BEAMSPLITTER CONFIGURATION FOR OPTICAL SUBTRACTION OF SELF EMISSION WITH FOURIER TRANSFORM SPECTROMETER IN DUAL INPUT PORT MODE

摘要

A four port scanning Michelson interferometer suppresses self-emission by using either a beamsplitter that is uncoated or a beamsplitter that has reflection enhancing dielectric coatings in the splitting and combining areas of the substrate on opposite sides of the substrate. Both beamsplitters are fabricated from infrared optical materials that have a predetermined absorptivity in a predetermined wavelength interval which is from 2 µm (5000 cm-1) to 13 µm (770 cm-1) in the infrared. The optical materials of the uncoated beamsplitter are selected from a group of materials made up of ZnSe, ZnS, CdS, CdTe, Silicon, Germanium or Diamond. The optical materials of the other beamsplitter are selected from a group of materials made up of KBr, KCl, NaCl, CsI, BaF, CaF and the like.