Filters for soft x-ray solar telescopes

Soft x-ray telescopes require filters that block visible and infrared light and have good soft x-ray transmission. The optical properties of possible materials are discussed, and the fabrication and testing methods for the filters used in a 10-inch normal incidence telescope for X = 63 A are described. The best performances in the X = 44-114 A wavelength range are obtained with foils of carbon and rhodium. © 1990 Society of Photo-Optical Instrumentation Engineers.