Abstract: A self-adjusting, adjustable, light-diffusing mechanism adapted for use in an optical scanner and including a light source to be projected on or transmitted through an object to be scanned, such as a photograph or transparency, including a light-permeable plate extending along the length and width of the light source, and having a varying degree of thickness so as to permit a varying degree of light transmitted therethrough and onto the object to be scanned, and, including a reflector positioned on the side of the light source opposite the light-diffusing mechanism and including at opposed ends of the reflector enlarged, convergent reflecting surfaces which function to focus light from the opposed ends of the light source to a target area so as to make the illumination intensity at the target area substantially uniform throughout the length of the light source, and so as to easily and conveniently adjust and control the degree of illumination projected on or through the object to be scanned.