Height measurement using optical interference
AssigneeInternational Business Machines Corporation
InventorsRichard A. Haight, James B. Hannon, Rudolf M. Tromp
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Abstract
Methods and systems for measuring a distance include measuring a first interference pattern between a lens and a target surface using a light source at a first wavelength. A second interference pattern is measured between the lens and the target surface using a light source at a second wavelength, different from the first wavelength. An absolute measurement of a distance between the lens and the target surface is determined based on the first interference pattern and the second interference pattern.
Claims20
A method for measuring a distance, comprising:
- measuring a first interference pattern between a reflection from a lens and a reflection from a target surface using a light source at a first wavelength;
- measuring 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;
- and
- determining an absolute measurement of a distance between the lens and the target surface using a processor based on the first interference pattern and the second interference pattern.
A computer readable storage medium comprising a computer readable program for distance measurement, wherein the computer readable program when executed on a computer causes the computer to perform the steps of:
- measuring a first interference pattern between a reflection from a lens and a reflection from a target surface using a light source at a first wavelength;
- measuring 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;
- and
- determining an absolute measurement of a distance between the lens and the target surface using a processor based on the first interference pattern and the second interference pattern.
A method for measuring a distance, comprising:
- measuring a first interference pattern between a reflection from a lens and a reflection from a target surface using a light source at a first wavelength;
- measuring 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;
- and
- determining an absolute measurement of a distance between the lens and the target surface using a processor based on the first interference pattern and the second interference pattern.
Dependencies are inferred from the claim text.