US Patent 7324272 Spectroscopic microscope with multi-mode illumination

A spectroscopic microscope allowing both molecular spectrometry and visible microscopy of a sample has a light source for its spectrometer which provides Koehler illumination of the sample, i.e., light from points on the light source is projected across an area of the sample, as opposed to directly projecting an image of the light source onto the sample (as with critical illumination). However, the device may be adjusted to alternatively provide critical illumination of the sample, which is useful where spectrometric readings are to be obtained from a smaller area of the sample.