Spectral Imaging: Fluorescence and Brightfield

Abstract

Spectral imaging is a relatively new technique that provides images of a scene at multiple wavelengths and can generate precise optical spectra at every pixel. Mathematical approaches may then be used to extract the maximum information from the spectral image. Spectral imaging is routinely used in “remote sensing”, that is, the analysis of distant landscapes and structures from airplanes or satellites. Minor differences in spectra can be used to detect different crops, or mineral deposits, for example. Closer in, spectral imaging has uses in industrial process control, detection of otherwise invisible bruising in fruit, vascular integrity in transplanted organs, and so on. Finally, spectral imaging has newly been adapted for easy use in microscopy, with applications in surgical pathology, multicolor fluorescence and immunohistochemistry, and in DNA expression arrays, among others. A variety of technologies can be used to perform imaging spectroscopy, including Fourier transform interferometry, tunable filters, line-scanning prism or gratings-based devices, and others based on polarization effects. Recently, CRI has developed a novel approach for brightfield microscopy which uses a spectrally agile light source. The latter has a number of advantages over previous techniques.