Height measurement using optical interference
AssigneeInternational Business Machines Corporation
InventorsRichard A. Haight, James B. Hannon, Rudolf M. Tromp
Life of this patent
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Abstract
Systems for measuring a distance include a lens positioned a distance above a target surface. A camera is configured to measure a first interference pattern between the lens and the target surface using a light source at a first wavelength and to measure a second interference pattern between the lens and the target surface using a light source at a second wavelength. A processor is configured to determine an absolute measurement of the distance between the lens and the target surface based on the first interference pattern and the second interference pattern.
Claims20
A system for measuring a distance, comprising:
- a lens positioned a distance above a target surface;
- a camera configured to measure a first interference pattern between a reflection from the lens and a reflection from the target surface using a light source at a first wavelength and to measure a second interference pattern between a reflection from the lens and a reflection from the target surface using a light source at a second wavelength;
- a processor configured to determine an absolute measurement of the distance between the lens and the target surface based on the first interference pattern and the second interference pattern.
A system for measuring a distance, comprising:
- a lens positioned a distance above a target surface;
- a camera configured to measure a first interference pattern between a reflection from the lens and a reflection from the target surface using a light source at a first wavelength and to measure a second interference pattern between a reflection from the lens and a reflection from the target surface using a light source at a second wavelength, different from the first wavelength, by measuring a radius of a smallest ring in the second interference pattern;
- a processor configured to determine an absolute measurement of the distance between the lens and the target surface based on the first interference pattern and the second interference pattern.
A system for measuring a distance, comprising:
- a spherical lens positioned a distance, within a maximum measurement distance, above a target surface;
- a camera configured to measure a first interference pattern between a reflection from the spherical lens and a reflection from the target surface using a laser at a first wavelength, by measuring a radius of a smallest ring in the first interference pattern, and to measure a second interference pattern between a reflection from the spherical lens and a reflection from the target surface using a laser at a second wavelength, different from the first wavelength, by measuring a radius of a smallest ring in the second interference pattern;
- a processor configured to determine an absolute measurement of the distance between the spherical lens and the target surface based on the radius of the smallest ring of the first interference pattern and the radius of the smallest ring of the second interference pattern.
Dependencies are inferred from the claim text.