A thin film heater includes at least two open regions formed along each of two spaced-apart edges of the thin film material, which edges are parallel to two spaced-apart edges of the underlying substrate. The open regions expose areas of underlying substrate. When electrical power is coupled to the two spaced-apart edges of the thin film material, uniformity of the heat generated across the thin film material is enhanced. The substrate may be planar or curved, and the open regions in the thin film material may be removed from deposited thin film material, or may be formed by preventing deposition of thin film material in such regions.