Methods and systems for programming momentum and increasing light efficiency in deeper roundtrips of folded optics via axial refraction
Some implementations of the disclosure relate to an optical system, including: a first light source; a secondary light source that is optically coupled to the first light source; a reflective element that is transparent with respect to the first light source but reflective with respect to the secondary light source, the reflective element being disposed between the first light source and the secondary light source; and a semi-reflective layer disposed on the secondary light source, such that reflection of light from the secondary light source by the reflective element and back through the semi-reflective element results in greater than 25% of the light from first light source exiting the optical system.
1. An optical system comprising:
a light source;
a first element having optical properties that do not vary macroscopically, on a scale greater than five to ten times the optical wavelength, transverse to the optic axis, while collecting light emitted from the light source; and
a second element having optical properties that do not vary macroscopically, wherein that the second element redirects the collected light from the first element to a viewer, such that light emitted by the light source through the first and the second element appears to a viewer as a virtual image located at a virtual depth different than a location of the optical system.
2. The optical system of claim 1 , wherein the first element is a graded-index (GRIN) element.
3. The optical system of claim 2 , wherein the GRIN element includes a profile that is optimized by a computer algorithm to minimize unwanted distortions.
4. The optical system of claim 1 , wherein the second element is a transversely periodic structure selected from the group consisting of: a photonic crystal, a nano-cone forest, a metamaterial, and a discrete set of metasurfaces.
5. The optical system of claim 2 , wherein a variation of a refractive index of the GRIN element is decreasing in a direction of propagation of the light.
6. The optical system of claim 5 , wherein the light is coupled out via total internal reflection (TIR) modulation.
7. The optical system of claim 1 , wherein at least one element is a nonlinear optical element.
8. The optical system of claim 1 , wherein the first element or the second element comprises a photonic crystal.
9. The optical system of claim 1 , wherein the light source is embedded within the first element, such that light emitted from the light source in any direction is redirected to the viewer by the first element.
10. The optical system of claim 1 or claim 2 , wherein the light source is located on an edge of the system, and wherein a virtual image is coherently coupled out through a birefringent GRIN element.
11. The optical system of claim 1 , wherein the light source is replaced by an imaging sensor in order to image light that has entered the system and formed an image on the imaging sensor.
12. The optical system of claim 11 , further comprising a lens to further focus the light.
13. The optical system of claim 1 , wherein the system is worn on a human body as a near-eye display, personal accessory, or disposed far from the face.
14. The optical system of claim 13 , wherein the system is a display system configured as a component of a cellphone, tablet, viewer, viewfinder, monitor, television, or vehicle instrument cluster with virtual depth.