EP0364984A2
Expired / Lapsed
EP
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Interferometer using multi-mode semiconductor laser
Assignee: Canon Inc
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Filing: 1989-10-18
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Granted: —
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Expires: 2009-10-18
Abstract
Abstract An interferometer for measuring the displacement of a diffraction grating includes a multi-mode semiconductor laser (1) for generating a laser beam; a device (20) for supplying a predetermined current to the laser so that at least five vertical modes occur in an oscillation spectrum of the laser beam generated by the laser at an intensity ratio of at least 0.05; and an optical system (3) for splitting the laser beam generated by the laser into first and second beams. The optical system also directs the first and second beams to the diffraction grating (6) and effects interference between a first diffracted light beam generated by the diffraction of the first beam at the diffraction grating and a second diffracted light beam generated by the diffraction of the second beam at the diffraction grating to produce an interference light beam. Also provided is a photoelectric convertor (13) for converting the interference light beam into an electrical signal.
Inventors
- 👤 Ko Ishizuka
- 👤 Tetsuharu Nishimura
- 👤 Yoichi Kubota
- 👤 Masaaki Tsukiji
- 👤 Satoshi Ishii
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 17:28
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
48 words
An interferometer comprising: a multi-mode semiconductor laser generating a laser beam having at least five vertical modes each having an intensity ratio of at least 0.05; generation means for generating interference light from a laser beam generated by said laser; and detection means for detecting the interference light.
Claim 2
Dependent Claim
48 words
An interferometer comprising: a multi-mode semiconductor laser generating a laser beam having at least five vertical modes each having an intensity ratio of at least 0.05; generation means for generating interference light from a laser beam generated by said laser; and detection means for detecting the interference light.
Claim 3
Dependent Claim
56 words
An interferometer according to Claim 1, wherein said laser is constructed to generate a laser beam having an envelop that envelopes peaks of the respective vertical modes of an oscillation spectrum of the laser beam having an intensity ratio of at least 0.05, and wherein said envelop has a width of no greater than 6 nm.
Claim 4
Dependent Claim
35 words
An interferometer according to Claim 1, wherein said laser is constructed to generate the laser beam such that the half width of each of the at least five vertical modes is at least 0.03 nm.
Claim 5
Dependent Claim
25 words
An interferometer according to Claim 1, wherein said laser is constructed to generate the laser beam having a coherence length of at least 100 µm.
Claim 6
Dependent Claim
31 words
An interferometer according to Claim 1, wherein said generation means includes an optical system for splitting the laser beam into first and second beams and superposing the first and second beams.
Claim 7
Dependent Claim
26 words
An interferometer according to Claim 5, wherein said detection means includes a photodetector capable of converting the interference light into electricity to generate a predetermined signal.
Claim 8
Dependent Claim
29 words
An interferometer according to Claim 6, further comprising means for supplying a driving current to said laser, said driving current determining the number of vertical modes of said laser.
Claim 9
Independent Claim
50 words
A method of measuring interference light, comprising the steps of: supplying laser radiation with a laser operated to have a predetermined spectrum with at least five vertical modes each having an intensity ratio of at least 0.05; forming an interference beam with the laser radiation; and detecting the interference beam.
Claim 10
Independent Claim
50 words
A method of measuring interference light, comprising the steps of: supplying laser radiation with a laser operated to have a predetermined spectrum with at least five vertical modes each having an intensity ratio of at least 0.05; forming an interference beam with the laser radiation; and detecting the interference beam.
Claim 11
Independent Claim
89 words
An apparatus for measuring the displacement of a diffraction grating, comprising: a multi-mode semiconductor laser generating a laser beam having at least five vertical modes each having an intensity ratio of at least 0.05; interference means for directing the laser beam from said laser to the diffraction grating and causing first and second diffracted light beams generated at the diffraction grating to interfere with each other to generate an interference light beam; and conversion means for converting the interference light supplied by said interference means into an electrical signal.
Claim 12
Independent Claim
89 words
An apparatus for measuring the displacement of a diffraction grating, comprising: a multi-mode semiconductor laser generating a laser beam having at least five vertical modes each having an intensity ratio of at least 0.05; interference means for directing the laser beam from said laser to the diffraction grating and causing first and second diffracted light beams generated at the diffraction grating to interfere with each other to generate an interference light beam; and conversion means for converting the interference light supplied by said interference means into an electrical signal.
Claim 13
Dependent Claim
56 words
An apparatus according to Claim 9, wherein said laser is constructed to generate a laser beam having an envelop which envelopes peaks of the respective vertical modes of an oscillation spectrum of the laser beam having an intensity ratio of at least 0.05, and wherein said envelop has a width of no greater than 6 nm.
Claim 14
Dependent Claim
35 words
An apparatus according to Claim 10, wherein said laser is constructed to generate the laser beam such that the half width of each of the at least five vertical modes is at least 0.03 nm.
Claim 15
Dependent Claim
25 words
An apparatus according to Claim 9, wherein said laser is constructed to generate the laser beam having a coherence length of at least 100 µm.
Claim 16
Dependent Claim
32 words
An apparatus according to claim 9, wherein said interference means is arranged to cause the optical paths of the first and second diffracted light beams to be substantially equal to each other.
Claim 17
Independent Claim
145 words
An apparatus for measuring the displacement of a diffraction grating, comprising: a multi-mode semiconductor laser for generating a laser beam; supply means for supplying a predetermined current to said laser so that at least five vertical modes occur in an oscillation spectrum of the laser beam generated by said laser at an intensity ratio of at least 0.05; interference means for splitting the laser beam generated by said laser into first and second beams, for directing the first and second beams to the diffraction grating, and for effecting interference between a first diffracted light beam generated by diffraction of the first beam at the diffraction grating and a second diffracted light beam generated by diffraction of the second beam at the diffraction grating to produce an interference light; and conversion means for converting the interference light produced by said interference means into an electrical signal.
Claim 18
Independent Claim
145 words
An apparatus for measuring the displacement of a diffraction grating, comprising: a multi-mode semiconductor laser for generating a laser beam; supply means for supplying a predetermined current to said laser so that at least five vertical modes occur in an oscillation spectrum of the laser beam generated by said laser at an intensity ratio of at least 0.05; interference means for splitting the laser beam generated by said laser into first and second beams, for directing the first and second beams to the diffraction grating, and for effecting interference between a first diffracted light beam generated by diffraction of the first beam at the diffraction grating and a second diffracted light beam generated by diffraction of the second beam at the diffraction grating to produce an interference light; and conversion means for converting the interference light produced by said interference means into an electrical signal.
Claim 19
Dependent Claim
48 words
An apparatus according to Claim 14, wherein said laser is constructed to generate a laser beam having an envelop that envelopes peaks of the respective vertical modes of an oscillation spectrum of the laser beam and wherein said envelop has a width of no greater than 6 nm.
Claim 20
Dependent Claim
34 words
An apparatus according to Claim 15, wherein said laser is constructed to generate the laser beam such that half width of each of the at least five vertical modes is at least 0.03 nm.
Claim 21
Dependent Claim
25 words
An apparatus according to Claim 14, wherein said laser is constructed to generate the laser beam having a coherence length of at least 100 µm.
Claim 22
Dependent Claim
32 words
An apparatus according to claim 14, wherein said interference means is arranged to cause the optical paths of the first and second diffracted light beams to be substantially equal to each other.
Claim 23
Independent Claim
66 words
A method of measuring the displacement of a diffraction grating, comprising the steps of: directing to the diffraction grating laser radiation with a laser operated to produce a predetermined spectrum having at least five vertical modes each having an intensity ratio of at least 0.05; forming an interference beam from diffraction beams generated at the diffraction grating; and converting the interference beam into an electrical signal.
Claim 24
Independent Claim
66 words
A method of measuring the displacement of a diffraction grating, comprising the steps of: directing to the diffraction grating laser radiation with a laser operated to produce a predetermined spectrum having at least five vertical modes each having an intensity ratio of at least 0.05; forming an interference beam from diffraction beams generated at the diffraction grating; and converting the interference beam into an electrical signal.
Claim 25
Dependent Claim
40 words
A method according to claim 19, wherein said forming step includes a step of superposing ±1-order diffraction beams generated by the diffraction grating to form the interference beam, the optical path lengths of the ±1-order diffraction beams being substantially equal.
Claim 26
Dependent Claim
69 words
A method according to claim 20, wherein said directing step comprises the step of directing to the diffraction grating laser radiation having an envelop which envelopes peaks of respective vertical modes of the oscillation spectrum of the laser beam, wherein the envelop has a width no more than 6 nm, and wherein the half width of each of the at least five vertical modes is at least 0.03 nm.
Claim 27
Dependent Claim
37 words
A method according to claim 20, wherein said directing step includes the steps of: providing a multi-mode semiconductor laser; and supplying a predetermined current to said laser so as to emit the laser radiation from said laser.
References Cited (Backward Citations)
No citation records indexed.
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