Method of forming and mounting an angled reflector
View Patent ↗In a method of forming a device so as to include a reflective surface at a specific angle to an incident optical axis, a region of a first major surface of a substrate is exposed to an anisotropic etchant to form a surface having the specific angle with respect to the first major surface, but the etched surface is then used as a mounting surface. That is, rather than anisotropically etching a reflective surface, the etching provides the mounting surface and the second major surface of the substrate functions as the reflective surface when the fabricated device is properly mounted. The substrate may be a <100> silicon wafer having a 9.74 degree off-axis cut. Then, a 45 degree mirror is formed by the process. When the reflector is used in an optical device, the <111> crystalline plane will be generally parallel to the surface of the support.
1. A method of forming a device having a reflective surface that is at a specific angle to an incident optical axis, the method comprising:
providing a substrate having first and second major surfaces, wherein said second major surface constitutes the reflective surface;
exposing a region of said first major surface to an anisotropic etchant thereby forming a mounting surface of said device, the mounting surface having a first angle relative to said first major surface; and
using said mounting surface to mount said device upon a support surface whereby said second major surface is automatically oriented at said specific angle relative to said incident optical axis.
2. The method of claim 1 further comprising forming a reflective coating on said second major surface to enhance reflectivity with respect to a beam directed to said second major surface along said incident optical axis.
3. The method of claim 1 wherein said mounting surface is oriented in a <111> crystal plane of said substrate.
4. The method of claim 1 wherein providing said substrate includes providing a silicon wafer having a 9.74 off-axis cut, said exposing including utilizing photolithography to define said region.
5. The method of claim 4 wherein exposing said region to said anisotropic etchant includes selecting said anisotropic etchant such that said mounting surface is substantially 45 degrees with respect to said first major surface.
6. A method of fabricating a reflector comprising:
providing a <100> silicon wafer having opposed first and second surfaces and having an off-axis cut;
forming a protective pattern on said first surface of said wafer to expose a region of said first surface;
anisotropically etching said wafer via said exposed region of said first surface to provide a generally 45 degree surface;
dividing said wafer to isolate an optical member that includes said generally 45 degree surface and a portion of said second surface; and
treating and orienting said optical member such that said generally 45 degree surface is configured for attachment to a support and such that said portion of said second surface provides beam reflection when said generally 45 degree mirror is attached to said support.
7. The method of claim 6 wherein forming said protective pattern includes using photolithographic techniques.
8. The method of claim 6 further comprising coating said second surface to enhance beam reflection properties of said second surface.
9. The method of claim 6 wherein said anisotropically etching said wafer includes continuing material removal to reach said second surface opposite to said first surface.
10. The method of claim 9 wherein dividing said wafer includes removing a toe section of said generally 45 degree surface.
11. The method of claim 6 further comprising anisotropically etching said wafer via an exposed region of said second surface of said wafer, thereby enabling simultaneous formation of a second optical member, said first surface being a reflective surface of said second optical member.
12. The method of claim 6 wherein forming said protective pattern includes patterning layers of oxide and nitride.