为了改善半导体激光光束质量,使其能够满足大距离高精度干涉测量的要求,使用空间光调制器对半导体激光光束进行整形,提出了一种基于复振幅调制算法的光束整形方法。利用该方法可将半导体激光光束整形为准直性好、光强分布均匀的无像散基模高斯光束。通过光束质量分析对整形后的光束进行评估,实验结果显示整形后半导体激光光束在x和y方向的M²因子均趋于1,像散接近于0,验证了该光束整形方法的有效性。将提出的半导体激光光束整形方法应用于大距离干涉测量中,在8 m处进行了微米级步进位移测量,与纳米位移工作台相比,所得结果达到了亚波长的测量精度。实验结果表明整形后的光束能够满足大距离高精度干涉测量的要求,验证了提出的半导体激光光束整形方法的可行性。

In order to improve the beam quality of the laser diode and make it meet the requirement of high precision interferometric measurement for large distance, we propose a beam shaping method by using spatial light modulator based on the complex amplitude modulation algorithm. The laser diode beam is shaped to the non-astigmatic fundamental mode Gaussian beam, which has the advantages of good collimation and symmetrical spot shape. Experiment for analyzing the beam quality of the shaped beam is performed, and the results show that the M2 factors in the x and y directions of the shaped beam are close to 1 and the astigmatism of the shaped beam is close to 0, which verify the effectiveness of the proposed beam shaping method. The beam shaping method is applied to large distance interferometric measurement. Displacement measurement with micrometer steps is carried out at a distance of 8 m, and sub-wavelength accuracy is achieved compared with a nanometer stage. Experimental results indicate that the shaped beam can meet the requirement of large distance interferometric measurement, which verify the feasibility of the proposed beam shaping method.