The optical quality of the Micro Power-Light gas-discharge source ( MPL ) is such that it is well suited for use in ellipsoidal reflector systems. In other reflector systems (parabolic/Free Shape) a kind of “shielding” should be applied to block light from zones in the MPL, which cause glare in the beam pattern. Another approach is to redesign the MPL to optimize the optical quality. Thereby the relation between arc luminance, characteristics of the reflector system and illumination values in the beam pattern is important.By reducing the diameter of the arc chamber, the optical quality is improved through less contribution of glare-producing elements. From a evalution of a range of MPLs with reduced arc chamber, it is concluded that a MPL with 1.4 mm inner diameter is applicable to present Free Shape headlamp designs. This results in ECE beam patterns with glare levels comparable to, but with illumination values far exceeding those of, halogen lighting.