Optical low pass filter
US4093346A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 27, 1975 |
| Grant date | Jun 6, 1978 |
| Priority date | — |
| Expiry date | May 27, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J29/89
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical low-pass filter in the form of a rectangular wave phase grating including at least two sets of parallel phase retardation laminae, the laminae in each set being at an angle to the laminae of the other set. The optical filter is disposed in an optical system provided with a color-encoding filter, such as a single tube color television camera, and the high frequency components of an image on the color-encoding filter are attenuated below a predetermined level. The degree of blur, which is larger than the value calculated from the grating period of the color-encoding filter, is effected by a first set of laminae and beats appearing in the image defocused on the color-encoding filter due to the laminae is attenuated by another set or the other set of laminae.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.