Comparisons of glass and plastic waveguides for augmented reality glasses

Augmented reality (AR) waveguides are often treated as perfectly flat, but some degree of roughness present will blur the final image. By comparing the optical system's modulation transfer function (MTF), we find that glass waveguides with smoother surfaces can transmit higher resolutions than the untreated plastic waveguides with rougher surfaces. However, the coated plastic waveguides, achieved by spin-coating acrylic resin material to the plastic surface, can significantly reduce the roughness and attain surface quality comparable to that of glass. Additionally, we find that changing factors that widen the field of view such as refractive index and incident angle will make the system more sensitive to surface roughness.