Method and apparatus for generating coherent radiation in the ultra-violet region and above by use of distributed feedback
US3972008A · kind A · utility
Inventors
Key dates
| Filing date | Dec 17, 1974 |
| Grant date | Jul 27, 1976 |
| Priority date | — |
| Expiry date | Dec 17, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S3/1068
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Helium in the superfluid state has been found to emit copious amounts of radiation in the ultra-violet region when excited by an electron stream. Conventional laser action using mirrors is impossible in superfluid helium because there are no mirrors that will reflect VUV radiation. By utilizing the well known method of "distributed feedback" the superfluid helium can be made to lase. By setting up a standing wave in superfluid helium that has a wavelength equal to, or harmonically related to, half the wavelength of the photon radiation chosen to be emitted as laser radiation by the superfluid helium, the need for end mirrors to produce reflection of the laser radiation is eliminated and reflection occurs instead at the wavefronts of the standing wave. The photons leave the superfluid helium at right angles to the standing wave as coherent radiation having a very high intensity. The standing wave established in the superfluid helium may be an acoustical standing wave, a thermal standing wave (second sound), or an electric standing wave.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.