The opening area needs to be set when constantly sending in and out parts on a dangerous high-speed operation machine. If a protective door is set here, it will seriously affect the production and certainly not be able to take both production and safety into account. Safety light curtain is a safety device set in these openings, and it realizes safety protection through the light beams. It is a type of sensor that install through beam photoelectric sensors in rows from top to bottom. It monitors a certain range of amplitude, when the machine is running, it intercepts the light when a human body intrudes, and stops the machine to achieve the purpose of protecting personal safety. However, when processed parts are fed in and out through the light curtain, they do not cause the machine to stop working. In this way, the operators are effectively protected from harm without affecting the production at the same time.