Patent US3037205A successfully refreshed from Google Patents.
Patent US3612695A successfully refreshed from Google Patents.
US3612695A
Expired / Lapsed
US
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Arrangement for measuring the rotation of a first object relative to a second object
Assignee: US Philips Corp
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Filing: 1969-09-23
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Granted: 1971-10-12
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Expires: 1989-09-23
Abstract
Abstract An arrangement for measuring the rotation of a first object relative to a second object is disclosed. Light from a source of radiation attached to the first object is directed to a first zone on a grating attached to the second object, is then directed via polarization modulators and concave mirrors to a second zone on the grating and finally impinges upon a pair of photocells. The output of the photocells is processed to determine both the magnitude and direction of the relative rotation.
Inventors
- 👤 Gijsbertus Bouwhuis
- 👤 Hendrik De Lang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:29
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/363
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
328 words
An arrangement for measuring the rotation of a second object relative to a first object, comprising a source of radiation attached to the first object, a grating attached to the second object and having lines substantially at right angles to the direction of rotation of the second object and having sufficient line density for diffraction of the radiation from the source, means for directing the radiation from the source to a first zone of the grating, whereby the so directed radiation is diffracted into subbeams of the orders +1 and -1, a polarization-separating plane mirror diagonally orientated in the path of both subbeams for reflecting and transmitting a portion of each of the subbeams into two orthogonal paths, a separate lambda /4 plate mutually orthogonally located in the paths of the portions Of the subbeams reflected and transmitted from the plane mirror, a separate concave mirror in the path of the radiation passing through each of the lambda /4 plates for reflecting the radiation back through each of the lambda /4 plates whereby the radiation reflected from the concave mirrors and passing again through the lambda /4 plates are linearly polarized in mutually orthogonal planes and redirected to the plane mirror so that the portion of radiation formerly transmitted through the plane mirror is reflected therefrom as a reflected linearly polarized beam and the portion formerly reflected by the plane mirror is transmitted therethrough as a transmitted linearly polarized beam, means for directing the reflected and transmitted linearly polarized beams onto a second zone of the grating, whereby the separate beams are recombined into a beam having mutually orthogonally polarized portions, a polarization beam splitter in the path of the recombined radiation for dividing the recombined beam, and a photocell in the path of each of the divided beams from the beam splitter for detecting the intensity of each of the divided beams, whereby the rotation of said second object relative to said first object can be determined.
Claim 2
Dependent Claim
328 words
An arrangement for measuring the rotation of a second object relative to a first object, comprising a source of radiation attached to the first object, a grating attached to the second object and having lines substantially at right angles to the direction of rotation of the second object and having sufficient line density for diffraction of the radiation from the source, means for directing the radiation from the source to a first zone of the grating, whereby the so directed radiation is diffracted into subbeams of the orders +1 and -1, a polarization-separating plane mirror diagonally orientated in the path of both subbeams for reflecting and transmitting a portion of each of the subbeams into two orthogonal paths, a separate lambda /4 plate mutually orthogonally located in the paths of the portions Of the subbeams reflected and transmitted from the plane mirror, a separate concave mirror in the path of the radiation passing through each of the lambda /4 plates for reflecting the radiation back through each of the lambda /4 plates whereby the radiation reflected from the concave mirrors and passing again through the lambda /4 plates are linearly polarized in mutually orthogonal planes and redirected to the plane mirror so that the portion of radiation formerly transmitted through the plane mirror is reflected therefrom as a reflected linearly polarized beam and the portion formerly reflected by the plane mirror is transmitted therethrough as a transmitted linearly polarized beam, means for directing the reflected and transmitted linearly polarized beams onto a second zone of the grating, whereby the separate beams are recombined into a beam having mutually orthogonally polarized portions, a polarization beam splitter in the path of the recombined radiation for dividing the recombined beam, and a photocell in the path of each of the divided beams from the beam splitter for detecting the intensity of each of the divided beams, whereby the rotation of said second object relative to said first object can be determined.
Claim 3
Dependent Claim
103 words
An arrangement as claimed in claim 1, wherein the means for directing the radiation onto the first and second zones of the grating each comprise a system of plane mirrors in the beams of radiation, each of the systems of mirrors comprising a first mirror inclined at an angle of approximately 45* to the plane of the grating and to the lines of the grating, and a second mirror arranged approximately 90* to the plane of the grating and in a plane intersecting the lines of the grating at acute angles, the planes of the second mirrors of each system being mutually orthogonal.
Claim 4
Dependent Claim
95 words
An arrangement as claimed in claim 1, characterized in that a planoconvex lens is arranged in the immediate proximity of each of the first and second zones, the convex surfaces of these lenses having the same or substantially the same centers of curvature as the respective concave mirrors, the radii of curvature of which are equal or substantially equal to the optical distance from the first and second zone respectively to the respective concave mirror, the said centers of curvature lying on the grating so as to be diametrical relative to the axis of rotation.
Claim 5
Dependent Claim
33 words
An arrangement as claimed in claim 1, wherein between either concave mirror and the first and second zones respectively a lens is disposed at the center of curvature of the respective concave mirror.
Claim 6
Dependent Claim
18 words
An arrangement as claimed in claim 1, wherein a central aperture is provided in the polarization-separating plane mirror.
Claim 7
Dependent Claim
44 words
An arrangement as claimed in claim 1, wherein in each of the subbeams of different orders of diffraction an electro-optical crystal is arranged, these crystals having principal directions which are at right angles to one another and having identical alternating voltages applied to them.
Claim 8
Dependent Claim
19 words
An arrangement as claimed in claim 6, wherein the alternating voltage has a high frequency and a small amplitude.
Claim 9
Dependent Claim
47 words
An arrangement as claimed in claim 1, wherein the concave mirrors are oriented so that the image of the first zone formed by one mirror on the second zone is shifted through 1/16 part of a grating period relative to the image formed by the other mirror.
Claim 10
Dependent Claim
59 words
An arrangement as claimed in claim 1, wherein there is inserted in the path of the radiation beam between the first zone and the polarization-separating plane mirror a thick birefringent plate with inclined optical axis and having a thickness and orientation such as to produce an image displacement through 1/16 part of a period for both directions of polarization.
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) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |