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提出了一种用于光栅成像位置传感器的偏振调制技术,利用米勒矩阵对其调制原理进行了详细的分析。该偏振调制器主要由起偏器、萨伐尔板、两块1/4波片、光弹调制器和检偏器构成。起偏器、萨伐尔板置于探测光栅之前,在探测光栅位置上形成两个错位的偏振方向正交的像光栅。两块1/4波片、光弹调制器和检偏器置于探测光栅之后,实现对莫尔信号的高频调制。该偏振调制技术消除了光源光强波动和电路增益变化引入的测量误差,抑制了杂散光、探测器噪声对测量结果的影响。实验验证了该偏振调制技术的有效性,结果表明这一技术使光栅成像位移传感器获得了优于12 nm的重复测量精度。
A polarization modulation technique for grating imaging position sensor is proposed. Its modulation principle is analyzed in detail by using Miller matrix. The polarization modulator is mainly composed of a polarizer, a Saber plate, two 1/4 wave plates, a photoelastic modulator and an analyzer. Polarizer, Sawfal board placed in front of the detection grating, the detection grating position on the formation of two misaligned orthogonal polarization image grating. Two quarter-wave plates, a photoelastic modulator and an analyzer are placed behind the detection grating to achieve high-frequency modulation of the moiré signal. The polarization modulation technique eliminates measurement errors introduced by fluctuations in light intensity and circuit gain, suppresses the effects of stray light and detector noise on the measurement results. Experiments show the effectiveness of this polarization modulation technique. The results show that this technique enables the grating imaging displacement sensor to obtain repeat measurement better than 12 nm.