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US 2024/0191986 A1Published application
Systems and methods for measuring height properties of surfaces
AssigneeNikon Corporation
InventorsEric Peter Goodwin, Goldie Lynne Goldstein
Life of this patent
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Abstract
The problem of measuring height properties (for instance, for aspheric optical components) is addressed by systems and methods that employ heterodyne optical interferometry to detect a plurality of interference patterns corresponding to a plurality of orientations of the surface and that determine a height property (such as a mid-spatial frequency spectrum or topography) of the surface from the plurality of interference patterns.
Claims20
A method for measuring a height property of a surface, comprising:
- a) for each angle of a plurality of angles:
- i) rotating the surface through the angle;
- ii) directing a first line of light at the surface;
- iii) directing a second line of light at the surface;
- iv) receiving the first and second lines of light, the first and second lines of light having a shear distance between one another;
- and
- v) detecting an interference pattern between the first and second lines of light;
- b) generating a plurality of interference patterns, each interference pattern of the plurality of interference patterns corresponding to an angle of the plurality of angles;
- and
- c) determining the height property of the surface based upon the plurality of interference patterns.
7 more elements
A system for measuring a height property of a surface, comprising:
- a) a rotational module configured to rotate the surface through a plurality of angles;
- b) an optical source module configured to, for each angle of the plurality of angles, direct a first line of light and a second line of light at the surface;
- c) an optical detector configured to, for each angle of the plurality of angles, receive the first and second lines of light and detect an interference pattern between the first and second lines of light, the first and second lines of light having a shear distance between one another;
- and
- d) a storage module configured to store the interference pattern associated with each angle of the plurality of angles, thereby generating a plurality of interference patterns.
2 more elements
20-48. (canceled)
Dependencies are inferred from the claim text.