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available refractive index modulation and —of course— attainable diffraction efficiency
and bandwidth. An analytical model of ∆n is introduced in order to treat real holographic
materials in the context of a numerical propagation method for light through volume
holograms.
Chapter 4 discusses several diffusing materials and holographic-optical elements (HOE)
concerning their utilization in the holographic mastering process. Especially polarization
states and scattered light angles are emphasized during this investigations. As a result, one
type for reflective and transmissive diffusers each are selected for holographic reproduction
(the reflective screen fabric ”Silver Matte” from Da-Lite and the POC holographic diffusers
for transmission).
Chapter 5 introduces the mentioned scanned exposure of holograms. An exposure system
employing a galvano-scanner combination, cw- and pulsed lasers as well as an AOM for
intensity control was implemented and tested with monochromatic holograms. Successful
recording of a front-projection hologram is reported and a resulting projection screen is
analyzed regarding efficiency and compared to a standard screen fabric under several ambient
light conditions.
Finally in chapters 6 and 7 the process of color holography is modelled and material
investigations concerning color reproduction are conducted. As one of the main results
of this thesis, a numerical algorithm is introduced which is capable of calculating energy
doses to be deposited during the holographic recording process, in order to achieve a well
defined color rendition during holographic playback. The novelty regarding this treatment
is the modelling of the whole holographic process including the lamp spectra used for
reconstruction. This allows the optimization of the holographic diffraction efficiency with
regard to the spectrum of the projection light sources. The proposed solution includes:
• the recording process with several wavelengths and free intensity ratios
• the characteristics of real holographic materials
• the choice of recording and replay geometry
• the implementation of the spectra of popular projection technologies (UHP-lamps,
LED- and laser-projectors) as well as arbitrary spectra.
• evaluation of system performance and color impression in CIE color space.
Finally a set of recording parameters for chosen holographic materials are calculated in
order to expose perfectly balanced white, efficient front projection screens optimized for
modern projection technologies (UHP-lamps, laser- and LED-projectors).
The thesis closes with a summary of the achievements and a discussion of possible future
work.
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