US3883233A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic, recording refractometer
Assignee: Optische Werke G Rodenstock
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Filing: 1973-12-21
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Granted: 1975-05-13
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Expires: 1993-12-21
Abstract
Abstract An automatic recording refractometer employs a pair of rotatable test figures, the image of one of which is projected into the retina of an eye being examined. The light from the retina then passes through a second test marker by way of a rotatable prism and is received by a photodetector. The electric signal output of the photodetector is analyzed by measurement circuitry and recorded. The test figures are rotatable in synchronism and may be relatively displaced. A fixation marker may also be imaged into the optical path of the light ultimately received by the photodetector.
Inventors
- 👤 Gunther Guilino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:18
CPC Classifications
A; A61; A61B; A61B3/00; A61B3/10; A61B3/103
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
158 words
An automatic, recording refractometer for determining visual defects comprising: first means for directing the image of a first rotatable test figure along a first prescribed optical path into the eye; second means for directing the image from the retina of the eye along a second optical path through a second rotatable test figure; third means for projecting the image of a fixation marker into said second optical path; fourth means, responsive to light passing through said second rotatable test figure from the eye, for providing a measurement of visual anomalies of the eye; fifth means, coupled to said test figures, for effecting a relative displacement of said test figures in such a way that the image of the first rotatable test figure reflected from the retina of the eye under examination is focused on the second rotatable test figure; and sixth means for coupling the displacement of said fixation marker in an optional manner with said fifth means.
Claim 2
Dependent Claim
158 words
An automatic, recording refractometer for determining visual defects comprising: first means for directing the image of a first rotatable test figure along a first prescribed optical path into the eye; second means for directing the image from the retina of the eye along a second optical path through a second rotatable test figure; third means for projecting the image of a fixation marker into said second optical path; fourth means, responsive to light passing through said second rotatable test figure from the eye, for providing a measurement of visual anomalies of the eye; fifth means, coupled to said test figures, for effecting a relative displacement of said test figures in such a way that the image of the first rotatable test figure reflected from the retina of the eye under examination is focused on the second rotatable test figure; and sixth means for coupling the displacement of said fixation marker in an optional manner with said fifth means.
Claim 3
Dependent Claim
35 words
An automatic, recording refractometer according to claim 1, wherein each of said test markers comprises a grating which is rotatable about an optical axis passing therethrough synchronously with the rotation of the other test marker.
Claim 4
Dependent Claim
33 words
An automatic, recording refractometer according to claim 1, further including a rotating prism disposed in said second optical path for displacing the image of said first test marker on said second test marker.
Claim 5
Dependent Claim
26 words
An automatic, recording refractometer according to claim 1, wherein said fixation marker includes means for projecting a set of concentric circles into said second optical path.
Claim 6
Dependent Claim
27 words
An automatic, recording refractometer according to claim 1, further including means for adjusting tHe brightness of the test markers and said fixation marker relative to each other.
Claim 7
Dependent Claim
34 words
An automatic, recording refractometer according to claim 1, further including means for effecting observation of the image in the retina of the eye along the optical path by which said fixation marker is projected.
Claim 8
Dependent Claim
33 words
An automatic, recording refractometer according to claim 2, further including a rotating prism disposed in said second optical path for displacing the image of said first test marker on said second test marker.
Claim 9
Dependent Claim
71 words
An automatic, recording refractometer according to claim 7, wherein said fourth means comprises a photodetector which receives the light passing through said second rotatable test marker and converts the received light into an electrical signal, a filter circuit for separating said electric signal into prescribed frequency components, and means for combining said frequency components in accordance with a selected function for generating an indication of the measurement of the visual defects.
Claim 10
Dependent Claim
70 words
An automatic, recording refractometer according to claim 8, wherein said filter circuit comprises a low-pass filter coupled to said photodetector, a first difference circuit for subtracting the output from said photodetector and said low-pass filter, a band-pass filter coupled to said first difference circuit, and an integrating phase-sensitive detector synchronized with the frequency of rotation of said rotary prism for eliminating background noise from the output of said difference circuit.
Claim 11
Dependent Claim
64 words
An automatic, recording refractometer according to claim 9, wherein said means for combining said generating an indication includes means for generating a signal representative of the ratio of the output of said low-pass filter and said integrating phase-sensitive detector and a recorder coupled to receive said ratio signal and signals representative of the rotation and displacement of said first and second rotatable test markers.
Claim 12
Dependent Claim
30 words
An automatic, recording refractometer according to claim 3, wherein the frequency of rotation of said prism is greater than the frequency of rotation of said first and second test markers.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |