Zeeman Laser Linewidth Measuring System
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
A Zeeman split laser differential microscope can be used to measure linewidths of both reflective and transparent films down to 0.5 mm with an accuracy of better than 1 nm. The system is based on a technique for very precise measurement of the differential phase. In the figure, the source is a Zeeman split, frequency-stabilized, single mode laser 1. This provides two polarizations (horizontal and vertical) at frequencies (Wo + Wm) and (Wo - Wm), respectively, where Wo is the optical frequency and Wm is determined by the axial magnetic field applied to the laser head. The output of the laser is directed towards a beamsplitter 2 where a portion of the beam is reflected towards the retro-reflector 4 via a quarter-wave plate 3.