Magneto-Optic Laser Beam Steering
Technical rept. 1 Mar 1974-1 Mar 1975
SPERRY UNIVAC ST PAUL MN APPLIED PHYSICS LAB
Pagination or Media Count:
An effort to apply magneto-optic laser beam steering to laser recording has been conducted. The approach is based on diffraction of laser beams by stripe domains which exist in bismuth ytterbium iron garnet crystals BiYbIG. The preparation of BiYbIG crystals by liquid phase epitaxy is complicated by a surprisingly large thermal expansivity of the bismuth substituted garnet. Special substrates, graded interfaces, top seeded rods, bulk crystals, and LPE on very thin 10 micrometer substrates were tested as a means of crystal fabrication. LPE on very thin substrates appears to be the single best short term approach. With this method, lead free, crack free, high bismuth content garnets were for the first time grown by liquid phase epitaxy. At this time, high inductance approximately 400 muH drive coils are required to generate the drive field. An azimuth scan uses a resonant circuit but requires a 25-30 Oe field for scan initiation and so wastes spots. The radial scan uses all of the spots but requires a broad band drive circuit which limits the number of lines available at 30 frames per sec. When LPE BiYbIG crystals are prepared free of misfit dislocations by making the in-plane lattice match perfect, then the drive requirements will be reduced, and then all of the device goals of the laser recording application can be met or surpassed with the magneto-optic beam steering approach.
- Lasers and Masers