Abstract: One or more hollow, light transparent elements filled with a liquid coolant-filter are interposed between a high intensity mercury vapor lamp and an object to be illuminated in order to simultaneously filter out infrared radiation and focus the illumination from the lamp. In two embodiments the light transparent elements include two hollow quartz tubes which, in the first embodiment, are parallel to each other and to the lamp and in the second embodiment surround the lamp but are separated from it by an annular air space. In a third embodiment the light transparent elements include a hollow, rectangular, quartz box, for containing the liquid coolant-filter, and a Fresnel lens affixed to the underside of the box for focusing the light.