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Title: Visor projected helmet mounted display for fast jet aviators using a Fourier video projector
Author: Freeman, J. P.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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Abstract:
Although the pixel failure integrity is widely published as the key advantage of a Fourier projector, the potential high luminance image may prove to be more important for such things as the display of aircraft symbology. We have shown here that it is possible to achieve image luminance levels in excess of 34000cd/cm2 at the eye using a laser source less than 0.1mW. One of the key development areas of CGH calculation has been to try to get an even replay field. In this thesis it is shown that the problem is largely due to overlapping fields from neighbouring pixels. There is no acceptable solution using one hologram that does not sacrifice other key features of the replay field. We have therefore derived a simple new algorithm, TSP, that allows us to show neighbouring pixels on separate CGHs, simply circumventing the problem of cross-pixel interference. This results in a diffraction limited performance from the hologram with negligible interference, even when defocused. The Fourier transform used a form the CGH was then taken back to a more basic level. By re-writing the algorithm, we have access to the wavefront for each pixel and the ability to modify each separately before assembling them all to form CGH. This forms the basis of our second new technique of PWPS. This resulted in a very powerful method that could correct the aberrations of almost any system. It was demonstrated by creating a 120° video projector using a glass marble as the projection lens. This method also opens up new opportunities of simpler optics, 3D, plus the ability to put pixels anywhere in the replay field. The use of a FT projector to replace CRTs requires a screen. Various technologies and methods were investigated to increase the exit pupil and reduce sparkle. The final system was a working aviators helmet mounted display, using the visor as the final collimating element.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.599216  DOI: Not available
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