A surgical instrument includes a light guide configured to convey light energy, a lens configured to focus the light energy into a light beam, a mounting tube, a jaw assembly coupled to the mounting tube, and a handle assembly. The jaw assembly includes a first jaw member non-movably secured to the mounting tube, a second jaw member movably secured to the mounting tube, and a window secured to the first jaw member and forming a tissue contacting surface. The window is oriented in a plane oblique to a longitudinal axis of the mounting tube and forms a liquid-tight seal between tissue and the lens. The handle assembly is coupled to the jaw assembly to move the second jaw member between an open position in which the second jaw member is spaced part from the window and a closed position.
