Low-Cost Optical File Laser Monitor
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
An improvement has been made in monitoring the output of a diode laser used in an optical recording system. The conventional method is shown in Fig. 1. Waste light detector A is placed to intercept the light which is reflected by surface 1 of prism B. This surface, for a magneto-optic file, is coated to reflect all "S" polarized light and 10%-30% of "P" polarized light. A detector so mounted will, therefore, receive a fraction of "P" light (as desired), but it will also detect the "S" light emitted by the laser, which is not desirable. Also, this detector itself is an additional component which means added cost, size, mass, alignment and termination requirements. Fig. 2 shows the new concept. There is unavoidably some light (about 0.2% to 4.0%, depending on coating, if any) reflected from surface 2 of prism B.