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This project seeks to provide solutions to the color mixing problem present in optical combiners for Augmented Reality.
- Jounal paper - link
Sri, please add here the references (and link to the paper on the ACM) to Gabbard's work, color correction on projectors, and colorimetric compensation.
Reflective Waveguide: The reflective technologies have the advantage of using straight reflective optical components (no exotic components or multilayer coatings). They do not suffer from the color non-uniformity issues since they use “normal” semi reflective mirrors therefore reflecting white light without any degradation. The possibility to use a molded plastic substrate for the light guide is also a key advantage of this technique. Two wedge shaped pieces are glued together precisely (one is coated with a semi reflective coating and the other is bare) in order to produce the waveguide. These wedge shaped structures need to be molded with high precision molding techniques. This is the main challenge of this technique. As with the other waveguide technologies, an optical collimator magnifies the image generated by a micro display and injects it into the light guide. Through the TIR principle (total internal reflection), the light travels through the light guide and is extracted using a semi reflective mirrored structure using traditional coatings found throughout the optics industry. This will allow the components to be made using traditional coating techniques, therefore reducing cost. Consequently, any type of micro display can be used in this system since there is no polarization required (LCD, LCOS, OLED). These reflective systems also tend to be more efficient in power consumption because there is no light loss due to polarization or grating/holographic effects. This type of system is used by Epson in their Moverio product, the Google Glass prototypes, and by Optinvent in the Clear-Vu technology. The approach taken by both Epson and Google uses a single reflector embedded into the light guide (although Google implementation does not use TIR). Other than the lack of innovation, and therefore low entry barrier, the problem with this approach is that the size of the reflector is directly proportional the FOV (Field of View) and eye motion box dimension, therefore the light guide becomes quite thick. In both the Google and Epson cases, the light guide thickness is around 1cm as seen in the figure below.
Taken from: http://optinvent.com/pdf/optinvent_position_paper_2012_AR_standards.pdf