基于激光光束质量测量的超消色差物镜设计

Design of Superachromatic Lens Based on Laser Beam Quality Measurement

在激光光束质量测量时，为了避免每次测量不同波长激光都要对聚焦透镜的焦平面位置进行标定，降低测量误差，研究和设计了覆盖紫外至近红外波段的超消色差物镜。基于波像差的理论，推导了超消色差物镜初始结构求解的方程组。应用光学设计软件Zemax设计了工作波段为350—1100nm的宽光谱超消色差物镜，焦距为200mm，入瞳直径为25mm。给出了光学系统图、纵向像差曲线、焦移曲线及调制传递函数（MTF）曲线。设计结果表明，采用该方法设计的物镜，在0．707孔径处不同波长光线的球差曲线基本相交于一点，实现了超消色差；工作波段内的焦移仅为26．3um，基本固定了焦平面的位置；在截止频率范围内的MTF均接近衍射极限，满足了紫外至近红外波段激光光束质量的测量要求。

When measuring the laser beam quality of different wavelengths, in order to avoid the calibration of focal plane position and reduce the measurement error, the superachromatic lens is researched and designed covering the ultraviolet to the near infrared band. Based on the theory of wave aberration, the equations for the initial structure of the superachromatic lens are derived. The superachromatic lens of wide spectral range is designed by the optical design software Zemax. Its waveband is 350-1100 nm, the focal length is 200 mm and the entrance pupil diameter is 25 ram. The structure of optical system, longitudinal aberration, focal shift curve and modulation transfer function （MTF） are given. Design results show that the spherical aberration curves of different wavelengths at 0.707 aperture intersect at one point approximately, achieving the superachromatism; the focal shift in the working waveband is only 26.3 um , and the focal plane position is fixed basically; the MTF is close to the diffraction limit in the range of cutoff frequency, meeting the measurement requirement of laser beam quality from ultraviolet to near infrared.