The E-beam systems are still too expensive for most labs to own.

Presently, Honeywell, General Dynamics, MIT, the Office of Naval

Research and several integrated circuit companies in California are

producing E-beam holograms for CGH researchers. Each of these systems

caters primarily to the integrated circuit industry, and hologram

producers must wait in line. Turn-around times of over a month are

typical, with cost per hologram exceeding $1000. Obviously, the E-beam

holograms, while superior in their spatial resolution, must be

supplemented with in-house holograms of lesser quality until research

and testing indicate that a hologram is ready for production.

 Examples of CGH Matched Filters

 The following section does not attempt to quantitatively verify

the simulations. That work is needed and is continuing. However, the

figures shown here indicate that indeed the appropriate patterns can

be placed on film or glass plates, and that their reconstructions

verify qualitatively results predicted by the appropriate simulations.

In each case, the holograms shown here were produced using the

Allebach-Keegan (A-K) algorithm and written to chrome-on-glass plates

using the Honeywell E-beam writer. These CGH matched filters are

amplitude-modulated holograms and do not provide the high efficiency

possible with phase-modulation relief holograms. However, the

holograms do include examples of various preprocessing techniques,

namely frequency emphasis and phase-only filtering.

 Figure 8.5 shows magnified views of one of the E-beam written

holograms indicating the fine detail possible. Figure 8.6 contains

A-K CGH matched filters using no pre-processing, frequency emphasis

and phase-only filtering. These photographs are taken of the actual