linear lamp energy output is tuned by adjusting the reflectivity of reflectors or shade members used to direct , focus and filter energy output of a linear bulb . reflectivity is reduced in areas of the reflector contributing to high irradiance levels in a target area allowing , for example , overall equalization of irradiance across the target area . an outer surface of the linear bulb may have a modified diameter , light transmission reducing surface treatment or an added sleeve to linear bulb areas contributing to irradiance levels in specific locations in the target area that are higher than desired . alternatively and or additionally , a lens or shade member having a graduated convergence , reflectivity and or transmisivity may be used .