CN104977156A - Calibration system for measuring beam quality beta factor according to CCD far-field method - Google Patents

Abstract

The invention discloses a calibration system for measuring a beam quality beta factor according to a CCD far-field method. A combined transmission aberration plate in the calibration system is mounted on a fixed base. An annular shield with a variable diameter is arranged in front of the fixed base. The pitch angle and the azimuth angle of the fixed base can be accurately adjusted. A laser interferometer is used for measuring the wavefront distortions of the transmission aberration plates in different combination modes. Then parallel light source output beams are vertically emitted to the combined transmission aberration plate. The output light beams enter a calibrated light beam quality beta factor measurement system. Measurement system calibration is finished through comparing the light beam quality beta factor value which is obtained through testing the wavefront distortion by the combined transmission aberration plate with the light beam quality beta factor value that is actually measured by the calibrated light beam quality beta factor measurement system. The calibration system has advantages of simple operation in a calibration method, effective capability of satisfying the calibration requirement of the light beam quality beta factor measurement system with different wavelengths and different calibers, relatively high precision and convenient use.

Description

A kind of calibration system measured for CCD far field method beam quality β factor

Technical field

The invention belongs to laser beam beam quality Measurement and calibration technical field, be specifically related to a kind of calibration system for the measurement of CCD far field method beam quality β factor and calibration steps, be applicable to the calibration of CCD far field method beam quality β factor measuring system.

Background technology

Beam quality is one of the key technical indexes evaluating laser beam performance.Laser beam quality parameter has multiple, wherein the β factor is a kind of evaluating generally adopted, in laser instrument development or application, usual employing CCD far field method carries out Measurement accuracy to the Laser Output Beam quality β factor, and it is simple and can obtain the advantage of far-field spot spatial light intensity distribution in real time that it has measuring method.At present, the reference instrument product also not having beam quality β factor to measure both at home and abroad, primarily of being certainly ground into, affect the many factors of CCD far field method beam quality β factor measurement result accuracy, comprise ccd detector performance parameter (pixel dimension, target surface size, linear dynamic range, cryogenic radiometry etc.), Focused Optical system face shape error and software for calculation Processing Algorithm etc., measurement model is obviously in non-linear, the relation that influences each other between each factor also more complicated, is difficult to adopt uncertainty transmission rule to evaluate; Meanwhile, still lack the measurement and calibration ability that beam quality β factor is measured both at home and abroad at present, also do not propose corresponding calibration steps.Existing research work mainly concentrates in laser beam quality evaluating and measuring method, as " discussion of Evaluating Beam Quality of High Energy Lasers with Unstable Resonators " (Liu Zejin, Chinese laser, 1998, the 25th volume the 3rd phase: 193 ~ 196 pages) describe beam quality β factor and measuring method thereof, for ccd detector device performance, the impact of optical system face shape error also has some to study, as " impact of Surface Error of Optical Elements on Beam Quality ", (ten thousand is quick, Acta Optica, 2002, 22nd volume the 4th phase: 495 ~ 500 pages), " CCD photoelectric response nonlinear characteristic is on the impact that laser far field focal spot is measured and beam quality calculates " (He Yuanxing, Chinese laser, 2012, 39th volume the 4th phase: 0408001) etc., these study as the exploitation of beam quality β factor design of measuring system provides guidance foundation, but the demand of beam quality β factor measuring system high-precision measuring calibration cannot be met.

Summary of the invention

The object of the invention is to solve in prior art the problem lacking CCD far field method beam quality β factor measuring system rated capacity, the invention provides a kind of calibration system measured for CCD far field method beam quality β factor, another object of the present invention is to provide a kind of calibration steps measured for CCD far field method beam quality β factor.

The present invention adopts following technical scheme for achieving the above object:

For the calibration system that CCD far field method beam quality β factor is measured, comprise previous calibration system and later stage calibration system,

In described previous calibration system, the light of source of parallel light enters laser interferometer through variable picture element device;

In described later stage calibration system, the light of source of parallel light enters through variable picture element device and is calibrated beam quality β factor measuring system.

In technique scheme, described variable picture element device comprises combination transmission aberration plate, annulus blocks and hold-down support; Described combination transmission aberration plate and annulus block and are arranged on hold-down support, and annulus blocks and is arranged between combination transmission aberration plate and source of parallel light.

In technique scheme, described combination transmission aberration plate comprises some blocks of transmission aberration plates, and beam quality corresponding to combination transmission aberration Lamb wave front-distortion is by the beam quality β factor measuring system calibration range of school.

In technique scheme, described transmission aberration plate comprises aberroscope, picture frame; Wherein aberroscope is arranged in picture frame.

In technique scheme, the effective aperture of aberroscope is not less than by school beam quality β factor measuring system use bore, and 0 ° of angle transmission uses; The effective aperture of picture frame is identical with aberroscope, and has angle rotation regulating mechanism.

In technique scheme, the outer shroud that described annulus blocks is concentric with inner ring, carries out size change according to the outer shroud blocked annulus by the change of school beam quality β factor measuring system central obscuration size and inner ring.

In technique scheme, described hold-down support has the angle of pitch, position angle minute adjustment function.

In technique scheme, described source of parallel light operation wavelength is identical with by school beam quality β factor measuring system operation wavelength, output beam bore is not less than by school beam quality β factor measuring system use bore, and output beam wavefront distortion PV value is less than λ/5.

The present invention also provides a kind of calibration steps of the calibration system for the measurement of CCD far field method beam quality β factor, comprises the following steps:

A variable picture element device is arranged on laser interferometer exit position by (), regulate annulus to block outside diameter, interior circular diameter, make annulus block clear aperture and use bore identical with by school beam quality β factor measuring system;

B () starts laser interferometer, outgoing beam is made to incide on variable picture element device with 0 ° of angle, and ensure that the central shaft of outgoing beam overlaps with variable picture element device central shaft, reflected by standard flat mirror again, former for light beam road is back to laser interferometer, and laser interferometer need be calibrated through the legal unit of measurement;

C () is according to calibration range needed for the beam quality β factor measuring system of school, adjust the array mode of variable picture element device combination transmission aberration plate or rotate the angle of aberroscope, guaranteeing that beam quality β factor corresponding to the wavefront error of variable picture element device is distributed in by the calibration range of school beam quality β factor measuring system;

D the wavefront error of the variable picture element device (2) of () laser interferometer measurement, obtains wavefront error zernike polynomial expression formula 36 rank coefficient a _i(λ ₁), λ ₁for laser interferometer operation wavelength, wherein i value is from 1 to 36;

E () is at laser interferometer operation wavelength λ ₁with by school beam quality β factor measuring system operation wavelength λ ₂time not identical, calculate λ by following formula ₂variable picture element device wavefront error zernike polynomial expression formula each rank coefficient under wavelength;

$a_i\left({\mathrm{\λ}}_2\right)=\frac{a_i\left({\mathrm{\λ}}_1\right)\×{\mathrm{\λ}}_1}{{\mathrm{\λ}}_2}$

In above formula, λ ₁for laser interferometer operation wavelength, λ ₂for by school beam quality β factor measuring system operation wavelength, a _i(λ ₁) be laser interferometer measurement variable picture element device wavefront error zernike polynomial expression formula i-th rank coefficient, a _i(λ ₂) for calculating corresponding λ ₂variable picture element device wavefront error zernike polynomial expression formula i-th rank coefficient under wavelength, wherein i value is from 1 to 36;

F () is according to λ ₂under wavelength, variable picture element device wavefront error Ze Nike expression formula, calculates the beam quality β that variable picture element device wavefront error is corresponding ₀₁;

(g) keep combining in variable picture element device the array mode of transmission aberration plate (3) and use angle constant, variable picture element device (2) is moved to source of parallel light exit position, source of parallel light need be calibrated through the legal unit of measurement, outgoing beam is made to incide on variable picture element device with 0 ° of angle, and ensure that the central shaft of outgoing beam overlaps with variable picture element device central shaft, coaxially again enter by school beam quality β factor measuring system, by the beam quality β being measured output beam by school beam quality β factor measuring system ₁₁;

H () changes the array mode or the anglec of rotation that combine transmission aberration plate in variable picture element device, make beam quality corresponding to variable picture element device wavefront error being changed by the calibration range of school beam quality β factor measuring system, and corresponding beam quality number of data points is not less than 4, is designated as β respectively ₀₂, β ₀₃, β ₀₄, β ₀₅;

I () repeats step (d) ~ (g), by being obtained the beam quality that in correspondence (h), under various combination mode, variable picture element device is corresponding by school beam quality β factor measuring system measurement, be designated as β respectively ₁₂, β ₁₃, β ₁₄, β ₁₅;

(j) contrast beam quality β ₀₁~ β ₀₅with β ₁₁~ β ₁₅numerical value, provides the calibration correction factor, uncertainty of measurement.

In described step (g), the transmitance of variable picture element device under source of parallel light operation wavelength should meet is measured requirement by school beam quality β factor measuring system.

A kind of calibration system for the measurement of CCD far field method beam quality β factor of the present invention and calibration steps, its ultimate principle is: according to by school beam quality β factor measuring system calibration range, adjust the array mode of variable picture element device combination aberrations plate, produce multiple different beam quality value in corresponding calibration range, and by laser interferometer measurement wavefront error, theory calculate draws corresponding beam quality β ₀; Again variable picture element device is placed on source of parallel light exit position, by by the beam quality β of school beam quality β factor measuring system actual measurement output beam ₁, contrast the calculated results β ₀with actual measured results β ₁, thus complete by the calibration of school beam quality β factor measuring system.

Beneficial effect of the present invention is: adopt variable picture element unit simulation to produce the beam quality of the different beta factor, contrasted by calculated value and measured value, thus realize the calibration of beam quality β factor measuring system, solve a difficult problem for CCD far field method beam quality β factor uncertainty of measurement calibration, method is simply effective, and precision is high.Calibration system of the present invention and calibration steps are that the accurate calibration of laser beam beam quality β factor measuring instrument has established technical foundation.

Accompanying drawing explanation

Examples of the present invention will be described by way of reference to the accompanying drawings, wherein:

Fig. 1 is the calibration system structural representation measured for CCD far field method beam quality β factor of the present invention.

Fig. 2 is the structural representation for the transmission aberration plate of variable picture element device in the calibration system of CCD far field method beam quality β factor measurement of the present invention.

Fig. 3 is the variable picture element device wavefront error optical path schematic diagram measured for CCD far field method beam quality β factor of the present invention.

Fig. 4 is of the present invention for CCD far field method beam quality β factor measuring system calibration light path schematic diagram.

In figure, 1. the variable picture element device 3. of source of parallel light 2. combines transmission aberration plate 4. annulus and blocks 5. hold-down support 6. transmission aberration plate 7. aberroscope 8. picture frame 9. angle rotation regulating mechanism 10. standard flat mirror 11. interferometer main frame 12. acquisition process computing machines 13. by school beam quality β factor measuring system.

Embodiment

In Fig. 1 ~ 4, the calibration system measured for CCD far field method beam quality β factor of the present invention comprises source of parallel light, variable picture element device, combination transmission aberration plate, annulus block, hold-down support, transmission aberration plate, aberroscope, picture frame, angle rotation regulating mechanism, standard flat mirror, interferometer main frame, acquisition process computing machine, by school beam quality β factor measuring system.

The operation wavelength of source of parallel light is identical with by school beam quality β factor measuring system operation wavelength, and output beam bore is not less than by school beam quality β factor measuring system use bore, and output beam wavefront distortion PV value is less than λ/5.

Variable picture element device comprises combination transmission aberration plate, annulus blocks, hold-down support; Wherein combine transmission aberration plate and annulus to block and be arranged on hold-down support; Annulus blocks and is arranged on before combination transmission aberration plate, and the center that annulus blocks overlaps with the center of combining transmission aberration plate.

Combination transmission aberration plate comprises polylith transmission aberration plate, and beam quality corresponding to combination transmission aberration Lamb wave front-distortion is by the beam quality β factor measuring system calibration range of school.

Transmission aberration plate comprises aberroscope, picture frame; Wherein aberroscope is arranged in picture frame, and aberroscope effective aperture is not less than by school beam quality β factor measuring system use bore, and 0 ° of angle transmission uses, and is mainly coma aberration.Picture frame effective aperture is identical with aberroscope, and has angle rotation regulating mechanism.

The outer shroud that annulus blocks is concentric with inner ring, and the size of outer shroud, inner ring can change, to mate by school beam quality β factor measuring system central obscuration size.

Hold-down support has the angle of pitch, position angle minute adjustment function.

Laser interferometer comprises interferometer main frame, standard flat mirror, acquisition process computing machine.

In the present embodiment, used bore Φ 270mm by school beam quality β factor measuring system, central obscuration Φ 50mm, operation wavelength is 1.319 μm, β factor Measurement and calibration scope 2 ~ 10; Adopt monolithic transmission aberration plate 6 effective aperture Φ 300mm, adopt material, thickness 30mm, not plated film, the front-back angle of wedge, quantity is 4 pieces, adopts ZyGo GPI-300 digital laser interferometer measurement wavefront error under Φ 270mm bore, central obscuration Φ 50mm.

Calibration steps for the measurement of CCD far field method beam quality β factor of the present invention comprises the following steps successively:

A variable picture element device is arranged on laser interferometer exit position by (), regulate annulus to block outside diameter, interior circular diameter, make annulus block clear aperture and use bore identical with by school beam quality β factor measuring system;

B () starts laser interferometer, outgoing beam is made to incide on variable picture element device with 0 ° of angle, and ensure that the central shaft of outgoing beam overlaps with variable picture element device central shaft, reflected by standard flat mirror again, former for light beam road is back to laser interferometer, and laser interferometer need be calibrated through the legal unit of measurement;

C () is according to calibration range needed for the beam quality β factor measuring system of school, adjust the array mode of variable picture element device combination transmission aberration plate or rotate the angle of aberroscope, guaranteeing that beam quality β factor corresponding to the wavefront error of variable picture element device is distributed in by the calibration range of school beam quality β factor measuring system;

D the wavefront error of the variable picture element device of () laser interferometer measurement, obtains wavefront error zernike polynomial expression formula 36 rank coefficient a _i(λ ₁), λ ₁for laser interferometer operation wavelength, wherein i value is from 1 to 36;

E () is at laser interferometer operation wavelength λ ₁with by school beam quality β factor measuring system operation wavelength λ ₂time not identical, calculate λ by following formula ₂variable picture element device wavefront error zernike polynomial expression formula each rank coefficient under wavelength;

$a_i\left({\mathrm{\λ}}_2\right)=\frac{a_i\left({\mathrm{\λ}}_1\right)\×{\mathrm{\λ}}_1}{{\mathrm{\λ}}_2}$

In above formula, λ ₁for laser interferometer operation wavelength, λ ₂for by school beam quality β factor measuring system operation wavelength, a _i(λ ₁) be laser interferometer measurement variable picture element device wavefront error zernike polynomial expression formula i-th rank coefficient, a _i(λ ₂) for calculating corresponding λ ₂variable picture element device wavefront error zernike polynomial expression formula i-th rank coefficient under wavelength, wherein i value is from 1 to 36;

F () is according to λ ₂under wavelength, variable picture element device wavefront error Ze Nike expression formula, calculates the beam quality β that variable picture element device wavefront error is corresponding ₀₁;

(g) keep the array mode of the combination transmission aberration plate in variable picture element device and use angle constant, variable picture element device is moved to source of parallel light exit position, source of parallel light need be calibrated through the legal unit of measurement, outgoing beam is made to incide on variable picture element device with 0 ° of angle, and ensure that the central shaft of outgoing beam overlaps with variable picture element device central shaft, coaxially again enter by school beam quality β factor measuring system, by the beam quality β being measured output beam by school beam quality β factor measuring system ₁₁;

H () changes array mode or the anglec of rotation of the combination transmission aberration plate in variable picture element device, make beam quality corresponding to variable picture element device wavefront error being changed by the calibration range of school beam quality β factor measuring system, and corresponding beam quality number of data points is not less than 4, is designated as β respectively ₀₂, β ₀₃, β ₀₄, β ₀₅;

I () repeats step (d) ~ (g), by being obtained the beam quality that in correspondence (h), under various combination mode, variable picture element device is corresponding by school beam quality β factor measuring system measurement, be designated as β respectively ₁₂, β ₁₃, β ₁₄, β ₁₅;

(j) contrast beam quality β ₀₁~ β ₀₅with β ₁₁~ β ₁₅numerical value, provides the calibration correction factor, uncertainty of measurement.

Embodiment 2

The present embodiment is identical with the basic structure of embodiment 1, and difference is: described source of parallel light be Φ 250mm by the bore of school beam quality β factor measuring system.

Embodiment 3

The present embodiment is identical with the basic structure of embodiment 1, and difference is: described source of parallel light be 1.064 μm by school beam quality β factor measuring system operation wavelength.

Embodiment 4

The present embodiment is identical with the basic structure of embodiment 1, and difference is: described combination transmission aberration plate aberration-types is spherical aberration, and spherical aberration term coefficient accounting is 90%.

The foregoing is only preferred embodiment of the present invention, and non-limiting protection scope of the present invention.

The present invention is not limited to aforesaid embodiment.The present invention expands to any new feature of disclosing in this manual or any combination newly, and the step of the arbitrary new method disclosed or process or any combination newly.

Claims (9)

1., for the calibration system that CCD far field method beam quality β factor is measured, it is characterized in that comprising previous calibration system and later stage calibration system,

In described previous calibration system, the light of source of parallel light enters laser interferometer through variable picture element device;

In described later stage calibration system, the light of source of parallel light enters through variable picture element device and is calibrated beam quality β factor measuring system.

2. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 1, is characterized in that described variable picture element device comprises combination transmission aberration plate, annulus blocks and hold-down support; Described combination transmission aberration plate and annulus block and are arranged on hold-down support, and annulus blocks and is arranged between combination transmission aberration plate and source of parallel light.

3. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 2, it is characterized in that described combination transmission aberration plate comprises some blocks of transmission aberration plates, beam quality corresponding to combination transmission aberration Lamb wave front-distortion is by the beam quality β factor measuring system calibration range of school.

4. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 3, is characterized in that described transmission aberration plate comprises aberroscope, picture frame; Wherein aberroscope is arranged in picture frame.

5. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 4, it is characterized in that the effective aperture of aberroscope is not less than and used bore by school beam quality β factor measuring system, 0 ° of angle transmission uses; The effective aperture of picture frame is identical with aberroscope, and has angle rotation regulating mechanism.

6. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 2, it is characterized in that the outer shroud that described annulus blocks is concentric with inner ring, carry out size change according to the outer shroud blocked annulus by the change of school beam quality β factor measuring system central obscuration size and inner ring.

7. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 2, is characterized in that described hold-down support has the angle of pitch, position angle minute adjustment function.

8. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 1, it is characterized in that described source of parallel light operation wavelength is identical with by school beam quality β factor measuring system operation wavelength, output beam bore is not less than by school beam quality β factor measuring system use bore, and output beam wavefront distortion PV value is less than λ/5.

9. a kind of calibration system measured for CCD far field method beam quality β factor according to claim 1, adopt following calibration steps, its feature comprises the following steps:

A variable picture element device is arranged on laser interferometer exit position by (), regulate annulus to block outside diameter, interior circular diameter, make annulus block clear aperture and use bore identical with by school beam quality β factor measuring system;

B () starts laser interferometer, outgoing beam is made to incide on variable picture element device with 0 ° of angle, and ensure that the central shaft of outgoing beam overlaps with variable picture element device central shaft, reflected by standard flat mirror again, former for light beam road is back to laser interferometer, and laser interferometer need be calibrated through the legal unit of measurement;

C () is according to calibration range needed for the beam quality β factor measuring system of school, adjust the array mode of variable picture element device combination transmission aberration plate or rotate the angle of aberroscope, guaranteeing that beam quality β factor corresponding to the wavefront error of variable picture element device is distributed in by the calibration range of school beam quality β factor measuring system;

D the wavefront error of the variable picture element device (2) of () laser interferometer measurement, obtains wavefront error zernike polynomial expression formula 36 rank coefficient a _i(λ ₁), λ ₁for laser interferometer operation wavelength, wherein i value is from 1 to 36;

E () is at laser interferometer operation wavelength λ ₁with by school beam quality β factor measuring system operation wavelength λ ₂time not identical, calculate λ by following formula ₂variable picture element device wavefront error zernike polynomial expression formula each rank coefficient under wavelength;

$a_i\left({\mathrm{\λ}}_2\right)=\frac{a_i\left({\mathrm{\λ}}_1\right)\×{\mathrm{\λ}}_1}{{\mathrm{\λ}}_2}$

In above formula, λ ₁for laser interferometer operation wavelength, λ ₂for by school beam quality β factor measuring system operation wavelength, a _i(λ ₁) be laser interferometer measurement variable picture element device wavefront error zernike polynomial expression formula i-th rank coefficient, a _i(λ ₂) for calculating corresponding λ ₂variable picture element device wavefront error zernike polynomial expression formula i-th rank coefficient under wavelength, wherein i value is from 1 to 36;

F () is according to λ ₂under wavelength, variable picture element device wavefront error Ze Nike expression formula, calculates the beam quality β that variable picture element device wavefront error is corresponding ₀₁;

(g) keep combining in variable picture element device the array mode of transmission aberration plate (3) and use angle constant, variable picture element device (2) is moved to source of parallel light exit position, source of parallel light need be calibrated through the legal unit of measurement, outgoing beam is made to incide on variable picture element device with 0 ° of angle, and ensure that the central shaft of outgoing beam overlaps with variable picture element device central shaft, coaxially again enter by school beam quality β factor measuring system, by the beam quality β being measured output beam by school beam quality β factor measuring system ₁₁;

H () changes the array mode or the anglec of rotation that combine transmission aberration plate in variable picture element device, make beam quality corresponding to variable picture element device wavefront error being changed by the calibration range of school beam quality β factor measuring system, and corresponding beam quality number of data points is not less than 4, is designated as β respectively ₀₂, β ₀₃, β ₀₄, β ₀₅;

I () repeats step (d) ~ (g), by being obtained the beam quality that in correspondence (h), under various combination mode, variable picture element device is corresponding by school beam quality β factor measuring system measurement, be designated as β respectively ₁₂, β ₁₃, β ₁₄, β ₁₅;

(j) contrast beam quality β ₀₁~ β ₀₅with β ₁₁~ β ₁₅numerical value, provides the calibration correction factor, uncertainty of measurement.