A coupler for coupling a light source to a fiber optic, comprising an adapter having a cavity for receiving the fiber optic, said adapter including pins extending in a direction perpendicular to the fiber optic's axis; a coupler body having an aperture for receiving the adapter, said aperture including a pair of through slots for receiving the pins, said body including interior pin sockets radially offset from the slots; a plate mounted within the coupler body; and biasing means urging said plate towards the aperture in the coupling body wherein when the adapter is inserted into the aperture of the coupler body, the adapter initially urges the plate in a direction away from the aperture, whereupon the adapter is rotated until the pins become aligned with and captured within the pin sockets allowing the plate to be urged in a direction back towards the aperture locking the coupler in place.