EP0157227A2
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EP
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Interferometer
Assignee: HP Inc
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Filing: 1985-03-09
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Granted: —
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Expires: 2005-03-09
Abstract
Abstract An interferometer apparatus is disclosed for determining the spatial relationship of two or more observed points (26, 28) such as the height of a magnetic transducer as it moves over the surface of a spinning recording disc. A light beam having two components of characteristic polarization and frequency is separated with one component being directed upon the two observation points (26, 28) one of which may be on the transducer head and the other may be on the spinning disc. The other component is simultaneously directed upon a reference surface (32). The reflected beams are then combined to produce an optical beat frequency which is subsequently detected electronically and converted to a voltage representative of the phase shift between images of the two points and utilized to provide the display of the distance between the two points.
Inventors
- 👤 Robert J. Davidson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:08
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/60; G11B5/6005; G01; G01B; G01B9/00; G01B9/02; G01B9/02001; G01B9/02002; G01B9/02003; G01B9/02012; G01B9/02015; G01B9/02016; G01B9/02027; G01B9/02028; G01B2290/00; G01B2290/70
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
227 words
An interferometer apparatus comprising: - means for producing a beam of radiation having two components, each component having a characteristic frequency and polarization; characterized by: - separating means (22) for receiving the beam of radiation and for directing one of the two components of the beam upon a test area having at least a first (26) and a second (28) test point whose spatial relationship is to be determined and for directing the other component upon a reference surface (32) to derive optical reflections respectively from the test area (26, 28) and from the reference surface (32), and for combining the respective optical reflections into a combined beam; - means for interacting the optical reflections and for forming two identical images from the combined beam; - directing means (38) for directing a portion of one of the images containing an image of the first test point (26) into a first optical path (40) and for directing a portion of the other of the images containing an image of the second test point (28) into a second optical path (42); - converting means disposed in the optical paths for converting the images of the test points (26,28) into corresponding electrical signals; and - means for deriving from the electrical signals a further signal indicative of the spatial relationship between the first (26) and the second (28) test point.
Claim 2
Dependent Claim
227 words
An interferometer apparatus comprising: - means for producing a beam of radiation having two components, each component having a characteristic frequency and polarization; characterized by: - separating means (22) for receiving the beam of radiation and for directing one of the two components of the beam upon a test area having at least a first (26) and a second (28) test point whose spatial relationship is to be determined and for directing the other component upon a reference surface (32) to derive optical reflections respectively from the test area (26, 28) and from the reference surface (32), and for combining the respective optical reflections into a combined beam; - means for interacting the optical reflections and for forming two identical images from the combined beam; - directing means (38) for directing a portion of one of the images containing an image of the first test point (26) into a first optical path (40) and for directing a portion of the other of the images containing an image of the second test point (28) into a second optical path (42); - converting means disposed in the optical paths for converting the images of the test points (26,28) into corresponding electrical signals; and - means for deriving from the electrical signals a further signal indicative of the spatial relationship between the first (26) and the second (28) test point.
Claim 3
Dependent Claim
52 words
An interferometer as in claim 1, characterized in that the means for deriving a signal indicative of the spatial relationship between the first (26) and the second (28) test point are designed for determining the phase difference between the signals corresponding to the images of the first and second test points, respectively.
Claim 4
Dependent Claim
39 words
An interferometer as in claim 1 or 2, characterized in that at least two optical fibre members (40,42) are provided for transmitting respective images of the first (26) and of the second (28) test point to the converting means.
Claim 5
Dependent Claim
25 words
An interferometer as in claim 3, characterized in that the converting means comprise photodetectors (43,44) coupled to each of the optical fibre members (40,42), respectively.
Claim 6
Dependent Claim
54 words
An interferometer as in any of the preceding claims, characterized by means (20) disposed in the beam path for expanding the beam of radiation before impinging on the separating means (22), and focusing means (36) for focusing the optical images, interposed between the means for interacting the optical reflections and the directing means (38).
Claim 7
Dependent Claim
36 words
An interferometer as in any of the preceding claims, characterized in that the two components of the beam of radiation impinging on the separating means (22) have a respective plane of polarization orthogonal to each other.
Claim 8
Dependent Claim
24 words
An interferometer as in any of the preceding claims, characterized in that the means for interacting the optical reflections comprise a half-wave plate (34).
Claim 9
Dependent Claim
50 words
An interferometer as in any of the preceding claims, characterized by - means for directing one component of the beam of radiation onto a plurality of test areas, and - means for interacting each of the reflections from the different test areas with the reflections from the reference surface (32).
References Cited (Backward Citations)
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