Sources of photochemically acive radiation, radiant flux measurement, Negative photoresists: photochemical processes by photoinduced crosslinking, Physical chemistry of crosslinking, Gel-point and resist sensitivity. Quantum yield of crosslinking. Photoinitiated polymerization. Radical generation, photofragmentation, hydrogen abstraction, photoinitiated cationic polymerization. Positive photoresists, photochemical transformation of diazonaphtochinons. Positive photoresists for UV-B region. Photoresist sensitometry.