The diffraction efficiencies of a Fresnel zone plate (ZP), fabricated by Xradia Inc. using the electron-beam writing technique, were measured using polarized, monochromatic synchrotron radiation in the extreme ultraviolet wavelength range 3.4-22 nm. The ZP had 2 mm diameter, 3330 zones, 150 nm outer zone width, and a 1 mm central occulter. The ZP was supported by a 100 nm thick Si 3 N 4 membrane. The diffraction patterns were recorded by CMOS imagers with phosphor coatings and with 5.2 µm or 48 µm pixels. The focused +n orders (n=1-4), the diverging -1 order, and the undiffracted 0 order were observed as functions of wavelength and off-axis tilt angle. Sub-pixel focusing of the +n orders was achieved. The measured efficiency in the +1 order was in the 5% to 30% range with the phase-shift enhanced efficiency occurring at 8.3 nm where the gold bars are partially transmitting. The +2 and higher order efficiencies were much lower than the +1 order efficiency. The efficiencies were constant when the zone plate was tilted by angles up to ±1 o from the incident radiation beam. This work indicates the feasibility and benefits of using zone plates to measure the absolute EUV spectral emissions from solar and laboratory sources: relatively high EUV efficiency in the focused +1 order, good out-of-band rejection resulting from the low higher-order efficiencies and the ZP focusing properties, insensitivity to (unfocused) visible light scattered by the ZP, flat response with off-axis angle, and insensitivity to the polarization of the radiation based on the ZP circular symmetry. EUV sensors with Fresnel zone plates potentially have many advantages over existing sensors intended to accurately measure absolute EUV emission levels, such as those implemented on the GOES N-P satellites that use transmission gratings which have off-axis sensitivity variations and poor out-of-band EUV and visible light rejection, and other solar and laboratory sensors using reflection gratings which are subject to response variations caused by surface contamination and oxidation.

While nonlinear optics has become increasingly important in theory and applications few undergraduate laboratories include nonlinear optics experiments in their program. The purpose of the paper is to describe a few simple experiments and their theoretical interpretations at the senior undergraduate level. Liquids containing traces of absorbing dyes were used as the nonlinear media. Nonlinear effects such as self-diffraction and phase conjugation were observed with laser power as low as 100 mW.

This report describes the facility, experimental methods, characterizations, and uncertainty analysis of the Cryo Distortion Measurement Facility (CDMF) at the Goddard Space Fligght Center (GSFC). This facility is designed to measure thermal distortions of structural elements as the temperature is lowered from 320K to below 40 K over multiple cycles, and is capable of unattended running and data logging. The first measurement is to be the change in length and any bending of composite tubes with Invar end-fittings. The CDMF includes a chamber that is efficiently cooled with two cryo-coolers (one single-stage and one two-stage) rather than with liquid cryogens. Five optical ports incorporate sapphire radiation shields -transparent to the interferometer -on each of two shrouds and a fused silica vacuum-port window. The change in length of composite tubes is monitored continuously with displacement-measuring interferometers; and the rotations, bending, and twisting are measured intermittently with theodolites and a surfacefigure interferometer. Nickel-coated invar mirrors and attachment mechanisms were developed and qualified by test in the CDMF. The uncertainty in measurement of length change of 0.4 m tubes is currently estimated at 0.9 micrometers.

The Ultraviolet and Optical Telescope (UVOT) is one of the three astronomical instruments onboard the SWIFT spacecraft. The optical calibration of this instrument, which was done prior to integration to the SWIFT spacecraft optical bench, is key to determine if UVOT will meet its science objectives. In this paper, we describe the optical ground support equipment (GSE) used for the calibration of UVOT. These tests, which were carried out in the Diffraction Grating Evaluation Facility (DGEF), at NASA Goddard Space Flight Center, required building an optical stimulus. We report the radiometric measurements of all the optical components used in putting together this stimulus. This includes a vacuum collimator with a Cassegrain design, a Pt/Cr-Ne light source, a complete set of neutral density filters spanning 6 orders of magnitude in transmission levels, a set of narrow-band filters matching the center of each of the six bands of UVOT, a set of pinholes of various sizes, flat fielding diffusers, and a set of parabolic mirrors.