Spatially multiplexed diffraction grating for color consistency optimization in waveguide display

Augmented reality head-mounted displays (AR-HMDs) face challenges in full-color reconstruction due to wavelength-dependent diffraction and non-optimized intensity efficiency in waveguide (WG) displays based on surface relief gratings or volume-holographic gratings. To overcome this limitation, we introduce a spatially multiplexed diffraction grating (SMDG) incorporating holographic optical elements (HOEs) to enhance the color consistency by adjusting the RGB diffraction directions and efficiencies, addressing issues like non-uniform color output. The proposed diffractive grating considers both the characteristics of the HOE and the RGB wavelength sensitivity of the observer to optimize the color consistency. Experiments measured efficiencies with an optical power meter and demonstrated AR output using a CCD camera. Diffraction efficiencies reached up to 80 % for optimized wavelengths, with WG efficiencies producing balanced output in AR demonstrations. The SMDG-HOE approach validates enhanced color consistency in WG display, offering a user-immersive AR solution for compact and improved color reconstruction.