... , 08, 10……40) STDxx80 (xx=02, 04, 06, 08……40)Light axis pitch10mm, 20mm, 40mm, and 80mmProtection height Height=(xx-1 ... )×light axis pitch STDxx10 230,310,390,470......1350mm STDxx20 140, ... receiver, a controller and two signal cables. The emitter launches light to receiver, forms the protection light curtain