Method of detecting a topology of a reflective surface
A method detects a topology of a reflective surface. The method includes providing an optical fiber positioned such that light emitted from the optical fiber is reflected by at least a portion of the reflective surface. The optical fiber and the portion of the reflective surface form an optical resonator having an optical resonance with a resonance lineshape. The method further includes emitting light from the optical fiber while the optical fiber is at a plurality of positions along the reflective surface. The light emitted from the optical fiber irradiates a corresponding plurality of portions of the reflective surface. The method further includes measuring a change of the resonance lineshape due to the irradiation of the plurality of portions of the reflective surface.
1. A method of detecting a topology of a reflective surface, the method comprising:
providing a spatial mode filter positioned such that light emitted from the spatial mode filter is reflected by at least a portion of the reflective surface, wherein the spatial mode filter and the portion of the reflective surface form an optical resonator having an optical resonance with a resonance lineshape;
emitting light from the spatial mode filter while the spatial mode filter is at a plurality of positions along the reflective surface, the light emitted from the spatial mode filter irradiating a corresponding plurality of portions of the reflective surface; and
measuring a change of the resonance lineshape due to the irradiation of the plurality of portions of the reflective surface.
2. The method of claim 1 , wherein the spatial mode filter comprises an optical fiber.
3. The method of claim 1 , wherein the resonance lineshape is asymmetric as a function of wavelength, wherein a degree of asymmetry of the resonance lineshape is dependent on the topology of the irradiated portion of the reflective surface, and measuring the change of the resonance lineshape comprises measuring the degree of asymmetry of the resonance lineshape.
4. The method of claim 1 , wherein the resonance lineshape has a magnitude dependent on the topology of the irradiated portion of the reflective surface, and measuring the change of the resonance lineshape comprises measuring the magnitude.
5. The method of claim 1 , wherein the spatial mode filter comprises an optical fiber having a first end that is partially reflective and partially transmissive to light emitted by the optical fiber, the first end of the optical fiber and the portion of the reflective surface forming a Fabry-Perot optical resonator.
6. The method of claim 1 , wherein the spatial mode filter comprises an optical fiber having a fiber Bragg grating, wherein the fiber Bragg grating and the portion of the reflective surface form a Fabry-Perot optical resonator.
7. The method of claim 6 , wherein the fiber Bragg grating and the portion of the reflective surface have a cavity therebetween.
8. The method of claim 7 , wherein the cavity comprises a gas.
9. The method of claim 7 , wherein the cavity comprises a liquid.
10. The method of claim 1 , wherein at least a portion of the light reflected by the portion of the reflective surface is transmitted through the spatial mode filter.
11. The method of claim 1 , wherein the spatial mode filter comprises a single-mode optical fiber.
12. The method of claim 1 , wherein the spatial mode filter comprises an optically transmissive portion and an optically non-transmissive portion which bounds at least a portion of the optically transmissive portion.
13. The method of claim 12 , wherein the optically transmissive portion is a hole through the optically non-transmissive portion.
14. The method of claim 1 , wherein the spatial mode filter comprises a metal layer.
15. The method of claim 1 , wherein the spatial mode filter comprises a dielectric mirror.