Abstract: There is disclosed an electromagnetic energy collector assembly in which a transparent cylindrical glass tube made from common glass tubing lengths is sealed under vacuum at one end to an inner cylindrical energy absorber having a plurality of grooves on the exterior surface. The inner absorber may be constructed of glass, metal, or other material and the energy absorbing surfaces have grooves which may be helical, or parallel or longitudinal to the normal axis of the absorber. One or more of energy collectors are connected into a manifold for circulation of a fluid working media, e.g., gas or water, which is eventually utilized in any application of thermal energy, e.g., heating, cooling or driving a turbine. The collector assembly is particularly useful in the collection of solar energy.