Metal multilayer mirrors for EUV wide field telescopes

Conference · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5892434

Smith, B W; Bloch, J J; Roussel-Dupre, D

Metal multilayer mirrors have been designed for the ALEXIS satellite, which is to carry six wide field telescopes to perform an all-sky survey in three or four narrow wavelength bands in the EUV. Comprised of alternating layers of molybdenum and silicon, the mirrors are optimized to provide maximum reflectivity at angles from 11.5 to 17/degree/ off normal incidence and at wavelengths of 133, 171, or 186A. Simultaneously, the mirrors use a ''wavetrap'' described below to suppress reflectivity at 304A, where the extremely strong geocoronal line of He II causes severe background problems. Low reflectivity at 304A is achieved by superposing two layer pairs that provide destructive interference with an effective 2d spacing of 152A. The Mo layers in this wavetrap must be very thin, about 10A each, in order to allow the shorter wavelengths desired for peak reflectivity to penetrate without significant attenuation. Because refraction changes the effective angle of passage through the wavetrap, a joint optimization between layer thicknesses in the deep layers and the wavetrap layers must be performed for each target peak wavelength. For the 186A mirror, the optimum design from substrate upward is 40 layer pairs, each 74A Si and 31A Mo, followed by 2 layer pairs, each 55A Si and 10A Mo. Calculations predict this design will have a peak reflectivity at 186A of 35 percent and a 304A reflectivity less than 10/sup /minus/5/, if available optical constants are correct and the multilayer can be fabricated without difficulty. We will present details of the calculations and laboratory measurements of the reflectivity performance attained with prototype mirrors. 6 refs., 2 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5892434
• Report Number(s): LA-UR-89-2381; CONF-890836-2; ON: DE89015262
• Country of Publication: United States
• Language: English

Related Subjects

640100* -- Astrophysics & Cosmology
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DESIGN
ELECTROMAGNETIC RADIATION
ELEMENTS
EXTREME ULTRAVIOLET RADIATION
LAYERS
METALS
MIRRORS
MOLYBDENUM
OPTICAL PROPERTIES
OPTICS
PHYSICAL PROPERTIES
RADIATIONS
REFLECTIVITY
SATELLITES
SEMIMETALS
SILICON
SPACE VEHICLE COMPONENTS
SURFACE PROPERTIES
TELESCOPES
TRANSITION ELEMENTS
ULTRAVIOLET RADIATION