Design of Differential Signal Processing Circuitry for Single-Frequency Laser Interferometry Displacement Measurement

Abstract

This thesis addresses the issues existing in traditional laser tracking displacement measurement technology in the field of ultraprecision metrology by designing a differential signal processing circuit for high-precision laser interferometric displacement measurement. A stable power supply module is designed to provide low-noise voltage to the entire circuit. An analog circuit system is constructed, including key circuits such as photoelectric sensors, I-V amplification, zero adjustment, fully differential amplification, and amplitude modulation filtering. To acquire and process signals, the PMAC Acc24E3 data acquisition card is selected, which realizes phase demodulation through reversible square wave counting, inverts displacement information, and a visual interface for the host computer is designed. Experimental verification shows that the designed system achieves micrometer-level measurement accuracy within a range of 0–10mm, with a maximum measurement error of less than 1.2μm, a maximum measurement speed of 6m/s, and a resolution better than 0.158μm.