Frequency Modulation Heterodyne Spectroscopy With a Spatially Separated Carrier Beam
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
Frequency modulation (FM) heterodyne spectroscopy using a spatially separated carrier beam enables holes in a frequency domain storage system to be read more easily and over a greater range. This system enables one to use FM with low light levels on the sample while still using a strong carrier for noise reduction and signal enhancement. As shown in the drawing, a laser beam 10 is passed through an optical component system 12 to produce a beam 14 having a 90-degree angle between the polarization directions of the carrier and the sidebands. The beam 14 passes through a Glan-Thompson beamsplitting prism 16 which separates beam 14 into a carrier beam 20 and a sideband containing beam 18.