测量非连续曲面的偏振光差动像散传感技术

A Polarized Heterodyne Astigmatic Sensing Technique for Measurement of Discontinuous Surface

提出一种基于激光偏振光差动像散原理的非连续曲面绝对跟踪检测方法与技术。该方法依据被测表面反射到位于两柱面镜焦面、焦后等距放置的两探测器上的偏振光的形状,再经两探测器探测信号差动相减和光强归一化处理得到聚焦误差信号,进而达到对非连续三维被测表面的绝对测量和触发瞄准。偏振光差动像散传感器中,由于引入偏振光入射和偏振分光镜分光,使构成的偏振光差动像散检测技术有效抑制光源波动、光学器件间光束的多次反射等对测量结果的影响,显著改善了差动像散离焦检测技术的抗干扰能力和线性。该光学传感器的测量范围为±10μm,分辨力优于0.005μm,可测表面倾角达20°。

An approach based on laser polarizing heterodyne astigmatic principle was proposed for absolute tracing measurement of discontinuous surfaces.The approach proposed uses the shape of reflected polarized light of the object received from two detectors,which are placed at the same distance before and behind the focal plane of two cylindrical lenses,and uses the focal error signal obtained through the heterodyne subtraction of two signals received from two detectors and the normalization of the intensity,to achieve absolute measurement and aiming trigger of discontinuous 3D surfaces.In a polarized heterodyne astigmatic sensor,the introduction of polarized incident light and light splitting of polarized beam splitter can effectively suppress the undesired influence on measurements caused by the disturbance of the laser source in intensity and multi-reflection among optical elements,and obviously improve the anti-interference capability and linearity of heterodyne astigmatic defocused measurement.Experimental results indicate that the optical sensor has a resolution of better than 0.005 μm and it can measure the surface with tilt angle of 20°,while the it has a measurement range of ±10 μm.