The LG-900 series detectors are reflection type optical (LG-916) and photoelectric detectors developed for medium distance detection applications. The LG-916 adopts glass fiber at the tip end and can be protective enough against the external turbulent light because of pulse modulation system as the light projection source. The LG-930 also uses a pulse-lighting method, it is practically unaffected by disturbance light, furthermore, featuring a hybrid structure with the all light-projecting, light-receiving, amplifying, and waveform-shaping sections built into the unit to offer a compact design with easy-to-operate functions. By simply attaching the reflection mark to a rotating object, the detectors can detect the rotation of the object without actually touching the object.