Dichroic optical filter
US5296961A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 1991 |
| Grant date | Mar 22, 1994 |
| Priority date | — |
| Expiry date | Apr 23, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/282
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A dichroic optical filter including a substrate that is substantially transparent to visible radiation, and an oxide semiconductor layer on the substrate for reflecting an infrared wavelength (such as an infrared treatment beam wavelength). An example of a suitable oxide semiconductor for reflecting a treatment beam from a CO.sub.2 layer is indium tin oxide. Preferably, the filter includes a specially designed multilayer coating on the oxide semiconductor layer to enhance the reflection of infrared and longer wavelength radiation. This multilayer coating includes alternating quarter-wave layers of high and low refractive index materials, each having an optical thickness substantially equal to a quarter-wavelength of infrared radiation to be reflected. Preferably also, the multilayer coating includes a thin multilayer coating between each pair of adjacent quarter-wave layers, with these thin multilayer coatings being designed to enhance the filter's transmission of visible radiation, while not significantly affecting the filter's reflection of infrared wavelengths. Also preferably, the multilayer coating includes a second multilayer coating which reflects a narrow band of visible ra…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.