A novel self-mixing sensor architecture using a PLL for noise immunity

The accuracy and maximum range of a self-mixing laser range finder are limited by the SNR of the self-mixing signal. In this work we have proposed a PLL sweep technique that was demonstrated to dramatically improve the noise immunity of a self-mixing range finder. It allowed operation with a non-cooperative target over a range of 200–900 mm and improved the self-mixing SNR by more than 20 dB.