Computer-generated holograms with error compensation.
We analyze computer-generated holograms (CGH) of Lohmann types I and III and discuss their overall errors employing the following modifications, listed in order of increasing importance: phase-only correction (Ptype), virtual increase of the cell number, optimized use of the available plotting area, expansion of the amplitude dynamic range (D-type), circular overflow correction (OFC), and iterative overall error compensation. We compare the computing and plotting times for the listed CGH variants and their accuracy. As an application, we show the reconstruction of very complicated fields which may excite multimode and singlemode optical fibers, and a line grating with an in-between phase shift of 180 degrees ; the latter structure is useful in producing lambda/4-shifted semiconductor DFB lasers. Finally, we comment on some advanced techniques employing a desk-top computer and laser printer for producing hologram masks.
W
W
Freude
G K
GK
Grau
W
W
Liebler
B
B
Wuppermann