X ray collimator is the part that restricts and restricts X-ray. The closure size of lead leaf in beam limiter determines the range of light. The beam limiter directly aims at the human body to emit X-ray, but X-ray radiates and can not scan the human body at will. So in order to adjust X-ray conveniently, the beam limiter is equipped with a lamp to simulate X-ray positioning adjustment. The main function of halogen lamp of x ray collimator is to simulate light source. In the manual beam limiter, the halogen lamp of x ray collimator also needs electricity supply. The wire on the manual beam limiter can supply power to the halogen lamp of the beam limiter. Generally, the beam limiter needs external power supply. In the beam limiter, the lamp generally has the LED lamp of the beam limiter besides the halogen lamp of x ray collimator. LED lamp is the type of lamp that replaces halogen lamp. Their function is the same.