Imaging Spectroscopy Using Fiber Optics

Abstract

Optical fiber probes are routinely used with optical spectrometers to allow measurements to be made on remotely located samples. In most of these systems, however, the optical fibers are used as non-imaging “light pipes” for the transmission of laser light, and luminescence or Raman signals to and from the sample. Thus, while these systems are suitable for remote spectroscopy, they are limited to single-point measurements. In a recent paper, we showed that a small-diameter (i.e., 350 μm) coherent optical fiber bundle can be combined with an AOTF-based imaging spectrometer for fluorescence and Raman spectral micro-imaging with increased flexibility in terms of sample positioning and in-situ capabilities. The previous paper described the operation of the fiber-optic microimaging probe and AOTF imaging system and showed preliminary Raman and fluorescence images for model compounds with 4 μm resolution. We have extended this work to include a discussion of the lateral and vertical spatial resolution of the fiber-optic microprobe in a non-contact proximity-focused configuration.