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NIST/ARPA National Extreme Ultraviolet (EUV) Reflectometry Facility

The NIST/ARPA EUV Reflectometry Facility is a multipurpose beamline covering the 3 nm to 40 nm (400 eV to 30 eV) spectral range. Although dedicated to serving the EUV optics community by providing accurate measurements of multilayer mirror reflectivities, this versatile beamline has been used for many other types of measurements since its commissioning in early 1993. Among the other measurements performed recently are grating efficiencies, photocathode conversion efficiencies, phosphor conversion efficiencies, film dosimetry, and determination of EUV optical constants through angle dependent reflectance measurements.

Figure 1

Figure 1: Schematic of downstream end of NIST/ARPA EUV Reflectometry Facility.

Beamline Description

The EUV reflectometry beamline consists of a grazing incidence, varied line space grating monochromator and a sample chamber able to accommodate optics up to 10 cm in diameter. The downstream part of the beamline is shown schematically in Figure 1. Not shown are the collection mirror, which collects 3 mrad vertically by 20 mrad horizontally of the output from SURF III, the entrance slit, and a set of elemental filters to reject both short and long wavelength radiation. Two interchangable varied line spaced gratings enable scanning of the wavelength region from 3 nm to 40 nm, and an adjustable slit varies the resolving power from 200 to 2000. Wavelength is scanned by rotating and translating a plane mirror. Radiation is detected by an EUV sensitive photodiode. The combination of high throughput and sensitivity of the photodiode leads to a dynamic range of six orders of magnitude.

The current sample chamber is capable of accepting optics up to 10 cm in diameter and scanning an area of 25 mm × 50 mm through angles of 3 degrees to 85 degrees from normal incidence. This chamber will be replaced with the large chamber pictured above that will allow us to generate a reflectivity map of the entire surface of large optics (up to 35 cm in diameter and 40 kg in mass) such as those expected to be used in such applications as EUV astronomy and lithography. Figure 2 shows the result of one recent reflectivity measurement. This measurement covers the entire region around the first, second, and third order Bragg peaks of a Si/B4C multilayer mirror at an angle of incidence of 5 degrees. Note the wide dynamic range indicated by the signal-to-noise over the entire measurement and the resolution indicated by the detail that is visible in the fringes between the Bragg peaks.

 Figure 2

Figure 2: Normal incidence reflectivity, measured on beamline 7, of a 15-period Si-B4C Multilayer mirror.

For information on the reflectometry facility or our measurement services, contact:

Charles Tarrio
Physics, A253
NIST
Gaithersburg, MD 20899
(301) 975-3737
ctarrio@nist.gov

NIST: National Institute of Standards and TechnologyNIST Physics Laboratory Home Measurements and Calibrations Page designed and maintained by rvest@nist.gov, SURF III, NIST.
Inquiries or comments: ctarrio@nist.gov
Online: November 1994   -   Last update: March 2001