EP0449335A2
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Interferometer
Assignee: Pilkington Group Ltd
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Filing: 1986-10-14
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Granted: —
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Expires: 2006-10-14
Abstract
Abstract An interferometer is provided for producing an interference pattern from light such as laser light which travels along first and second optical paths (2b, 3b) and at the end of each such path there is a respective fixed mirror (26, 27) for directing light to a common optical path (7). An optical flat (29) is provided to vary the optical path length of light in the first and second optical paths to produce an interference pattern in the common optical path, the optical flat being oscillated in a rotational manner to produce a linearly varying optical path length. First detector means (36) detects a reference part of the interference pattern produced to derive a reference signal, and second detector means (41) receives the interference pattern to derive signals indicative of successive parts of the interference pattern.
Inventors
- 👤 Barry Raymond Hill
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 02:35
CPC Classifications
G; G01; G01J; G01J9/00; G01J9/02
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
133 words
An interferometer for producing an interference pattern from light travelling along respective first and second optical paths (2, 3; 2a, 3a; 2b, 3b), each path having reflector means (5, 6; 10, 6a; 26, 27) for returning light components to a common optical path (7), and light refraction means (8, 9; 12; 29) positioned in the said first and second paths and arranged so that angular movement of the refraction means causes substantially linearly changing variations of the path length difference between the first and second paths, the interferometer being characterised by being arranged to produce an interference pattern from substantially monochromatic light and by means (31) for oscillating the refraction means so that the said path length difference is varied to produce the interference pattern in the common optical path in the interferometer.
Claim 2
Dependent Claim
92 words
An interferometer according to claim 1, characterised in that the refraction means of the interferometer comprises a pair of plane-parallel optical plates (8, 9), one positioned in the first optical path and the other positioned in the second optical path, the arrangement being such that an increase in angular position in one path occurs simultaneously with a decrease in angular position in the other path such that non-linearities in each respective path tend to cancel each other out and thus provide a substantially linear variation in optical path length in the interferometer.
Claim 3
Dependent Claim
64 words
An interferometer according to claim 1, characterised in that the first optical path and the second optical path intersect at a given point within each path length and a single plane optical plate (12; 29) is provided, the arrangement being such that angular movement of the plate increases the length of one optical path and correspondingly decreases the length of the other optical path.
Claim 4
Dependent Claim
30 words
An interferometer according to claim 3, characterised in that the single optical plate (12; 29) is arranged to bisect the angle of intersection of the first and second optical paths.
Claim 5
Dependent Claim
41 words
An interferometer according to claim 1, characterised by scanning means (37, 38) in the common optical path for scanning a beam in a raster pattern over detector means (41), thereby to derive signals indicative of successive parts of the interference pattern.
Claim 6
Dependent Claim
73 words
An interferometer according to any preceding claim characterised by first detector means (36) for detecting a reference part of the interference pattern to derive therefrom a reference signal, second detector means (41) for receiving the interference pattern thereby to derive signals indicative of successive parts of the interference pattern, and means for comparing the reference and successive signals to derive therefrom signals indicative of the optical phase difference corresponding to the interference pattern.
Claim 7
Dependent Claim
36 words
An interferometer according to claim 6, wherein the first detector means (36) is arranged to be supplied with light from the interference pattern produced on the common optical path by means of a beam splitter (33).
Claim 8
Dependent Claim
28 words
An interferometer according to claim 7, wherein the first detector means (36) is disposed in an optical path substantially orthogonal to the axis of the common optical path.
Claim 9
Dependent Claim
73 words
An interferometer according to claim 7 or claim 8, characterised in that the beam splitter (33) is rotatable such that the interference pattern can be selectively directed into an imager such as a screen (35) for example a ground glass screen, the arrangement affording means whereby the reflection means in the interferometer can be aligned to ensure that the axes of the first and second optical paths coincide at the common optical path.
Claim 10
Dependent Claim
44 words
An interferometer according to any of claims 6 to 9, characterised in that the second detector means (41) comprises an array of detectors, each being representative of one particular respective part of the interference pattern, and the pattern is imaged directly onto the array.
References Cited (Backward Citations)
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