Narrow band radiation filter films

A satellite peak free, narrow band radiation filter comprising a crystalline colloidal array of charged particles of a copolymer of styrene and a comonomer selected from the group consisting of 1-sodium, 1-allyloxy-2-hydroxylpropane sulfonate;

• styrene sulfonate;
• 2-acrylamido-2-methylpropane sulfonate;
• 3-sulfopropyl methacrylate potassium salt and vinyl sulfonate fixed in a self-supporting film of polymeric hydrogel wherein said hydrogel film is a copolymer comprising acrylamide, an optional water-soluable comonomer selected from the group consisting of vinyl pyrrolidone and hydroxyethylmethacrylic acid ester and N,N-methylenebisacrylamide, the ratio of acrylamide and optional water soluble comonomer to N,N-methylenebisacrylamide ranging from about 1:8 to about 1:12 on a weight basis.