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US3604778A
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Fourier transform recording with random phase shifting
Assignee: AT&T Inc
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Filing: 1969-10-22
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Granted: 1971-09-14
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Expires: 1989-10-22
Abstract
Abstract In making a record of the exact Fourier transform of an array of beams of electromagnetic radiation, the phase of each of a substantial fraction of the beams is shifted by a constant amount before recording the transform.
Inventors
- 👤 Christoph B Burckhardt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 09:26
CPC Classifications
G; G03; G03H; G03H1/00; G03H1/04; G03H1/16; G06; G06E; G06E3/00; G06E3/001
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
83 words
Apparatus for forming a record of the Fourier transform of an array of beams of electromagnetic radiation, comprising: means for forming an array of beams of electromagnetic radiation, means for shifting the phase of at least one-third of the beams in the array by an amount that is at least ninety degrees and is substantially constant across each beam, wherein the beams that are phase shifted are distributed approximately randomly throughout said array and means for recording the Fourier transform of the beams.
Claim 2
Dependent Claim
83 words
Apparatus for forming a record of the Fourier transform of an array of beams of electromagnetic radiation, comprising: means for forming an array of beams of electromagnetic radiation, means for shifting the phase of at least one-third of the beams in the array by an amount that is at least ninety degrees and is substantially constant across each beam, wherein the beams that are phase shifted are distributed approximately randomly throughout said array and means for recording the Fourier transform of the beams.
Claim 3
Dependent Claim
22 words
The apparatus of claim 1 wherein the probability that a particular beam is phase shifted ranges from approximately one-third to approximately two-thirds.
Claim 4
Dependent Claim
37 words
The apparatus of claim 1 wherein the amount of phase shift is the same for all the phase-shifted beams and ranges from approximately 140* to approximately 220* with respect to the beams that are not phase shifted.
Claim 5
Dependent Claim
67 words
The apparatus of claim 3 wherein: the probability that a particular beam is phase shifted ranges from approximately two-fifths to approximately three-fifths, the record of the Fourier transform is a Fourier transform hologram, the beams of electromagnetic radiation have a constant phase relation with a reference beam with which they interfere to form the hologram, and the beams of electromagnetic radiation are disposed in an ordered array.
Claim 6
Dependent Claim
27 words
The apparatus of claim 4 wherein the amount of phase shift is approximately 180* and the probability that a particular beam is phase shifted is approximately one-half.
Claim 7
Dependent Claim
41 words
The apparatus of claim 4 wherein the means for shifting the phase of the beams is a phase mask comprised of an ordered array of phase-shifting areas that have a one-to-one correspondence with the ordered array of beams of electromagnetic radiation.
Claim 8
Dependent Claim
21 words
The apParatus of claim 6 wherein the phase mask is a glass slide in which the phase-shifting areas have been etched.
Claim 9
Dependent Claim
81 words
The apparatus of claim 1 wherein: the phase shift in at least some of the phase-shifted beams is different from the phase shift in some of the other phase-shifted beams, the means for shifting the phase of the beams is a phase mask comprised of an array of phase-shifting areas that have a one-to-one correspondence with the array of beams of radiation, there being an approximately equal number of phase-shifting areas for each of the different phase shifts that are effected.
Claim 10
Dependent Claim
45 words
The apparatus of claim 8 wherein the number of different phase shifts is (N-1) and each of the different phase shifts that can be effected in the phase-shifted beams of radiation is one of the multiples of n360/N where n ranges from 1 to (N-1).
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-13 | 1975-03-15 | 1975-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-13 | 1979-03-15 | 1979-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-13 | 1983-03-15 | 1983-09-14 | $7700.00 | Window Closed / Lapsed |