Design for A Highly Stable Laser Source Based on the Error Model of HighSpeed HighResolution Heterodyne Interferometers Heterodyne interferometers with two opposite Doppler shift interference signals have been proposed for highresolution measurement with high measurement speed, which can be used in the background of highspeed highresolution measurement. However, a measurement error model for highspeed highresolution heterodyne interferometers (HSHRHIs) has not yet been proposed. We established a HSHRHI measurement error model, analyzed the influence of beat frequency stability with a simplified optical structure, and then designed an offsetlocked dualfrequency laser source with a digital control system to reduce the impact of beat frequency drift. Experiments were used to verify the correction of the measurement error model and the validity of the laser source. The results show that the new laser source has a maximum beat frequency range of 45 MHz, which shows the improvements in the measuring speed and resolution.

A 63.3ps TDC Measurement System Based on FPGA for Pulsed Laser Ranging For pulsed laser ranging systems, the accuracy of the timetodigital converter (TDC) measurement directly determines the accuracy of the systemu0027s ranging. This work uses the internal carry chain of the FPGA to construct the delay chain, together with the encoder, coarse time counter, mean filtering and the trigger modules build up the proposed TDC design. In order to ensure the consistency of the delay chain, this work utilizes the entire CARRY4 carry chain as a single delay unit, and the total delay of the delay chain needs to be more than one clock cycle. Therefore, with careful verifications, 160 delay units are connected in series to form a completed delay chain. In order to reduce the complexity of the design, this work partitions the 160bit input encoder into five 32bit input encoders, which is equivalent to divide the delay chain into five segments and then accumulate all the statistical results. The measured results show that the TDC measurement resolution can reach 63.3ps, and the ranging accuracy of the ranging system is 0.95cm, while the measurement error is 0.38cm, and the logic complexity is 3k LUTS and 4k DFFS.