The innovation involves the design of a system (to be referred to as a thermal precollimator) to provide a thermalgradient in fron of grazing incidence x-ray telescopes whileminimizing obscuration of the telescope field-of-view. The system should occupy a minimum of space (3 inches) above the telescope and it should be designed not to distort due to thermal gradients and thereby change the percentage of obscuration. The section of the telescope under investigation is its aperture which is consisted of four individual (90-degree) segments. The reflecting surfaces (0.005 inch thin polished--name plate finish--aluminum--type1145), occupy the telescope aperture, are placed concentrically with an average spacing of 1/16 of an inch. The main concern is the deformation (and, therefore, the obscuration of the telescope field-of-view) of these reflecting surfaces due to thermal gradients. Severe thermal gradients may be developed, especially when the telescope is aimed at distant stars (deep space). This is due to the fact that the inner side of the aperture is facedtowards a 20 degree c environment (telescope interior), while the outer side is exposed to deep space at -273 degreec.
