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30 September 1996 High-gain wide-viewing-angle null-hot-spot optical diffuser useful for display screen application
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Proceedings Volume 2892, Display Devices and Systems; (1996)
Event: Photonics China '96, 1996, Beijing, China
A high-gain, wide-viewing-angle optical diffuser without hot spots is presented. Such type of optical diffuser has potential applications in front and rear projection screens, LED display illumination, LCD backlights, beam homogenizer, etc. By shaping the diffused light pattern to be elliptical, high-gain is achieved by narrowing and thus enhancing 1D intensity distribution while the other dimension satisfies the wide-viewing-angle requirement. Optical diffuser can be implemented by illuminating a ground glass and recording the speckle pattern on a photoresist plate. Shaping the diffuser light pattern of resultant optical diffuser can be conveniently controlled by shaping the illuminating light pattern on ground glass. However the diffuser must be optimized such that hot spots can be totally eliminated. For surface relief optical diffusers, surface-roughness is the major factor affecting elimination of hot spots and, hence, efficiency of optical diffuser. Suitable exposure and development conditions for controlling surface roughness are investigated. After this recording process, a nickel plate is electro-formed from the photoresist plate. Under our design conditions, the nickel plate is measured to be with viewing-angle of 100 degree(s) horizontal X 40 degree(s) vertical (full angular width of 1/10 maximum) and gain of 5.24 (relative to 3M's wall screen). Hot spots are totally suppressed. Such plate can be used as master in industrial embossing processes for mass production. Controllability and simplicity in design and manufacture would make such optical diffuser very attractive for display screen as well as other applications mentioned above.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hoang Yan Lin, Wann-Diiang Tyan, and Ying Tsung Lu "High-gain wide-viewing-angle null-hot-spot optical diffuser useful for display screen application", Proc. SPIE 2892, Display Devices and Systems, (30 September 1996);

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