CN101013030A - Microlen array based laser beam divegence angle testing method - Google Patents

Abstract

The invention is a laser beam divergence angle testing method based on the micro-lens array, and the invention belongs to the optical field, specifically relating to the laser beam divergence angle testing method. It overcomes the existing deficiencies of the existing beam scattered angle method with larger measurement error and less measurement real-time feature. It includes the following steps: the measured beam is incidence to the telescope system, matching the output beam diameter and the micro-lens array shape, and the micro-lens array contains mXn matrix sub-lens; using micro-lens array to divide the measured beam into the sub-beams, and through CCD to detect the launch angle of each sub-beam, and through statistical method to calculate the measured beam divergence angle, the measurement accuracy reaching 0.1mu rad. Because this method does not require the measurement light spot diameter, it avoids the problem that the light spot diameter is difficult to be accurately measured. This method in the invention is only measuring in the one position of the optical path; therefore the method can facilitate to realize the real-time measurement of the beam divergence angle.

Description

Laser beam divergent angle test method based on microlens array

Technical field

The invention belongs to optical field, be specifically related to the method for testing of laser beam divergent angle.

Background technology

Laser beam divergent angle is the important parameter of existing laser beam emitting device, to its accurately measure be the development of high-precision laser emitter with use in major issue.Existing method of testing is generally at diverse location measuring light spot diameter, according to its situation of change with distance, calculates beam divergence angle.In practical operation,, bring bigger measuring error because the beam edge vignetting makes spot diameter be difficult for measuring accurately.Because this method need take multiple measurements at diverse location, real-time is relatively poor in addition.

Summary of the invention

The purpose of this invention is to provide a kind of laser beam divergent angle test method, to overcome the big and relatively poor defective of test real-time of existing beam divergence angle method of testing measuring error based on microlens array.It is realized by following step: one, tested light beam incident telescopic system 5, the spot diameter of tested light beam of output and the physical dimension of microlens array 8 are complementary, microlens array 8 comprise m * n identical, be arranged in rectangular sub-lens 8-3; Two, microlens array 8 is divided into m * n to the hot spot of tested light beam and organizes beamlet, and beamlet is focused on the focal plane, forms m * n sub-hot spot; Three, use area array CCD detector 4 antithetical phrase hot spots to survey, the photosurface of area array CCD detector 4 is divided into m * n sub-search coverage 4-1, and the optical axis line of each sub-lens 8-3 all passes the central point of a sub-search coverage 4-1; I in the photosurface of area array CCD detector 4, j sub-search coverage 4-1 neutron hot spot off-center Δ X _Ij, Δ Y _Ij, i then, j bundle beamlet is along the emission angle θ of azimuth axis X and pitch axis Y direction _x(i, j), θ _Y(i j) is

${\mathrm{\θ}}_y(i,j)=\frac{{\mathrm{\ΔX}}_{\mathrm{ij}}}{\mathrm{\β}\·f};$ ${\mathrm{\θ}}_y(i,j)=\frac{{\mathrm{\ΔY}}_{\mathrm{ij}}}{\mathrm{\β}\·f}$

Wherein, β is the enlargement factor of telescopic system, and f is the focal length of sub-lens in the microlens array;

M * n group beamlet emission angle is carried out following calculating, and the bidimensional that can get tested light beam points to the angle

For:

${\stackrel{\‾}{\mathrm{\θ}}}_x=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\θ}}_x(i,j)\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}};$ ${\stackrel{\‾}{\mathrm{\θ}}}_y=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\θ}}_y(i,j)\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}}$

The variance δ θ of the bidimensional angle of divergence of tested light beam then _x, δ θ _yFor:

$\mathrm{\δ}{{\mathrm{\θ}}_x}^2=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{({\stackrel{\‾}{\mathrm{\θ}}}_x-{\mathrm{\θ}}_x(i,j))}^2\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}};$ $\mathrm{\δ}{{\mathrm{\θ}}_y}^2=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{({\stackrel{\‾}{\mathrm{\θ}}}_y-{\mathrm{\θ}}_y(i,j))}^2\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}}$

Then, the angle of divergence δ θ of tested light beam is:

$\mathrm{\δ\θ}=2\sqrt{2}{(\mathrm{\δ}{\mathrm{\θ}}_x^2+\mathrm{\δ}{\mathrm{\θ}}_y^2)}^{1/2}$

E _IjBe i, total gray-scale value of j sub-hot spot, with i, the luminous energy that j bar beamlet is comprised is directly proportional.

The present invention proposes a kind of measuring method of the laser transmitting system beam divergence angle based on microlens array.Utilize microlens array that tested light beam is decomposed into beamlet, survey the emission angle of each beamlet by CCD, and calculate tested beam divergence angle by statistical method, measuring accuracy can reach 0.1 μ rad.Because this method does not need to measure the diameter of hot spot, has avoided spot diameter and has been difficult for measuring a difficult problem accurately.Guaranteeing the high-precision while and since the inventive method only a position measurement in light path get final product, need not take multiple measurements, so the inventive method can realize the real-time measurement of beam divergence angle easily at diverse location.

Description of drawings

Fig. 1 is the synoptic diagram of the inventive method, Fig. 2 is the synoptic diagram that microlens array is divided into the hot spot of tested light beam m * n group beamlet, Fig. 3 is that beamlet projects the synoptic diagram on the area array CCD detector 4, and Fig. 4 is that a branch of beamlet projects a synoptic diagram among the sub-search coverage 4-1.

Embodiment

Embodiment one: specify present embodiment below in conjunction with Fig. 1 to Fig. 4.Present embodiment realizes by following step: one, the telescopic system 5 be made up of lens 5-1 and lens 5-2 of tested light beam incident, the spot diameter of tested light beam of output and the physical dimension of microlens array 8 are complementary, microlens array 8 comprise m * n identical, be arranged in rectangular sub-lens 8-3; Two, microlens array 8 is divided into m * n to the hot spot of tested light beam and organizes beamlet, and beamlet is focused on the focal plane, forms m * n sub-hot spot; Three, use area array CCD detector 4 antithetical phrase hot spots to survey, the photosurface of area array CCD detector 4 is divided into m * n sub-search coverage 4-1, and the optical axis line of each sub-lens 8-3 all passes the central point of a sub-search coverage 4-1; When group beam Propagation direction is parallel with the optical axis of sub-lens 8-3, its focal beam spot will be positioned at the center of sub-search coverage 4-1.I in the photosurface of area array CCD detector 4, j sub-search coverage 4-1 neutron hot spot off-center Δ X _Ij, Δ Y _Ij, i then, j bundle beamlet is along the emission angle θ of azimuth axis X and pitch axis Y direction _x(i, j), θ _Y(i j) is:

${\mathrm{\θ}}_y(i,j)=\frac{\mathrm{\Δ}{X}_{\mathrm{ij}}}{\mathrm{\β}\·f};$ ${\mathrm{\θ}}_y(i,j)=\frac{\mathrm{\Δ}{Y}_{\mathrm{ij}}}{\mathrm{\β}\·f}$

Wherein, β is the enlargement factor of telescopic system, and f is the focal length of sub-lens in the microlens array; M * n group beamlet emission angle is carried out following calculating, and the bidimensional that can get tested light beam points to the angle

,

For:

${\stackrel{\‾}{\mathrm{\θ}}}_x=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\θ}}_x(i,j)\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{\mathrm{ij}}};$ ${\stackrel{\‾}{\mathrm{\θ}}}_y=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\θ}}_y(i,j)\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{\mathrm{ij}}}$

The variance δ θ of the bidimensional angle of divergence of tested light beam then _x, δ θ _yFor:

$\mathrm{\δ}{{\mathrm{\θ}}_x}^2=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{({\stackrel{\‾}{\mathrm{\θ}}}_x-{\mathrm{\θ}}_x(i,j))}^2\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{\mathrm{ij}}};$ $\mathrm{\δ}{{\mathrm{\θ}}_y}^2=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{({\stackrel{\‾}{\mathrm{\θ}}}_y-{\mathrm{\θ}}_y(i,j))}^2\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}}$

Then the angle of divergence δ θ of tested light beam is:

$\mathrm{\δ\θ}=2\sqrt{2}{(\mathrm{\δ}{\mathrm{\θ}}_x^2+\mathrm{\δ}{\mathrm{\θ}}_y^2)}^{1/2}$

E _IjBe i, total gray-scale value of j sub-hot spot, with i, the luminous energy that j bar beamlet is comprised is directly proportional.

Embodiment two: specify present embodiment below in conjunction with Fig. 1.The difference of present embodiment and embodiment one is: it is 300mm that telescopic system 5 adopts bore, and enlargement ratio is 50 transmission-type telescope.It can compress 50 times with the spot diameter of tested light beam.Other step is identical with embodiment one.

Embodiment three: the difference of present embodiment and embodiment one is: the sub-lens 8-3 in the microlens array is arranged in 64 * 64 square formation, and the focal length of each sub-lens 8-3 is 1mm, diameter 0.1mm.Other step is identical with embodiment one.

Embodiment four: the difference of present embodiment and embodiment one is: the MTV-1801 planar array type ccd video camera that ccd detector 4 selects for use Taiwan Min Tong company to produce.Its major parameter is as follows: spectral response range 400nm～1100nm; Several 795 (H) * 596 (V) of pixel; Pixel dimension 10 μ rad; Line frequency 15625Hz; Field frequency 50Hz; Resolution 600TVL; Detection sensitivity 0.02lx; Signal to noise ratio (S/N ratio) is greater than 46dB; Working temperature-10 ℃～50 ℃; Power supply DC12V (2W).The beam deflection scope of correspondence ± 1mrad, effective pixel number of getting CCD is 500 (H) * 500 (V), utilizes this CCD hot spot detecting for spaces precision can reach 1 μ m.Other step is identical with embodiment one.

Embodiment five: the difference of present embodiment and embodiment one is: adopt the video capture card based on 1394 agreements, the image information input computing machine 6 that ccd detector 4 is gathered carries out corresponding calculated.Other step is identical with embodiment one.

Claims (4)

1, based on the laser beam divergent angle test method of microlens array, it is characterized in that it realizes by following step: one, tested light beam incident telescopic system (5), the spot diameter of tested light beam of output and the physical dimension of microlens array (8) are complementary, microlens array (8) comprise m * n identical, be arranged in rectangular sub-lens (8-3); Two, microlens array (8) is divided into m * n to the hot spot of tested light beam and organizes beamlet, and beamlet is focused on the focal plane, forms m * n sub-hot spot; Three, use area array CCD detector (4) antithetical phrase hot spot to survey, the photosurface of area array CCD detector (4) is divided into m * n sub-search coverage (4-1), and the optical axis line of each sub-lens (8-3) all passes the central point of a sub-search coverage (4-1); I in the photosurface of area array CCD detector (4), j sub-search coverage (4-1) neutron hot spot off-center Δ X _Ij, Δ Y _Ij, i then, j bundle beamlet is along the emission angle θ of azimuth axis X and pitch axis Y direction _x(i, j), θ _Y(i j) is:

${\mathrm{\θ}}_y(i,j)=\frac{\mathrm{\Δ}{X}_{\mathrm{ij}}}{\mathrm{\β}\·f};$ ${\mathrm{\θ}}_y(i,j)=\frac{\mathrm{\Δ}{Y}_{\mathrm{ij}}}{\mathrm{\β}\·f}$

Wherein, β is the enlargement factor of telescopic system, and f is the focal length of sub-lens in the microlens array;

M * n group beamlet emission angle is carried out following calculating, and the bidimensional that can get tested light beam points to the angle

For:

${\stackrel{-}{\mathrm{\θ}}}_x=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\θ}}_x(i,j)\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}};$ ${\stackrel{-}{\mathrm{\θ}}}_y=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\θ}}_y(i,j)\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}}$

The variance δ θ of the bidimensional angle of divergence of tested light beam then _x, δ θ _yFor:

$\mathrm{\δ}{\mathrm{\θ}}_x^2=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{({\stackrel{-}{\mathrm{\θ}}}_x-{\mathrm{\θ}}_x(i,j))}^2\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}};$ $\mathrm{\δ}{\mathrm{\θ}}_y^2=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{({\stackrel{-}{\mathrm{\θ}}}_y-{\mathrm{\θ}}_y(i,j))}^2\·E_{i,j}}{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{E}_{i,j}}$

Then, the angle of divergence δ θ of tested light beam is:

$\mathrm{\δ\θ}=2\sqrt{2}{(\mathrm{\δ}{\mathrm{\θ}}_x^2+\mathrm{\δ}{\mathrm{\θ}}_y^2)}^{1/2}$

E _IjBe i, total gray-scale value of j sub-hot spot, with i, the luminous energy that j bar beamlet is comprised is directly proportional.

2, the laser beam divergent angle test method based on microlens array according to claim 1 is characterized in that it is 300mm that telescopic system (5) adopts bore, and enlargement ratio is 50 transmission-type telescope.

3, the laser beam divergent angle test method based on microlens array according to claim 1 is characterized in that sub-lens (8-3) in the microlens array is arranged in 64 * 64 square formation, and the focal length of each sub-lens (8-3) is 1mm, diameter 0.1mm.

4, the laser beam divergent angle test method based on microlens array according to claim 1, it is characterized in that adopting the video capture card based on 1394 agreements, the image information input computing machine (6) that ccd detector (4) is gathered carries out corresponding calculated.