Illumination optical system
US11248770B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Nov 25, 2020 |
| Grant date | Feb 15, 2022 |
| Priority date | — |
| Expiry date | Nov 25, 2040 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/425
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An illumination optical system having a light source and a single convex lens with a diffractive structure, wherein the phase function of the diffractive structure is represented by where r represents distance from the central axis of the lens, the relationship |β2|·(0.3R)2<|β4|·(0.3R)4 is satisfied where R represents effective radius of the lens, the second derivative of the phase function has at least one extreme value and at least one point of inflection where r is greater than 30% of R, and the area of a surface of the light source is equal to or greater than 3% of the area of the entrance pupil when the light source side of the lens is defined as the image side.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.