Diffractive optical elements and applications thereof
View Patent ↗A fanout diffractive optical element having a discrete periodic surface relief structure having a 2-dimensional (x,y) shape is described. The surface relief structure can include a first lobe and a second lobe separated by a waist region having a width less than the first lobe and the second lobe. The 2-dimensional (x,y) shape of surface relief structure can have an inversion center and can lack symmetry about any plane that is normal to the surface relief structure. Also described are apparatuses having a fanout diffractive optical element and methods of producing a plurality of light diffracting orders using a fanout diffractive optical element.
1. A fanout diffractive optical element comprising:
a discrete periodic surface relief structure having a 2-dimensional (x,y) shape comprising a first lobe and a second lobe separated by a waist region, the waist region having a width less than the first lobe and the second lobe, the 2-dimensional (x,y) shape having an inversion center and lacking symmetry about any plane that is normal to the surface relief structure.
2. The fanout diffractive optical element of claim 1 , wherein the surface relief structure has a single plateau profile having a base area and a top area, wherein a ratio of the top area to the base area is at least about 0.80.
3. The fanout diffractive optical element of claim 2 , wherein the ratio of the top area to the base area is at least about 0.90.
4. The fanout diffractive optical element of claim 2 , wherein the ratio of the top area to the base area is at least about 0.95.
5. The fanout diffractive optical element of claim 1 , wherein a ratio of the width of the waist region to a length of the surface relief structure is less than about 0.7.
6. The fanout diffractive optical element of claim 5 , wherein the ratio of the width of the waist region to the length of the surface relief structure is less than about 0.6.
7. The fanout diffractive optical element of claim 1 , wherein the surface relief structure has a height of at least about 0.5 μm.
8. The fanout diffractive optical element of claim 1 , wherein the surface relief structure has a height of at least about 0.9 μm.
9. The fanout diffractive optical element of claim 1 comprising a plurality of discrete periodic surface relief structures.
10. The fanout diffractive optical element of claim 1 , wherein a first surface relief structure is spatially separated from a second surface relief structure by at least about 0.25 μm.
11. The fanout diffractive optical element of claim 1 , wherein the surface relief structure is periodic in two directions.
12. The fanout diffractive optical element of claim 11 , wherein the periodicity of the surface relief structure is different in orthogonal directions.
13. The fanout diffractive optical element of claim 1 , wherein the fanout diffractive optical element is a 3×3 fanout diffractive optical element.
14. The fanout diffractive optical element of claim 1 , wherein the surface relief structure comprises borosilicate glass or fused silica.
15. The fanout diffractive optical element of claim 1 having a diffraction efficiency of at least about 70%.
16. The fanout diffractive optical element of claim 1 , wherein the surface relief structure is substantially symmetrical about a C 2 rotational axis.
17. An apparatus comprising:
a light source; and
a fanout diffractive optical element positioned to receive light from the light source, the fanout diffractive optical element comprising a periodic surface relief structure, the surface relief structure having a 2-dimensional (x,y) shape comprising a first lobe and a second lobe separated by a waist region, the waist region having a width less than the first lobe and the second lobe, the 2-dimensional (x,y) shape having an inversion center and lacking symmetry about any plane that is normal to the surface relief structure.
18. The apparatus of claim 17 , wherein the surface relief structure comprises a single plateau profile having a base area and a top area, wherein a ratio of the top area to the base area is at least about 0.80.
19. The apparatus of claim 17 , wherein light from the light source is substantially monochromatic.
20. The apparatus of claim 17 , wherein light from the light source has a wavelength ranging from about 600 nm to about 900 nm.
21. The apparatus of claim 17 , wherein the light source is a laser.
22. The apparatus of claim 17 further comprising at least one refractive optical element positioned between the light source and the fanout diffractive optical element.
23. The apparatus of claim 22 , wherein the at least one refractive optical element is a collimating lens.
24. The apparatus of claim 22 further comprising at least one spacer between the at least one refractive optical element and the fanout diffractive optical element.
25. The apparatus of claim 17 further comprising at least one diffractive optical element positioned between the light source and the fanout diffractive optical element.
26. The apparatus of claim 25 , wherein the at least one diffractive optical element is a collimating diffractive optical element.
27. The apparatus of claim 25 , wherein the at least one diffractive optical element is coupled to the fanout diffractive optical element.
28. A method of producing a plurality of light diffraction orders comprising:
providing a light source;
providing a fanout diffractive optical element comprising a periodic surface relief structure, the surface relief structure having a 2-dimensional (x,y) shape comprising a first lobe and a second lobe separated by a waist region, the waist region having a width less than the first lobe and the second lobe, the 2-dimensional (x,y) shape having an inversion center and lacking symmetry about any plane that is normal to the surface relief structure;
passing at least a portion of light from the light source through the fanout diffractive optical element; and
splitting the light received from the light source into the plurality of diffraction orders.
29. The method of claim 28 , wherein the plurality of diffraction orders have substantially the same power.
30. The method of claim 28 , wherein the plurality of diffraction orders are in an array.
31. The method of claim 30 , wherein the array is a two-dimensional array.
32. The method of claim 28 further comprising collimating light from the light source prior to passing the light through the fanout diffractive optical element.
33. The method of claim 28 , wherein collimating light comprises passing the light through at least one refractive optical element.
34. The method of claim 28 , wherein collimating light comprises passing the light through at least one diffractive optical element.