Designing optics for photometry in the long-wavelength portion of the EUV spectrum (400–900 Å) poses different problems from those arising for optics, operating shortward of 400 Å. The available filter materials which transmit radiation longward of 400 A are also highly transparent at wavelengths shortward of 100 Å. Conventional EUV optics, with grazing angles of ≲10°, have very high throughput in the EUV, which persists to wavelengths shortward of 100 Å. Use of such optics with the longer-wavelength EUV filters thus results in an unacceptably large soft x-ray leak. We have overcome this problem by developing a mirror design with larger graze angles ≥20°, which has high throughput at wavelengths longer than 400 Å but at the same time very little throughput shortward of 100 Å.
© 1988 Optical Society of America
David S. Finley, Patrick Jelinsky, Stuart Bowyer, and Roger F. Malina, "Design of the Extreme Ultraviolet Explorer long-wavelength grazing incidence telescope optics," Appl. Opt. 27, 1476-1480 (1988)