Mask inspection apparatus and method of controlling the same

A mask inspection apparatus comprising:

• a mask transfer unit comprising at least one of a conveyor or a carrier to transfer a mask in one of a first direction and a direction opposite to the first direction;
• a displacement sensor unit comprising a displacement sensor, the displacement sensor unit being arranged above the conveyor or the carrier to measure a distance from the displacement sensor to an upper surface of a sheet of the mask transferred by the mask transfer unit;
• and
• a photographic unit comprising a camera, the camera being arranged above the conveyor or the carrier to photograph the upper surface of the sheet of the mask transferred by the mask transfer unit, a height of the photographic unit being controllable according to the distance measured by the displacement sensor.