Panasonic st4 safety beam sensor system panasonic st4 a1 j02v this sensor head is part of the st4 safety beam sensor system the sensor has an operating detection range of between 01 and 15m and can detect opaque objects down to just oslash9mm the st4 is a safety light beam system that is extremely effective in both wide areas and narrow spaces the fully featured system has a long sensing range enabling the securing of facilities where the installation of a guardian fence is not feasib