when the temperature difference ΔT is 1 ° C. as described later, and this is stored in the memory. It is stored in 10.

The CPU 11 receives the temperature T ₁ of the reflector antenna 3 from the temperature sensor 4 and the reference temperature T ₀ from the memory 10 to calculate the temperature difference ΔT as shown in FIG. The correction force f corresponding to each actuator 5 stored in the memory 10 is calculated using the difference ΔT.
₁ , f ₂ , ..., F _n are sequentially taken out, and the command value of the correction force for each actuator is calculated by the following equation and output to the actuator controller 9.

[0046]

(Equation 5)

On the other hand, the actuator controller 9
It receives the command value Δf _i of the correction force supplied from the CPU 11, determines which actuator 5 this command value Δf _i should be applied to, and supplies the command value Δf _i corresponding to that actuator 5. In this determination, an address may be added to the command value Δf _i , and the corresponding actuator 5 may be selected by determining this address.

Further, each of these command values is transmitted to the drive section 7 of the actuator 5, for example, a current corresponding to the command value is flowed, and a correction force corresponding to the command value is generated by the electromagnetic force and is applied. It is configured to apply a force to the stack 2. Here, a method for obtaining the correction forces f ₁ , f ₂ , ..., F _n stored in the memory 10 by using the finite element method will be described. If the Δα or Δβ of each stack 2 forming the reflector antenna 3 is known, the finite element method can be used to calculate the amount of thermal deformation at each point of the reflector with respect to an arbitrary temperature change. Now m stacks 2
Considering the reflector antenna 3 consisting of, the stacks 2 are numbered as shown in FIG.
Will be referred to as Δαj, and Δβ will be referred to as Δβj (j = 1, 2, ..., M).

As shown in FIG. 14, the finite element method divides a mirror surface into a large number of minute elements, and gives each element a plant value such as Young's modulus, Poisson's ratio, linear expansion coefficient or a load to calculate deformation. Finally, the displacement at each vertex (lattice point) of the element can be obtained.

On the other hand, in addition to the above, according to the finite element method, a matrix (rigidity matrix) that links the load applied to the actuator point and the deformation amount at the actuator point can be calculated. The relationship is that the displacement at each actuator point is ΔZ ₁ , ΔZ ₂ , ..., Z _n , and the load applied to each actuator point is f ₁ , f ₂ , ..., F _n , n.
When the stiffness matrix of × n is K, it can be expressed as the following equation.

[0051]

(Equation 6)

Therefore, the stiffness matrix K calculated
Using the inverse matrix K ^{−1 of} , the load necessary to cause the deformation can be obtained from the deformation amount as in the following equation.

[0053]

(Equation 7)

Therefore, if the amount of thermal deformation generated when the temperature difference ΔT = 1 ° C. calculated in advance by the finite element method is substituted into ΔZj on the right side of the above equation, it is necessary to generate such deformation. , Forces f ₁ , f ₂ , ..., F _n are obtained. Therefore, those in which f ₁ , f ₂ , ..., F _n are reversed are the correction forces necessary to cancel the thermal deformation. In this way, the correction force to be applied to the actuator when ΔT = 1 ° C. is obtained and stored in the memory 9.

As described above, according to the second embodiment, when the reflector antenna is thermally deformed, the correction force for the unit temperature corresponding to each actuator is stored in the storage means, and the correction force is reflected. By calculating the correction force to be actually applied to each actuator by measuring the temperature of the mirror antenna, and by supplying the correction force to the corresponding actuator by the control means, thermal deformation of the reflector antenna is performed. It is possible to realize a reflector antenna device capable of automatically correcting the above and always maintaining a predetermined concave shape even in an area where the temperature changes drastically.

Embodiment 3 Next, FIG. 15 is a configuration diagram showing a reflector antenna device according to a third embodiment of the present invention. In the figure, 3 is a reflector antenna, 5 is an actuator, 8 is a memory 10 and a CPU as a calculation means.
A processing unit including 11 and an actuator controller 9 as a control unit are the same as or equivalent to those denoted by the same reference numerals in FIG. 10, and therefore detailed description thereof will be omitted. Reference numeral 12 denotes a mirror surface deformation measuring device as a deformation measuring means for detecting the interference of light or the deviation of reflected light and measuring the deformation of each point on the surface of the reflecting mirror antenna 3.

Next, the operation will be described. First, the mode expansion of the surface deformation of the reflector antenna 3 will be described.
As is well known, string vibration can be considered as a superposition of natural vibration modes. FIG. 16 is a diagram explaining the vibration of the string and its natural vibration mode. In this way, each mode φ _k (x), k = 1 ... And amplitudes A _k , k = 1 ... Are obtained, and the vibration of the string φ (x) is expressed in the form of the sum of the following equations. It is said that vibration is expanded into modes.

[0058]

(Equation 8)

The mode expansion of surface deformation can be considered in the same manner. Modes used for expansion include Zernike series, infinite term or finite term series represented by a function of spatial frequency such as two-dimensional Fourier series, and natural vibration mode. Here, an example of developing in the natural vibration mode will be described.

FIG. 17 is an example of a contour map of the natural vibration mode of the reflector antenna 3 in which three points at equal intervals on the outer periphery are fixed. This can be calculated from the model of the reflector antenna 3 using the finite element method. The number assigned to each mode is a mode number, which has the property that the spatial frequency is small and the force required to obtain the same maximum amplitude may be small in ascending order. Hereinafter, a mode with a small mode number is called a low-order mode, and a mode with a large mode number is called a high-order mode.

If the deformation pattern of the mode with the mode number k is _represented by φ _k (γ, θ) (γ and θ are polar coordinates of the position on the mirror surface), the mirror surface deformation φ (γ, θ) is It can be expressed by superposition of each mode as in the following equation.

[0062]

[Equation 9]

Here, A _k is a mode coefficient (corresponding to the amplitude of each mode). As the expansion method, there are a method of taking the inner product of the deformation measurement value and each mode, a method of fitting by the least square method, and the like. Since the natural vibration modes are orthogonal to each other, both methods are essentially the same.

As described above, the natural vibration modes are likely to occur in the order of mode numbers. Therefore, the higher-order mode is less likely to occur than the lower-order mode, and thus has a small amplitude. However, when the correction force that directly cancels the deformation is obtained from the surface deformation measurement value, the fine pitch deformation,
That is, since the higher-order mode is also a correction target, a large correction force is required to correct it, and the effect is small because the amplitude is originally small. Therefore, once the mode expansion is performed and only the main deformation mode is selected and corrected, the correction can be efficiently performed with a small correction force.

FIG. 18 is a flowchart of the processing in the processing unit 8 of the third embodiment. In the case of the natural vibration mode, since the mode pattern cannot be obtained in the functional form, it is obtained as a value at each coordinate point on the reflecting mirror surface and stored in the memory 10 in the processing unit 8 together with the mode number and the coordinate.

When the measurement data is input from the mirror surface deformation measuring device 12, the CPU 11 of the processing unit 8 causes the memory 10 to read the data.
The value of this mode is called from and the mode coefficient A _k of the mode to be corrected is calculated using the least square method. Next, CP
U11 calculates the deformation correction amount at each actuator point using the mode coefficient A _k and the mode value.

Assuming that the correction is made from mode numbers 1 to N, first, A _k is obtained from k = 1 to N, and then the deformation correction amount ΔZ _i , i = 1 ... At the i-th actuator point. n will be calculated by the following equation. However, γ _i and θ _i are polar coordinates of the actuator point i.

[0068]

(Equation 10)

This ΔZ _i is the actual deformation φ (γ _i , θ _i ).
From N + 1 higher modes. Here, K ⁻¹ for converting the deformation correction amount ΔZ _i into the correction force Δf _j is obtained in advance by the method described above and stored in the memory 10 of the processing unit 8.

Therefore, the CPU 11 of the processing unit 8 calls the matrix K ^-1 for converting the deformation correction amount stored in the memory 10 into the correction force, and obtains the calculated correction amount ΔZ.
_The correction force for each actuator 5 is calculated by multiplying _i , i = 1 ... N and output to the actuator controller 7.

The actuator controller 9 uses this C
Upon receiving the correction force supplied from the PU 11, the corresponding command value is supplied to each actuator 5. Each actuator 5
Generates a correction force corresponding to the command value and applies the force to the reflector antenna 3 to correct the deformation.

As described above, since the residual deformation is less than the amount designated in advance, the mode to be corrected is selected and the correction is applied. Therefore, the correction of the deformation having a high spatial frequency which does not need to be corrected is not performed. The force required for correction becomes smaller. Further, since the surface deformation is expanded to the mode once, even if one of the measured values is measured as an erroneous value due to noise etc., the amount of deformation can be estimated almost correctly and the correct correction force can be calculated. .

As described above, according to the third embodiment, the surface deformation amount of the reflector antenna is developed into a mode, and the mode to be corrected in order to make the residual deformation equal to or less than the predetermined deformation amount is determined. A reflecting mirror antenna device that is less likely to be affected by noise and that is capable of efficiently correcting deformation with a small force is realized by sequentially selecting and calculating the correction force and driving the actuator based on that.

[0074]

As described above, claims 1 and 2 are as described above.
According to the invention described above, the stacking is performed in the order of the magnitude of the rate of change of the average expansion coefficient or the coefficient of linear expansion in the thickness direction so that the generated thermal deformation pattern is a relatively simple antenna. Since it is configured, there is an effect that a reflector antenna device capable of correcting thermal deformation with a small number of actuators can be obtained.

According to the third aspect of the present invention, the correction force to each actuator is automatically calculated based on the difference between the detected temperature of the reflector antenna and the reference temperature. Since it is configured to correct the deformation, it is possible to always maintain a predetermined shape even when installed in an area where the temperature changes drastically, and it is possible to effectively reduce the spread of the image due to the thermal deformation of the reflector antenna. There is an effect that the antenna device can be obtained.

According to the fourth aspect of the present invention, the surface deformation of the reflector antenna is mode-developed, and the mode to be corrected is selected and corrected in a predetermined order so that the residual deformation becomes equal to or less than the predetermined deformation amount. Since the force is calculated and the actuator is driven based on the calculated force, it is possible to efficiently correct the deformation with a small force, it is not easily affected by noise, and the reflector antenna can maintain a highly accurate mirror surface. There is an effect that the device can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a reflector antenna portion of a reflector antenna device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a light intensity distribution of a light image on a focal plane.

FIG. 3 is an explanatory diagram showing reflection of light by a reflecting mirror antenna which has been thermally deformed and its light intensity distribution.

FIG. 4 is a characteristic diagram showing the intensity of a focal point with respect to mirror surface deformation.

FIG. 5 is an explanatory diagram showing a linear expansion coefficient distribution in the stack thickness direction.

FIG. 6 is a plan view of a reflector antenna device showing a stacking method according to the first embodiment of the present invention.

FIG. 7 is a contour diagram showing an example of thermal deformation of a reflector antenna.

8 is a cross-sectional view taken along line XX of thermal deformation of the reflector antenna shown in FIG. 7 (a).

FIG. 9 is an explanatory diagram showing thermal deformation of a reflector antenna.

FIG. 10 is a configuration diagram showing a reflector antenna device according to a second embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a processing unit thereof.

FIG. 12 is a flowchart showing processing by the processing unit.

FIG. 13 is an explanatory diagram for explaining the finite element method.

14 is an explanatory diagram for explaining the finite element method with FIG. 13. FIG.

FIG. 15 is a configuration diagram showing a reflector antenna device according to a third embodiment of the present invention.

FIG. 16 is an explanatory diagram showing development of the vibration of a string in a natural vibration mode.

FIG. 17 is a contour diagram showing an example of a natural vibration mode of a reflector antenna.

FIG. 18 is a flowchart showing processing of the processing unit in the third embodiment shown in FIG.

FIG. 19 is an explanatory diagram showing a conventional reflector antenna device.

[Explanation of symbols]

2 stack (partial mirror material), 3 reflector antenna, 4
Temperature sensor (temperature measuring means), 5 actuators, 9
Actuator controller (control means), 10 memory (storage means), 11 CPU (calculation means), 12
Mirror surface deformation measuring device (deformation measuring means).

Claims (4)

[Claims] 1. A plurality of partial mirror materials, whose magnitudes of average linear expansion coefficients have been measured in advance, are arranged adjacent to each other in the order of their magnitudes of average linear expansion coefficient, and have a spiral shape or one end to the other end. And a plurality of reflector antennas arranged in the order of the magnitude of the average linear expansion coefficient between adjacent lines in a line shape toward each other and joined to each other, and a plurality of reflector antennas on the back surface side of the reflector antenna. A reflector antenna device that is disposed and that has an actuator that corrects the thermal deformation that has occurred in the reflector antenna when driven. 2. A plurality of partial mirror materials, whose magnitudes of change rates have been measured beforehand from the linear expansion coefficient distribution in the thickness direction, are arranged adjacent to each other in the order of magnitude of change rates,
A spiral reflector, or a linear mirror extending from one end to the other end, which is arranged between adjacent lines in the order of the magnitude of the change rate, and is joined to each other. A plurality of reflector antenna devices are provided on the back surface side of the reflector, and an actuator that corrects the thermal deformation generated in the reflector antenna by driving the reflector antenna device. 3. A reflecting mirror antenna comprising a plurality of partial mirror materials arranged on the basis of their linear expansion coefficients and joining them together, and the reflecting mirror antenna arranged on the back surface side of the reflecting mirror antenna. A plurality of actuators for applying a force to the reflecting mirror antenna, temperature measuring means for measuring the temperature of the reflecting mirror antenna or in the vicinity thereof, and when the reflecting antenna has a predetermined shape. A predetermined temperature is stored, and when the temperature difference between the predetermined temperature and the temperature of the reflector antenna is a unit temperature, a correction force applied to each actuator is applied to correct the reflector antenna to the predetermined shape. Storage means for storing,
The temperature difference between the temperature from the temperature measuring unit and the predetermined temperature from the storage unit is calculated, and the correction force to be applied to each actuator with respect to the temperature difference is calculated based on the correction force from the storage unit. A reflecting mirror antenna device comprising: a calculation unit that performs the above operation; and a control unit that supplies the correction force from the calculation unit to the corresponding actuator to drive the actuator. 4. A reflector antenna, and a plurality of actuators provided on the back surface side of the reflector antenna and for applying a force to the reflector antenna to correct its shape.
Deformation measuring means for measuring the deformation of the surface of the reflector antenna, from the measured value of the amount of deformation measured by the deformation measuring means, the mode expansion of the deformation of the surface of the reflector antenna,
The residual deformation, which is the residual deformation obtained by subtracting the mode to be corrected by the actuator from the original deformation, should be selected in a predetermined order to correct the residual deformation so as to be equal to or less than a predetermined deformation amount, and should be applied to the actuator. A reflector antenna device comprising: a calculation unit that calculates a correction force; and a control unit that supplies the correction force from the calculation unit to the corresponding actuator to drive the actuator.