Restricted off-axis field optical system
US4293186A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 21, 1979 |
| Grant date | Oct 6, 1981 |
| Priority date | — |
| Expiry date | Dec 21, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70308
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
This invention provides, in a restricted off-axis field optical system having a broad spectral range, which includes refracting elements, the improvement comprising: PA1 an optical system constructed and arranged so that the Petzval sum is substantially zero, said refracting elements including elements for balancing the effects of the variation in the Petzval sum due to variation in color by introducing axial chromatic aberration of the opposite sense so that the position of focus at the off-axis field remains substantially constant; PA1 according to the invention in one form thereof, the elements for balancing the effects of the variation in the Petzval sum due to variation in color include a symmetrically disposed nearly concentric meniscus element whose convex radius is larger than its concave radius and whose thickness is greater than the difference between its convex and concave radii; PA1 further, according to a form of the invention, the system includes at least one convex and one concave mirror, said mirrors being nearly concentrically arranged along an optical axis; PA1 further, according to one form thereof, the system includes a color trimming element; PA1 the invention …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.