A boundary layer disturber for removing heat from the platen of a copier is in the form of an improved scanning reflector which has a portion thereof in the form of a "scoop". During scanning motion, the reflector entrains air flow which disturbs and peels the thermal boundary layer from underneath the platen glass, thus passively improving platen glass cooling. Also, the reflector is contoured to allow air to entrain over the lamp assembly, resulting in enhanced cooling. As a result of changing the form of the reflector there is increased cooling characteristics in the optics cavity, thus allowing blowers with lower power and noise levels to be utilized in the optics cavity.