From Flat Substrate to Elliptical KB Mirror by Profile Coating

Journal Article · Wed May 12 04:00:00 EDT 2004 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.1757893· OSTI ID:20653047

Chian, Liu; Conley, R; Assoufid, L; Cai, Z; Qian, J; Macrander, A T ^[1]

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1. Experimental Facilities Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

For microfocusing x-ray mirrors, an elliptical shape is essential for aberration-free optics. However, it is difficult to polish elliptical mirrors to x-ray-quality smoothness. Profile coatings have been applied on both cylindrical and flat Si substrates to make the desired elliptical shape. In a profile-coating process, the sputter source power is kept constant, while the substrate is passed over a contoured mask at a constant speed to obtain a desired profile along the direction perpendicular to the substrate-moving direction. The shape of the contour was derived from a desired profile and the thickness distribution of the coating material at the substrate level. The thickness distribution was measured on films coated on Si wafers using a spectroscopic ellipsometer with computer-controlled X-Y translation stages. The mirror coating profile is determined from the difference between the ideal surface figure of a focusing ellipse and the surface figure obtained from a long trace profiler measurement on the substrate. The number of passes and the moving speed of the substrate are determined according to the required thickness and the growth-rate calibration of a test run. A KB mirror pair was made using Au as a coating material and cylindrically polished mirrors as substrates. Synchrotron x-ray results using this KB mirror pair showed a focused spot size of 0.4 x 0.4 {mu}m2. This technique has also been applied for making elliptical KB mirrors from flat Si substrates. The challenges and solutions associated with elliptical profile coating on flat substrates will be discussed.

• OSTI ID: 20653047
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 705; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
BEAM OPTICS
CALIBRATION
COATINGS
COMPUTERIZED CONTROL SYSTEMS
CYLINDRICAL CONFIGURATION
FILMS
FOCUSING
MIRRORS
ROUGHNESS
SHAPE
SILICON
SUBSTRATES
SURFACE COATING
SYNCHROTRON RADIATION
SYNCHROTRONS
THICKNESS
X RADIATION