Holographic Scanner With Compensation for Substrate Non-Parallelism
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-19
Holographic scanners with compensation for substrate non-parallelism utilize either a corner cube or a retroreflector. As shown in Fig. 1, the reconstructing beam 10 first passes through a blank area 12 on the glass disk substrate 14 near the hologram 16. If the substrate 14 does not have any non-parallelism, the beam takes path 10 to the cube corner 18 where it is always reflected exactly parallel to the incoming beam 10 as beam 20. Beam 20 illuminates and is diffracted by hologram 16 to form beam 22. When the substrate 14 has non-parallelism, a misaligned beam 24 is reflected by cube corner 18 as beam 26. Beam 26 is diffracted by hologram 16 to form beam 28 which is laterally displaced but has the proper direction.