Color shifted optical system for near-eye displays

A method for designing a coating for a specific facet of a light-guide optical element (LOE), the method comprising:

• defining a relevant angular spectrum that the specific facet of the LOE will transmit;
• calculating using a computer processor proportions of light impinging on the specific facet for transmittance beams having an angle in the relevant angular spectrum, wherein the proportion of light for a transmittance beam is calculated based on a summation of a product of the illuminated intensity of the transmittance beam for the wavelengths included in the transmittance beam and a weighting function for the wavelength describing a sensitivity of the human eye to the wavelength;
• setting an initial reference value to 0;
• defining using the computer processor a nominal color vector based on the initial reference value and the calculated proportions of light, such that the transmittance beams having an angle in the relevant angular spectrum are weighted by the calculated proportions of light;
• designing using the computer processor a facet coating profile for the nominal color vector for transmittance corresponding to the specific facet by optimizing color uniformity for three angular bands including two bands that have a respective totally transmissive portion and one band that has a partially reflective portion and is adjacent to one of the two bands that have the respective totally transmissive portion;
• and
• evaluating from the designed facet coating profile a weighted color vector transmittance after reflection;
• and
• applying to a facet of the LOE a coating having the designed facet coating profile.