Infrared and Raman Instrumentation for Mapping and Imaging

This chapter describes the design of the instruments used to acquire hyperspectral data. The analysis of localized regions of samples by vibrational microspectroscopy can be accomplished in two ways, mapping or imaging. Mapping involves the sequential measurement of the spectrum of each adjacent region of a sample by moving each region of the sample into the beam after recording the spectrum. In hyperspectral imaging, the images at more than 10 wavelength regions are recorded simultaneously with a two-dimensional array detector. Vibrational hyperspectral imaging can be accomplished through the measurement of either the mid-infrared, near-infrared (NIR), or Raman spectrum. The measurement of each type of spectrum is accomplished in different ways, although the instruments that have been developed for the measurement of NIR and Raman spectra are more closely related than that of mid-infrared hyperspectral imaging spectrometers.