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Spectral imaging permits two-dimensional mapping of the backscattering properties of biological systems. Such mapping requires broadband illumination of the entire area of interest. However, imaging of turbid biological media under these conditions often involves mean photon path lengths that exceed the pixel size. Using a numerical Monte Carlo model, we have studied the effects of photon scattering in a hemoglobin-bearing model system. We find that photon migration and the resulting wavelength-dependent optical coupling between pixels can complicate the analysis of imaging spectroscopy data. In fact, the wavelength dependence of photon trajectories also alters the distribution of photon exit angles at the tissue surface. We therefore find that the finite optical field of view of an imaging spectrometer can affect the measured spectra in the absence of chromatic aberrations.

We describe fluorescence spectral imaging results with the microscope computed-tomography imaging spectrometer (muCTIS). This imaging spectrometer is capable of recording spatial and spectral data simultaneously. Consequently, muCTIS can be used to image dynamic phenomena. The results presented consist of proof-of-concept imaging results with static targets composed of 6-mum fluorescing microspheres. Image data were collected with integration times of 16 ms, comparable with video-frame-rate integration times. Conversion of raw data acquired by the muCTIS to spatial and spectral data requires postprocessing. The emission spectra were sampled at 10-nm intervals between 420 and 710 nm. The smallest spatial sampling interval presented is 1.7 mum.