Complex sentence: Exposure times of several minutes are typical when using quite powerful gas lasers and silver halide emulsions and all the elements within the optical system will to be stable to fractions of a um over that period.
Split into simpler sentences: Exposure times of several minutes are typical when using quite powerful gas lasers and silver halide emulsions. All the elements within the optical system will have to be stable to fractions of a um over that period.