Apparatus and method for optical characterization of a sample over a broadband of wavelengths with a small spot size
Assigneen&k Technology, Inc.
InventorsRay Hebert, Marc Aho, Abdul Rahim Forouhi
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Abstract
An apparatus and method for optically characterizing the reflection and transmission properties of a sample with a beam of light having a small diameter on a surface of the sample over a broadband of wavelengths, from 190 nm to 1100 nm. Reflective optical components, including off-axis parabolic mirrors with a collimated incident or reflected broadband beam of light, minimize non-chromatic aberration. The apparatus and method further disclose an optical light path that can be focused by adjusting the position of an off-axis parabolic mirror and a planar mirror.
Claims34
An apparatus for characterizing optical properties of a sample, comprising:
- a) a light source for generating a broadband beam;
- b) at least a first set of components defining a first light path, said components including at least a first component pair of a first planar mirror and a first parabolic mirror with a first focal length and a second component pair of a second planar mirror and a second parabolic mirror with a second focal length;
- c) an element onto which said broadband beam is illuminated;
- and
- d) a means of mechanically displacing said second component pair without altering a position of said second parabolic mirror relative to said second planar mirror, whereby a focus position of said broadband beam can be altered without moving said first component pair;
- wherein said first set of components is disposed between said source and said sample on said first light path.
A method of characterizing optical properties of a sample comprising:
- a) providing a sample to be characterized;
- b) generating light in a broadband beam;
- c) providing said broadband beam to a top surface of said sample with a first set of reflective components defining a first light path, wherein said first set of components includes at least a first component pair of a first planar mirror and a first parabolic mirror with a first focal length and a second component pair of a second planar mirror and a second parabolic mirror with a second focal length;
- d) adjusting a focus position of said broadband beam by mechanically displacing said second component pair without altering a position of said second parabolic mirror relative to said second planar mirror, whereby the focus position can be altered without moving said first component pair;
- e) receiving a broadband response beam from said sample at a first detector in a second set of reflective components defining a second light path;
- f) measuring an intensity of said broadband response beam from said sample with said first detector;
- and
- g) determining optical properties of said sample based on said measured intensity, and providing said determined optical properties as an output.
Dependencies are inferred from the claim text.