阅读说明：本技术 基于相位载波的提高光束质量的方法 (The method of raising beam quality based on phase carrier ) 是由 高雅茹 刘德安 张盼 于 2018-05-18 设计创作，主要内容包括：一种基于相位载波的提高近场光束质量的方法,该方法只需要在光路中设置反射式相位型空间光调制器,并在反射式相位型空间光调制器上加载一个合适的空间频率的矩形相位载波,即可解决空间滤波器中堵孔尺寸与滤波尺寸的矛盾问题,保证滤波效果,提高近场光束质量。本发明具有结构简单、操作方便的特点。(A method of the raising near field beam quality based on phase carrier, this method only needs that reflective phase type spatial light modulator is arranged in the optical path, and the rectangle phase carrier of a suitable spatial frequency is loaded on reflective phase type spatial light modulator, the contradictory problems of plug-hole size and filtering size in spatial filter can be solved, guarantee filter effect, improves near field beam quality.The present invention has the characteristics that structure is simple and convenient to operate.)

1. a kind of method of the raising beam quality based on phase carrier, which is characterized in that this method includes the following steps:

1) spatial filter is made of the first lens (2), filtering aperture (3) and the second lens (4), in the spatial filter The first reflecting mirror (6), the second reflecting mirror (7), polarizing film (8) are sequentially placed in the optical path of periodic modulation light beam (1) before With Amici prism (9), which is divided into transmitted light and reflected light for incident light, is arranged in the reflection light direction Reflective phase type spatial light modulator (11) is arranged in the transmission light direction in detector (10), described reflective The reflection light direction of phase type spatial light modulator (11) is successively the Amici prism (9), third reflecting mirror (12) and institute The output end of the spatial filter stated, the detector (10) is connected with the input terminal of computer (13), the computer (13) output end is connected with the control terminal of the reflective phase type spatial light modulator (11), the polarizing film (8) Polarization direction it is consistent with the long axis direction of reflective phase type spatial light modulator (11) liquid crystal display panel, described is anti- The front focal plane that formula phase type spatial light modulator (11) are located at the first lens (2) is penetrated, the Amici prism (9) arrives the spy Survey distance and Amici prism (9) being equidistant to reflective phase type spatial light modulator (11) of device (10)；

2) light distribution and phase distribution of detector (10) the detection light beam, i.e., reflective phase type spatial light tune are utilized The light distribution I of incident beam at device (11) processed₀(x₀,y₀) and phase distributionAnd input the computer (13)；

3) computer (13) described in is fitted an ideal Gaussian beam according to the light distribution of incident beam, as target beam Light distribution I_t(x₀,y₀), target wavefront is free of aberration；

4) according to the light distribution I of incident beam at reflective phase type spatial light modulator (11)₀(x₀,y₀), phase distributionWith the light distribution I of target beam_t(x₀,y₀), determine the lower limit of rectangle phase carrier phase amplitude And the upper limitIt is respectively as follows: with the variation of position

Then the phase distribution of rectangle phase carrier is expressed from the next:

In formula, T is the period of rectangle phase carrier, and n is the number of cycles for including in rectangle phase carrier overall width；

5) phase distribution of the rectangle phase carrier is converted into corresponding grayscale image by the computer (13) described in, and is loaded Onto the reflective phase type spatial light modulator (11)；

6) the periodic modulation light beam (1) described in exports high beam from the spatial filter after above structure and processing The output light of quality.

Technical field

The present invention relates to laser technology fields, and more specifically, the present invention is to be related to a kind of raising based on phase carrier The method of near field beam quality.

Background technique

In high power laser system, light beam is in hundreds of meters of transmission process, due to the ash in optical element quality, environment The reasons such as dirt, pollution particulate matter can introduce various amplitude modulations and phase-modulation near field light beam, this not only lowers The beam quality of system, and the probability of optic element damage is increased, also improve the operation and maintenance cost of system.These Modulation, which is broadly divided into, blocks modulation caused by object, the modulation of acyclic random distribution and periodic modulation three as single local Seed type.Wherein, periodic modulation can also introduce secondary lobe to far field, correspond to other than introducing periodically modulation near field In the spatial frequency of periodic modulation.Under high-throughput running environment, when considering the nonlinear effect of medium, certain periodicity The spatial frequency of modulation will appear it is non-linear increase rapidly, cause Small-scale Self-focusing phenomenon, and subsequent optical element can be excited Damage.Spatial filter is to filter out the most common method of periodic modulation, and structural schematic diagram is as shown in Figure 1, thoroughly by two It mirror and is formed with filtering aperture.But in high power laser system, in order to obtain better filter effect, it is normally set up Filter aperture radius very little, and filter aperture it is too small when, in addition to can give output near field introduce low frequency diffraction ring other than, also easily It causes the secondary lobe of periodic modulation and aperture edge material to have an effect at focal plane and leads to the problem of plug-hole, plug-hole problem is to influence The key factor that superpower laser load capacity is promoted.The size for increasing filtering aperture to a certain extent can be to avoid The generation of plug-hole problem, but the requirement of filtering is reduced simultaneously, ideal filter effect cannot be reached.Bagnoud V in 2004 With Zuegel J D [referring to Bagnoud V, Zuegel J D.Independent phase and amplitude control of a laser beam by use of a single-phase-only spatial light modulator[J] .Optics letters, 2004,29 (3): 295-297] propose the amplitude that near field light beam is controlled using rectangle phase carrier method And phase, to carry out shaping to light beam.But the rectangle phase carrier distribution finally loaded needs two different spaces frequencies The superposition of the one-dimensional rectangle phase carrier of rate and periodic modulation light beam is not considered.

Summary of the invention

The method for improving near field beam quality based on phase carrier that the purpose of the present invention is to provide a kind of, this method is only It needs to be arranged in the optical path reflective phase type spatial light modulator, and loads one on reflective phase type spatial light modulator The rectangle phase carrier of a spatial frequency, i.e., the contradictory problems of plug-hole size and filtering size, guarantee in solution spatial filter Filter effect improves near field beam quality.

In order to achieve the above-mentioned object of the invention, technical solution of the invention is as follows:

A method of the raising beam quality based on phase carrier, it is characterized in that, this method includes the following steps:

1) spatial filter is made of the first lens, filtering aperture and the second lens, before the spatial filter Periodic modulation light beam optical path in be sequentially placed the first reflecting mirror, the second reflecting mirror, polarizing film and Amici prism, the light splitting Incident light is divided into transmitted light and reflected light by prism, detector is arranged in the reflection light direction, in the transmitted light side To reflective phase type spatial light modulator is arranged, the reflective phase type spatial light modulator reflection light direction according to Secondary is the Amici prism, third reflecting mirror and the spatial filter, the output end and computer of the detector Input terminal be connected, the control terminal phase of the output end of the computer and the reflective phase type spatial light modulator Even, make the polarization direction of the polarizing film and the long axis direction of the reflective phase type spatial light modulator liquid crystal display panel Unanimously, the reflective phase type spatial light modulator is located at the front focal plane of the first lens, and the Amici prism is described in Detector distance with Amici prism being equidistant to reflective phase type spatial light modulator；

2) light distribution and phase distribution of the detector detection light beam described in, i.e., reflective phase type spatial light modulator Locate the light distribution I of incident beam₀(x₀,y₀) and phase distributionAnd input the computer；

3) computer described in is fitted an ideal Gaussian beam according to the light distribution of incident beam, as target beam Light distribution I_t(x₀,y₀), target wavefront is free of aberration；

4) according to the light distribution I of incident beam at reflective phase type spatial light modulator₀(x₀,y₀), phase distributionWith the light distribution I of target beam_t(x₀,y₀), determine the lower limit of rectangle phase carrier phase amplitude And the upper limitIt is respectively as follows: with the variation of position

Then the phase distribution of rectangle phase carrier is expressed from the next:

In formula, T is the period of rectangle phase carrier, and n is the number of cycles for including in rectangle phase carrier overall width；

5) phase distribution of the rectangle phase carrier is converted into corresponding grayscale image by the computer described in, and is loaded Onto the reflective phase type spatial light modulator；

6) the periodic modulation light beam described in exports high beam from the spatial filter after above structure and processing The output light of quality.

Due to the distance and Amici prism to reflective phase type spatial light of the Amici prism to the detector Modulator is equidistant, so, the beam intensity and phase distribution of the detector detection are reflective phase The beam intensity and phase distribution near field at type spatial light modulator.

The phase distribution of the rectangle phase carrier is converted into corresponding grayscale image by the computer, and is loaded into On reflective phase type spatial light modulator, and is filtered out with filtering aperture and occurred after reflective phase type spatial light modulator The high-order light of diffraction.

Compared with prior art, the beneficial effects of the present invention are:

The present invention is to have added a rectangle phase carrier in the front focal planes of spatial filter first lens, when filtering aperture not When can effective filter out space periodicity modulation, effective filtering is realized near field light beam, to improve the light beam of near field light beam Quality；

In high power laser system, aperture is filtered in order to avoid plug-hole problem occurs and introduces low frequency to output near field to spread out When penetrating ring cannot be arranged too small, filter effect can be reduced, and filter effect can be improved using method of the invention, and solve It filters aperture plug-hole size and filters the contradictory problems of size；

In short, the present invention only needs to be arranged in the optical path reflective phase type spatial light modulator, and in reflective phase The rectangle phase carrier that a suitable spatial frequency is loaded in type spatial light modulator, can be solved plug-hole in spatial filter The contradictory problems of size and filtering size, guarantee filter effect, improve near field beam quality.The present invention is simple with structure, grasps Make convenient feature.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of existing space filter；

Fig. 2 is the structural schematic diagram of the method for the raising beam quality the present invention is based on phase carrier；

Fig. 3 is the measuring device figure of the raising beam quality the present invention is based on phase carrier；

Fig. 4 is the corresponding one-dimensional average power spectra of laser near-field light beam loaded before and after phase carrier in the embodiment of the present invention Densogram, wherein before (a) load phase carrier, after (b) loading phase carrier.

Specific embodiment

Present invention will be further explained below with reference to the attached drawings and examples, but should not successively limit protection model of the invention It encloses.

First referring to Fig. 2, Fig. 2 is the structural schematic diagram of the method for the raising beam quality the present invention is based on phase carrier, As seen from the figure, the present invention is based on the methods of the raising beam quality of phase carrier, including the following steps:

1) spatial filter by the first lens 2, filtering aperture 3 and the second lens 4 form, the spatial filter it The first reflecting mirror 6, the second reflecting mirror 7, polarizing film 8 and Amici prism are sequentially placed in the optical path of preceding periodic modulation light beam 1 9, which is divided into transmitted light and reflected light for incident light, detector 10 is arranged in the reflection light direction, described Transmission light direction reflective phase type spatial light modulator 11 is set, in the reflective phase type spatial light modulator 11 Reflection light direction be successively the Amici prism 9, third reflecting mirror 12 and the spatial filter, the detector 10 output end is connected with the input terminal of computer 13, and the output end of the computer 13 and the reflective phase type are empty Between optical modulator 11 control terminal be connected, make the polarizing film 8 polarization direction and the reflective phase type spatial light The long axis direction of 11 liquid crystal display panel of modulator is consistent, and the reflective phase type spatial light modulator 11 is located at the first lens 2 Front focal plane, the Amici prism 9 to the detector 10 distance and Amici prism 9 arrive reflective phase type spatial light Modulator 11 is equidistant；

2) light distribution and phase distribution of light beam, i.e., reflective phase type spatial light are detected using the detector 10 The light distribution I of incident beam at modulator 11₀(x₀,y₀) and phase distributionAnd input the computer 13；

3) computer 13 described in is fitted an ideal Gaussian beam according to the light distribution of incident beam, as target light The light distribution I of beam_t(x₀,y₀), target wavefront is free of aberration；

4) according to the light distribution I of incident beam at reflective phase type spatial light modulator 11₀(x₀,y₀), phase distributionWith the light distribution I of target beam_t(x₀,y₀), determine the lower limit of rectangle phase carrier phase amplitude And the upper limitIt is respectively as follows: with the variation of position

Then the phase distribution of rectangle phase carrier is expressed from the next:

In formula, T is the period of rectangle phase carrier, and n is the number of cycles for including in rectangle phase carrier overall width；

5) phase distribution of the rectangle phase carrier is converted into corresponding grayscale image by the computer 13 described in, and is added It is downloaded on the reflective phase type spatial light modulator 11；

6) the periodic modulation light beam 1 described in exports bloom from the spatial filter after above structure and processing The output light of beam quality.

Fig. 3 is the method for the present invention one embodiment and its measuring device figure, and photoelectricity is placed at the back focal plane of the second lens 4 Coupled detector CCD14, for detecting the light distribution of outgoing beam, in the present embodiment, the periodic modulation light beam 1 Amplitude modulation factor is 0.1, spatial frequency 12mm^-1, the cutoff frequency of the filtering aperture 3 in spatial filter is 13.35mm^-1, It can not be by 12mm in light beam^-1Spatial frequency filter out, the focal length of the first lens 2 and the second lens 4 is all 17.5cm, be divided rib Mirror 9 is 5:5 commonly unpolarized Amici prism, and reflective phase type spatial light modulator 11 is using model LETO, 1920 The pure phase spatial light modulator of × 1080 pixels, photoelectric coupling detector C CD14 using Daheng DH-SV1411GM, The black-white CCD of 1392 × 1040 pixels；

2) using the light distribution and phase distribution of detector detection light beam, i.e., at reflective phase type spatial light modulator The light distribution and phase distribution of incident beam；

3) one ideal Gaussian beam is fitted according to the light distribution of incident beam using computer, as target beam Light distribution, target wavefront are free of aberration；

4) according to the light distribution I of incident beam at reflective phase type spatial light modulator₀(x₀,y₀), phase distributionWith the light distribution I of target beam_t(x₀,y₀), it may be determined that the lower limit of rectangle phase carrier phase amplitudeAnd the upper limitWith the variation of position are as follows:

Then the phase distribution of rectangle phase carrier can be expressed from the next:

In formula, T is the period of rectangle phase carrier, and n is the number of cycles for including, this reality in rectangle phase carrier overall width It applies in example, the cycle T of rectangle phase carrier is set as 2 reflective phase type spatial light modulator pixels, and the number of n is 960.

5) reflective phase type spatial light modulator 11 be using computer 13 draw gray level image gradation data come Coordination electrode voltage, and then variation of the single liquid crystal pixel to beam phase is controlled, phase and gradation data are linear (referring to: Xu Guiquan, Feng Shaotong, Nie Shouping wait the Phase Modulation Properties of reflective spatial light modulator to test [J] laser Technology, 2009,33 (6): 571-574.), the phase distribution of the rectangle phase carrier is converted into using computer 13 Corresponding grayscale image, and be loaded on reflective phase type spatial light modulator 11, and filtered out with filtering aperture 3 by reflective The high-order light that diffraction occurs after phase type spatial light modulator 11 detects load phase using photoelectric coupling detector C CD14 and carries The light distribution of output beam after wave, and its corresponding one-dimensional average power spectral density curve graph is calculated, such as Fig. 4 (b) institute Show, the gradation data by load in the grayscale image of reflective phase type spatial light modulator is all set to 0, is equivalent to and is not loaded with phase Position carrier wave, the light distribution of output beam is detected with photoelectric coupling detector C CD14, and it is corresponding one-dimensional average that its is calculated Power spectral density plot figure, as shown in Fig. 4 (a), with Fig. 4 (b) comparison it is found that spatial frequency is 12.4mm^-1The intensity at place declines An order of magnitude, and be reduced near background values.

Experiment shows that the present invention only needs that reflective phase type spatial light modulator is arranged in the optical path, and reflective The rectangle phase carrier that a suitable spatial frequency is loaded on phase type spatial light modulator, can be solved in spatial filter The contradictory problems of plug-hole size and filtering size, guarantee filter effect, improve near field beam quality.The present invention has structure letter Single, easy to operate feature.

Above-described is only specific implementation case of the invention, it is noted that for those skilled in the art, Do not depart from the principle of the invention and realize under the premise of, can make it is any modification, replacement or improve etc., these modification, replacement or Improvement is all included in the scope of protection of the present invention.