Refraction measuring apparatus
Abstract
Abstract A SYSTEM FOR MEASURING THE REFRACTIVE INDEX ALONG A PATH IS PROVIDED WHEREIN TWO LIGHT SIGNALS, WHICH ARE OF DIFFERENT COLORS AND WHICH ARE INTENSITY-MODULATED WITH DIFFERENT FREQUENCIES, ARE TRANSMITTED ALONG THE PATH TO A RECEIVER INCLUDING A PHASE DETECTOR. THE PHASE DETECTOR PRODUCES AN OUTPUT IN ACCORDANCE WITH THE PHASE DIFFERENCE BETWEEN THE SIGNALS, WHICH OUTPUT IS A MEASURE OF THE DIFFERENCE IN REFRACTIVE INDEX FOR THE TWO COLORS. THE RECEIVER INCLUDES A PHOTOMULTIPLIER TUBE WHICH PROVIDES HETERODYNING OF THE SIGNALS TO FORM A DIFFERENCE-FREQUENCY SIGNAL WHOSE PHASE REPRESENTS THE PHASE DIFFERENCE BETWEEN THE TWO COLOR SIGNALS. EACH COLOR IS ALTERNATELY MODULATED WITH ONE OR THE OTHER OF TWO FREQUENCIES RESULTING IN A DOUBLING OF THE SIGNAL AT THE RECEIVER. ONE OF THE SIGNALS MAY BE DELAYED AT THE TRANSMITTER SO THAT THE SIGNALS ARE OF EQUAL PHASE AT THE RECEIVER, THE RECEIVER SERVING AS A NULL INSTRUMENT AND THE DELAY BEING A MEASURE OF THE REFRACTIVE INDEX.
Inventors
- 👤 Carl-Erik Granqvist
Bibliographic Details
Claims Analysis
Total Claims: 0References 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) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |