Thomas C. Voigt

Evaluation of a high-throughput liquid crystal tunable filter for Raman chemical imaging of threat materials

Liquid crystal tunable filters (LCTF) have been used in systems developed for Raman Chemical Imaging spectroscopy of chemical, biological and explosives threat materials. However, an ongoing challenge in detecting trace levels of materials is the limited throughput provided by previous generation LCTFs. In this article, we describe a new class of birefringent LCTFs based on a Multi-Conjugate Filter design that provides high throughput over an extended wavelength range (440 nm-750 nm). The spectral resolution, tuning accuracy, out-of-band rejection efficiency have been evaluated and are demonstrated on a Raman chemical imaging microscope platform. Detection of trace threat particulate matter in the presence of complex background with improved overall detection performance is demonstrated.