Patent US2557691A successfully refreshed from Google Patents.
US3560875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Beam angle limiter
Assignee: Boeing North American Inc
•
Filing: 1967-09-11
•
Granted: 1971-02-02
•
Expires: 1987-09-11
Abstract
Abstract THE LIGHT EMITTED FROM A LASER IS FIRST PASSED THROUGH A LINEAR POLARIZER AND THEN THROUGH A QUARTER-WAVE PLATE TO PRODUCE CIRCULARLY POLARIZED LIGHT. THE CIRCULARLY POLARIZED LIGHT IS THEN TRANSMITTED THROUGH A BIREFRINGENT CRYSTAL, WHICH MAY BE EITHER UNIAXIAL OR BIAXIAL, WITH THE OPTIC AXIS OF THE CRYSTAL POSITIONED SUBSTANTIALLY PARALLEL TO THE LIGHT BEAM. THE LIGHT EMERGENT FROM THE CRYSTAL PASSES THROUGH A SECOND QUARTER-WAVE PLATE AND THROUGH A SECOND POLARIZER AND IS THEN REFLECTED BACK THROUGH THE SYSTEM.
Inventors
- 👤 John A Macken
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:57
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/05; H01S3/08; G; G02; G02B; G02B27/00; G02B27/28
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
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) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |