Holographic gratings that are recorded as a whole in a single exposition are limited in size because of the available power of suitable laser sources and nonlinear response of and/or reciprocity effects in a recording medium. A sequential-illumination technique can help in this case. This technique relies on piecewise grating recording that consists in scanning with a relatively narrow laser beam, a pencil, across the grating surface employing an appropriate optical set up. The contribution describes a method utilizing a small parallel displacement of the laser pencil by turning a plane-parallel plate, which is then transferred to a larger angular deflection by a short focus lens. Simultaneously, the beam is expanded angularly. This all can take place either before light enters the beam-splitter or along paths of both the interfering beams. In this way, uniform diffraction efficiency gratings that are much larger than the cross-section of the beam can be achieved. The laser pencil can be moved in polar or rectangular coordinates. Recording of larger gratings supposes large precise collimating mirrors. If they are not available e.g. due to their high price, they can be replaced by long propagating homocentric beams with their origins in the same distance from the recording plate.

Date Published: 18 April 2006
PDF: 8 pages
Proc. SPIE 6180, Photonics, Devices, and Systems III, 61801F (18 April 2006);

Published in SPIE Proceedings Vol. 6180:
Photonics, Devices, and Systems III
Pavel Tománek; Miroslav Hrabovský; Miroslav Miler; Dagmar Senderákova, Editor(s)