Diffractive waveguides for Augmented Reality (AR) are often stacks of 2 or 3 single waveguides, with each individual waveguide designed for 1 or 2 narrow-band wavelength bands. For best image quality, the optical axes of all elements of the waveguide stack must coincide to well below 1 arcmin for all 3 RGB colors, otherwise chromatic aberration effects at edges occur, severely reducing the image quality for the user.
Therefore,1) the optical axis of each waveguide in the stack must be characterized after manufacturing and compatible sets of waveguides must be matched; 2) the stacking process must not introduce tilt errors.
Metrology solutions for both 1) and 2) and the effect of errors on the image quality of the finished waveguide will be presented.
|