Processing Photo Definable Glasses Processing of photosensitive (photodefinable) glasses. Exposure to mid UV light, followed by a two step baking stage, then etching in HF acid. and finally an annealing stage. Nano and Micro Devices Center, University of Alabama in Huntsville. Produced by Khalid H. Tantawi and John D. Williams. Become Partners with the NMDC! Be sure to visit our Partners page to learn what the NMDC can do for you!