ABSTRACT
The desire for continuously gaining new knowledge in astronomy has pushed the frontier of engineering methods to deliver lighter, thinner, higher quality mirrors at an affordable cost for use in an x-ray observatory. To address these needs, we have been investigating the application of magnetic smart materials (MSMs) deposited as a thin film on mirror substrates. MSMs have some interesting properties that make the application of MSMs to mirror substrates a promising solution for making the next generation of x-ray telescopes. Due to the ability to hold a shape with an impressed permanent magnetic field, MSMs have the potential to be the method used to make light weight, affordable x-ray telescope mirrors. This paper presents the experimental setup for measuring the deformation of the magnetostrictive bimorph specimens under an applied magnetic field, and the analytical and numerical analysis of the deformation. As a first step in the development of tools to predict deflections, we deposited Terfenol-D on the glass substrates. We then made measurements that were compared with the results from the analytical and numerical analysis. The surface profiles of thin-film specimens were measured under an external magnetic field with white light interferometry (WLI). The analytical model provides good predictions of film deformation behavior under various magnetic field strengths. This work establishes a solid foundation for further research to analyze the full three-dimensional deformation behavior of magnetostrictive thin films.
ABSTRACT
Electroformed grazing incidence mirrors were tested with x rays and were measured with an optical profiler. Their total effective areas are ?70% of the theoretical values both for 1.5- and 6.4-keV x rays. The half-power diameters (HPDs) are ?2 min of arc at 1.5 keV. Comparing the x-ray test result with the optical measurement, we set requirements of high-frequency roughness <14 A and a midfrequency roughness <70 A for a HPD <1.5 min of arc at 7 keV. We also present a design of the mirror array telescope for high energies (MARTHE) which has a total effective area of ~1000 cm(2) for 7- keV x rays.
ABSTRACT
Grazing incidence Wolter type I mirrors for higher-energy x rays have been replicated from two superpolished mandrels by electroforming. Single mirrors and a nested pair were tested with 1.5- and 6.4-keV x rays, and their subminute of arc resolution and reflectivity close to the theoretical values are confirmed. We present the design of the mandrels, mirror mounting scheme, and results of the x-ray test. The microroughnesses of the mirrors measured using an optical profilometer were compared with the x-ray test results.
ABSTRACT
Work done to produce x-ray mirrors via electroform replication is reported. Several advances have been made over previous work. We have produced lower grazing incidence angle (30 min) mirrors, obtained quantitative measurements up to higher energies (6.40 keV), produced about four times as many replicas from one mandrel, and obtained angular resolutions better than other work done with replicated metal mirrors.
