Etendue-preserving raman sampling optics

Abstract

Sampling optics for spectroscopic analysis include an array of optical elements as opposed to a single objective as used in conventional systems, achieving enhanced collection, inherent signal integration/averaging and improved measurement uniformity. At the same time, the etendue using the array is substantially the same as the etendue using a single-element objective. The array of closely packed optical elements may have spherical or aspherical surfaces and may be transmissive or reflective. An array of lenses and reflective elements may be arranged together in flow cell configurations and/or for signal amplification involving multiple passes through a sample medium. The array elements may be arranged in hexagonal, linear, radial or other packing geometries and may be implemented as a flat or curved panel. The present disclosure is applicable to remote fiber probes and flow cell geometries to measure solids, liquids, gasses and semi-liquid such as slurries.