SCALABLE AND STABLE, CW PHOTOLYTIC ATOMIC IODINE LASER

摘要

The present invention is a scalable and stable, cw photolytically excited atomic iodine laser (10) operating at 1.315 microns. An initial power level of 55 watts/liter was obtained via the cw photolysis of an alkyl-iodide gas (20) like C3F7I. The greatly enhanced laser performance was achieved using a microwave (16) excited, electrodeless Hg plasma lamp (18) excited with a d.c., low ripple (1%) cw microwave radiation. Both high flow, air cooling and above ambient temperature (50 - 150 .degree.C) liquid, dimethyl polysiloxane cooling of these high pressure Hg lamps (atmospheres) provided long lifetime operation with the latter promoting stable laser operation. Transverse flow for the removal of the quenching by-product I2 is incorporated into the laser (10). To insure good laser amplitude stability, both the high power magnetrons (operated at 1.5 KW but capable of 3 KW performance) and the lamp (18) (normally Hg) are liquid cooled, respectively by H2O and dimethyl polysiloxane. The use of the high ultraviolet transmissve properties of the dimethyl polysiloxane lamp coolant removed the requirement for large flow air cooling (150 cfm) of the lamps (18); thereby, allowing good amplitude stability. Elimination of air coolant enabled use of a slow N2 purge; thereby preventing the formation of ozone, 03, a strong absorber of the UV radiation exciting this cw photolytic atomic iodine laser (10). The scalable, prolonged and stable operation of this cw photolytic iodine laser system (10) is possible via use of closed cycle, condensative/evaporative fuel system coupled to a high flow (10 meters/sec), internal blower for heavy gases (20) like the alkyl iodide C3F7I. Over an excitation length of 25 cm, an average small signal gain coefficient of 2 %/cm is produced by exciting the transvesely flowing C3F7I from one side. High powers are achievable by exciting the gas (20) from both sides, increasing the ultraviolet lamp radiation with higher microwave power and/or more efficient UV operating plasma lamps (18), and/or "tailoring" the UV lamp emission into the C3F7I absorption in the 240-320 nm region. Enhanced efficiencies (I to 6 %) are possible by optimizing all components associated with the d.c. microwave excited lamps (18).