Research on a measurement method of precision linear displacement based on single-alternating light field

A high-precision linear displacement measurement method based on digital phase shift of a single light source is proposed. This method uses four-channel sine grating modulation with a 90° difference in spatial position to modulate single alternating light source, then obtains four-channel light intensity signals with the same phase in time and differences phases of 90° in space. Two channels of standing wave signals with a time difference of 90° are obtained through micro-control digital phase shift processing. Using these two standing wave signals to synthesize an electric traveling wave signal containing position information. The reference signal and electric traveling wave signal are phase-discriminated by a high-frequency clock to obtain the phase difference, and it is also the position information. The principle of displacement measurement based on space-time modulation of single-alternating light field and the principle of digital phase-shift of micro control are introduced in detail, and the feasibility of the method is verified through experiments. Finally, by analyzing the reasons for the error, the sensor is optimized and designed, and the measurement accuracy of ±0.2μm is achieved in the 100mm range with a 0.6mm grating period.