Papers by Keyword: Parabolic Mirror

Abstract: Needs of precision optical mirrors are increasing in the astronomical space telescope. In the space having extremely large temperature differences, the aspheric optical mirror made of low thermal expansion ceramic is very effective in reducing the focus errors due to the thermal expansion. In order to develop the mirror made of a new low thermal expansion ceramic, parabolic mirror of the ceramic is ground and polished to test. By the grinding and polishing test, changes of form deviation profiles and surface roughness profiles are evaluated and machinability of the proposed ceramic is studied.

Abstract: Concentrating solar collectors direct the sunlight towards a focus point or focus line. Relevant parameters are the fidelity of the concentrator with respect to its ideal parabolic shape, its stiffness under wind and gravitational loads, the angular accuracy of the tracking and the solar weighted specular reflectance of the reflector. Additional aspects refer to the long term durability and ease of cleaning of the reflector surface. Solar concentrators require lower geometrical precision than astronomic apparatus. Therefore, more cost effective designs are possible by using up the overall acceptable error budget to a level that collection efficiency of the reflected sun rays is still very efficient. Understanding the impact of the different parameters describing the quality of the concentrator with respect to system performance and cost is necessary for an advanced and efficient concentrator design. DLR has recently developed guidelines to measure the most relevant concentrator characteristics in its qualification center QUARZ. This paper presents the relevant parameters of mirrors for concentrating solar collectors and discusses their economic impact.

Abstract: A simple analytical approach is given to calculate the performance of parabolic mirrors for various wavelengths. Expressions are given for the efficiency of the parabolic mirror system and insertion gain. As examples, parameters for some mirrors for CuKα and MoKα radiation are calculated.