Two-lens f.theta. lens
US4770517A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 27, 1985 |
| Grant date | Sep 13, 1988 |
| Priority date | — |
| Expiry date | Nov 27, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/0005
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
This invention relates to an f.theta. lens for scanning a laser beam whose deflection half-angle reaches 30.degree.. If a deflection angle increases, the curvature of field and f.theta. characteristic are rapidly deteriorated. According to the present invention, the f.theta. lens is composed of two lenses. A first lens near a beam deflection point is formed by a meniscus lens substantially in the form of a concentric spherical surface. A power of the lens and a length between a common center of two refractive surfaces and a beam deflection point are suitably selected to well-correct the curvature of field and f.theta. characteristic over a wide scanning angle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.