Multipass Spectroscopic Cell Optical Folding Prisms

The patent applies dimensional transformation by folding the optical path using prisms arranged in a three-dimensional configuration. Instead of extending the cell length linearly in one dimension, the optical path is folded back on itself multiple times within a compact volume, effectively converting a one-dimensional path length problem into a three-dimensional spatial arrangement. This allows achieving long interaction paths (e.g., 100 meters) within a short physical cell length while maintaining structural integrity.

The patent changes the optical parameters by using prisms instead of mirrors for folding the optical path. Prisms provide near-perfect reflection through total internal reflection, eliminating the reflectivity losses inherent in mirrored surfaces. This parameter change allows for a much higher number of optical passes (e.g., 500 passes) without significant optical loss, thereby increasing the interaction path length and detection sensitivity while minimizing energy loss.

The patent introduces prisms as intermediary optical elements that mediate the folding of the optical path. These prisms provide fixed, stable reference surfaces for alignment and maintain consistent optical geometry throughout the multipass sequence. The prism interfaces are designed with precise angular relationships that reduce sensitivity to alignment errors, making the system easier to operate and maintain while allowing for a high number of optical passes.