JP2001056254A - Wave front sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a wave front with high accuracy even with a change in the condition of incident light by changing the installation angle of an optical system to light emitted from a reference light source, by an angle controller, and obtaining the distance between a lens array and a photoelectric converter on the basis of the output of the photoelectric converter obtained before and after the change of the installation angle. SOLUTION: Light of an angle of incidence θ is made incident to a wave front sensor, and a discrepancy quantity Δr from a reference spot position is measured to obtain the distance lm between a micro array 9 and a CCD 10 by an expression tan θ=Δr/lm. That is, a wave front computing element 21 measures the reference spot position by a reference light source 29, and a wave front sensor angle controller 502 sends an angle of inclination θ at which an optical system 1 is inclined, to a calibration value computing element 501. The wave front computing element 21 measures a calibration data spot position and sends the discrepancy quantity Δr of the spot position to the calibration value computing element 501. The calibration value computing element 501 computes the distance lm between the lens array 9 with picture elements as units and the CCD 10 from Δr and θ, and the wave front computing element 21 stores data in a memory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavefront sensor for measuring a wavefront of a light wave, and more particularly to a wavefront sensor for measuring the wavefront with high accuracy even when the use environment or the condition of incident light changes.

[0002]

2. Description of the Related Art Conventionally, this type of device has been known as CSGardne.
r et al. "design and Performance Analysis of Adapti
ve Optical Telescopes Using Laser Guide Stars "Pro
c.IEEEvol.78 NO.11 p1721-1743 (1990), and T. Noguc
hi et al. "active Optics Experiments 1" Publ. Natl.
Astr. Obs. Japan vol.1 P49-55 (1989). FIG. 11 shows a combination of the above-mentioned documents. In the drawing, 1 is a primary mirror of a telescope, 2 is a secondary mirror, 3 is a primary mirror controller, 30 is an active support mechanism, 4 is a lamp for a reference light source, 5 is a lamp light condensing lens, 6 is a pinhole, and 29 is a reference. Light source, 7 is a beam splitter, 8 is a collimator lens, 9 is a lens array, 10 is a CCD,
11 is an optical system of a Shack-Hartmann type wavefront sensor,
25 is a field stop of the optical system 11 of the wavefront sensor, 12 is an optical collimator lens to be measured, 13 is a deformable mirror,
14 is a beam splitter, 15 is a reference wavefront generator, 16
Is an objective lens, 17 is an eyepiece, 28 is 16, 17,
Reference numeral 18 denotes a lens array, reference numeral 19 denotes a CCD, reference numeral 20 denotes an optical system of a Shack-Hartmann wavefront sensor, reference numeral 26 denotes a field stop of the optical system 20 of a wavefront sensor, reference numeral 21 denotes a wavefront calculator, and reference numeral 22 denotes a wavefront calculator. A deformable mirror controller, 23 is a condenser lens for the observation device, 24 is an image plane of the observation device, and 50 and 51 are wavefront sensors.

[0003] First, the outline of the above-mentioned device will be described.
The light from the star is collected by the primary mirror 1 and the secondary mirror 2, passes through the field stop 25 and the beam splitter 7, and is converted into parallel light by the collimator lens 12. After that, the condenser lens 23 is passed through the deformable mirror 13 and the beam splitter 14.
Is focused on the image plane 24 of the observation device and observed. The above-mentioned primary mirror 1 is a large telescope having a length of several meters, and the primary mirror is easily deformed by its own weight. As a countermeasure, an active support mechanism 30 is provided in the primary mirror 1 to perform correction to an optimum shape. Since the star light is considered to be a plane wave if averaged over time, the light reflected by the beam splitter 7 is reflected by the wavefront sensor 11.
, And the shape of the primary mirror 1 can be known by calculating the wavefront shape by the wavefront calculator 21 based on the output. The primary mirror controller 3 uses the active support mechanism 3 based on the output of the wavefront calculator 21.
0 is driven to correct the shape of the primary mirror 1.

[0004] When a short time interval is considered, the atmosphere has spatial and temporal fluctuations in the refractive index. as a result,
Light from a star is disturbed by a plane wave, and the image of the star moves or blurs even with a telescope that provides an ideal imaging state. The deformable mirror 13 is for correcting the movement and blurring of the star image which occurs in such a short time period as cannot be corrected by the primary mirror 1. The wavefront fluctuation of the light from the star is obtained by the wavefront sensor 20, and the deformable mirror controller 22 controls the deformable mirror 13 based on the measurement result to correct the wavefront.

Next, the configuration of the wavefront sensors 50 and 51 will be described. Optical systems 11 and 12 of wavefront sensors 50 and 51
The basic parts of 0 are lens arrays 9, 18 and CCD1
0,19. The wavefront sensor of this method measures the wavefront of the light to be measured at the positions of the lens arrays 9 and 18. Since the wavefront changes due to propagation, in the optical system 11 of the wavefront sensor, the wavefront of the primary mirror 1 is projected onto the lens array 9 by the collimator lens 8. The afocal optical system 28 of the wavefront sensor 51 matches the measurement range determined by the dimensions of the microlens array 18 with the diameter of the wavefront to be measured.

Next, the measurement principle of the wavefront sensors 50 and 51 will be described. The wavefront calculator 21 measures the inclination of the wavefront incident on each lens (lenslet) of the lens arrays 9 and 18 from the movement of the condensed spot on the CCDs 10 and 19, and the inclination of the wavefront ΔW _i measured by each lenslet. To obtain the wavefront. The amount of movement Δr of the focused spot is determined by the inclination angle θ of the wavefront incident on the lenslet and the focal length f of the lens array.
It is obtained from _m by the following equation. _{Δr = f m · tanθ (1} ) Now, the wavefront slope to be measured by the i-th lenslets Δ
_Wi is obtained by the following equation, where _Dm is the lenslet aperture. The measurement wavefront W is expressed by the following equation. W = ΣΔW _i (3)

Since the wavefront measurement is performed based on the displacement of the spot from the reference position, a reference spot position is required. A light spot focused by the reference light source is used as a reference spot position. By measuring the output wavefront of the reference light source in advance, the reference wavefront indicated by the reference spot position can be determined. From the displacement of the spot position when the light to be measured enters, a change in the wavefront is determined, and the wavefront of the measurement light is determined by adding the change to the reference wavefront.

The reference light sources 15, 29 must have an outgoing light wavefront suitable for the wavefront sensor. Since the wavefront sensor 50 measures a mirror-shaped light wave, the incident light needs to be a spherical wave. The reference light source 29 is for obtaining a reference spot position of the wavefront sensor 11. The light emitted from the lamp 4 is focused on the pinhole 6 by the lens 5, and a spherical wave without distortion due to diffraction at the pinhole 6 is obtained. The wavefront sensor 51 having the afocal optical system 28 is provided with a reference wavefront generator 15 that emits collimated reference light.

[0009]

SUMMARY OF THE INVENTION Conventional wavefront sensors are:
With the above configuration, when the environmental temperature of the wavefront sensor changes, aberration occurs due to a change in the refractive index of the optical system, a change in the shape, and a change in the lens interval due to the thermal expansion of the lens barrel. there were.

[0010] Another problem is that aberrations in the optical system of the wavefront sensor are caused by changes in the refractive index of air due to changes in air pressure, resulting in a wavefront measurement error.

Further, since it is assumed that the focal position of the lens array 9, 18 installing CCD10,19, uses the focal length f _m in Formula (2). However, FIG.
As shown in the figure, the values required to calculate the inclination of the wavefront are the lenslets 31 of the lens arrays 9 and 18, the CCD 10,
19 intervals l _m . CC from lens array 9, 18
In spite of the fact that the distance to D10 and D19 differs from the focal length due to manufacturing tolerances, the conventional example uses the focal length to calculate the inclination of the wavefront, and thus has a problem that a wavefront measurement error occurs.

The reference wavefront generator 1 of the wavefront sensor 51
In the case of No. 5, there is a problem that an optical system that is stable against changes in environmental conditions must be formed in order to form a stable wavefront, and the configuration becomes complicated.

When light other than the light to be measured (hereinafter referred to as stray light) enters the wavefront sensor, a malfunction may occur. FIG. 13 is a diagram for explaining that the wavefront sensor 51 malfunctions when the stray light 32 enters the optical system 20 of the wavefront sensor 51. As shown in the figure, when the stray light 32 is incident together with the measured light, a condensed spot by the stray light 32 is generated by the lens array 18 in addition to the condensed spot of the measured light. When the wavefront measurement is performed based on the spot by the stray light 32, it is obvious that a malfunction occurs. In a conventional device, as a countermeasure, a fixed aperture field stop 2
6 prevents stray light. However, when the wavefront of the measurement light is disturbed, the light beam diameter at the position of the field stop 26 becomes large, so that the field stop 2 does not block the measurement light.
It is necessary to increase the opening diameter of No. 6. As a result, stray light 3
2 could not be blocked sufficiently, causing a problem that a malfunction or a measurement error occurs.

Further, in the wavefront sensor 21, since the measurement wavefront is spatially divided by a lens array for measurement, when the F value of the measurement light increases, as shown by a hatched portion in FIG. There is a problem that the resolution is reduced. One solution is to increase the number of lens arrays so that a sufficient spatial resolution can be obtained even when the F value is large. However, if the number of lens arrays is increased, the spatial resolution is improved, but on the other hand, the S / N is reduced because the amount of incident light per lens array is reduced, and
There is a problem that the time required to measure all spot positions increases due to an increase in the number of lens arrays. From the above, there is an optimum value for the number of lens arrays in the system. Therefore, in order to maintain the same performance irrespective of the change of the incident light, it is necessary to replace the collimator lens 8 with the F value of the measurement light or to provide a wavefront sensor for each F value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide an apparatus for measuring a wavefront with high accuracy even when a use environment condition or an incident light condition changes.

[0016]

In order to achieve the above object, a wavefront sensor according to the first aspect of the present invention comprises a lens array, a photoelectric converter for detecting a position of a condensed spot of the lens array, and a light receiving device. An optical system that makes the measurement wavefront and the lens array conjugate, and a wavefront calculator that determines a wavefront based on the output of the photoelectric converter, a wavefront sensor that measures the wavefront of the light to be measured, An angle controller of the wavefront sensor for changing the installation angle of the wavefront sensor with respect to the incident light of the reference light source; and the lens array and the photoelectric converter based on the outputs of the photoelectric converter obtained before and after the change of the installation angle of the wavefront sensor. And a calibration value calculator for obtaining a calibration value of the distance between the two.

According to a second aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a photoelectric converter for detecting a condensing spot position of the lens array; and an optical system for making a wavefront to be measured and the lens array conjugate. And a wavefront calculator that determines the wavefront based on the output of the photoelectric converter, and a wavefront sensor that measures the wavefront of the light to be measured, wherein a half mirror inclined from the optical axis immediately before the photoelectric converter is provided. At the same time, the translucent flat plate optical element is installed facing the light to be measured of the wavefront sensor, and the number of lens arrays is set at the mirror image position of the photoelectric converter generated by the half mirror and the translucent flat plate optical element. And an array-like light source having the same number of light sources.

According to a third aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a photoelectric converter for detecting a condensed spot position of the lens array; and an optical system for making the measured wavefront and the lens array conjugate. And a wavefront calculator that determines the wavefront based on the output of the photoelectric converter, and a wavefront sensor that measures the wavefront of the light to be measured, wherein a half mirror inclined from the optical axis immediately before the photoelectric converter is provided. At the same time, the polarizing plate is installed facing the measured light incident side of the wavefront sensor, and the polarization direction orthogonal to the measured light is located at the mirror image position of the photoelectric converter generated by the half mirror and the polarizing plate. And an array-shaped polarized light source having the same number of light sources as the number of lens arrays.

According to a fourth aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a photoelectric converter for detecting a condensing spot position of the lens array; and an optical system for making a wavefront to be measured and the lens array conjugate. And a wavefront calculator that determines the wavefront based on the output of the photoelectric converter, and a wavefront sensor that measures the wavefront of the light to be measured, wherein a half mirror inclined from the optical axis immediately before the photoelectric converter is provided. At the same time, a dichroic mirror is installed facing the measured light incident side of the wavefront sensor, and a wavelength different from the measured light is provided at the mirror image position of the photoelectric converter generated by the half mirror and the dichroic mirror. An array light source having the same number of light sources as the number of lens arrays is installed.

According to a fifth aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a photoelectric converter for detecting a condensing spot position of the lens array; a diameter of incident light is adjusted; A wavefront sensor for measuring a wavefront of light to be measured, comprising: an afocal optical system having a lens array in a conjugate relationship; and a wavefront calculator for obtaining a wavefront based on the output of the photoelectric converter. A variable-diameter diaphragm for limiting the field of view of the wavefront sensor installed at the focal position of the objective lens, FFT operation means for performing a Fourier transform on the operation result of the wavefront calculator, and an afocal optical system obtained by the above Fourier transform Aperture diameter calculation means for determining the diameter of the aperture based on the light quantity distribution at the focal position of the objective lens, and an aperture diameter controller for controlling the diameter of the variable aperture based on the output of the aperture diameter calculation means. Are those provided and over La, a.

According to a sixth aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a photoelectric converter for detecting a condensing spot position of the lens array; and an optical system for making a wavefront to be measured and the lens array conjugate. And a wavefront calculator that determines a wavefront based on the output of the photoelectric converter, and a wavefront sensor that measures the wavefront of the light to be measured. A dichroic mirror is provided, and the transmitted light transmitted through the first dichroic mirror is transmitted to the incident side of the measured light of the lens array, and the measured light separated by the first dichroic mirror is incident on the lens array. A second dichroic mirror is provided to conjugate the wavefront to be measured and the lens array in the optical path separated by the first and second dichroic mirrors. It is provided with a separate optical system.

[0022]

In the wavefront sensor according to the first aspect of the present invention, the angle of installation of the wavefront sensor with respect to the incident light from the reference light source is changed at the time of calibration to obtain the wavefront sensor before and after the angle change of the wavefront sensor. By obtaining the calibration value of the distance between the lens array of the optical system and the photoelectric converter in the mounted state based on the output of the obtained photoelectric converter, the wavefront measurement accuracy can be improved.

In the wavefront sensor according to the second aspect of the present invention, a half mirror inclined from the optical axis is provided immediately before the photoelectric converter.
A translucent flat optical element is installed facing the measured light incident side of the wavefront sensor, and the same number as the number of lens arrays provided at the mirror image position of the photoelectric converter generated by the half mirror and the translucent flat optical element By providing an array-shaped light source having a light source, a reference wavefront generator having a simple configuration and an accurate arrangement can be obtained, and when the installation position of the array-shaped light source is moved in the optical axis direction, the photoelectric conversion is performed. The conjugate relationship with the device is broken, and spot blurring occurs. However, by using the wavefront calculator (not shown) as the spot measurement position, the stability with respect to temperature changes of the wavefront sensor can be increased. it can.

In the wavefront sensor according to the third aspect of the present invention, a half mirror inclined from the optical axis is installed immediately before the photoelectric converter.
A polarizing plate is installed facing the measured light incident side of the wavefront sensor, and has the same number of light sources as the number of lens arrays provided at the mirror image position of the photoelectric converter generated by the half mirror and the polarizing plate. By providing the light source, it is possible to obtain a reference wavefront generator with a simple configuration and an accurate arrangement, and when the installation position of the array-like light source moves in the optical axis direction, the conjugate relationship with the photoelectric converter is reduced. Although the collapse spot blurs, the stability with respect to temperature changes of the wavefront sensor can be increased by setting the center of gravity of the spot in the wavefront calculator (not shown) as the spot measurement position.

In the wavefront sensor according to the fourth aspect of the present invention, a half mirror inclined from the optical axis is provided immediately before the photoelectric converter.
A dichroic mirror is installed facing the measured light incident side of the wavefront sensor, and has an array shape having the same number of light sources as the number of lens arrays provided at the mirror image position of the photoelectric converter generated by the half mirror and the dichroic mirror. By providing the light source, it is possible to obtain a reference wavefront generator with a simple configuration and an accurate arrangement, and when the installation position of the array-like light source moves in the optical axis direction, the conjugate relationship with the photoelectric converter is reduced. Although the collapse spot blurs, the stability with respect to temperature changes of the wavefront sensor can be increased by setting the center of gravity of the spot in the wavefront calculator (not shown) as the spot measurement position.

In the wavefront sensor according to the fifth aspect of the present invention, the calculation result of the wavefront calculator is subjected to Fourier transform, and the focal position of the afocal optical system obtained by the Fourier transform is determined by the objective lens. The diameter of the variable aperture that limits the field of view of the wavefront sensor is determined based on the light amount distribution at the point, and by controlling the aperture of the variable diameter, stray light (other than the light to be measured) can be obtained without interrupting the required light to be measured. (Light), and the occurrence of malfunctions and measurement errors can be suppressed.

In the wavefront sensor according to the sixth aspect of the present invention, the first dichroic mirror is provided on the measured light incident side of the optical system that conjugates the measured wavefront and the lens array. A second dichroic mirror is provided on the measured light incident side of the lens array to transmit the transmitted light of the first dichroic mirror and make the measured light separated by the first dichroic mirror incident on the lens array. On the other hand, by providing another optical system that conjugates the wavefront to be measured and the lens array in the optical path separated by the first and second dichroic mirrors, the F value of the light to be measured changes. The beam diameter of the light to be measured incident on the lens array can be kept constant without replacing the entire optical system, so that the spatial resolution of the measurement wavefront can be maintained without deterioration. That. In addition, since the entire optical system is not replaced, there is no movable part of the optical system, and the tolerance of the optical system can be reduced, and high-accuracy wavefront measurement can be performed.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a first embodiment of the present invention. 1, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 1, 1 is a primary mirror of a telescope, 2 is a secondary mirror of a telescope, 8 is a collimator lens,
9 is a lens array, 10 is a CCD, 11 is an optical system of a wavefront sensor, 100 is a wavefront sensor, 101 is a temperature sensor, 1
02 is an error wavefront calculator and 103 is a wavefront calculator.

As described in the conventional example, a wavefront measurement error occurs due to an aberration caused by a change in refractive index and shape of an optical material due to a change in temperature, a change in a lens interval due to thermal expansion of a lens barrel, and the like. In the present embodiment, a temperature sensor 101 and an error wavefront calculator 102 are provided, an aberration generated at a use temperature is obtained as an error wavefront, and the error wavefront is subtracted from the measurement wavefront obtained from the output of the CCD 10 by the wavefront calculator 103. Temperature compensation.

The details of the error wavefront calculator 102 will be described below. The error wavefront calculator 102 is connected to the temperature sensor 10
The change of the focus position generated in the collimator lens 8 due to the temperature change based on the output of 1 is calculated from a predetermined formula, and this is converted into a wavefront. Further, the error wavefront calculator 102 calculates a wavefront caused by a displacement of the spot position due to a difference in linear expansion rate between the lens array 9 and the CCD 10. The error wavefront calculator 102 outputs the sum of the two wavefronts to the wavefront calculator 103 as an error wavefront.

The calculation performed by the error wavefront calculator 102 is
A method for calculating a change in the focus position of the collimator lens 8 due to a change in temperature, a method for obtaining an error wavefront from the change in the focus position, a method for calculating the lens array 9 and the CCD 1
The method will be described below in order of the method of obtaining the error wavefront due to the difference in the linear expansion coefficient of 0.

A change in the focus position of the collimator lens 8 is caused by a change in power caused by a change in the refractive index of the collimator lens due to a change in temperature, and by expansion and contraction of the lens barrel. Assuming that the back focus of the collimator lens 8 is f _b and the linear expansion coefficient of the lens barrel is α, a change in the focus position with respect to a change in the temperature T can be expressed as in Expression (101). Here, β = (1 / φ) · dφ / dT: heat dispersion coefficient

Therefore, a change in focus position when a change in temperature is known can be obtained by the following equation.

[0034] The focus position change Δx and error wavefront [Delta] W _T is related as follows. ΔW _T = Δx / 8λF ² (103) where λ is the wavelength and F is the F value of the lens.

Therefore, the error wavefront can be calculated from the following equation from the equation (103) and the equation (102) for the change in the focus position of the collimator lens due to the temperature change.

Next, a description will be given of an error wavefront generated due to a difference in linear expansion coefficient between the lens array and the CCD. The linear expansion coefficient of the lens array substrate material is α _m , and the linear expansion coefficient of the CCD is α _c
Let r be the distance from the optical axis. The spot movement amount Δr generated by a shape change due to a temperature change is expressed by the following equation.

The relationship between the spot movement amount Δr and the error wavefront is related as follows. _n Here, n is the number of lens arrays, f _m is the focal length of the lens array, and D _m is the aperture diameter of the lenslet.

From the above, the relationship between the change in the error wavefront and the change in temperature is expressed by the following equation. dW _M / dT

Therefore, the error wavefront when the temperature change ΔT occurs can be calculated by equation (108).

The equations (104) and (1) described above
08), the error wavefront calculator 102 calculates the error wavefront ΔW
_T and ΔW _M are obtained, and the correct wavefront W _I can be obtained by subtracting the error wavefront from the measurement wavefront W affected by the temperature change by the wavefront calculator 103 as shown in Expression (109).

Embodiment 2 FIG. FIG. 2 is a configuration diagram showing a second embodiment of the present invention. 2, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 2, 1 is a telescope primary mirror, 2 is a telescope sub-mirror, 8 is a collimator lens, 9 is a lens array, 10 is a CCD, 11 is an optical system of a wavefront sensor, 200 is a wavefront sensor, 201 is a barometric pressure sensor, 202
Is an error wavefront calculator, and 203 is a wavefront calculator.

As shown in the conventional example, a change in the refractive index of the atmosphere due to a change in the atmospheric pressure causes a wavefront measurement error. In this embodiment, the pressure sensor 201 is used as the compensation means.
And an error wavefront calculator 202 are provided to obtain an error wavefront at the used atmospheric pressure, and the wavefront calculator 203 performs pressure compensation by subtracting the error wavefront from the measurement wavefront affected by the pressure change obtained from the output of the CCD 10. Things.

The details of the error wavefront calculator 202 will be described below. The error wavefront calculator 202 is a
A change in the lens power generated in the collimator lens 8 due to a change in the atmospheric pressure is calculated based on the output of No. 1 and converted into a wavefront, which is output to the wavefront calculator 203 as an error wavefront.

Hereinafter, a method of calculating the power change of the collimator lens 8 due to the atmospheric pressure change performed by the error wavefront calculator 202 will be described.
Two points of a method of converting a power change into an error wavefront will be described.

First, the collimator lens 8 due to a change in air pressure
The calculation method of the power change will be described. The change in the power φ due to the change in the atmospheric pressure P is expressed by the following equation.

From this, the change Δx in the focus position due to the change in air pressure is expressed by the following equation.

Accordingly, the ratio of the defocus wavefront aberration due to the change in atmospheric pressure is expressed by the following equation through the change in the refractive index of the medium between lenses.

[0048] Therefore, the wavefront [Delta] W _P at the time when the change in air pressure ΔP caused can be calculated from equation (205). ΔW = (dW _P / dP) · ΔP (205)

[0049] As described above, determine the error wavefront [Delta] W _P in error wavefront calculator 202 according to equation (205), the wavefront calculator 2
In 03, the correct wavefront W _I can be obtained by subtracting the error wavefront from the measurement wavefront W affected by the atmospheric pressure change as in the equation (206). W _I = W−ΔW _P (206)

Embodiment 3 FIG. FIG. 3 is a configuration diagram showing a third embodiment of the present invention. 3, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. 3, reference numeral 301 denotes a temperature-compensated afocal optical system, 302 denotes a lens array, 303 denotes an objective lens, 304 denotes an eyepiece, and 19 denotes a CCD. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In this embodiment, the lens array 302 and the CC
The error wavefront caused by the difference in linear expansion rate from
Compensation is performed by the residual aberration of the compensation afocal optical system 301.
Things. Linear expansion of substrate material of lens array 302
Rate α_m , The linear expansion coefficient of CCD 19 is α _c And Spot
The relationship between the travel distance and the error wavefront is expressed by the above equation (107).
Where θ isHere, n is the number of lens arrays, f_m Is the focus of the lens array
Point distance, D_m Is the aperture diameter of the lenslet.

Next, the lens power of the afocal optical system 301 satisfying the temperature compensation condition will be described. First, a method of calculating a power change of the afocal optical system 301 due to a temperature change will be described. The power of the afocal optical system 301 is expressed by equation (302). Where φ _o : power of the objective lens 303 φ _e : power of the eyepiece 304 m = φ _e / φ _o : magnification of the afocal optical system 301 : Interval between the objective lens 303 and the eyepiece 304

The temperature change rate of the power of the afocal optical system 301 is expressed by equation (304). The afocal optical system 3 can be obtained by making the heat dispersions β _o and β _e of the power of the objective lens 303 and the eyepiece 304 equal.
Assuming that the magnification m of 01 does not change with temperature,
It is expressed by the following equation. dm / dT = 0 (305) Using the above equations (303), (304), and (305), the temperature change rate of the power of the afocal optical system 301 is expressed by equation (306). dφ / dT = − (m + 1) φ _o (α _B + β _o ) (306) where α _B = (1 / e) · (de / dT): linear expansion coefficient of the lens barrel β _o = (1 / φ _o) ) ・ (Dφ _o / dT)

Therefore, as a temperature compensation condition, a wavefront that cancels the error wavefront θ generated by the spot movement is generated.
The following equation must be satisfied. (DW _T / dT) = (８λF ² ) · (dΔx / dφ) · (dφ / dT) = (１ ／ λF ² ) · (−1 / φ ² ) · (dφ / dT) = − θ ( 307)

On the other hand, in a synthetic lens in which thin lenses composed of a plurality of types of materials are brought close to each other, when the variance of the i-th material is μ _i and the lens power is φ _i , Must be satisfied. The power of each lens is determined from this equation and three equations obtained by adding the equation (307) relating to the power satisfying the above temperature compensation condition.

As described above, by constructing the objective lens 303 and the eyepiece 304 using at least three types of materials, the wavefront that satisfies the combined power condition and achromatizes, and always satisfies the two conditions of temperature compensation. A sensor can be configured.

Embodiment 4 FIG. FIG. 4 is a configuration diagram showing a fourth embodiment of the present invention. 4, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 4, reference numeral 1 denotes a primary mirror of the telescope, 2 denotes a sub-mirror of the telescope, 400 denotes a wavefront sensor, and 401 denotes a pressure-compensating collimator lens. Here, CCD
A wavefront calculator for obtaining a wavefront based on the output of the reference numeral 10 is not shown.

The pressure variance γ represented by the equation (401) can be treated in the same manner as the dispersion μ in a so-called achromatic lens. γ = 1 / (n-n a) (401)

When the collimator lens 401 is composed of a plurality of lenses combining different materials, it is possible to equivalently produce a material characteristic such as atmospheric pressure dispersion γ. In a synthetic lens in which thin lenses made of a plurality of types of materials are brought close to each other, when the ith material has a dispersion of μ _i , a pressure dispersion of γ _i , and a lens power of φ _i , the following conditions apply to the collimator lens 401. Needs to be satisfied.

As described above, if the collimator lens is formed by using at least three kinds of materials, the afocal optical system which satisfies the combined power condition and achromatizes and always satisfies the two conditions of the atmospheric pressure compensation is required. Can be.

Embodiment 5 FIG. FIG. 5 is a configuration diagram showing a fifth embodiment of the present invention. 5, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 5, reference numeral 501 denotes a calibration value calculator, 502 denotes a wavefront sensor angle controller, and 29 denotes a reference light source.

In the present embodiment, the distance between the CCD 10 and the lens array 9 required for accurately calculating the inclination of the wavefront is not directly measured, but is measured and calibrated in the mounted state.

As shown in the conventional example, the relationship between the deviation amount Δr of the spot position on the CCD 10 and tan θ is expressed by the following equation. _{tanθ = Δr / l m (501} ) , where, l _m is the distance between the microlens array 9 and CCD 10. Now, light having an incident angle θ is incident on the wavefront sensor, the deviation Δr from the reference spot position is measured, and the distance l _m is obtained from the above θ and Δr by the equation (501).

Hereinafter, a method of calibrating the wavefront sensor will be described. (1) The wavefront calculator 21 measures the reference spot position by the reference light source 29. (2) The wavefront sensor angle controller 502 tilts the optical system 11 of the wavefront sensor by θ, and calculates the tilt angle θ as a calibration value calculator 501. To send to. (3) The wavefront calculator 21 measures the calibration data spot position, and (4) the wavefront calculator 21 subtracts the reference spot position from the calibration data spot position to obtain a displacement Δr of the spot position.
Is sent to the calibration value calculator 501. (5) The calibration value calculator 501 calculates a distance l _m between the lens array 9 and the CCD 10 in pixel units from Δr and θ, and the wavefront calculator 21 stores data in an internal memory. Thus, the calibration is completed.

When the wavefront measurement is performed, the actual calibration of the lens array 9 and the CCD 10
The distance between them is accurately determined, and the accuracy of wavefront measurement can be improved.

Embodiment 6 FIG. FIG. 6 is a configuration diagram showing a sixth embodiment of the present invention. 6, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 6, 600 is a wavefront sensor, 601 is a half mirror, 602 is a calibration light introducing half mirror, 603 is an array-shaped light source NA adjustment mask, 60
4 is an array-like light source, and 605 is a shutter. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In this embodiment, reference light is obtained with a simple configuration instead of the reference wavefront generator 15 which emits collimated reference light required for the wavefront sensor having the afocal system 28 described in the section of the prior art. Like that.

First, the configuration of the wavefront sensor will be described. The light emitted from the array-shaped light source 604 is converted into an optical system
0, the half mirror 602 for introducing the calibration light
Are arranged in front of the CCD 19. An array light source 604 is installed at a mirror image position of the CCD 19 generated by the half mirrors 601 and 602. Array light source 6
The NA adjustment mask 603 provided on the front surface of the light source 04 has a number of openings corresponding to the number of the array light sources 604 in a flat plate, and limits the emission angle of each light source constituting the array light source 604. The light emitted from the light source and the lenses constituting the lens array 18 are made to correspond one-to-one. F of lens array 18
When the value is F and the distance from the array light source 604 to the mask 603 is x, the aperture diameter D of the mask 603 is obtained by the following equation. D = x / F (601)

The light emitted from the array light source 604 is introduced into the wavefront sensor via the calibration light introduction half mirror 602,
After being reflected by the half mirror 601, the light is focused on the CCD 19 by the lens array 18. When the reference light source is used, the measured light is blocked by the shutter 605.

Next, a method of correcting a measurement wavefront using a reference light source will be described. The output light of the array light source 604 is
Since the light passes through the optical system of the wavefront sensor twice, the effect of twice the optical system aberration is measured. Array light source 60
In No. 4, an accurate arrangement can be obtained by using, for example, a laser diode array, and the disturbance of the arrangement of the spots is caused by the influence of the optical system aberration. The wavefront is determined based on the measured disorder of the arrangement of the spots, and the half is obtained.
Is the error wavefront caused by the aberration of the optical system,
By subtracting the previously obtained error wavefront from the measured wavefront at the time of wavefront measurement, the correct wavefront can be measured.

In the conventional method, when the position of the reference light source 29 moves in the optical axis direction due to a change in ambient temperature or the like, a distorted spherical wave is incident on the wavefront sensor, and the position of the spot changes. However, in this embodiment, when the installation position of the array-like light source 604 moves in the optical axis direction, spot blurring occurs due to collapse of the conjugate relationship with the CCD. But,
If the wavefront calculator 21 defines spot position measurement using the center of gravity of a commonly used spot, the position of the center of gravity does not change even when blur occurs.

As described above, it is possible to realize a reference light source that is strong against a change in use environment conditions. This also reduces the manufacturing tolerance when the arrangement position of the array-like light source is conjugate with the CCD. Can be taken.

Embodiment 7 FIG. FIG. 7 is a configuration diagram showing a seventh embodiment of the present invention. 7, the same reference numerals as those in FIGS. 11 and 6 indicate the same or corresponding parts. In FIG. 7, 700
Denotes a wavefront sensor, 701 denotes a polarizing plate, and 704 denotes an array-shaped polarized light source. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In this embodiment, the light to be measured is polarized.
A polarizing plate 701 is used instead of the half mirror 601 of the sixth embodiment, and an array-like polarized light source 704 is used as the array-like light source 604.
Is used.

The array-shaped polarized light source 704 is installed at a mirror image position of the CCD 19 generated by the half mirror 602 and the polarizing plate 701, and is orthogonal to the polarization direction of the light to be measured. When the polarization direction of the polarizing plate 701 and the polarization direction of the measured light are set to coincide with each other, the measured light transmits through the polarizing plate 704,
A focused spot is formed on the CCD 19. The reference light is reflected by the polarizing plate 701 and forms a spot on the CCD 19. When the array-shaped polarized light source 704 is used, the measured light is blocked by the shutter 605. Other operations are the same as in the sixth embodiment.

As described above, the polarizing plate 701 reflects the calibration light almost 100%, and reflects the measured light almost 100%.
Since the light is transmitted, it is possible to realize an optical system in which the amount of light loss of the reference light and the light to be measured by the polarizing plate 701 inserted for calibration is extremely small.

Embodiment 8 FIG. FIG. 8 is a configuration diagram showing Embodiment 8 of the present invention. 8, the same reference numerals as those in FIGS. 11 and 6 denote the same or corresponding parts. In FIG. 8, 800
Is a wavefront sensor, 801 is a dichroic mirror, 804
Is an array-like light source having a different wavelength from the light to be measured. In addition,
Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In the present embodiment, the wavelengths of the measured light and the reference light are different. The dichroic mirror 801 is configured to transmit light in the wavelength range of the light to be measured and reflect the light in the wavelength range of the reference light.

The array-like light source 804 is
CCD 19 generated between the light source 2 and the dichroic mirror 801
It is installed at the mirror image position of. The measured light passes through the dichroic mirror 801 to form a spot on the CCD 19. On the other hand, the light emitted from the array light source 804 is introduced by the half mirror 602 and reflected by the dichroic mirror 801 to form a spot on the CCD 19. When the reference light source is used, the measured light is blocked by the shutter 605. Other operations are the same as in the sixth embodiment.

As described above, the dichroic mirror 80
1 reflects almost 100% of the reference light and transmits almost 100% of the light to be measured, so that it is possible to realize an optical system in which the dichroic mirror 801 has a very small loss of light amount of the reference light and the light to be measured.

Embodiment 9 FIG. FIG. 9 is a configuration diagram showing a ninth embodiment of the present invention. 9, the same reference numerals as those in FIG. 11 denote the same or corresponding parts. 9, reference numeral 900 denotes a wavefront sensor, 901 denotes a variable-diameter diaphragm, 902 denotes a diaphragm-diameter controller, 903 denotes a diaphragm-diameter calculator which is a diaphragm-diameter calculator, 90
Reference numeral 4 denotes an FFT operation unit which is an FFT operation means.

In this embodiment, in order to suppress stray light, the aperture diameter is changed in accordance with the state of focusing by the objective lens 16 of the afocal optical system.

In order to suppress stray light, it is necessary to reduce the diameter of the stop so as not to cut off the light to be measured. When the front focal plane of the objective lens 16 is set as the wavefront measurement position, the point image intensity distribution by the objective lens 16 follows the Fourier transform result of the measurement wavefront. The FFT calculator 904 performs a Fourier transform of the measured wavefront obtained by the wavefront calculator 21 to obtain a point image intensity distribution. An aperture diameter calculator 903 gives a threshold value to the point image intensity distribution, and sets a range exceeding the threshold value as an aperture diameter. The aperture diameter controller 902 adjusts the aperture diameter based on this information.

As described above, stray light which has been a problem in the case of a fixed aperture can be reduced, and malfunction can be suppressed.

Embodiment 10 FIG. FIG. 10 shows Embodiment 10 of the present invention.
FIG. 10, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 10, reference numeral 8 denotes a first collimator lens;
And a second dichroic mirror, 114 and 115 are band-pass filters, 116 and 118 are mirrors, 117 is a second collimator lens, and 110 is a wavefront sensor. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

The telescope has a configuration in which the sub-mirror 2 is exchanged, and the F-number changes as the sub-mirror 2 changes, as indicated by the broken line in FIG. As shown in the conventional example, it is necessary to replace the collimator lens 8 according to a change in the F value or to prepare another wavefront sensor corresponding to each F value.

To make the diameters of the wavefronts incident on the lens array 18 with different F-numbers the same, the first collimator lens 8
May be changed according to the F value. In the present embodiment, the optical path is separated by the first dichroic mirror 111, and a second collimator lens 117 suitable for the F value is installed in the separated optical path to cope with a change in the F value.

Since the second collimator lens 117 and the optical path length can be freely set by changing the optical path, the second collimator lens 117 suitable for the F-number can be used, and the lens array 18 and the following can be shared. it can. Since light of two wavelengths enters the lens array, the wavelength selection is performed by exchanging the bandpass filters 114 and 115.

As described above, it is not necessary to replace the entire optical system depending on the F value, and since there are no movable parts other than the band-pass filters 114 and 115, the tolerance of the optical system can be suppressed to a small value and high accuracy can be achieved. Wavefront measurement can be realized.

[0090]

According to the present invention configured as described above, it is possible to obtain a wavefront sensor capable of measuring the wavefront of the light to be measured with high accuracy even when the use environment conditions and the incident light conditions change. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wavefront sensor according to a first embodiment.

FIG. 2 is a configuration diagram of a wavefront sensor according to a second embodiment.

FIG. 3 is a configuration diagram of a wavefront sensor according to a third embodiment.

FIG. 4 is a configuration diagram of a wavefront sensor according to a fourth embodiment.

FIG. 5 is a configuration diagram of a wavefront sensor according to a fifth embodiment.

FIG. 6 is a configuration diagram of a wavefront sensor according to a sixth embodiment.

FIG. 7 is a configuration diagram of a wavefront sensor according to a seventh embodiment.

FIG. 8 is a configuration diagram of a wavefront sensor according to an eighth embodiment.

FIG. 9 is a configuration diagram of a wavefront sensor according to a ninth embodiment.

FIG. 10 is a configuration diagram of a wavefront sensor according to a tenth embodiment.

FIG. 11 is a configuration diagram of an apparatus (telescope) including a conventional wavefront sensor.

FIG. 12 is a diagram for explaining the relationship between the distance between the lens array and the CCD and the focal length of the lens array.

FIG. 13 is a diagram for explaining a malfunction of the wavefront sensor due to stray light.

FIG. 14 is a diagram for explaining a change in the number of effective lens arrays due to a difference in F value.

[Explanation of symbols]

 1: Primary mirror of telescope 2: Secondary mirror of telescope 4: Lamp for reference light source 5: Lamp light focusing lens 6: Pinhole 7: Beam splitter 8: Collimator lens (first collimator lens) 9: Lens array 10: CCD 11: Optical system of wavefront sensor 13: Deformable mirror 14: Beam splitter 16: Objective lens 17: Eyepiece 18: Lens array 19: CCD 20: Optical system of wavefront sensor 21: Wavefront calculator 22: Deformable mirror 28: Afocal optical system 29: Reference light source 50: Wavefront sensor 51: Wavefront sensor 100: Wavefront sensor 101: Temperature sensor 102: Error wavefront calculator 103: Wavefront calculator 110: Wavefront sensor 111, 113: Dichroic mirror 114, 115: Band Pass filter 117: second collimator lens 11 6, 118: mirror 200: wavefront sensor 201: barometric pressure sensor 202: error wavefront calculator 203: wavefront calculator 301: temperature compensation afocal optical system 302: lens array 303: objective lens 304: eyepiece 400: wavefront sensor 401: Barometric pressure compensation collimator lens 501: Calibration value calculator 502: Wavefront sensor angle controller 600: Wavefront sensor 601: Half mirror 602: Half mirror for introducing calibration light 603: Array-shaped light source NA adjustment mask 604: Array-shaped light source 605: Shutter 700: Wavefront sensor 701: Polarizing plate 704: Array-like polarized light source 800: Wavefront sensor 801: Dichroic mirror 804: Array-like light source having a different wavelength from the light to be measured 900: Wavefront sensor 901: Variable-diameter aperture 902: Aperture diameter controller 903: Aperture Diameter calculator 904: FFT calculator

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[Procedure amendment]

[Submission date] July 28, 2000 (2007.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Wavefront sensor

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavefront sensor for measuring a wavefront of a light wave, and more particularly to a wavefront sensor for measuring the wavefront with high accuracy even when the use environment or the condition of incident light changes.

[0002]

2. Description of the Related Art Conventionally, this type of device has been known as CSGardne.
r et al. "Design and Performance Analysis of Adapti
ve Optical Telescopes Using Laser Guide Stars "Pro
c.IEEEvol.78 NO.11 p1721-1743 (1990), and T. Noguc
hi et al. "Active Optics Experiments 1" Publ. Natl.
Astr. Obs. Japan vol.1 P49-55 (1989). FIG. 11 shows a combination of the above-mentioned documents. In the figure, 1 is a primary mirror of a telescope, 2 is a secondary mirror, 3 is a primary mirror controller, 4 is a lamp for a reference light source, 5
Is a lamp light focusing lens, 6 is a pinhole, 29 is a reference light source, 7 is a beam splitter, 8 is a collimator lens, 9
Is a lens array, 10 is a CCD, 11 is an optical system of a Shack-Hartmann type wavefront sensor, 25 is a field stop of the optical system 11 of the wavefront sensor, 12 is an optical collimator lens to be measured, 13 is a deformable mirror, and 14 is a beam splitter. , 15 is a reference wavefront generator, 16 is an objective lens, 17
Is an eyepiece, 28 is an afocal optical system comprising 16, 17, and 26, 18 is a lens array, 19 is a CCD,
0 is the optical system of the Shack-Hartmann wavefront sensor, 2
6 is a field stop of the optical system 20 of the wavefront sensor, 21 is a wavefront calculator, 22 is a deformable mirror controller, 23
Is the condenser lens for the observation device, 24 is the image plane of the observation device, 5
Numerals 0 and 51 are wavefront sensors.

[0003] First, the outline of the above-mentioned device will be described.
The light from the star is collected by the primary mirror 1 and the secondary mirror 2, passes through the field stop 25 and the beam splitter 7, and is converted into parallel light by the collimator lens 12. After that, the condenser lens 23 is passed through the deformable mirror 13 and the beam splitter 14.
Is focused on the image plane 24 of the observation device and observed. The above-mentioned primary mirror 1 is a large telescope having a length of several meters, and the primary mirror is easily deformed by its own weight. As a countermeasure against this, an active support mechanism is provided on the primary mirror 1 to correct the shape to an optimum shape. Since the light of the star is considered to be a plane wave when averaged over time, the light reflected by the beam splitter 7 is reflected by the optical system 1 of the wavefront sensor.
1, the shape of the primary mirror 1 can be known by calculating the wavefront shape by the wavefront calculator 21 based on the output. The primary mirror controller 3 drives the active support mechanism based on the output of the wavefront calculator 21 to correct the shape of the primary mirror 1.

[0004] When a short time interval is considered, the atmosphere has spatial and temporal fluctuations in the refractive index. as a result,
Light from a star is disturbed by a plane wave, and the image of the star moves or blurs even with a telescope that provides an ideal imaging state. The deformable mirror 13 is for correcting the movement and blurring of the star image which occurs in such a short time period as cannot be corrected by the primary mirror 1. The wavefront fluctuation of the light from the star is obtained by the optical system 20 of the wavefront sensor, and the deformable mirror controller 22 controls the deformable mirror 13 based on the measurement result to correct the wavefront.

Next, the configuration of the wavefront sensors 50 and 51 will be described. Optical systems 11 and 12 of wavefront sensors 50 and 51
The basic parts of 0 are lens arrays 9, 18 and CCD1
0,19. The wavefront sensor of this method measures the wavefront of the light to be measured at the positions of the lens arrays 9 and 18. Since the wavefront changes due to propagation, in the optical system 11 of the wavefront sensor, the wavefront of the primary mirror 1 is projected onto the lens array 9 by the collimator lens 8. The afocal optical system 28 of the wavefront sensor 51 matches the measurement range determined by the dimensions of the microlens array 18 with the diameter of the wavefront to be measured.

Next, the measurement principle of the wavefront sensors 50 and 51 will be described. The wavefront calculator 21 measures the inclination of the wavefront incident on each lens (lenslet) of the lens arrays 9 and 18 from the movement of the condensed spot on the CCDs 10 and 19, and the inclination of the wavefront ΔW _i measured by each lenslet. To obtain the wavefront. The amount of movement Δr of the focused spot is determined by the inclination angle θ of the wavefront incident on the lenslet and the focal length f of the lens array.
It is obtained from _m by the following equation. _{Δr = f m · tanθ (1} ) Now, the wavefront slope to be measured by the i-th lenslets Δ
_Wi is obtained by the following equation, where _Dm is the lenslet aperture. The measurement wavefront W is expressed by the following equation. W = ΣΔW _i (3)

Since the wavefront measurement is performed based on the displacement of the spot from the reference position, a reference spot position is required. A light spot focused by the reference light source is used as a reference spot position. By measuring the output wavefront of the reference light source in advance, the reference wavefront indicated by the reference spot position can be determined. From the displacement of the spot position when the light to be measured enters, a change in the wavefront is determined, and the wavefront of the measurement light is determined by adding the change to the reference wavefront.

The reference light sources 15, 29 must have an outgoing light wavefront suitable for the wavefront sensor. Since the wavefront sensor 50 measures a mirror-shaped light wave, the incident light needs to be a spherical wave. The reference light source 29 is for obtaining a reference spot position of the wavefront sensor 11. The light emitted from the lamp 4 is focused on the pinhole 6 by the lens 5, and a spherical wave without distortion due to diffraction at the pinhole 6 is obtained. The wavefront sensor 51 having the afocal optical system 28 is provided with a reference wavefront generator 15 that emits collimated reference light.

[0009]

SUMMARY OF THE INVENTION Conventional wavefront sensors are:
Be configured as described above, since it is assumed that the focal position of the lens array 9, 18 installing CCD10,19, is used in equation (2) the focal length f _m. However, as shown in FIG. 12, the values required for calculating the inclination of the wavefront are the lenslets 31 and C of the lens arrays 9 and 18.
The distance between CDs ₁₀ and 19 is 1 _m . Lens array 9.1
In spite of the fact that the distance from 8 to the CCDs 10 and 19 differs from the focal length due to manufacturing tolerances, the conventional example uses the focal length to calculate the inclination of the wavefront, and thus has a problem that a wavefront measurement error occurs.

The reference wavefront generator 1 of the wavefront sensor 51
In the case of No. 5, there is a problem that an optical system that is stable against changes in environmental conditions must be formed in order to form a stable wavefront, and the configuration becomes complicated.

Further, when light other than the light to be measured (hereinafter referred to as stray light) enters the wavefront sensor, a malfunction may occur. FIG. 13 is a diagram for explaining that the wavefront sensor 51 malfunctions when the stray light 32 enters the optical system 20 of the wavefront sensor 51. As shown in the figure, when the stray light 32 is incident together with the measured light, a condensed spot by the stray light 32 is generated by the lens array 18 in addition to the condensed spot of the measured light. When the wavefront measurement is performed based on the spot by the stray light 32, it is obvious that a malfunction occurs. In a conventional device, as a countermeasure, a fixed aperture field stop 2
6 prevents stray light. However, when the wavefront of the measurement light is disturbed, the light beam diameter at the position of the field stop 26 becomes large, so that the field stop 2 does not block the measurement light.
It is necessary to increase the opening diameter of No. 6. As a result, stray light 3
2 could not be blocked sufficiently, causing a problem that a malfunction or a measurement error occurs.

Further, in the wavefront sensor 51, since the measurement wavefront is spatially divided by a lens array for measurement, when the F value of the measurement light increases, the spatial wavefront as shown by the hatched portion in FIG. There is a problem that the resolution is reduced. One solution is to increase the number of lens arrays so that a sufficient spatial resolution can be obtained even when the F value is large. However, when the number of lens arrays is increased, the spatial resolution is improved, but on the other hand, the S / N is reduced because the amount of incident light per lens array is reduced.
There is a problem that the time required to measure all spot positions increases due to an increase in the number of lens arrays. From the above, there is an optimum value for the number of lens arrays in the system. Therefore, in order to maintain the same performance irrespective of the change in the incident light, it is necessary to replace the collimator lens 8 with the F value of the measurement light or to provide a wavefront sensor for each F value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an apparatus for measuring a wavefront with high accuracy even when conditions of incident light change.

[0014]

According to a first aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a lens for projecting light to be measured on the lens array; A photoelectric converter for detecting a position of a converging spot of the lens array by the measured light; and a condensing spot of the lens array when light from a reference light source is incident on the lens. A wavefront sensor that measures a wavefront of the measured light based on a displacement between a position and a focused spot position of the lens array when the measured light is incident on the lens. An angle controller for changing the installation angle of the optical system, and an output of the photoelectric converter obtained before and after the change of the installation angle of the optical system based on the angle controller. A calibration value calculator lens array and determine the distance between the photoelectric converter, in which the provided.

According to a second aspect of the present invention, there is provided a wavefront sensor for detecting a lens array, a lens for projecting light to be measured on the lens array, and a condensing spot position of the lens array based on the projected light for measurement. Photoelectric converter,
An optical system having a first half mirror that is installed between the lens array and the photoelectric converter so as to be inclined with respect to the optical axis of the measured light, and on the measured light incident side of the lens. A second half mirror installed facing the lens, and the same number as the number of lenses constituting the lens array at a mirror image position of the photoelectric converter by the first half mirror and the second half mirror And an array-like light source having the above light sources.

According to a third aspect of the present invention, in the wavefront sensor according to the third aspect, the photoelectric converter obtains a disturbance in the arrangement of the condensed spot positions of the lens array based on light emitted from the array-like light source, and determines the disturbance based on the disturbance. And an error wavefront calculator for calculating an error wavefront, and a wavefront calculator for subtracting the error wavefront from the wavefront of the measured light obtained based on the output of the photoelectric converter.

In the wavefront sensor according to the present invention, a deflection plate is provided instead of the second half mirror.
The polarization direction of the deflecting plate is made to coincide with the polarization direction of the measured light.

According to a fifth aspect of the present invention, in the wavefront sensor according to the fifth aspect, instead of the second half mirror, light is transmitted in a wavelength range of the light to be measured and is transmitted in a wavelength range of light emitted from the array light source. A mirror for reflecting light is provided.

According to a sixth aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a lens comprising an objective lens and an eyepiece for projecting light to be measured onto the lens array; and the lens using the projected light to be measured. An optical system having a photoelectric converter that detects a converging spot position of the array,
A wavefront calculator for calculating the wavefront of the measured light based on the output of the photoelectric converter, a variable-diameter aperture installed at the focal position of the objective lens, and a wavefront of the measured light determined by the wavefront calculator. FFT calculating means for performing Fourier transform of the aperture, aperture diameter calculating means for determining the diameter of the variable-diameter aperture based on the light amount distribution at the focal position of the objective lens obtained as a result of the Fourier transform, and the aperture diameter A diaphragm diameter controller for controlling the diameter of the variable diameter diaphragm based on the output of the calculating means.

According to a seventh aspect of the present invention, there is provided a wavefront sensor, comprising: a lens array; a first lens for projecting light to be measured on the lens array; and a condensing spot of the lens array by the projected light to be measured. An optical system having a photoelectric converter for detecting a position, a first dichroic mirror on a measurement light incident side of the first lens, and a first dichroic mirror provided between the first lens and the lens array; A second dichroic mirror that transmits light transmitted through one dichroic mirror to the lens array, and separated by the first dichroic mirror, and the light to be measured is transmitted to the lens array through the second dichroic mirror. A second lens provided in the optical path of the measured light to be projected.

[0021]

In the wavefront sensor according to the first aspect of the present invention, the installation angle of the optical system with respect to the incident light from the reference light source is changed at the time of calibration, and the angle is obtained before and after the angle change of the optical system. By obtaining the calibration value of the distance between the lens array of the optical system and the photoelectric converter in the mounted state based on the output of the photoelectric converter, the wavefront measurement accuracy can be improved.

In the wavefront sensor according to the second aspect of the present invention, the first half mirror inclined from the optical axis is provided immediately before the photoelectric converter, and the wavefront sensor is provided with the first half mirror. A second half mirror is installed facing the measurement light incident side, and the same number of light sources as the number of lens arrays provided at the mirror image position of the photoelectric converter generated by the first half mirror and the second half mirror. By providing an array-like light source having a, the configuration is simple, a reference wavefront generator of an accurate arrangement is obtained, and, when the installation position of the array-like light source is moved in the optical axis direction, the photoelectric converter and The conjugate relationship is broken, and spot blurring occurs. However, by using the wavefront calculator (not shown) as the spot measurement position, the stability with respect to temperature changes of the wavefront sensor can be improved. It can be.

In the wavefront sensor according to the third aspect of the present invention, the arrangement of the converging spot positions of the lens array is determined using the light emitted from the array-like light source. Since the wavefront is calculated and the error wavefront is subtracted from the wavefront of the measured light obtained based on the output of the photoelectric converter, a reference wavefront generator having a simple configuration and an accurate arrangement can be obtained.

In the wavefront sensor according to the fourth aspect of the present invention, a half mirror inclined from the optical axis is provided immediately before the photoelectric converter.
A polarizing plate is installed facing the measured light incident side of the wavefront sensor, and has an array shape having the same number of light sources as the number of lens arrays provided at the mirror image position of the photoelectric converter generated by the half mirror and the polarizing plate. By providing the light source, it is possible to obtain a reference wavefront generator with a simple configuration and an accurate arrangement, and when the installation position of the array light source is moved in the optical axis direction, the conjugate relationship with the photoelectric converter is reduced. Although the collapse spot blurs, the stability with respect to temperature changes of the wavefront sensor can be increased by setting the center of gravity of the spot in the wavefront calculator (not shown) as the spot measurement position.

In the wavefront sensor according to the fifth aspect of the present invention, a half mirror inclined from the optical axis is provided immediately before the photoelectric converter.
A mirror that transmits light in the wavelength range of the measured light and reflects light in the wavelength range of the emitted light of the array-like light source is directly installed on the side of the measured light incident side of the wavefront sensor. By providing an array-like light source having the same number of light sources as the number of lens arrays provided at the mirror image position of the photoelectric converter generated by the mirror and the half mirror, the reference wavefront generator having a simple configuration and an accurate arrangement is provided. When the installation position of the array-like light source is moved in the optical axis direction, the conjugate relationship with the photoelectric converter is broken and spot blur occurs, but the center of gravity of the spot is spotted by a wavefront calculator (not shown). By setting the measurement position as described above, it is possible to increase the stability against a change in the temperature of the wavefront sensor or the like.

In the wavefront sensor according to the sixth aspect of the present invention, the calculation result of the wavefront calculator is Fourier-transformed, and the light quantity distribution at the focal position of the objective lens obtained by the Fourier transformation is obtained. Determine the diameter of the variable aperture that limits the field of view of the wavefront sensor based on the basis, by controlling the aperture of the variable diameter, without blocking the required measured light, stray light (light other than the measured light), It is possible to suppress malfunction and measurement error.

In the wavefront sensor according to the seventh aspect of the present invention, a first dichroic mirror is provided on the measured light incident side of the optical system, and the first dichroic mirror is provided on the measured light incident side of the lens array. Providing a second dichroic mirror, transmitting the light transmitted through the first dichroic mirror, and causing the light to be measured separated by the first dichroic mirror to enter the lens array,
By providing another optical system that conjugates the measured wavefront and the lens array in the optical path separated by the first and second dichroic mirrors, even if the F value of the measured light changes, Since the beam diameter of the light to be measured incident on the lens array can be made constant without replacing the entire system, the spatial resolution of the measurement wavefront can be maintained without deterioration. In addition, since the entire optical system is not replaced, there is no movable part of the optical system, and the tolerance of the optical system can be reduced, and high-accuracy wavefront measurement can be performed.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention. 1, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 1, 1 is a primary mirror of a telescope, 2 is a secondary mirror of a telescope, 8 is a collimator lens, 9 is a lens array, 10 is a CCD, 11 is an optical system of a wavefront sensor, 100 is a wavefront sensor, 101 is a temperature sensor, 102 is an error wavefront calculator, and 103 is a wavefront calculator.

As described in the conventional example, a wavefront measurement error occurs due to an aberration caused by a change in refractive index and shape of an optical material due to a change in temperature, a change in a lens interval due to thermal expansion of a lens barrel, and the like. In the present embodiment, a temperature sensor 101 and an error wavefront calculator 102 are provided, an aberration generated at a used temperature is obtained as an error wavefront, and the wavefront calculator 103 subtracts the error wavefront from the measurement wavefront obtained from the output of the CCD 10. Temperature compensation.

The details of the error wavefront calculator 102 will be described below. The error wavefront calculator 102 is connected to the temperature sensor 10
The change of the focus position generated in the collimator lens 8 due to the temperature change based on the output of 1 is calculated from a predetermined formula, and this is converted into a wavefront. Further, the error wavefront calculator 102 calculates a wavefront caused by a displacement of the spot position due to a difference in linear expansion rate between the lens array 9 and the CCD 10. The error wavefront calculator 102 outputs the sum of the two wavefronts to the wavefront calculator 103 as an error wavefront.

The calculation performed by the error wavefront calculator 102 is
A method for calculating a change in the focus position of the collimator lens 8 due to a change in temperature, a method for obtaining an error wavefront from the change in the focus position, a method for calculating the lens array 9 and the CCD 1
The method will be described below in order of the method of obtaining the error wavefront due to the difference in the linear expansion coefficient of 0.

A change in the focus position of the collimator lens 8 is caused by a change in power caused by a change in the refractive index of the collimator lens due to a change in temperature, and by expansion and contraction of the lens barrel. Assuming that the back focus of the collimator lens 8 is f _b and the linear expansion coefficient of the lens barrel is α, a change in the focus position with respect to a change in the temperature T can be expressed as in Expression (101). Here, β = (1 / φ) · dφ / dT: heat dispersion coefficient

Therefore, a change in focus position when a change in temperature is known can be obtained by the following equation.

[0034] The focus position change Δx and error wavefront [Delta] W _T is related as follows. ΔW _T = Δx / 8λF ² (103) where λ is the wavelength and F is the F value of the lens.

Therefore, the error wavefront can be calculated from the following equation from the equation (103) and the equation (102) for the change in the focus position of the collimator lens due to the temperature change.

Next, a description will be given of an error wavefront generated due to a difference in linear expansion coefficient between the lens array and the CCD. The linear expansion coefficient of the lens array substrate material is α _m , and the linear expansion coefficient of the CCD is α _c
Let r be the distance from the optical axis. The spot movement amount Δr generated by a shape change due to a temperature change is expressed by the following equation.

The relationship between the spot movement amount Δr and the error wavefront is related as follows. Here, n is the number of lens arrays, f _m is the focal length of the lens array, and D _m is the aperture diameter of the lenslet.

From the above, the relationship between the change in the error wavefront and the change in temperature is expressed by the following equation.

Therefore, the error wavefront when the temperature change ΔT occurs can be calculated by equation (108).

The equations (104) and (1) described above
08), the error wavefront calculator 102 calculates the error wavefront ΔW
_T and ΔW _M are obtained, and the correct wavefront W _I can be obtained by subtracting the error wavefront from the measurement wavefront W affected by the temperature change by the wavefront calculator 103 as shown in Expression (109).

Embodiment 2 FIG. FIG. 2 is a configuration diagram showing Embodiment 2 of the present invention. 2, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 2, 1 is a telescope primary mirror, 2 is a telescope sub-mirror, 8 is a collimator lens, 9 is a lens array, 10 is a CCD, 11 is an optical system of a wavefront sensor, 200 is a wavefront sensor, 201 is a barometric pressure sensor, 202
Is an error wavefront calculator, and 203 is a wavefront calculator.

As shown in the conventional example, a change in the refractive index of the atmosphere due to a change in the atmospheric pressure causes a wavefront measurement error. In the present embodiment, the pressure sensor 20 is used as the compensation means.
1 and an error wavefront calculator 202 are provided to obtain an error wavefront at the used atmospheric pressure, and the wavefront calculator 203 subtracts the error wavefront from the measurement wavefront affected by the pressure change obtained from the output of the CCD 10 to compensate for the atmospheric pressure. Is what you do.

The details of the error wavefront calculator 202 will be described below. The error wavefront calculator 202 is a
A change in the lens power generated in the collimator lens 8 due to a change in the atmospheric pressure is calculated based on the output of No. 1 and converted into a wavefront, which is output to the wavefront calculator 203 as an error wavefront.

Hereinafter, a method of calculating the power change of the collimator lens 8 due to the atmospheric pressure change performed by the error wavefront calculator 202 will be described.
Two points of a method of converting a power change into an error wavefront will be described.

First, the collimator lens 8 due to a change in air pressure
The calculation method of the power change will be described. The change in the power φ due to the change in the atmospheric pressure P is expressed by the following equation.

From this, the change Δx in the focus position due to the change in air pressure is expressed by the following equation. dΔx / dP = (dΔx / dφ ) (dφ / dn a) (dn a / dP) = (- 1 / φ 2) (dφ / dn a) (dn a / dP) = (1 / φ) (1 / _{n-n a) (dn a} / dP) = (1 / φ) · γ · (dn a / dP) (202) where, γ = 1 / n-n a: pressure variance (203)

Accordingly, the ratio of the defocus wavefront aberration due to the change in atmospheric pressure is expressed by the following equation through the change in the refractive index of the medium between lenses.

[0048] Therefore, the wavefront [Delta] W _P at the time when the change in air pressure ΔP caused can be calculated from equation (205). ΔW = (dW _P / dP) · ΔP (205)

[0049] As described above, determine the error wavefront [Delta] W _P in error wavefront calculator 202 according to equation (205), the wavefront calculator 2
In 03, the correct wavefront W _I can be obtained by subtracting the error wavefront from the measurement wavefront W affected by the atmospheric pressure change as in the equation (206). W _I = W−ΔW _P (206)

Embodiment 3 FIG. FIG. 3 is a configuration diagram showing Embodiment 3 of the present invention. 3, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 3, reference numeral 301 denotes a temperature-compensated afocal optical system; 302, a lens array;
Reference numeral 3 denotes an objective lens, 304 denotes an eyepiece, and 19 denotes a CCD. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In this embodiment, the lens array 302 and C
The error wavefront caused by the difference in the linear expansion rate from CD19 is
Compensation by residual aberration of afocal optical system 301
Is what you do. Linear expansion of substrate material of lens array 302
The expansion rate is α_m , The linear expansion coefficient of CCD 19 is α _c And Sports
The relationship between the amount of shift and the error wavefront is expressed by the above equation (107).
And let this be θHere, n is the number of lens arrays, f_m Is the focus of the lens array
Point distance, D_m Is the aperture diameter of the lenslet.

Next, the lens power of the afocal optical system 301 satisfying the temperature compensation condition will be described. First, a method of calculating a power change of the afocal optical system 301 due to a temperature change will be described. The power of the afocal optical system 301 is expressed by equation (302). Where φ _o : power of the objective lens 303 φ _e : power of the eyepiece 304 m = φ _e / φ _o : magnification of the afocal optical system 301 : Interval between the objective lens 303 and the eyepiece 304

The temperature change rate of the power of the afocal optical system 301 is expressed by equation (304). The afocal optical system 3 can be obtained by making the heat dispersions β _o and β _e of the power of the objective lens 303 and the eyepiece 304 equal.
Assuming that the magnification m of 01 does not change with temperature,
It is expressed by the following equation. dm / dT = 0 (305) Using the above equations (303), (304), and (305), the temperature change rate of the power of the afocal optical system 301 is expressed by equation (306). Here, α _B = (1 / e) · (de / dT): linear expansion coefficient of the lens barrel β _o = (1 / φ _o ) · (dφ _o / dT)

Therefore, as a temperature compensation condition, a wavefront that cancels the error wavefront θ generated by the spot movement is generated.
The following equation must be satisfied. (DW _T / dT) = (８λF ² ) · (dΔx / dφ) · (dφ / dT) = (１ ／ λF ² ) · (−1 / φ ² ) · (dφ / dT) = − θ ( 307)

On the other hand, in a synthetic lens in which thin lenses composed of a plurality of types of materials are brought close to each other, when the variance of the i-th material is μ _i and the lens power is φ _i , Must be satisfied. The power of each lens is determined from this equation and three equations obtained by adding the equation (307) relating to the power satisfying the above temperature compensation condition.

As described above, by constructing the objective lens 303 and the eyepiece 304 using at least three types of materials, the wavefront that satisfies the combined power condition and achromatizes, and always satisfies the two conditions of temperature compensation. A sensor can be configured.

Embodiment 4 FIG. FIG. 4 is a configuration diagram showing Embodiment 4 of the present invention. 4, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 4, 1 is a primary mirror of the telescope, 2 is a secondary mirror of the telescope, 400 is a wavefront sensor, 401
Is a pressure compensating collimator lens. Here, CC
A wavefront calculator for obtaining a wavefront based on the output of D10 is not shown.

The pressure variance γ represented by the equation (401) can be treated in the same manner as the dispersion μ in a so-called achromatic lens. γ = 1 / (n-n a) (401)

When the collimator lens 401 is composed of a plurality of lenses combining different materials, it is possible to equivalently produce a material characteristic such as atmospheric pressure dispersion γ. In a synthetic lens in which thin lenses made of a plurality of types of materials are brought close to each other, when the ith material has a dispersion of μ _i , a pressure dispersion of γ _i , and a lens power of φ _i , the following conditions apply to the collimator lens 401. Needs to be satisfied.

As described above, if the collimator lens is formed by using at least three kinds of materials, the afocal optical system which satisfies the combined power condition and achromatizes and always satisfies the two conditions of the atmospheric pressure compensation is required. Can be.

Embodiment 5 FIG. 5 is a configuration diagram showing Embodiment 5 of the present invention. 5, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 5, reference numeral 501 denotes a calibration value calculator; 502, a wavefront sensor angle controller;
Is a reference light source.

In the present embodiment, the distance between the CCD 10 and the lens array 9 required for accurately calculating the inclination of the wavefront is not directly measured, but is measured and calibrated in the mounted state.

As shown in the conventional example, the relationship between the deviation amount Δr of the spot position on the CCD 10 and tan θ is expressed by the following equation. _{tanθ = Δr / l m (501} ) , where, l _m is the distance between the microlens array 9 and CCD 10. Now, light having an incident angle θ is incident on the wavefront sensor, the deviation Δr from the reference spot position is measured, and the distance l _m is obtained from the above θ and Δr by the equation (501).

Hereinafter, a method of calibrating the wavefront sensor will be described. (1) The wavefront calculator 21 measures the reference spot position by the reference light source 29. (2) The wavefront sensor angle controller 502 tilts the optical system 11 of the wavefront sensor by θ, and calculates the tilt angle θ as a calibration value calculator 501. To send to. (3) The wavefront calculator 21 measures the calibration data spot position, and (4) the wavefront calculator 21 subtracts the reference spot position from the calibration data spot position to obtain a displacement Δr of the spot position.
Is sent to the calibration value calculator 501. (5) The calibration value calculator 501 calculates a distance l _m between the lens array 9 and the CCD 10 in pixel units from Δr and θ, and the wavefront calculator 21 stores data in an internal memory. Thus, the calibration is completed.

When the wavefront measurement is performed, the actual calibration of the lens array 9 and the CCD 10
The distance between them is accurately determined, and the accuracy of wavefront measurement can be improved.

Embodiment 6 FIG. 6 is a configuration diagram showing Embodiment 6 of the present invention. 6, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. 6, reference numeral 600 denotes a wavefront sensor, 601 is a half mirror, 602 is a calibration light introducing half mirror, 603 is an array-shaped light source NA adjustment mask,
604 is an array-like light source, and 605 is a shutter. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In the present embodiment, the reference light is obtained by a simple configuration instead of the reference wavefront generator 15 for emitting the collimated reference light required for the wavefront sensor having the afocal system 28 described in the section of the prior art. Like that.

First, the configuration of the wavefront sensor will be described. The light emitted from the array-shaped light source 604 is converted into an optical system
0, the half mirror 602 for introducing the calibration light
Are arranged in front of the CCD 19. An array light source 604 is installed at a mirror image position of the CCD 19 generated by the half mirrors 601 and 602. Array light source 6
The NA adjustment mask 603 provided on the front surface of the light source 04 has a number of openings corresponding to the number of the array light sources 604 in a flat plate, and limits the emission angle of each light source constituting the array light source 604. The light emitted from the light source and the lenses constituting the lens array 18 are made to correspond one-to-one. F of lens array 18
When the value is F and the distance from the array light source 604 to the mask 603 is x, the aperture diameter D of the mask 603 is obtained by the following equation. D = x / F (601)

The light emitted from the array light source 604 is introduced into the wavefront sensor via the calibration light introduction half mirror 602,
After being reflected by the half mirror 601, the light is focused on the CCD 19 by the lens array 18. When the reference light source is used, the measured light is blocked by the shutter 605.

Next, a method of correcting a measurement wavefront using a reference light source will be described. The output light of the array light source 604 is
Since the light passes through the optical system of the wavefront sensor twice, the effect of twice the optical system aberration is measured. Array light source 60
In No. 4, an accurate arrangement can be obtained by using, for example, a laser diode array, and the disturbance of the arrangement of the spots is caused by the influence of the optical system aberration. The wavefront is determined based on the measured disorder of the arrangement of the spots, and the half is obtained.
Is the error wavefront caused by the aberration of the optical system,
By subtracting the previously obtained error wavefront from the measured wavefront at the time of wavefront measurement, the correct wavefront can be measured.

In the conventional method, when the position of the reference light source 29 moves in the optical axis direction due to a change in ambient temperature or the like, a distorted spherical wave is incident on the wavefront sensor, and the position of the spot changes. However, in the present embodiment, when the installation position of the array-like light source 604 moves in the optical axis direction, spot blurring occurs due to the collapse of the conjugate relationship with the CCD. However, if the wavefront calculator 21 defines spot position measurement using the center of gravity of a commonly used spot, the position of the center of gravity does not change even if blurring occurs.

As described above, it is possible to realize a reference light source that is strong against a change in use environment conditions. This also reduces the manufacturing tolerance when the arrangement position of the array-like light source is conjugate with the CCD. Can be taken.

Embodiment 7 FIG. FIG. 7 is a configuration diagram showing Embodiment 7 of the present invention. 7, the same reference numerals as those in FIGS. 11 and 6 indicate the same or corresponding parts. In FIG. 7, 7
00 is a wavefront sensor, 701 is a polarizing plate, and 704 is an array-polarized light source. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In this embodiment, the light to be measured is polarized, and the polarizing plate 7 is used instead of the half mirror 601 of the sixth embodiment.
01, and an array-like polarized light source 704 is used as the array-like light source 604.

The array-shaped polarized light source 704 is installed at a mirror image position of the CCD 19 generated by the half mirror 602 and the polarizing plate 701, and is orthogonal to the polarization direction of the light to be measured. When the polarization direction of the polarizing plate 701 and the polarization direction of the measured light are set to coincide with each other, the measured light transmits through the polarizing plate 704,
A focused spot is formed on the CCD 19. The reference light is reflected by the polarizing plate 701 and forms a spot on the CCD 19. When the array-shaped polarized light source 704 is used, the measured light is blocked by the shutter 605. Other operations are the same as in the sixth embodiment.

As described above, the polarizing plate 701 reflects the calibration light almost 100%, and reflects the measured light almost 100%.
Since the light is transmitted, it is possible to realize an optical system in which the amount of light loss of the reference light and the light to be measured by the polarizing plate 701 inserted for calibration is extremely small.

Embodiment 8 FIG. FIG. 8 is a configuration diagram showing Embodiment 8 of the present invention. 8, the same reference numerals as those in FIGS. 11 and 6 denote the same or corresponding parts. In FIG. 8, 8
00 is a wavefront sensor, 801 is a dichroic mirror, 8
Reference numeral 04 denotes an array light source having a wavelength different from that of the light to be measured. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

In the present embodiment, the wavelengths of the measured light and the reference light are different. The dichroic mirror 801 is configured to transmit light in the wavelength range of the light to be measured and reflect the light in the wavelength range of the reference light.

The array-like light source 804 is
CCD 19 generated between the light source 2 and the dichroic mirror 801
It is installed at the mirror image position of. The measured light passes through the dichroic mirror 801 to form a spot on the CCD 19. On the other hand, the light emitted from the array light source 804 is introduced by the half mirror 602 and reflected by the dichroic mirror 801 to form a spot on the CCD 19. When the reference light source is used, the measured light is blocked by the shutter 605. Other operations are the same as in the sixth embodiment.

As described above, the dichroic mirror 80
1 reflects almost 100% of the reference light and transmits almost 100% of the light to be measured, so that it is possible to realize an optical system in which the dichroic mirror 801 has a very small loss of light amount of the reference light and the light to be measured.

Embodiment 9 FIG. FIG. 9 is a configuration diagram showing Embodiment 9 of the present invention. 9, the same reference numerals as those in FIG. 11 denote the same or corresponding parts. In FIG. 9, 900 is a wavefront sensor, 901 is a diaphragm having a variable diameter, 902 is a diaphragm diameter controller, 903 is a diaphragm diameter calculator which is a diaphragm diameter calculator,
Reference numeral 904 denotes an FFT operation unit which is an FFT operation means.

In this embodiment, in order to suppress stray light, the aperture diameter is changed in accordance with the state of light condensing by the objective lens 16 of the afocal optical system.

In order to suppress stray light, it is necessary to reduce the diameter of the stop so as not to cut off the light to be measured. When the front focal plane of the objective lens 16 is set as the wavefront measurement position, the point image intensity distribution by the objective lens 16 follows the Fourier transform result of the measurement wavefront. The FFT calculator 904 performs a Fourier transform of the measured wavefront obtained by the wavefront calculator 21 to obtain a point image intensity distribution. An aperture diameter calculator 903 gives a threshold value to the point image intensity distribution, and sets a range exceeding the threshold value as an aperture diameter. The aperture diameter controller 902 adjusts the aperture diameter based on this information.

As described above, stray light which has been a problem in the case of a fixed aperture can be reduced, and malfunction can be suppressed.

Embodiment 10 FIG. FIG. 10 is a configuration diagram showing a tenth embodiment of the present invention. 10, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts. In FIG. 10, 8
Is a first collimator lens, 111 and 113 are first and second dichroic mirrors, 114 and 115 are bandpass filters, 116 and 118 are mirrors, 117
Is a second collimator lens, and 110 is a wavefront sensor. Here, a wavefront calculator for obtaining a wavefront based on the output of the CCD 19 is not shown.

The telescope has a configuration in which the sub-mirror 2 is exchanged, and the F-number changes as the sub-mirror 2 changes, as indicated by the broken line in FIG. As shown in the conventional example, it is necessary to replace the collimator lens 8 according to a change in the F value or to prepare another wavefront sensor corresponding to each F value.

To make the diameters of the wavefronts incident on the lens array 18 with different F-numbers the same, the first collimator lens 8
May be changed according to the F value. In the present embodiment, the optical path is separated by the first dichroic mirror 111, and a second collimator lens 117 suitable for the F value is provided in the separated optical path to cope with a change in the F value.

Since the second collimator lens 117 and the optical path length can be freely set by changing the optical path, the second collimator lens 117 suitable for the F-number can be used, and the lens array 18 and the following can be shared. it can. Since light of two wavelengths enters the lens array, the wavelength selection is performed by exchanging the bandpass filters 114 and 115.

As described above, it is not necessary to replace the entire optical system depending on the F value, and since there are no movable parts other than the band-pass filters 114 and 115, the tolerance of the optical system can be suppressed to a small value and high accuracy can be achieved. Wavefront measurement can be realized.

[0090]

According to the present invention configured as described above, it is possible to obtain a wavefront sensor capable of measuring the wavefront of the light to be measured with high accuracy even if the condition of the incident light changes.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a wavefront sensor according to a first embodiment.

FIG. 2 is a configuration diagram of a wavefront sensor according to a second embodiment.

FIG. 3 is a configuration diagram of a wavefront sensor according to a third embodiment.

FIG. 4 is a configuration diagram of a wavefront sensor according to a fourth embodiment.

FIG. 5 is a configuration diagram of a wavefront sensor according to a fifth embodiment.

FIG. 6 is a configuration diagram of a wavefront sensor according to a sixth embodiment.

FIG. 7 is a configuration diagram of a wavefront sensor according to a seventh embodiment.

FIG. 8 is a configuration diagram of a wavefront sensor according to an eighth embodiment.

FIG. 9 is a configuration diagram of a wavefront sensor according to a ninth embodiment.

FIG. 10 is a configuration diagram of a wavefront sensor according to a tenth embodiment.

FIG. 11 is a configuration diagram of an apparatus (telescope) including a conventional wavefront sensor.

FIG. 12 is a diagram for explaining the relationship between the distance between the lens array and the CCD and the focal length of the lens array.

FIG. 13 is a diagram for explaining a malfunction of the wavefront sensor due to stray light.

FIG. 14 is a diagram for explaining a change in the number of effective lens arrays due to a difference in F value.

[Description of Signs] 1: Primary mirror of telescope 2: Secondary mirror of telescope 4: Lamp for reference light source 5: Lamp light condensing lens 6: Pinhole 7: Beam splitter 8: Collimator lens (first collimator lens) 9: Lens array 10: CCD 11: Optical system of wavefront sensor 13: Deformable mirror 14: Beam splitter 16: Objective lens 17: Eyepiece 18: Lens array 19: CCD 20: Optical system of wavefront sensor 21: Wavefront calculator 22: Deformable mirror 28: Afocal optical system 29: Reference light source 50: Wavefront sensor 51: Wavefront sensor 100: Wavefront sensor 101: Temperature sensor 102: Error wavefront calculator 103: Wavefront calculator 110: Wavefront sensor 111, 113: Dichroic mirror 114, 115: band pass filter 117: second collimation Data lens 116, 118: mirror 200: wavefront sensor 201: barometric pressure sensor 202: error wavefront calculator 203: wavefront calculator 301: temperature compensation afocal optical system 302: lens array 303: objective lens 304: eyepiece 400: wavefront sensor 401 : Pressure compensation collimator lens 501: Calibration value calculator 502: Wavefront sensor angle controller 600: Wavefront sensor 601: Half mirror 602: Half mirror for introducing calibration light 603: Array light source NA adjustment mask 604: Array light source 605: Shutter 700 : Wavefront sensor 701: Polarizing plate 704: Array-like polarized light source 800: Wavefront sensor 801: Dichroic mirror 804: Array-like light source having a wavelength different from the light to be measured 900: Wavefront sensor 901: Variable aperture stop 902: Stop aperture control La 903: Diameter calculator 904: FFT calculator

Claims (6)

[Claims] 1. A lens array, a photoelectric converter for detecting a condensed spot position of the lens array, an optical system for making a wavefront to be measured and the lens array have a conjugate relationship, and an output from the photoelectric converter. A wavefront calculator for calculating a wavefront, and a wavefront sensor for measuring the wavefront of the light to be measured, wherein, during calibration, an angle controller of the wavefront sensor for changing an installation angle of the wavefront sensor with respect to the incident light of the reference light source; A wavefront sensor comprising: a calibration value calculator for calculating a calibration value of a distance between the lens array and the photoelectric converter based on an output of the photoelectric converter obtained before and after the change of the installation angle. . 2. A lens array, a photoelectric converter for detecting a condensing spot position of the lens array, an optical system for making a wavefront to be measured conjugate with the lens array, and an output from the photoelectric converter. A wavefront calculator for determining a wavefront, and a wavefront sensor for measuring the wavefront of the light to be measured, wherein a half mirror inclined from the optical axis is installed immediately before the photoelectric converter, and the light to be measured by the wavefront sensor is measured. A semi-transparent flat plate optical element is installed facing the incident side, and an array-like light source having the same number of light sources as the number of lens arrays is provided at a mirror image position of the photoelectric converter generated by the half mirror and the semi-transparent flat plate optical element. A wavefront sensor characterized in that: 3. A lens array, a photoelectric converter for detecting a condensing spot position of the lens array, an optical system for making a wavefront to be measured conjugate with the lens array, and an output from the photoelectric converter. A wavefront calculator for determining a wavefront, and a wavefront sensor for measuring the wavefront of the light to be measured, wherein a half mirror inclined from the optical axis is installed immediately before the photoelectric converter, and the light to be measured by the wavefront sensor is measured. A polarizing plate is installed facing the incident side, and at the mirror image position of the photoelectric converter generated by the half mirror and the polarizing plate, a light source having a polarization direction orthogonal to the measured light and the same number of lens arrays is provided. A wavefront sensor provided with an array-shaped polarized light source. 4. A lens array, a photoelectric converter for detecting the position of a condensed spot of the lens array, an optical system for making the wavefront to be measured and the lens array conjugate, and an output of the photoelectric converter. A wavefront calculator for determining a wavefront, and a wavefront sensor for measuring the wavefront of the light to be measured, wherein a half mirror inclined from the optical axis is installed immediately before the photoelectric converter, and the light to be measured by the wavefront sensor is measured. A dichroic mirror is installed facing the incident side, and an array having a wavelength different from that of the light to be measured and having the same number of light sources at the mirror image position of the photoelectric converter generated by the half mirror and the dichroic mirror is provided. A wavefront sensor comprising a light source. 5. A lens array, a photoelectric converter for detecting a condensing spot position of the lens array, and an afocal optical system that adjusts a diameter of incident light and makes a conjugate relationship between a wavefront to be measured and the lens array. And a wavefront calculator for calculating a wavefront based on the output of the photoelectric converter, and a wavefront sensor for measuring the wavefront of the light to be measured, wherein the wavefront sensor is provided at a focal position of an objective lens of the afocal optical system. A variable-diameter aperture for limiting the field of view, FFT calculating means for performing a Fourier transform on the calculation result of the wavefront calculator, and a light amount distribution at the focal position of the objective lens of the afocal optical system obtained by the Fourier transform. And a diaphragm diameter calculating means for determining the diameter of the diaphragm, and a diaphragm diameter controller for controlling the diameter of the variable diaphragm based on the output of the diaphragm diameter calculating means. Support. 6. A lens array, a photoelectric converter for detecting a condensing spot position of the lens array, an optical system for making a wavefront to be measured and the lens array have a conjugate relationship, and an output from the photoelectric converter. A wavefront calculator for calculating a wavefront, the wavefront sensor measuring the wavefront of the light to be measured, wherein a first dichroic mirror is provided on the incident side of the light to be measured of the optical system of the wavefront sensor, and a wavefront of the lens array is provided. A second dichroic mirror for transmitting the transmitted light transmitted through the first dichroic mirror and causing the measured light separated by the first dichroic mirror to be incident on the lens array is provided on the incident side of the measurement light. Characterized in that a wavefront to be measured and another optical system for conjugated with the lens array are provided in an optical path separated by a second dichroic mirror. Capacitors.