Converting a Lamp Pumped IR YAG Laser to Green?
Multiwatt Halogen, arc lamp, or flashlamp pumped solid state lasers are readily available at reasonable prices from laser surplus outfits, eBay, and elsewhere. What about adding a KTP (or other SHG crystal) and getting them to output nice 532 nm green? (Similar comments apply to higher harmonics but the difficulty level increases significantly.) While this would appear at first to be an easy project, the realities may be quite different. There are a number of issues all relating to peak power density available and shape of the beam inside the crystal. Maximum harmonic power will be generated when a narrow polarized collimated beam is properly phase matched to the KTP (Type-II critical phase matching). If the original laser isn’t polarized (e.g., Nd:YAG without Brewster angled rod ends), adding a polarizing element will significantly increase performance. Since harmonic generation is a non-linear process, it is desirable to maximize power density so long as it is safely less than the da
