Reflection microscopy techniques are typically the easiest to employ for routine sample analysis, as they require little or no sample preparation. Included in these methods are reflection- absorption spectroscopy (RAS), which emulates transmission spectroscopy, diffuse reflection infrared spectroscopy (DRIFT), specular or external reflectance, and attenuated total reflectance (ATR). For RAS, DRIFT, and specular reflection, the nature of the resultant spectra is determined by the nature of the sample. These techniques will be discussed in future articles. ATR is primarily a surface technique which provides a high quality absorbance-like infrared spectrum and can be used to readily analyze almost any liquid or solid sample.