单模VCSEL激光自混合测距精度的提高

Improvement of laser ranging precision using the self-mixing effect in a single-mode VCSEL

单模VCSEL激光自混合测距具有测距精度高、功耗低和结构简单等优点。对单模VCSEI。进行了大频偏的三角波电流调制，应用差频模拟锁相环处理自混合拍频信号，明显减小了拍频信号在三角波拐点处固相位突变、波形周期不等以及波形的调幅干扰和失真等因素造成的影响。实验结果表明，提高了测距精度和动态范围。室温下，在单模VCSEL输出功率0．7mW，波长850nm，调制三角坡的频率1．3kHz，幅度0．4Vrms，采样时间0．1S，散射面为粗糙金属片的条件下，测距范围达到50～500mm，测距精度达到2mm，分辨率优于2mm。

Laser range finding system using the self-mixing effect in a single-mode Vertical-Cavity Surface-Emitting Laser （VCSEL） has many advantages, such as high precision. low power consumption and simple configuration. We used triangular wave current to modulate the single-mode VCSEL to produce high optical frequency excursion, and used difference frequency Analog Phase-locked Loop （APLL） technique to process the self-mixing beat frequency signal. The influences on ranging precision of phase abrupt changes and asymmetry periods of beat signal and anomaly waveforms have been reduced obviously, and the ranging precision and the measurement dynamic range have been improved evidently. The experimental results show that, in the room temperature. the measurement dynamic range is as large as 50 - 500ram. the ranging precision is 2mm and the resolution is better than 2mm, when the laser＇s output power is 0.7mW, wavelength is 850nm, the triangular wave frequency is 1.3kHz and amplitude is 0.4Vrms, the sampling time is 0. 1s and the scattered target is coarse metal plate.