US3820902A
Expired / Lapsed
US
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Measuring method and apparatus which compensate for abbe s error
Assignee: Pentax Corp
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Filing: 1972-04-11
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Granted: 1974-06-28
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Expires: 1992-04-11
Abstract
Abstract A measuring method and apparatus for measuring linear magnitudes while compensating for Abbe''s error. A single laser unit measures a linear distance along an optical axis with a laser interferometer, this distance along the optical axis corresponding to an equal distance along a measuring axis which is parallel to and spaced from the optical axis by a given distance. Angular deviation of a body which moves along the optical axis to determine the measurement of the distance therealong produces at the measuring axis an error distance determined by the extent of angular deviation of the body and the distance between the optical and measuring axes. The extent of angular deviation of the body with respect to the optical axis is measured and converted by a detecting structure into compensating units which are of equal magnitude with units counted by a reversible counter in response to operation of the interferometer in order to determine the distance of movement of the body along the optical axis. The compensating units correspond to the error distance along the measuring axis resulting from angular deviation of the body at the optical axis, and these compensating units are added to or subtracted from the units counted during operation of the interferometer in order to achieve an accurate measurement which compensates for Abbe''s error.
Inventors
- 👤 H Kawasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:55
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/02055; G01B9/0207
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
175 words
In a measuring apparatus for measuring the linear distance of movement of a body along a measuring axis, laser means having an optical axis, which is parallel to and spaced at a given distance from the measuring axis, linear measuring means comprising an interferometer and coacting with said laser means along said optical axis for linearly measuring a distance along said optical axis, angular measuring means including an auto-collimator and coacting with said laser means along the measuring axis for measuring, simultaneously with operation of said linear measuring means, angular deviation of the body with respect to said optical axis, and output means cooperating with said angular measuring means for converting said angular deviation into a linear distance based upon said given distance between said two axes and for combining the last mentioned linear distance with the linear distance measured by the linear measuring means to provide the linear distance along the measuring axis, said laser means being in the form of a unitary laser assembly which is common to both of said measuring means.
Claim 2
Dependent Claim
175 words
In a measuring apparatus for measuring the linear distance of movement of a body along a measuring axis, laser means having an optical axis, which is parallel to and spaced at a given distance from the measuring axis, linear measuring means comprising an interferometer and coacting with said laser means along said optical axis for linearly measuring a distance along said optical axis, angular measuring means including an auto-collimator and coacting with said laser means along the measuring axis for measuring, simultaneously with operation of said linear measuring means, angular deviation of the body with respect to said optical axis, and output means cooperating with said angular measuring means for converting said angular deviation into a linear distance based upon said given distance between said two axes and for combining the last mentioned linear distance with the linear distance measured by the linear measuring means to provide the linear distance along the measuring axis, said laser means being in the form of a unitary laser assembly which is common to both of said measuring means.
Claim 3
Dependent Claim
26 words
The combination of claim 1 and further comprising a single light-reflecting means fixed to said body for movement therewith and forming part of both measuring means.
Claim 4
Dependent Claim
39 words
The combination of cLaim 2 and wherein said linear measuring means has a light-reflecting portion formed by part of said light-reflecting means and said angular measuring means including a light-reflecting surface formed by another part of said light-reflecting means.
Claim 5
Dependent Claim
87 words
The combination of claim 1 and wherein said output means includes a reversible counter means operatively connected with said linear measuring means for responding thereto to count measuring units which indicate the measured linear distance, and compensating means cooperating with said angular measuring means and said reversible counter means for responding to the angular error measured by said angular measuring means to transmit signals to said reversible counter means for adding to or subtracting from the units counted thereby units which will compensate for the angular error.
Claim 6
Dependent Claim
25 words
The combination of claim 1 and wherein said laser means includes a single laser light source supplying light utilized by both of said measuring means.
Claim 7
Dependent Claim
44 words
The combination of claim 5 and wherein said laser means includes a beam splitter means receiving light from said single light source and transmitting light on the one hand to said linear measuring means and on the other hand to said angular measuring means.
Claim 8
Dependent Claim
65 words
The combination of claim 6 and wherein said linear measuring means includes a light-reflecting means fixed to said body and having an internally reflecting portion for receiving internally one light beam and for reflecting a second light beam parallel to said one light beam, said light-reflecting means including an exterior surface portion which is totally reflecting and which forms part of said angular measuring means.
Claim 9
Dependent Claim
92 words
The combination of claim 7 and wherein said angular measuring means includes a member formed with a slit, means for sinusoidally reciprocating said member, means on one side of said member for directing a spot of light reflected from said surface of said light-reflecting means through said slit, means on the other side of said member for responding to light passing through said slit to generate correction signals, and counting means coacting with said linear measuring means for counting measuring units and for receiving said correction signals to compensate for angular error.
Claim 10
Dependent Claim
184 words
In a measuring method, the steps of directing a single laser light beam from a single laser light source to a laser interferometer which measures the linear distance through which a body moves along an optical axis of the light source and interferometer, counting a number of units each equal to a predetermined fraction of a wavelength of the laser light beam provided by said interferometer for determining the distance, the latter distance being equal to a distance along a measuring axis which is parallel to the optical axis and spaced therefrom by a given distance, simultaneously measuring with part of said laser light beam angular deviation of said body with respect to said optical axis while acting on the latter light with an auto-collimator, then converting said angular deviation into an error distance along said measuring axis by utilizing said given distance between said axes, and adding or subtracting the latter error distance from the number of units counted according to movement of said body along said optical axis each time said error distance reaches a magnitude corresponding to one of said units.
Claim 11
Dependent Claim
184 words
In a measuring method, the steps of directing a single laser light beam from a single laser light source to a laser interferometer which measures the linear distance through which a body moves along an optical axis of the light source and interferometer, counting a number of units each equal to a predetermined fraction of a wavelength of the laser light beam provided by said interferometer for determining the distance, the latter distance being equal to a distance along a measuring axis which is parallel to the optical axis and spaced therefrom by a given distance, simultaneously measuring with part of said laser light beam angular deviation of said body with respect to said optical axis while acting on the latter light with an auto-collimator, then converting said angular deviation into an error distance along said measuring axis by utilizing said given distance between said axes, and adding or subtracting the latter error distance from the number of units counted according to movement of said body along said optical axis each time said error distance reaches a magnitude corresponding to one of said units.
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) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |