Miniature multi‐pass cell design with high path‐to‐volume ratio based on trough reflector

Abstract Optical multi‐pass cell (MPC) is widely used in laser absorption spectroscopy, a powerful gas analysis tool. In this letter, a miniature MPC with a high optical path length to volume ratio (OPL/V), consisting of trough mirrors, is proposed. It allows compact beam propagation without paths cross and spots overlap. The cell is optimized twice to reduce aberration and spot diffusion. An OPL/V of 309.03 is obtained for the proposed model. In addition, an OPL of 2.5 m with a volume of 16 cm 3 is achieved as the number of mirrors is increased to 30. To our best knowledge, it is the smallest MPC with the same OPL. The miniature MPC shows great potential for its application in portable gas sensor.