US3871771A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical apparatus for determining deviations from a predetermined form of a surface
Assignee: Individual
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Filing: 1973-06-08
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Granted: 1975-03-18
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Expires: 1993-06-08
Abstract
Abstract A surface of which deviations from a predetermined form, defined by a laser beam, are to be determined is followed by a sensing means including an optical element disposed in the laser beam, so that the plane of polarisation of the laser beam rotates in accordance with any sensed deviation. If the deviation to be sensed is twist of the surface about the beam, the optical element may be a sheet of Polaroid. If lateral displacements of the surface are to be measured the optical element may be a quartz wedge intersecting the laser beam. The variably polarised light beam is incident on a splitter (Wollaston prism) yielding mutually perpendicularly polarised components which are applied to respective photo-elements yielding respective signals which are fed to a sum and to a difference amplifier. A further amplifier provides a signal denotive of the ratio of the difference to the sum and representative of the measured deviation. The optical path may be folded and the beam may pass twice through the same or through different optical elements of the sensing means.
Inventors
- 👤 Richard Nelson Scott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:25
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/26; G01B11/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
180 words
Optical apparatus for determining deviations from a predetermined form of a surface, comprising a laser light source means for projecting a beam of light from said source to establish a predetermined axis, a sensing means including an optical element traversed by said light beam, said sensing means arranged to travel with said optical element and including follower means producing displacement of said optical element in relation to said light beam in response to said deviation of said surface whereby said optical element produces a rotation of the plane of polarisation of said light beam which is representative of the measured deviation, and a detector means positioned to receive the light beam after traversing said optical element, said detector means including optical beam splitter mEans for dividing said light beam into two components having mutually perpendicular planes of polarisation, two photoelectric elements each responsive to one of the component beams to yield a respective output signal representative of the magnitude of that component, and circuit means for combining said output signals thereby to obtain a signal representative of the measured deviation.
Claim 2
Dependent Claim
180 words
Optical apparatus for determining deviations from a predetermined form of a surface, comprising a laser light source means for projecting a beam of light from said source to establish a predetermined axis, a sensing means including an optical element traversed by said light beam, said sensing means arranged to travel with said optical element and including follower means producing displacement of said optical element in relation to said light beam in response to said deviation of said surface whereby said optical element produces a rotation of the plane of polarisation of said light beam which is representative of the measured deviation, and a detector means positioned to receive the light beam after traversing said optical element, said detector means including optical beam splitter mEans for dividing said light beam into two components having mutually perpendicular planes of polarisation, two photoelectric elements each responsive to one of the component beams to yield a respective output signal representative of the magnitude of that component, and circuit means for combining said output signals thereby to obtain a signal representative of the measured deviation.
Claim 3
Dependent Claim
82 words
Apparatus as claimed in claim 1 wherein said circuit means includes respective sum and difference amplifiers, each fed with signals proportional to the output signals of said photoelectric elements and yielding signals respectively representative of their sum and of their difference, and a ratio amplifier fed with said amplifier output signals and yielding a ratio signal representative of the difference amplifier output signal divided by the sum amplifier output signal, the amplitude of said ratio signal being representative of the measured deviation.
Claim 4
Dependent Claim
32 words
Apparatus as claimed in claim 2 wherein said difference signal is applied to an electro-optical cell positioned in the path of the light beam between the sensing means and the splitter means.
Claim 5
Dependent Claim
32 words
Apparatus as claimed in claim 2 wherein said ratio signal is applied to an electro-optical cell positioned in the path of the light beam between the sensing means and the splitter means.
Claim 6
Dependent Claim
74 words
Apparatus in accordance with claim 1 wherein said laser light source includes a polarising means whereby said light beam has a plane of polarisation and said sensing means includes a quartz wedge disposed in the path of said light beam and arranged for displacement in response to the deviation to be measured whereby a varying thickness of quartz is introduced into the optical path to produce a corresponding rotation of said plane of polarisation.
Claim 7
Dependent Claim
59 words
Apparatus as claimed in claim 5 wherein said wedge is carried by spring members from a rotary mounting and is provided with a probe arranged to bear against the inner surface of a hollow member through which said light beam is projected, whereby to obtain a measure of the eccentricity of said surface with reference to said light beam.
Claim 8
Dependent Claim
28 words
Apparatus as claimed in claim 1 wherein said optical element of the sensing means consists of a lens arranged to focus the light source upon the detector means.
Claim 9
Dependent Claim
24 words
Apparatus as claimed in claim 1 wherein said light beam passes from said light source to said detector means by way of a reflector.
Claim 10
Dependent Claim
53 words
Apparatus in accordance with claim 8 wherein the light reflected from said reflector is caused to be changed in phase by 180* and wherein said optical element of said sensing means includes two quartz wedges producing opposite changes in rotation in response to like deviations of the wedges transversely of the optical path.
Claim 11
Dependent Claim
58 words
Apparatus in accordance with claim 8 wherein said optical element of said sensing means is traversed both by light passing from the light source to the reflector and by light passing from the reflector to the detector means, said optical element comprising matched quartz wedges producing opposite rotations of the plane of polarisation of a transmitted light beam.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-17 | 1978-09-16 | 1979-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-17 | 1982-09-16 | 1983-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-17 | 1986-09-16 | 1987-03-18 | $7700.00 | Window Closed / Lapsed |