US3643101A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser microaperture measurement instrument
Assignee: Laser Systems and Electronics Inc
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Filing: 1969-01-07
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Granted: 1972-02-15
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Expires: 1989-01-07
Abstract
Abstract A method and apparatus for determining the diameter of roughly circular apertures by employing a laser to pass a beam of coherent light through the aperture whose diameter is to be measured so that a Fraunhofer diffraction pattern is produced. The Fraunhofer pattern is split by appropriate means and the two identical patterns thus produced each focused upon appropriate photodetectors. For a first reference photodetector the entire Fraunhofer pattern is allowed to be incident upon the reference photocell while for the second detector only part of the inner portion of the bright central area of the pattern known as the Airy Disc is detected. The ratio of the voltages produced by the two photocells is then a function of the diameter of the aperture through which the beam has passed and by appropriate circuitry an output signal related to that diameter can be produced.
Inventors
- 👤 John I Shipp
- 👤 Nathan E Welch
- 👤 Thomas D Broadbent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:13
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/08; G01B11/12
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
192 words
Apparatus for determining the size of an aperture comprising, means for passing a beam of light through said aperture to produce a diffraction pattern, the distribution of energy in said pattern being a function of the size of said aperture, first signal-producing means for receiving said pattern with its energy distribution substantially undistorted and producing a signal having a characteristic which is a function of substantially all of the energy in said pattern, second signal-producing means for receiving a contiguous portion of said pattern with its energy distribution undistorted and for producing a signal having a characteristic which is a function of the energy of said pattern within a portion of said pattern less than the entire pattern, including means for preventing the remainder of said pattern from being received, means for receiving the beam of light which has passed through said aperture and directing said diffraction pattern in that beam to said first and second signal producing means with the energy distribution in said pattern substantially undistorted, and means for comparing the characteristics of the signals produced by the first and second signal-producing means to determine the size of said aperture.
Claim 2
Dependent Claim
192 words
Apparatus for determining the size of an aperture comprising, means for passing a beam of light through said aperture to produce a diffraction pattern, the distribution of energy in said pattern being a function of the size of said aperture, first signal-producing means for receiving said pattern with its energy distribution substantially undistorted and producing a signal having a characteristic which is a function of substantially all of the energy in said pattern, second signal-producing means for receiving a contiguous portion of said pattern with its energy distribution undistorted and for producing a signal having a characteristic which is a function of the energy of said pattern within a portion of said pattern less than the entire pattern, including means for preventing the remainder of said pattern from being received, means for receiving the beam of light which has passed through said aperture and directing said diffraction pattern in that beam to said first and second signal producing means with the energy distribution in said pattern substantially undistorted, and means for comparing the characteristics of the signals produced by the first and second signal-producing means to determine the size of said aperture.
Claim 3
Dependent Claim
17 words
Apparatus as in claim 1 including a source of coherent light for producing said beam of light.
Claim 4
Dependent Claim
11 words
Apparatus as in claim 2 wherein said source is a laser.
Claim 5
Dependent Claim
28 words
Apparatus as in claim 1 wherein said second signal-producing means receives a circular area of said pattern of a given radius located at the center of said pattern.
Claim 6
Dependent Claim
28 words
Apparatus as in claim 4 wherein said aperture is roughly circular, and said pattern is a Fraunhofer pattern comprising a central disc and a plurality of concentric rings.
Claim 7
Dependent Claim
17 words
Apparatus as in claim 5 wherein said second signal-producing means receives roughly half of said cenTral disc.
Claim 8
Dependent Claim
16 words
Apparatus as in claim 1 wherein said signal-producing means are photodetectors and said signals are electrical.
Claim 9
Dependent Claim
23 words
Apparatus as in claim 4 wherein said directing means includes a beam splitter for directing said diffraction pattern to each of said detectors.
Claim 10
Dependent Claim
26 words
Apparatus as in claim 8 wherein said comparing means includes means for obtaining the ratio of the amplitudes of the electrical signals produced by said photodetectors.
Claim 11
Dependent Claim
180 words
Apparatus for measuring the diameter of a roughly circular microaperture comprising, laser means for producing a beam of light and passing said beam through said microaperture so that a Fraunhofer diffraction pattern, comprising a bright central disc and a plurality of concentric bright rings and having an energy distribution which is a function of the size of said microaperture, is produced, a first photocell for receiving said pattern and producing a first electrical output signal having an amplitude which is a function of substantially all of the energy within said pattern, a second photocell for receiving a contiguous portion of said pattern and producing a second electrical output signal having an amplitude which is a function of the energy within said contiguous portion received, the energy within said portion varying with the diameter of said microaperture, means for directing said pattern to said first and second photocells so that said patterns are received by said first and second photocells substantially undistorted, and means for comparing the amplitudes of said first and second signals to determine the diameter of said microaperture.
Claim 12
Dependent Claim
180 words
Apparatus for measuring the diameter of a roughly circular microaperture comprising, laser means for producing a beam of light and passing said beam through said microaperture so that a Fraunhofer diffraction pattern, comprising a bright central disc and a plurality of concentric bright rings and having an energy distribution which is a function of the size of said microaperture, is produced, a first photocell for receiving said pattern and producing a first electrical output signal having an amplitude which is a function of substantially all of the energy within said pattern, a second photocell for receiving a contiguous portion of said pattern and producing a second electrical output signal having an amplitude which is a function of the energy within said contiguous portion received, the energy within said portion varying with the diameter of said microaperture, means for directing said pattern to said first and second photocells so that said patterns are received by said first and second photocells substantially undistorted, and means for comparing the amplitudes of said first and second signals to determine the diameter of said microaperture.
Claim 13
Independent Claim
148 words
A method of determining the size of an aperture comprising the steps of, passing a beam of light through said aperture so that a diffraction pattern is formed, directing said diffraction pattern with its energy pattern substantially undistorted onto a first signal-producing means which produces a signal having a characteristic which is a function of substantially all of the energy of said diffraction pattern, directing said diffraction pattern onto a second signal-producing means so that said second signal-producing means receives only a contiguous portion of said pattern, the energy portion of said pattern being substantially undistorted, and produces a signal having a characteristic which is a function of the energy within said portion of said diffraction pattern, the energy within said portion being a function of the size of said aperture, and comparing said characteristics of said first and second signals to determine the size of said aperture.
Claim 14
Independent Claim
148 words
A method of determining the size of an aperture comprising the steps of, passing a beam of light through said aperture so that a diffraction pattern is formed, directing said diffraction pattern with its energy pattern substantially undistorted onto a first signal-producing means which produces a signal having a characteristic which is a function of substantially all of the energy of said diffraction pattern, directing said diffraction pattern onto a second signal-producing means so that said second signal-producing means receives only a contiguous portion of said pattern, the energy portion of said pattern being substantially undistorted, and produces a signal having a characteristic which is a function of the energy within said portion of said diffraction pattern, the energy within said portion being a function of the size of said aperture, and comparing said characteristics of said first and second signals to determine the size of said aperture.
Claim 15
Independent Claim
139 words
A method of determining the size of a roughly circular microaperture comprising the steps of, producing a laser beam, directing said laser beam through said aperture, splitting said diffraction pattern to produce two patterns with the energy distribution substantially undistorted, directing the first of said two patterns onto a first photodetector which produces an electrical signal having an amplitude which is a function of substantially all of the energy within said diffraction pattern, directing a contiguous portion of the second of said two patterns onto a second photodetector which produces an electrical signal having an amplitude which is a function of the energy within said portion of said diffraction pattern, the energy within said portion being a function of the size of said aperture, and comparing the amplitudes of said electrical signals to determine the diameter of said aperture.
Claim 16
Independent Claim
139 words
A method of determining the size of a roughly circular microaperture comprising the steps of, producing a laser beam, directing said laser beam through said aperture, splitting said diffraction pattern to produce two patterns with the energy distribution substantially undistorted, directing the first of said two patterns onto a first photodetector which produces an electrical signal having an amplitude which is a function of substantially all of the energy within said diffraction pattern, directing a contiguous portion of the second of said two patterns onto a second photodetector which produces an electrical signal having an amplitude which is a function of the energy within said portion of said diffraction pattern, the energy within said portion being a function of the size of said aperture, and comparing the amplitudes of said electrical signals to determine the diameter of said aperture.
Claim 17
Independent Claim
222 words
A method of measuring the diameters of a number of microapertures in a device comprising the steps of, producing a laser beam, presenting each of said number of microapertures successively so that said beam passes through each said aperture sequentially, thus producing a Fraunhofer diffraction pattern for each microaperture comprising a bright central disc and a plurality of concentric rings and having an energy distribution which is A function of the diameter of the microaperture through which the beam is passing, directing each said pattern with its energy pattern substantially undistorted onto a first photodetector which produces an electrical signal having an amplitude which is a function of substantially all the energy within said pattern, the energy within said portion being a function of the square of the diameter of the microaperture through which the beam is passing, and onto a second photodetector which produces a second electrical signal having an amplitude which is a function of the energy within a circular contiguous area of said pattern centered at the center of said portion being a function of the cube of the diameter of the microaperture through which the beam is passing, and comparing the amplitudes of the first and second signals produced for each microaperture through which said beam passes to measure the diameters of all of said number of microapertures.
Claim 18
Independent Claim
222 words
A method of measuring the diameters of a number of microapertures in a device comprising the steps of, producing a laser beam, presenting each of said number of microapertures successively so that said beam passes through each said aperture sequentially, thus producing a Fraunhofer diffraction pattern for each microaperture comprising a bright central disc and a plurality of concentric rings and having an energy distribution which is A function of the diameter of the microaperture through which the beam is passing, directing each said pattern with its energy pattern substantially undistorted onto a first photodetector which produces an electrical signal having an amplitude which is a function of substantially all the energy within said pattern, the energy within said portion being a function of the square of the diameter of the microaperture through which the beam is passing, and onto a second photodetector which produces a second electrical signal having an amplitude which is a function of the energy within a circular contiguous area of said pattern centered at the center of said portion being a function of the cube of the diameter of the microaperture through which the beam is passing, and comparing the amplitudes of the first and second signals produced for each microaperture through which said beam passes to measure the diameters of all of said number of microapertures.
Claim 19
Dependent Claim
16 words
A method as in claim 13 wherein said presenting includes the step of rotating said device.
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) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |