FEATURES OF SPECTRAL AND DIFFRACTION CHARACTERISTICS OF HOLOGRAPHIC REFLECTION GRATINGS OF INPUT/OUTPUT RADIATION IN PLANAR WAVEGUIDES
E. F. Pen, V.N. Zatolokin
Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: input/output gratings, waveguide, spectral characteristics, diffraction efficiency, reflection hologram, photopolymer
Abstract
Spectral and diffraction characteristics of color monochrome single-layer (R, G and B) reflection holograms, as well as a three-layer RGB structure in the form of their superposition on each other (stacks), intended for use as gratings of input/output radiation of color LED devices in AR displays, were obtained and analyzed. An experimentally established mismatch between the spectral characteristic contour widths of the obtained holograms and the KY-016 LED diode used in the experiments. Because of this reason fractions of useful intensities of the R, G, and B components of this device are only 64 %, 32 %, and 34 %, respectively, of their potential values. Based on the well-known CIE RGB color specification model, the actual intensity ratios were found for mixing the emissions of the color components of an LED diode in interaction with reflection holographic gratings in order to synthesize white color. When assessing the energy efficiency of input/output of radiation using reflection holograms and color LED devices, the main criterion is the maximum brightness of the total illumination for a given set of color components and white balance conditions, and not the maximum intensities of individual components of R, G, and B radiation.
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