Patent ID: 7468797
Filing Date: 2008-12-23
Classification: G01J,G01N

Abstract:
1. A absorption spectroscopy instrument, comprising: an arrangement of two or more mirrors forming a stable optical cavity that is adapted to receive an absorption cell with a sample to be tested, the arrangement of mirrors defining both an axial light path in the cavity and a plurality of off-axis light paths in the cavity wherein successive reflections at any given mirror of the cavity occur at different locations for any of the off-axis light paths; a light source providing a light beam directed toward a first cavity mirror, a first portion of the light beam being coupled by transmission through the first cavity mirror into the cavity along an off-axis light path, and a second portion of the light beam being reflected back by the first cavity mirror and thereby initially failing to be coupled into the cavity; a re-injection mirror situated between the light source and the first cavity mirror and configured to collect and redirect the reflected second portion of the light beam back toward the first cavity mirror for one or more additional attempts to couple the second portion of the light beam into the cavity; a detector situated in a position to receive and measure another portion of the light beam extracted from the optical cavity through a second cavity mirror; and means for processing data representing the light measurement from the detector for analyzing a sample in said absorption cell.