Dual-comb velocity measurement

Abstract

Laser measurement systems occupy an important role in many application fields, such as autonomous driving, robotics, precision manufacturing, and basic science. The appearance of the optical frequency comb provides a new solution for measurement and has gradually become a hot topic of research. This paper proposes a speed measurement scheme based on dual optical frequency combs (OFCs) to realize dynamic speed monitoring for moving objects. The dual-comb scheme has the advantages of high speed, high resolution and high precision. It can not only use the periodic pulse in time domain to realize large scale and high accuracy measurement, but also the interference spectrum in frequency domain can obtain interference information. The experiment uses two OFCs with a small repetition rate difference, one is the signal laser and the other as the local oscillation (LO) laser. The cavity length of the two OFCs is continuously adjusted to control the repetition rate difference of the two OFCs at 2 kHz. And use the frequency counter to monitor the repetition rate of the two OFCs during the measurement, and compensate the drift of the OFC in real time. Set the measurement target on the high-speed guide rail, control the guide rail to move at different speeds, and measure the movement speed of the object in real time, which can accurately measure the speed of objects.