The basic mathematics of computer generated holography are well understood. The major difficulties are in two areas - computer resources and output media.
- As we increase the angle between the computed reference beam and the computed object beam, the fringe spacing becomes smaller and so the data set becomes very large. This requires vast amounts of data storage and computation time. Much work has gone into algorithms to simplify the calculations, but producing high quality imagery is still a difficult problem.
- As the fringe spacing decreases, we require higher and higher resolution printout to a transparency. Electron beam lithography is one method used for very high resolution output, but the equipment is extremely expensive and is typically only designed for small imaging areas.
These problems have made it so that only On-Axis (Gabor) Holograms and Fresnel Holograms are commonly produced nowadays.
Recording holograms on CD-ROMs
One possible high resolution medium is the surface of a CDROM. This has been explored and even used in such disks as Microsoft Windows Installation Disks. The software required to write this kind of dataset requires bypassing the driver software as the driver software limits the types of data possible.
Also, there is no easy way to align successive tracks on a CD ROM. Some of the new CD ROM drives are capable of writing images to the front surface and may prove to be more suitable to hack into.
There was a presentation at SPIE / IS&T Electronic Imaging 2004 (Practical Holography XVIII: Materials and Applications), which will be SPIE Proc. 5290:
Computer-generated holograms on a CD-R disk, Y. Sakamoto, Hokkaido Univ. (Japan); M. Morishima, A. Usui, Yamaha Corp. (Japan) [5290-02] journal article info page
Colin Kaminski contacted Y. Sakamoto and was told that this project was abandoned by the manufacturer and this code was no longer available.