A medical laser unit having a spring-loaded coupler cover for protecting a fiber optic coupler from damage when an optical fiber is not coupled to the laser unit. When an optical fiber is attached to the fiber optic coupler, a cam arrangement on the spring-loaded coupler cover minimizes the force applied to the optical fiber by the spring-loaded coupler. The spring-loaded coupler cover includes a hinge assembly mounted above the fiber optic coupler such that the spring-loaded coupler is rotatably positionable between closed and open positions relative to the fiber optic coupler.