US3628870A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for measuring amount of displacements with aid of gratings
Assignee: Olympus Corp
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Filing: 1970-07-02
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Granted: 1971-12-21
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Expires: 1990-07-02
Abstract
Abstract A device for measuring the magnitude of displacements with the aid of gratings having a real image optical system whose magnification is one with a reflection optical system adapted to reflect a light incident on a grating plane and project the light again on the same grating plane in a direction which is the same as that of the incident light to produce a moire fringe whose strength varies in response to the displacement of the grating. The moire fringe thus produced is observed to measure the amount of displacement of the grating. An elongated grating is used in case of measuring a linear displacement of the grating, while a radial grating is used in case of measuring an angular displacement of the grating.
Inventors
- 👤 Yoshisada Hayamizu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 03:20
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
244 words
A device for measuring the magnitude of displacement of diffraction gratings, which comprises a light-transmitting diffraction grating and a real image optical system whose magnification is unity, and including a light source, objectives a reflection optical system and a photocell in an arrangement such that light from the light source is initially projected through the grating in a direction substantially perpendicular thereto, is second directed substantially parallel with the lines of the grating, is third directed in a direction opposite to that of the initially projected light, is fourth directed again in parallel with the grating but in a direction opposite to that of the second direction, and finally again directed through the grating in the same direction as the initially projected light onto said photocell whereby to form a substantially closed and rectangular-shaped light passage, said real image optical system including optical elements all of which, inclusive of said light source and photocell, are arranged in sequence along said light passage, said objectives and reflection optical system producing on said grating an image of the portion of the grating illuminated by said initially projected light such that a moire fringe pattern is produced by the superposing of the image upon the grating, said image being left to right reversed and slightly angularly offset relative to said grating so as to produce said moire fringe pattern, which fringe pattern can be detected by said photocell to measure the amount of displacement of the grating.
Claim 2
Independent Claim
244 words
A device for measuring the magnitude of displacement of diffraction gratings, which comprises a light-transmitting diffraction grating and a real image optical system whose magnification is unity, and including a light source, objectives a reflection optical system and a photocell in an arrangement such that light from the light source is initially projected through the grating in a direction substantially perpendicular thereto, is second directed substantially parallel with the lines of the grating, is third directed in a direction opposite to that of the initially projected light, is fourth directed again in parallel with the grating but in a direction opposite to that of the second direction, and finally again directed through the grating in the same direction as the initially projected light onto said photocell whereby to form a substantially closed and rectangular-shaped light passage, said real image optical system including optical elements all of which, inclusive of said light source and photocell, are arranged in sequence along said light passage, said objectives and reflection optical system producing on said grating an image of the portion of the grating illuminated by said initially projected light such that a moire fringe pattern is produced by the superposing of the image upon the grating, said image being left to right reversed and slightly angularly offset relative to said grating so as to produce said moire fringe pattern, which fringe pattern can be detected by said photocell to measure the amount of displacement of the grating.
Claim 3
Dependent Claim
134 words
A device as claimed in claim 1 wherein said objectives and reflection optical System include a first rectangular prism for receiving light from said source, a first objective lens positioned to receive light from said prism, a pentagonal prism in the light path from said lens, a first reflecting mirror for reflecting light received from said pentagonal prism in said second direction, a second reflecting mirror for reflecting light from the first mirror in said third direction, a second rectangular prism for receiving light from the second mirror, a second objective lens for receiving light from the second prism and a condensing lens for transmitting and concentrating light from said second lens to said photocell, said grating being an angularly displaceable radial grating interposed between said first rectangular prism and said third rectangular prism.
Claim 4
Dependent Claim
117 words
A device as claimed in claim 1 wherein said objectives and reflection optical system include a first rectangular prism for receiving light from said source, a first objective lens positioned to receive light from said prism, a pentagonal prism in the light path from said lens, a parallelogram prism for refracting light from said pentagonal prism in said second direction, a second rectangular prism for receiving light from the parallelogram prism, a second objective lens for receiving light from the second prism and a condensing lens for transmitting and concentrating light from said second lens to said photocell, said grating being an angularly displaceable radial grating interposed between said first rectangular prism and said third rectangular prism.
Claim 5
Dependent Claim
122 words
A device as claimed in claim 1 wherein said objectives and reflection optical system include a first reflecting mirror for reflecting an image of said grating illuminated by said source in said second direction, a second reflecting mirror for reflecting the image from said first mirror in said third direction, a first objective lens in the light passage in said third direction, a fourth reflecting mirror for receiving the image from the first objective lens and reflecting the image in said fourth direction, a second objective lens in the path of the image in said fourth direction, and a fifth reflecting mirror for reflecting the image to said photocell via said grating in the final direction and producing the moire fringe pattern.
Claim 6
Dependent Claim
24 words
A device as claimed in claim 4 wherein said grating is an elongated planar grating adapted to measure the linear displacement of the grating.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |