LightTools-Based Ray Tracing and Spot Distribution Rules for Herriott Cells

Focusing on the problem of unclear ray-traced spots and their distribution rules in the design process of the Herriott cell, first, the characteristics of long-optical-path gas absorption cells were analyzed, and the calculation method of basic cavity length and the effective optical path of Herriott gas absorber cells were studied. Second, according to the transmission characteristics of geometric optics, a physical model of light transmission in Herriott cells was established via the LightTools software. Finally, simulation analysis was performed on Herriott cells with 5- and 14.4-m optical paths separately, determining the quantitative relationship between d/f and the number of spots reflected on the concave mirror, and optimizing the effective optical path and output laser energy of the Herriott cells. Through research analysis, the sizes and distribution positions of concave mirror spots in the Herriott cells were identified, as well as the factors affecting the number of reflections. It was also found that the number of reflected spots gradually decreases as d/f increases, revealing the light-tracing results and its spot distribution rule on the mirror surface, as well as verifying the accuracy of the theory. The findings of this study provide a basis for the optical path system design and optimization for Herriott cells with different optical path lengths.