Wavelength-selective phase-grating optical low-pass filter
US5237452A · kind A · utility
10Cited by
6References
4Claims
0Family size
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Key dates
| Filing date | Sep 10, 1992 |
| Grant date | Aug 17, 1993 |
| Priority date | — |
| Expiry date | Sep 10, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/6153
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A wavelength-selective phase-grating optical low-pass filter has a phase difference structure formed at a boundary face between two layer materials which have different refractive index distributions and an identical refractive index at an intended wavelength. A trapezoid form is adopted at the phase difference section of the phase grating to achieve an excellent MTF characteristic in the condition of: ##EQU1## thereby obtaining a wavelength-selective phase-grating optical low-pass filter capable of adjusting the cutoff characteristic and improving the characteristic in the low-frequency region of the spatial frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.