Fixed-focus triplet projection lens for overhead projectors
US5596455A · kind A · utility
9Cited by
55References
20Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jun 29, 1995 |
| Grant date | Jan 21, 1997 |
| Priority date | — |
| Expiry date | Jun 29, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/00
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A Cooke triplet projection lens for use in overhead projectors comprises two outer positive elements of an ophthalmic crown glass and one inner negative element of a light flint glass. The crown glass has a refractive index of roughly 1.523 and an Abbe value of 58.5. The flint has an index of less than 1.573 and an Abbe value of between 43 and 53. One of the positive elements is biconvex; the other is meniscus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.