US3751162A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Refractometer and reflectometer
Assignee: Individual
•
Filing: 1972-03-13
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Granted: 1973-08-07
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Expires: 1992-03-13
Abstract
Abstract An instrument is provided, primarily as a refractometer, and which has the unique capability of distinguishing and identifying finished gems and gem materials by their refractive index and/or ratio of reflected light to projected light, and for exposing spurious imitations. For gem stone analyzing purposes the instrument is based on the Fresnel formula, which requires a flat highly polished surface, the formula reading
Inventors
- 👤 R Long
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:04
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/41; G01N21/84; G01N21/87
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
198 words
An instrument for revealing the index of refraction of purported gem stones, as a means for indicating whether or not they are as represented, comprising, in combination, a. means for producing and projecting light of controlled, fixed intensity upon a flat surface of fixed predetermined area of a face of the purported gem stone at an angle near the normal, b. an electric circuit including an eleCtromotive source of fixed voltage and a light sensitive element so disposed that all the light reflected from such face of the purported gem stone is caused to impinge upon it, so that the resistance of the element (positive or negative) varies with the intensity of the reflected light, and c. means for comparing the voltage from said source of fixed voltage as affected by an arbitrary resistance with voltage from the same source as affected by the variable resistance produced by the light sensitive element, to produce a read-out proportional to the ratio of reflected light to projected light, which in the case of gem stones according to the Fresnel formula, is interpreted in terms of refractive index on a consistently open scale, throughout the gem stone range of refractive indexes.
Claim 2
Dependent Claim
198 words
An instrument for revealing the index of refraction of purported gem stones, as a means for indicating whether or not they are as represented, comprising, in combination, a. means for producing and projecting light of controlled, fixed intensity upon a flat surface of fixed predetermined area of a face of the purported gem stone at an angle near the normal, b. an electric circuit including an eleCtromotive source of fixed voltage and a light sensitive element so disposed that all the light reflected from such face of the purported gem stone is caused to impinge upon it, so that the resistance of the element (positive or negative) varies with the intensity of the reflected light, and c. means for comparing the voltage from said source of fixed voltage as affected by an arbitrary resistance with voltage from the same source as affected by the variable resistance produced by the light sensitive element, to produce a read-out proportional to the ratio of reflected light to projected light, which in the case of gem stones according to the Fresnel formula, is interpreted in terms of refractive index on a consistently open scale, throughout the gem stone range of refractive indexes.
Claim 3
Dependent Claim
51 words
An instrument as set forth in claim 1 which includes means for shielding the purported gem stone against exposure to all light except that provided by the aforesaid light producing means, and for shielding the light sensitive element against exposure to all light other than that reflected by the test specimen.
Claim 4
Dependent Claim
18 words
An instrument as set forth in claim 2 in which the light sensitive element is a photo-electric cell.
Claim 5
Dependent Claim
18 words
An instrument as set forth in claim 2 in which the light sensitive element is a solar cell.
Claim 6
Dependent Claim
79 words
An instrument as set forth in claim 2 in which the comparing means includes a wheatstone bridge having two legs of set resistance, a third leg including an electronic tube of fixed bias, a fourth including an electronic tube whose bias is affected by the resistance of the photo-sensitive element as modified by the light reflected by the purported gem stone, and a bridging read-out instrumentality responsive to imbalance of the third and fourth legs of the wheatstone bridge.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |