Optical combiner for near-eye display

A head mounted display (“HMD”) that combines image light with external scene light, the HMD comprising:

• an image source to generate the image light including first, second, and third color light;
• an optical combiner including a first color combiner layer (“CCL”) including a first diffractive grating coated with a first filter configured to reflect the first color light and pass the second and third color light, a second CCL including a second diffractive grating coated with a second filter configured to reflect the second color light, and pass the third color light, and a third CCL including a third diffractive grating coated with a third filter configured to partially reflect visible light;
• a frame assembly for wearing on a head of a user, the frame assembly supporting the image source and positioning the optical combiner in front of an eye of the user;
• and
• a transmissive dispersion element (“TDE”) positioned between the image source and the optical combiner, the TDE configured to diffract the image light into the first, second, and third color light at angles, wherein the first, second, and third diffractive gratings are each embedded in an index matched material and are angle-tuned diffractive gratings configured to respectively reflect the first, second, and third color light received from the TDE at an order of diffraction that directs the first, second, and third color light in a direction substantially normal to an eye of a user of the HMD, and wherein the index matched material is disposed between the first filter and the second filter and the index matched material is also disposed between the second filter and the third filter.