JP3322255B2 - Reflector antenna device - Google Patents

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 reflector 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 denotes 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 to a predetermined concave shape such as the above-described paraboloid or hyperboloid with extremely high precision, reflects electromagnetic waves such as visible light and infrared rays coming from a celestial body, 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 apparatus is constructed as described above, the non-uniformity of the rate of change of the remaining linear expansion coefficient in the thickness direction between the respective stacks 2 and the like. In addition, there is a problem that uneven heat deformation occurs in the entire reflector antenna 3 due to unevenness of the average linear expansion coefficient of each stack 2.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and controls a reflector antenna so as to have a relatively simple pattern which can easily correct the thermal deformation of the reflector antenna. Corrected by
An object of the present invention is to provide a reflector antenna device that reduces the spread of an image.

[0008]

According to a first aspect of the present invention, there is provided a reflector antenna device comprising a plurality of partial mirrors arranged on the basis of their linear expansion coefficients and joined to each other. An antenna, a plurality of actuators disposed on the back side of the reflector antenna and applying a force to the reflector antenna, deformation measurement means for measuring the deformation of the surface of the reflector antenna, and the deformation measurement From the measured value of the deformation amount measured by the means, the surface deformation of the reflector antenna is mode-expanded, and the residual deformation, which is the remaining deformation obtained by subtracting the mode corrected by the actuator from the original deformation, is specified in advance. A mode to be corrected is selected in a predetermined order to reduce the deformation amount or less, and the selected modes are combined to calculate a deformation correction amount in the actuator. A calculating means for calculating a correction force to be applied to Chueta, is supplied to the actuator corresponding correction force from said calculating means is obtained and a control means for driving the actuator.

In the reflector antenna device according to the second aspect of the present invention, a plurality of partial mirrors whose average linear expansion coefficient has been measured in advance are used to reduce the average linear expansion coefficient. Adjacent to each other in order, a spiral shape, or a line shape from one end to the other end, arranged in the order of the magnitude of the average linear expansion coefficient between the lines adjacent to each other, and a reflection formed by joining each other. A mirror antenna is provided.

In the reflector antenna device according to the present invention, a plurality of partial mirrors whose magnitude of the rate of change is measured in advance from the linear expansion coefficient distribution in the thickness direction are formed by changing the partial mirror material. Adjacent to each other in the order of the magnitude of the rate,
A reflector antenna is formed in a spiral shape or in a line shape from one end to the other end and arranged in the order of the rate of change between the lines adjacent to each other and joined to each other. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a perspective view showing a reflection antenna portion of a reflector antenna device according to Embodiment 1 of the present invention. In the figure, reference numeral 1 denotes a boule, 2 denotes a stack as a partial mirror material, and 3 denotes a reflector antenna device in which 37 stacks 2 are arranged and adjacent ones are bonded to each other and joined. The numbers "1" to "37" assigned to each of the stacks 2 indicate the order of the magnitude of the average linear expansion coefficient. Although not shown in the figure, a plurality of actuators are mounted on the back surface of the reflector antenna 3, and the deformation of the reflector antenna 3 can be corrected by pushing and pulling the actuator.

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 a combination of the boules 1 that cancel each other out of the thermal deformation, some rate of change in the coefficient of linear expansion in the thickness direction remains, and this rate of change is Between the two. 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 light diffraction phenomenon, and the theoretical limit based on the aperture D and the wavelength λ. FWHM (Full Width at Half Maxim
um). This FWHM is generally expressed by the following equation.

[0015]

(Equation 1)

The theoretical limit FWHM is that the light intensity in the light intensity distribution of the star image at the focal plane is 1 as shown in FIG.
/ 2 width. For example, visible light (λ = 0.5
μm), the diameter of the reflector antenna 1 is 7.5 m, and the focal point at an F ratio of 2 is 1.02 μm at the focal plane.

Thus, the theoretical limit FWH of the size of the star image
M is determined by the diameter D and the wavelength λ, and decreases as the diameter D increases, and the light collecting power increases. For this reason, the reflector antenna 3 has been conventionally made larger in diameter as an improvement of the reflector antenna device.

In other words, increasing the diameter of the reflector antenna 3 reduces the size of the star image, which is important for improving the resolution, improving the detection limit, and shortening the exposure time. However, in practice, the shape of the reflector antenna 3 is changed by the thermal expansion of the stack 2, for example, as shown in FIG.
Thermal deformation occurs as shown in FIG. When such thermal deformation occurs, the light incident from the stars is scattered, and the star image is shown in FIG.
As shown in (b), the intensity distribution is widened and becomes a blurred image.

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

[0020]

(Equation 2)

It is assumed that the focus intensity when the mirror antenna 3 is not deformed is 1.0. This relationship is as shown in FIG. Accordingly, in order not to deteriorate the imaging performance, it is necessary to suppress the mirror surface deformation to about one-tenths 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 thermal deformation of the reflector antenna 3 is large, the advantage of the increased diameter cannot be utilized, and if the diameter of the reflector antenna 3 is increased, each stack becomes larger. Due to the variation in the coefficient of linear expansion of 2, the thermal deformation of the reflector antenna 3 tends to increase.

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

[0024]

(Equation 3)

Where L ₀ Is the length at 0 ° C., and L is T
Length in ° C. From this, the temperature changes from 0 ° C to T ° C.
The amount of change ΔL in length when the length changes to (L−L)
₀ ), ΔT is (T−0), and the following expression is obtained, and the expansion is performed at this ratio in any direction.

[0026]

(Equation 4)

Therefore, regarding the thermal deformation of the reflector antenna 3, if the CTE is uniform, (1 + CT)
(E × ΔT) times. This is a similar deformation, and the property that the focal point converges to one point only by moving to a similar position does not change. However, actually, the reflector antenna 3
Are non-uniform in the coefficient of linear expansion CTE. For this reason, the reflector antenna 3 partially expands or contracts, causing a mirror surface distortion, and the star image does not converge at 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, the variation of the linear expansion coefficient between the stacks 2 of the reflector antennas 3 is 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 the stacks 2 constituting the stack and the average linear expansion coefficient of a predetermined stack 2 is defined as Δα of the stack. If this Δα varies from one stack 2 to another, the manner of changing the curvature differs for each stack 2, resulting in a mirror surface deformation of the reflector antenna 3.

(2) The case where the rate of change of the linear expansion coefficient in the thickness direction of each stack 2 varies between the stacks 2. In the thickness direction of the stack, the linear expansion coefficient CT as shown in FIG.
There is a distribution of E. The magnitude of the rate of change of the straight line when the linear expansion coefficient distribution is approximated by a straight line is defined as Δβ. The deformation due to Δβ is a bimetallic deformation, and the curvature of each stack 2 changes. Actually, since the change in the curvature differs for each stack 2, a mirror surface deformation occurs as a result.

As described above, Δα and Δβ exist in the deformation of the stack 2 as described above. By the way, since Δα and Δβ of each stack 2 have different values, for example, when focusing on the value of Δβ of each stack and performing a certain array in the order of larger values of Δβ, 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 of Δβ, the arrangement of the reflector antenna 3 is controlled by increasing the value of Δβ.
Can be generated in a desired pattern.

FIGS. 6 (a) and 6 (b) show a reflector antenna 3 which is sequentially arranged in a line from the one end to the other end in 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 periphery to the center and from the center to the periphery. In addition, an arrangement method as shown in FIG.

As described above, when the reflector antennas 3 are arranged in the order as shown in FIGS. 6A to 6E in order of the value of Δβ of each stack 2, the adjacent stacks 2 push and pull each other. And a thermal deformation occurs, which results in a very gentle, relatively simple pattern.

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

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

As described above, by the arrangement of the stacks 2 as shown in FIGS. 6A to 6E, the overall thermal deformation of the reflector antenna 3 becomes a relatively simple pattern. This means that when the thermal deformation of the reflector antenna 3 is corrected by applying a force to each of the stacks 2 using the actuators, 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 as shown in FIG. 9A and the case of the other case as shown in FIG. 9B, more actuators are required as the thermal deformation pattern becomes more complicated. Become. Note that FIG.
(B) shows the cross-sectional shape of the entire reflector antenna 3.

The above description has been made for the case where the deformation due to Δβ is larger than the deformation due to Δα. The same applies to the case where the deformation due to Δα is larger than the deformation due to Δβ. In addition, for some of the plurality of stacks 2, Δ
When the deformation due to β is larger than the deformation due to Δα, and for the rest, when the deformation due to Δα is larger than the deformation due to Δβ, attention may be paid to either Δα or Δβ depending on which stack 2 is larger. .

As described above, according to the first embodiment, a plurality of partial mirrors are used according to the magnitude of the average linear expansion coefficient, or each partial mirror is used according to the rate of change of the linear expansion coefficient in the thickness direction. By arranging them in the order of the size, the heat deformation pattern as a whole of the reflector antenna exhibits a relatively simple pattern, and a reflector antenna device capable of correcting the heat deformation with a small number of actuators is realized. I do.

Embodiment 2 FIG. 10 is a configuration diagram showing a reflector antenna device according to Embodiment 2 of the present invention.
In the figure, reference numeral 3 denotes a reflector antenna, which focuses on a rate of change Δβ when the linear expansion coefficient distribution of the plurality of stacks 2 in the thickness direction is linearly approximated. ) To any one of the arrangements shown in FIGS. Reference numeral 4 denotes a temperature sensor as a temperature measuring means provided on or near the rear surface of the reflector antenna 3. An actuator 5 has one end of a drive shaft 6 fixed to the back surface of the reflector antenna 3.
The drive unit 6 expands and contracts the drive shaft 6 so that the stack 2
Is to apply a force. Reference numeral 8 denotes a processing unit, and reference numeral 9 denotes an actuator controller as a control unit that supplies the correction force from the processing unit 8 to the corresponding actuator 5 and drives 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, reference numeral 10 denotes a memory as storage means, 11 denotes a CPU as arithmetic means, and the processing section 8 includes the memory 10 and the CPU 11. The memory 10 stores a reference temperature T ₀ , which is a reference when the reflector antenna 3 exhibits a predetermined concave shape, that is, an ideal paraboloid or hyperboloid, and also obtains the reference temperature obtained in advance. 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 to a predetermined concave shape. Is stored in correspondence with each actuator 5.

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

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 a temperature difference ΔT as shown in FIG. The correction force f corresponding to each actuator 5 stored in the memory 10 using the difference ΔT
_1, f _2, ..., sequentially remove the f _n, the command value of the correction force for each actuator, and outputs to the actuator controller 9 calculates the following equation.

[0045]

(Equation 5)

On the other hand, the actuator controller 9
CPU11 receives a command value Delta] f _i of the supplied correction force from the command value Delta] f _i is determined whether to apply any actuator 5, and supplies a command value Delta] f _i corresponding to the actuator 5. This is hitting the determination, previously added to address the command value Delta] f _i, may be selected actuator 5 that corresponds by discriminating the addresses.

Each of these command values is transmitted to the drive unit 7 of the actuator 5, for example, a current corresponding to the command value is passed, and a correction force corresponding to the command value is generated by an electromagnetic force. 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 using the finite element method will be described. If Δα or Δβ of each stack 2 constituting the reflector antenna 3 is known, it is possible to calculate the amount of thermal deformation at each point of the reflector with respect to an arbitrary temperature change by using the finite element method. Now m stacks 2
Considering a reflector antenna 3 composed of the following, a number is given to each stack 2 as shown in FIG.
Are called Δαj and Δβ is called Δβj (j = 1, 2,..., M).

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

On the other hand, separately from the above, the finite element method
For example, the load applied to the actuator
Matrix (stiffness)
Matrix). The relationship is
ΔZ₁ , ΔZ _Two , ..., Z_n , Each acti
The load applied to the₁ , F_Two , ..., f_n , N
Assuming that the × n rigid matrix is K,
Can appear.

[0050]

(Equation 6)

Therefore, the calculated rigidity matrix K
By using the inverse matrix K ⁻¹ , the load required to cause the deformation can be obtained from the deformation amount as in the following equation.

[0052]

(Equation 7)

Therefore, by substituting the thermal deformation generated when the temperature difference ΔT = 1 ° C. is calculated in advance by the finite element method into ΔZj on the right side of the above equation, it is necessary to generate such deformation. a force _{f 1, f 2, ...,} f n is obtained. Therefore this f _1, f _2, ..., obtained by the f _n in the opposite direction is a correction force required to offset 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 undergoes thermal deformation, the correction force for the unit temperature corresponding to each actuator is stored in the storage means, By calculating the corrective force to be actually applied to each actuator by measuring the temperature of the mirror antenna, the calculating means calculates the corrective force to be applied to each actuator, and the control means supplies the corrective force to the corresponding actuator. Is automatically corrected, and a reflector antenna device capable of always maintaining a predetermined concave shape even in a region where the temperature changes drastically is realized.

Embodiment 3 Next, FIG. 15 is a configuration diagram showing a reflector antenna device according to Embodiment 3 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 arithmetic means.
A processing unit 9 including 11 is an actuator controller as a control means, which is the same as or a part corresponding to the one denoted by the same reference numeral in FIG. Reference numeral 12 denotes a mirror surface deformation measuring device as deformation measuring means for detecting deformation of each point on the surface of the reflector antenna 3 by detecting light interference or deviation of reflected light.

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 illustrating the vibration of a string and its natural vibration mode. Thus, the modes φ _k (x), k = 1... And the amplitudes A _k , k = 1... Are obtained, and the expression of the string vibration φ (x) in the form of the sum of the following equations is expressed as follows. We say that the mode is developed by vibration.

[0057]

(Equation 8)

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

FIG. 17 is an example of a contour diagram of the natural vibration mode of the reflector antenna 3 in which three equally spaced points on the outer circumference are fixed. This can be obtained by calculation 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 smaller the spatial frequency is, the smaller the force required to obtain the same maximum amplitude is. 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, θ is a polar coordinate display of the position on the mirror surface), the mirror surface deformation φ (γ, θ) becomes It can be expressed by the superposition of each mode as in the following equation.

[0061]

(Equation 9)

Here, A _k is a mode coefficient (corresponding to the amplitude of each mode). Note that the expansion method includes a method of obtaining an inner product of the deformation measurement value and each mode, a method of fitting by a 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 likelihood of occurrence of the natural vibration mode is in the order of the mode number. Therefore, the higher-order mode is less likely to occur than the lower-order mode, and the amplitude is small. However, when a 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 of the correction is small because the amplitude is originally small. Therefore, once mode expansion is performed and only the main deformation mode is selected for correction, correction can be efficiently performed with a small correction force.

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

Measurement data is input from the mirror deformation measuring device 12.
When input, the CPU 11 of the processing unit 8
Recall the value of this mode from
Mode coefficient A of the mode to be corrected_k Is calculated. Next, CP
U11 is the mode coefficient A _k And the mode value
The amount of deformation correction at each actuator point is calculated.

[0066] Assuming that had to be corrected from the mode number 1 to N, firstly, determine the A _k to k = 1 to N, deformation correction amount in the next i-th actuator point [Delta] Z _i, i = 1 ... n is obtained by the following equation. Here, γ _i and θ _i are polar coordinates of the actuator point i.

[0067]

(Equation 10)

This ΔZ _i is the actual deformation φ (γ _i , θ _i )
From N + 1 or higher order modes. Here, it is assumed that 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.

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

As described above, the mode to be corrected is selected so that the residual deformation is equal to or less than the predetermined amount, 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 is reduced. In addition, since the surface deformation is once developed into a mode, even if one of the measured values is measured as an erroneous value due to noise or the like, the amount of deformation can be almost correctly estimated, and a correct correction force can be calculated. .

As described above, according to the third embodiment, the mode of the surface deformation of the reflector antenna is developed and the mode to be corrected in order to reduce the residual deformation to a predetermined deformation or less is determined. By sequentially selecting and calculating the correction force and driving the actuator based on the correction force, a reflector antenna device that is less susceptible to noise and that can efficiently perform deformation correction with a small force is realized.

[0073]

As described above, according to the first aspect of the present invention, the surface deformation of the reflector antenna is mode-expanded, and the mode to be corrected so that the residual deformation is equal to or less than a predetermined deformation amount. Since the correction force is selected and calculated in a predetermined order, and the actuator is driven based on the correction force, the deformation can be corrected efficiently with a small force. There is an effect that a reflector antenna device capable of maintaining a mirror surface can be obtained.

According to the second and third aspects of the present invention, the stacks are arranged in the order of the average expansion coefficient or the rate of change of the linear expansion coefficient in the thickness direction, and the generated thermal deformation pattern is reduced. Since the reflector antenna is configured to have a relatively simple pattern, there is an effect that a reflector antenna device capable of correcting thermal deformation with a small number of actuators is 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 light reflection by a reflector antenna having undergone thermal deformation 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 a stack thickness direction.

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

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

FIG. 8 is a cross-sectional view of the reflector antenna shown in FIG.

FIG. 9 is an explanatory diagram showing thermal deformation of the 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 the processing unit.

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

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

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

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 a string vibration in a natural vibration mode.

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

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

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

[Explanation of symbols]

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

Continuation of the front page (56) References JP-A-62-7018 (JP, A) JP-A-1-238604 (JP, A) JP-A-1-238603 (JP, A) , A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 5/10 G02B 7/198 H01Q 15/14 H01Q 15/16

Claims (3)

(57) [Claims] 1. A reflector antenna comprising a plurality of partial mirrors arranged based on their linear expansion coefficients and joined to each other, and a reflector antenna arranged on the back side of the reflector antenna, A plurality of actuators that apply a force to the antenna, a deformation measuring unit that measures the deformation of the surface of the reflector antenna, and a measured value of the amount of deformation measured by the deformation measuring unit. Mode expansion of the deformation, residual deformation which is the remaining deformation obtained by subtracting the mode to be corrected by the actuator from the original deformation, to select a mode to be corrected in a predetermined order in order to make the deformation amount equal to or less than a predetermined deformation amount, Calculating the deformation correction amount in the actuator by combining the selected modes,
A reflector antenna device comprising: a calculating means for calculating a correction force to be applied to the actuator; and a control means for supplying the correcting force from the calculating means to the corresponding actuator to drive the actuator. 2. The reflector antenna includes a plurality of partial mirrors whose average linear expansion coefficient is measured in advance.
Adjacent to each other in the order of the magnitude of the average linear expansion coefficient,
A spiral shape or a line shape extending from one end to the other end, arranged in the order of the magnitude of the average linear expansion coefficient between lines adjacent to each other, and joined together. 2. The reflector antenna device according to 1. 3. The reflector antenna includes a plurality of partial mirrors, whose magnitudes of change are measured in advance from a distribution of linear expansion coefficients in a thickness direction, adjacent to each other in the order of the magnitudes of the rates of change. A spiral shape or a line shape extending from one end to the other end, arranged between the lines adjacent to each other in the order of the magnitude of the rate of change, and joined together. 2. The reflector antenna device according to 1.