LASER PUMPING SOURCES

The use of shock tube radiation sources as a laser pumping source was explored. Two side pumping configurations were fabricated and were used in attempts to pump a Nd doped glass rod and ruby rods, 2 in. long by 14 in. diameter. The glass rod, having an electrical threshold of 80 joules produced strong laser oscillation when pumped by the shock tube source. However no laser output was produced from the ruby rods. Since the spectral studies indicated that the shock tube radiation source provides sufficient intensity and duration to pump ruby above threshold, several suspected difficulties were explored. The UV transmission of the thermal setting plastic used to encapsulate the rubies was measured and found to cut off at a wavelength of 3300A, thus ruling out removal of the upper laser levels by UV pumping below 3000A as a possible explanation. On the other hand a marked increase in the threshold of ruby was observed when it was pumped only from one side. This is currently thought to be the cause of the difficulty found in using the linear shock tube to pump ruby crystals.