大口径矩形SiC扫描反射镜组件的设计

Design of Large-Aperture Rectangular SiC Scanning Mirror Assembly

为了减轻大尺寸(740 mm×480 mm)矩形扫描反射镜的质量并保证反射镜的面形精度,结合二维和三维等效刚度模型设计了背部开口、以三角形轻量化孔为主、轻量化率为81.4%的轻量化结构。基于球头万向节与柔性铰链原理,设计了两种背部三点支撑方式的SiC扫描反射镜组件。有限元分析结果表明,在Y方向重力及40℃均匀温差耦合工况下,球头万向节与柔性铰链支撑方式的反射镜面形误差均方根(RMS)值满足小于等于0.025λ(波长λ=632.8 nm)的设计要求,分别为12.3 nm和12.9 nm,一阶固有频率分别为68.1 Hz和85.5 Hz,且柔性铰链结构的刚度更好。采用自准直法测量扫描反射镜组件的面形误差,结果表明,面形误差的RMS值为0.025λ,满足实际要求,为大口径矩形扫描反射镜组件的设计提供了参考依据。

To reduce the weight of the large-aperture(740 mm×480 mm)rectangular scanning mirror and ensure the surface accuracy of the mirror,this study proposes a lightweight structure design with back openings,mainly triangular lightweight holes,and a lightweight rate of 81.4%by combining the two-and three-dimensional equivalent stiffness models.Based on the principle of ball joint and flexible hinge,two types of scanning mirror components with different three-point back support modes are designed.The finite element analysis results show that under the coupling condition of Y-direction gravity and a uniform temperature difference of 40℃,the root-meansquare(RMS)value of the mirror surface error of the ball joint and flexible hinge support structure are 12.3 nm and12.9 nm,respectively,which satisfies the optical design requirement of less than or equal to 0.025λ(wavelengthλ=632.8 nm).Furthermore,the first-order natural frequencies are 68.1 Hz and 85.5 Hz,and the flexure hinge structure had better stiffness.The surface error of the flexure hinge scanning mirror is measured using the autocollimation method.The measurement results show that the surface error RMS value is 0.025λ.This result provides a reference for developing a large-aperture rectangular scanning mirror assembly.