复合式多点测量速度干涉仪光学系统设计

为满足爆炸冲击作用下物质界面的速度测量需求,设计了一种复合式多点测量的速度干涉仪。采用物方和像方双远心光路,将光纤阵列出射的照明激光定点投射到待测物面上,实现了针状滴注式照明,充分利用了照明激光能量,且保证了待测物面在运动过程中具有恒定的照度。成像系统像面采用末端为大芯径的锥形光纤接收信号光,既保证了物面运动过程中信号光与光纤的有效耦合,又保证了信号的单模输出,以便进入单模光纤马赫-曾德干涉仪进行差频干涉。采用具有微小楔角、沿直径方向镀矩形带状45°反射膜的反射镜,将照明光路与成像光路同轴,并校正了成像系统的大量像散。该干涉测量系统在物面运动10mm的行程中,物面滴注式照明照度保持恒定,像面光斑大小没有超出大芯径的光纤芯径。此光学系统能够满足爆炸冲击界面的大行程速度测量需求。

Optical system design of compound multi-point measurement velocity interferometer

In order to measure velocities of explosion loading surface driven by blast waves, a compound velocity interferometer was introduced.The illumination laser from fiber array was projected onto the target surface through a telecentric optical imaging system.Only several points on the target were illuminated, which got the utmost out of laser power.The illumination beam had so small numerical aperture that the illumination spot size kept constant while the target moving within 10 mm.A taper fiber array with large core diameter was mounted on the image surface of optical imaging system, thus the signals could coupled into the large core fibers effectively and could output in single mode for difference interference in single mode Mach-Zender interferometer during the target movement.A 45° beam splitter with a small wedge angle was employed before the first optical element of the imaging system, the illumination laser could be reflected to the object surface by the rectangular films on the first surface of the splitter.The small wedge angle of the splitter could compensate the astigmatism lead by titled parallel plate.During the object surface moving within 10 mm, the lighting power and spot sizes on object surface remain the same, and the coupling efficiency of Doppler frequency shift signals also remain constant.This optical system could meet the demand of explosion loading surface velocity measurement in long distance range.