Pattern formation in a model of photochemical reaction
  Stripe and columnar patterns were experimentally found in photopolymer films during irradiation of collimated UV light. We propose a mathematical model of photopolymerization, perform numerical simulation, and find a spatially periodic columnar structure. 
Hidetsugu Sakaguchi, Daishiro Kijima, Shunsuke Chatani, and Toshiaki   Hattori
cond-mat.soft