MEASUREMENT APPARATUS AND MEASUREMENT METHOD
First Claim
1. A measurement apparatus which measures a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the apparatus comprising:
- a detector configured to detect the interfering light to output an interference signal; and
a processor configured to obtain the surface position based on a sine signal and a cosine signal which are obtained from the interference signal output from said detector and have a phase corresponding to an optical path length difference between the measurement light and the reference light,wherein said processor includes a correction processing unit configured to correct the sine signal and the cosine signal to reduce frequency noise components contained in the sine signal and the cosine signal.
1 Assignment
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Accused Products
Abstract
A measurement apparatus, which measures a surface position of an object by detecting interfering light between measurement light reflected by the object and reference light reflected by a reference surface, includes: a detector configured to detect the interfering light to output an interference signal; and a processor configured to obtain the surface position based on a sine signal and a cosine signal which are obtained from the interference signal output from the detector and have a phase corresponding to an optical path length difference between the measurement light and the reference light. The processor includes a correction processing unit configured to correct the sine signal and the cosine signal to reduce frequency noise components contained in the sine signal and the cosine signal.
8 Citations
12 Claims
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1. A measurement apparatus which measures a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the apparatus comprising:
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a detector configured to detect the interfering light to output an interference signal; and a processor configured to obtain the surface position based on a sine signal and a cosine signal which are obtained from the interference signal output from said detector and have a phase corresponding to an optical path length difference between the measurement light and the reference light, wherein said processor includes a correction processing unit configured to correct the sine signal and the cosine signal to reduce frequency noise components contained in the sine signal and the cosine signal. - View Dependent Claims (2, 5, 6, 11)
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3. A measurement apparatus which measures a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the apparatus comprising:
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a detector configured to detect the interfering light to output an interference signal; and a processor configured to obtain the surface position based on a sine signal and a cosine signal which are obtained from the interference signal output from said detector and have a phase corresponding to an optical path length difference between the measurement light and the reference light, wherein said processor includes a correction processing unit configured to correct the interference signal to reduce a frequency noise component contained in the interference signal. - View Dependent Claims (4, 12)
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7. A measurement apparatus which measures a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the apparatus comprising:
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a first light source configured to generate first light of a first wavelength; a second light source configured to generate second light of a second wavelength; a first detector configured to detect first interfering light generated using the first light, and outputs a first interference signal; a second detector configured to detect second interfering light generated using the second light, and outputs a second interference signal; and a processor configured to obtain the surface position based on the first interference signal and the second interference signal, wherein said processor obtains, from the first interference signal and the second interference signal, a sine signal and a cosine signal having a phase of an interference signal corresponding to a synthetic wavelength of the first wavelength and the second wavelength, corrects the sine signal and the cosine signal to reduce frequency noise components contained in the obtained sine signal and the obtained cosine signal, and obtains the surface position by using the corrected sine signal and the corrected cosine signal, and the synthetic wavelength is larger than the first wavelength and the second wavelength.
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8. A measurement method of measuring a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the method comprising the steps of:
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detecting the interfering light to output an interference signal; correcting a sine signal and a cosine signal which are obtained from the output interference signal and have a phase corresponding to an optical path length difference between the measurement light and the reference light, to reduce frequency noise components contained in the sine signal and the cosine signal; and obtaining the surface position based on the corrected sine signal and the corrected cosine signal.
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9. A measurement method of measuring a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the method comprising the steps of:
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detecting the interfering light to output an interference signal; correcting the interference signal to reduce a frequency noise component contained in the output interference signal; and obtaining, from the corrected interference signal, a sine signal and a cosine signal having a phase corresponding to an optical path length difference between the measurement light and the reference light, and obtaining the surface position based on the obtained sine signal and the obtained cosine signal.
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10. A measurement method of measuring a surface position of an object to be measured by detecting interfering light between measurement light reflected by the object to be measured and reference light reflected by a reference surface, the method comprising the steps of:
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detecting first interfering light generated using first light of a first wavelength from a first light source to output a first interference signal; detecting second interfering light generated using second light of a second wavelength from a second light source to output a second interference signal; and obtaining the surface position based on the first interference signal and the second interference signal; wherein a sine signal and a cosine signal having a phase of an interference signal corresponding to a synthetic wavelength of the first wavelength and the second wavelength are obtained from the first interference signal and the second interference signal, the sine signal and the cosine signal are corrected so as to reduce frequency noise components contained in the obtained sine signal and the obtained cosine signal, and the surface position is obtained by using the corrected sine signal and the corrected cosine signal, and the synthetic wavelength is larger than the first wavelength and the second wavelength.
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Specification