a housing configured to be inserted into and withdrawn from an oral cavity, and comprising an open area in one end thereof, the open area allowing an internal shape (hereinafter, referred to as an image) of the oral cavity to enter the housing as light;

at least one camera disposed inside the housing, and configured to allow light entering through the open area of the housing to pass therethrough;

a light projector disposed on one side of the at least one camera to emit light into the oral cavity through the open area; and

a single polarizer filter located between the at least one camera and the open area and disposed parallel to the light projector, wherein the single polarizer filter is located in a position spaced apart a set distance (d) from a front end of the at least one camera.