CN103336366B - The device of uniform line laser beam is produced based on high-NA post lens focus - Google Patents

Abstract

The present invention relates to a kind of device producing uniform line laser beam based on high-NA post lens focus, be made up of linearly polarized laser light source, globe lens group, rectangular aperture, 1/2nd wave plates, discontinuous wave plate and high-NA post lens; The light beam that linearly polarized laser light source produces after globe lens group beam-expanding collimation by rectangular aperture choose spot center part almost uniform rectangular lines polarized light pass through; The rectangular lines polarized light of rectangular aperture injection through 1/2nd wave plates, then through or after discontinuous wave plate, produce uniform line laser beam by high-NA post lens focus at focal plane.This apparatus structure is simple, when using or not using discontinuous wave plate, by simply rotating the numerical aperture of 1/2nd wave plates and change high-NA post lens, namely can obtain the uniform line laser beam of center flat-top at focal plane place; Homogeneous line beam can be used for line sweep micro-imaging, micro Nano material processing and detects.

Description

The device of uniform line laser beam is produced based on high-NA post lens focus

Technical field

The invention belongs to laser beam shaping field, be specifically related to a kind of device producing uniform line laser beam based on high-NA post lens focus.

Background technology

Uniform line throw light on online scanning microscopy imaging, micro Nano material processing and detect field have a wide range of applications.In order to meet the requirement of above-mentioned use, the uniform line illumination of generation need have strong light intensity, good light intensity uniformity and superfine size.Uniform line illumination traditional natural light source being carried out to beam shaping acquisition is difficult to realize above-mentioned requirements simultaneously, and along with the appearance of high brightness laser light source, can obtain by carrying out optical shaping to laser beam the uniform line illumination met the demands.Be generally the uniform line laser beam obtaining flat-top, beam shaping system need adopt complicated structure, and the use of non-spherical lens makes it expensive.

Summary of the invention

For the defect existed in above-mentioned prior art or deficiency, the object of the invention is to, provide a kind of device producing uniform line laser beam based on high-NA post lens focus, this device can produce superfine uniform line laser beam.

In order to realize above-mentioned task, the present invention takes following technical solution:

Produce a device for uniform line laser beam based on high-NA post lens focus, it is characterized in that: be made up of linearly polarized laser light source, globe lens group, rectangular aperture, 1/2nd wave plates, discontinuous wave plate and high-NA post lens;

The light beam that linearly polarized laser light source produces, after globe lens group beam-expanding collimation, by rectangular aperture choose spot center part almost uniform rectangular lines polarized light pass through; From the rectangular lines polarized light of rectangular aperture injection through 1/2nd wave plates, then through or after discontinuous wave plate, produce uniform line laser beam by high-NA post lens focus at focal plane.

The device producing uniform line laser beam based on high-NA post lens focus of the present invention, structure is simple, when using or not using discontinuous wave plate, superfine uniform line laser beam can be produced by the numerical aperture of the polarization direction and high-NA post lens that change rectangular lines polarized light; Thin uniform line laser beam can be used for line sweep micro-imaging, micro Nano material processing and detects.

Accompanying drawing explanation

Fig. 1 is the apparatus structure schematic diagram producing uniform line laser beam based on high-NA post lens focus of the present invention;

Fig. 2 (a) is rectangular lines polarized light field distribution when not using discontinuous wave plate; B () is rectangle TEM after the discontinuous wave plate of use ₀₁linearly polarized light field distribution;

Fig. 3 is discontinuous wave chip architecture schematic diagram;

Fig. 4 (a) is rectangular lines polarized light (φ ₀=28.1 °) the even surface of intensity distribution of center flat-top that produces at focal plane place after the aplanasia post lens focus of numerical aperture NA=1; B () is for producing similar even light distribution, φ ₀with the graph of relation that NA meets;

Fig. 5 (a) is rectangle TEM ₀₁linearly polarized light (φ ₀=32 °) the even surface of intensity distribution of center flat-top that produces at focal plane place after the aplanasia post lens focus of numerical aperture NA=1; B () is for producing similar even light distribution, φ ₀with the graph of relation that NA meets.

Below in conjunction with drawings and Examples, the present invention is described in further detail.

Embodiment

Embodiment 1:

As shown in Figure 1, the present embodiment provides a kind of device producing uniform line laser beam based on high-NA post lens focus, is made up of linearly polarized laser light source 1, globe lens group 2, rectangular aperture 3,1/2nd wave plate 4 and high-NA post lens 6;

The light beam that linearly polarized laser light source 1 produces, after globe lens group 2 beam-expanding collimation by rectangular aperture 3 choose spot center part almost uniform rectangular lines polarized light pass through; The rectangular lines polarized light penetrated from rectangular aperture 3 is focused on by high-NA post lens 6 after 1/2nd wave plates 4, produces uniform line laser beam at focal plane place.

In the present embodiment, linearly polarized laser light source 1 is gas laser light source, semiconductor laser light resource, all-solid state laser light source or fiber laser light source.

Globe lens group 2 is made up of little focal length globe lens and long-focus globe lens, and before its medium and small focal length globe lens is placed on, long-focus globe lens is placed on after little focal length globe lens, carries out beam-expanding collimation for the light beam produced by linearly polarized laser light source 1.

Rectangular aperture 3 for choose spot center part almost uniform rectangular lines polarized light pass through.

/ 2nd wave plates 4 are for regulating the polarization direction of rectangular lines polarized light.

The bus of high-NA post lens 6 is parallel with x-axis.

As shown in Figure 2 (a) shows, polarization direction and y-axis angle are φ to the distribution of rectangular lines polarized light field ₀.

The device based on high-NA post lens focus generation uniform line laser beam of the present embodiment realizes principle and is: for the linearly polarized light of high-NA post lens focus, the optical field distribution near its focal plane need adopt vector diffraction methods analyst,

$\stackrel{\→}{E}(y_s,z_s)=E_x{\stackrel{\→}{e}}_x+E_y{\stackrel{\→}{e}}_y+E_z{\stackrel{\→}{e}}_z,---\left(1\right)$

Wherein y _s, z _sfor image planes rectangular coordinate system; with for the unit vector along x, y, z direction.

Focal plane place electric field component E _x, E _yand E _zcan be expressed as

Wherein image space position angle

θ _max=sin ^-1(NA/n) be the integration maximum angular of post lens numerical aperture decision; N is image planes medium refraction index; A=kf/2, k are wave vector, and f is the post focal length of lens.Relative amplitude E _{0, x}and E _{0, y}can be expressed as

$\left\{\begin{array}{c}{E}_{0,x}\left(\mathrm{\θ}\right)=\sin \left({\mathrm{\φ}}_0\right),\\ E_{0,y}\left(\mathrm{\θ}\right)=\cos \left({\mathrm{\φ}}_0\right).\end{array}\right.---\left(4\right)$

Can find out according to equation (2) and (4), by suitable selection φ ₀the uniform line that can realize center flat-top with NA combination focuses on light distribution.

If Fig. 4 (a) is rectangular lines polarized light (φ ₀=28.1 °) the even surface of intensity distribution of center flat-top that produces at focal plane place after the aplanasia post lens focus of numerical aperture NA=1, Ix, Iy, Iz represent x respectively, y, z electric field component light intensity; B () is for producing similar even light distribution, φ ₀with the graph of relation that NA meets.

Embodiment 2:

As shown in Figure 1, in the light path shown in embodiment 1, add a discontinuous wave plate 5, convert rectangular lines polarized light to rectangle TEM ₀₁linearly polarized light, rectangle TEM ₀₁linearly polarized light focuses on focal plane 7 place through aplanasia high-NA post lens 6, and other conditions of the present embodiment are with embodiment 1.

In the present embodiment, between the two halves of discontinuous wave plate 5, there is certain height difference, to make the relative phase difference producing π between light beam two halves, thus convert rectangular lines polarized light to rectangle TEM ₀₁line polarisation; And separatrix between discontinuous wave plate 5 two halves is parallel with x-axis.Discontinuous wave plate 5 structural representation as shown in Figure 3.

Rectangle TEM ₀₁linearly polarized light field distribution is as shown in Fig. 2 (b), and polarization direction and y-axis angle are φ ₀, upper and lower two parts field orientation is contrary.

The device producing uniform line laser beam based on high-NA post lens focus of the present embodiment, it is similar to Example 1 that it realizes principle, its focal plane place electric field component E _x, E _yand E _zcan be expressed as:

Can find out according to equation (4) and (5), by suitable selection φ ₀the uniform line focused light light distribution of center flat-top can be realized with NA combination.

If Fig. 5 (a) is rectangle TEM ₀₁linearly polarized light (φ ₀=32 °) the even surface of intensity distribution of center flat-top that produces at focal plane place after the aplanasia post lens focus of numerical aperture NA=1, Ix, Iy, Iz represent x respectively, y, z electric field component light intensity; B () is for producing similar even light distribution, φ ₀with the graph of relation that NA meets.

Claims (5)

1. one kind produces the device of uniform line laser beam based on high-NA post lens focus, it is characterized in that, be made up of linearly polarized laser light source (1), globe lens group (2), rectangular aperture (3), 1/2nd wave plates (4), discontinuous wave plate (5) and high-NA post lens (6);

The light beam that linearly polarized laser light source (1) produces, after globe lens group (2) beam-expanding collimation, by rectangular aperture (3) choose spot center part almost uniform rectangular lines polarized light pass through; The rectangular lines polarized light penetrated from rectangular aperture (3) is through 1/2nd wave plates (4), then through or after discontinuous wave plate (5), focus on focal plane (7) by high-NA post lens (6) and produce uniform line laser beam;

Wherein:

The bus of high-NA post lens (6) is parallel with x-axis; The polarization direction and the y-axis angle that incide the rectangular lines polarized light of high-NA post lens (6) are φ ₀, by suitable selection φ ₀with the combination of the numerical aperture NA of described post lens, focus on the above-mentioned uniform line laser beam of light distribution with the uniform line realizing having center flat-top;

Described 1/2nd wave plates (4) are for regulating the polarization direction of rectangular lines polarized light, certain height difference is there is between described discontinuous wave plate (5) two halves, to make the relative phase difference producing π between light beam two halves, thus convert rectangular lines polarized light to rectangle TEM ₀₁linearly polarized light; And separatrix between discontinuous wave plate (5) two halves is parallel with x-axis.

2. the device of uniform line laser beam is produced as claimed in claim 1 based on high-NA post lens focus, it is characterized in that, described linearly polarized laser light source (1) is gas laser light source, semiconductor laser light resource, all-solid state laser light source or fiber laser light source.

3. produce the device of uniform line laser beam as claimed in claim 1 based on high-NA post lens focus, it is characterized in that, described globe lens group (2) is made up of little focal length globe lens and long-focus globe lens.

4. produce as claimed in claim 1 the device of uniform line laser beam based on high-NA post lens focus, it is characterized in that, described discontinuous wave plate (5) choice for use or do not use.

5. produce the device of uniform line laser beam as claimed in claim 1 based on high-NA post lens focus, it is characterized in that, described rectangle TEM ₀₁linearly polarized light focuses on focal plane (7) place through aplanasia high-NA post lens (6).