Patent US4594003A successfully refreshed from Google Patents.
US4594003A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interferometric wavefront measurement
Assignee: Zygo Corp
•
Filing: 1983-07-20
•
Granted: 1986-06-10
•
Expires: 2003-07-20
Abstract
Abstract Apparatus is disclosed for the phase measurement of an interference pattern produced by an unequal path interferometer. The invention comprises in one embodiment the use of a diode laser light source whose wavelength is varied so that the phase difference between the two wavefronts producing the interference pattern is modulated by a known amount. The modulated interference pattern is photosensed with an imaging device, and the signals processed to provide a phase map representing the optical path difference between the reference and measurement wavefronts of the interferometer.
Inventors
- 👤 Gary E. Sommargren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:34
CPC Classifications
G; G01; G01J; G01J9/00; G01J9/02; G01B; G01B9/00; G01B9/02; G01B9/02001; G01B9/02002; G01B9/02055; G01B9/02056; G01B9/02057
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
134 words
An interferometer system comprising a source of a beam of coherent signal wavelength energy, comprising a laser; an unequal path optical interferometer means disposed for converting said beam into an interference pattern produced between a reference wavefront and a measurement wavefront; means for varying the wavelength of said source monotonically to provide phase modulation of said interference pattern; means for determining magnitude of the wavelength variation of said source required to provide at least one full cycle of said phase modulation of said interference pattern; and means for photosensing the radiant energy of said interference pattern over an array of points over a time period of at least one full cycle of said phase modulation, said wavelength varying means monotonically varying said wavelength over the time required for said photosensing of said interference pattern.
Claim 2
Dependent Claim
134 words
An interferometer system comprising a source of a beam of coherent signal wavelength energy, comprising a laser; an unequal path optical interferometer means disposed for converting said beam into an interference pattern produced between a reference wavefront and a measurement wavefront; means for varying the wavelength of said source monotonically to provide phase modulation of said interference pattern; means for determining magnitude of the wavelength variation of said source required to provide at least one full cycle of said phase modulation of said interference pattern; and means for photosensing the radiant energy of said interference pattern over an array of points over a time period of at least one full cycle of said phase modulation, said wavelength varying means monotonically varying said wavelength over the time required for said photosensing of said interference pattern.
Claim 3
Dependent Claim
17 words
The system of claim 1, in which said photosensing means is a two-dimensional, solid state array camera.
Claim 4
Dependent Claim
33 words
The system of claim 1 further comprising means for converting said photosensed radiant energy in said interference pattern into a phase map representing the optical path difference between said reference and measurement wavefronts.
Claim 5
Dependent Claim
13 words
The system of claim 3 in which said laser comprises a diode laser.
Claim 6
Dependent Claim
17 words
The system of claim 4 in which said photosensing means is a two-dimensional, solid state array camera.
Claim 7
Dependent Claim
66 words
The system of claim 4, in which said means for varying the wavelength of said diode laser is an AC current which is combined with a DC current to drive said diode laser and is a very small fraction of said DC current, the alternating changes in temperature caused by said AC current serving to vary the optical length of the cavity of said diode laser.
Claim 8
Dependent Claim
13 words
The system of claim 1 in which said laser comprises a diode laser.
Claim 9
Dependent Claim
66 words
The system of claim 7 in which said means for varying the wavelength of said diode laser is an AC current which is combined with a DC current to drive said diode laser and is a very small fraction of said DC current, the alternating changes in temperature caused by said AC current serving to vary the optical length of the cavity of said diode laser.
Claim 10
Dependent Claim
17 words
The system of claim 7 in which said photosensing means is a two-dimensional, solid state array camera.
Claim 11
Dependent Claim
17 words
The system of claim 7 in which said unequal path interferometer means comprises a plano type interferometer.
Claim 12
Dependent Claim
17 words
The system of claim 7 in which said unequal path interferometer means comprises a spherical type interferometer.
Claim 13
Dependent Claim
30 words
The system of claim 7 further comprising means optically associated with said unequal path optical interferometer means for reducing or destroying the coherence length of said coherent single wavelength energy.
Claim 14
Dependent Claim
19 words
The system of claim 12 and wherein said coherence length reducing or destroying means comprises a rotating ground glass.
Claim 15
Dependent Claim
17 words
The system of claim 1 in which said unequal path interferometer means comprises a plano type interferometer.
Claim 16
Dependent Claim
17 words
The system of claim 1 in which said unequal path interferometer means comprises a spherical type interferometer.
Claim 17
Dependent Claim
17 words
The system of claim 1 in which said unequal path interferometer means comprises a Fizeau type interferometer.
Claim 18
Dependent Claim
17 words
The system of claim 1 in which said unequal path interferometer means comprises a Twyman-Green type interferometer.
Claim 19
Dependent Claim
29 words
The system of claim 1 further comprising means optically associated with said unequal path optical interferometer for reducing or destroying the coherence length of said coherent single wavelength energy.
Claim 20
Dependent Claim
18 words
The system of claim 18 wherein said coherence length reducing or destroying means comprises a rotating ground glass.
References Cited (Backward Citations)
US3507596A
Cited
US3694088A
Cited
US4169980A
Cited
US4159522A
Cited
US4201473A
Cited
US4225240A
Cited
US4325637A
Cited
US4417813A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-09 | 1989-12-09 | 1990-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-09 | 1993-12-09 | 1994-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-09 | 1997-12-09 | 1998-06-10 | $7700.00 | Window Closed / Lapsed |