Provided is a collimator including a base unit configured to form a radiation path of light; a pair of first moving members rotatably installed in the base unit; a pair of second moving members movably installed in the base unit; and an actuator configured to externally receive power and transmit the power to the first moving members and the second moving members, wherein a first space may be formed between the first moving members, a second space may be formed between the second moving members, and the light may pass through a radiation area corresponding to an overlapping area of the first space and the second space.