Feasibility of remote Raman imaging using tunable filters

We are investigating the use of small, transportable, Roman systems for remote Roman measurements at intermediate ranges (e.g. < 20 m). Previous work focused on the use of an imaging spectrograph and a fiber-optic coupled probe for making single point measurements. More recently we have considered the use of tunable filters for remote Raman imaging. For this work, acousto-optical (AOTF) and liquid crystal tunable filters (LCTF) are being used both with, and in place of dispersive spectrometers and fixed filtering devices. In addition, we have improved the system by the use of a modified holographic fiber-optic Raman probe for light and image collection. In these experiments, a 100 micron collection optical fiber is replaced with a small diameter image guide for light collection and imaging. The feasibility of tunable filter technology for remote Raman imaging will be discussed along with the merits of image transfer devices using small-diameter image guides.