Multi-focal length miniature refractive element and method for making the same
View Patent ↗A monolithic multi-focal length miniature refractive element comprising a first surface region and a second surface region. The first surface region has a first characteristic radius of curvature. The second surface region has a second radius of curvature that is different from the first characteristic radius of curvature. The first and second surface regions are formed on a single optical element blank. The optical element blank can be a composite of two or more materials.
1. A monolithic multi-focal length refractive element comprising:
a single monolithic optical element blank comprising:
a first surface region having a first characteristic radius of curvature; and
a second surface region having a second characteristic radius of curvature, wherein said monolithic multi-focal length refractive element has a maximum dimension of less than five millimeters.
2. The monolithic multi-focal length refractive element as recited in claim 1 , wherein a value of an optical property for said first surface region is different from a value of said optical property for said second surface region.
3. The monolithic multi-focal length refractive element as recited in claim 2 wherein said optical element blank comprises silica (SiO 2 ).
4. The monolithic multi-focal length refractive element as recited in claim 2 wherein said optical element blank comprises gallium arsenide (GaAs).
5. The monolithic multi-focal length refractive element as recited in claim 1 , wherein said monolithic optical element blank comprises a third surface region having a third characteristic radius of curvature.
6. A method for making a multi-focal length refractive element, said method comprising:
forming in an optical element blank a first surface region characterized by a first radius of curvature by etching said optical element blank using a first etch process having a first etch selectivity; and
forming on said optical element blank a second surface region characterized by a second radius of curvature by etching said optical element blank using a second etch process having a second etch selectivity.
7. The method as recited in claim 6 wherein said first etch selectivity is less than said second etch selectivity.
8. The method as recited in claim 6 additionally comprising forming a first shape transfer mask and etching said first shape transfer mask using said first etch process.
9. The method as recited in claim 8 additionally comprising etching said first shape transfer mask using said second etch process.
10. The method as recited in claim 8 additionally comprising forming a second shape transfer mask.
11. The method as recited in claim 10 additionally comprising using said second etch process to etch said second shape transfer mask.
12. A method for making a multi-focal length refractive element, said method comprising:
forming in an optical element blank a first surface region characterized by a first radius of curvature;
forming on said optical element blank a second surface region characterized by a second radius of curvature;
forming a first shape transfer mask and etching said first shape transfer mask using a first etch process; and
etching said first shape transfer mask using a second etch process.
13. The method as recited in claim 12 wherein said forming said first surface region comprises etching said optical element blank using said first etch process having a first etch selectivity.
14. The method as recited in claim 13 wherein said forming said second surface region comprises etching said optical element blank using said second etch process having a second etch selectivity.
15. The method as recited in claim 14 wherein said first etch selectivity is less than said second etch selectivity.
16. The method as recited in claim 12 additionally comprising forming a second shape transfer mask.
17. The method as recited in claim 16 additionally comprising using said second etch process to etch said second shape transfer mask.