Optics fabrication and metrology for nanofocusing of hard x-rays
Progress in the fabrication and metrology of both Multilayer Laue Lenses (MLLs) and Kirkpatrick-Baez (K-B) mirrors at the Advanced Photon Source (APS) is on-going as part of the world-wide race to achieve ever smaller focusing. Successful MLLs require multilayer depositions consisting of many layers. Focusing to 30 nm for 19.5 keV has been demonstrated at APS beamlines with a WSi2/Si MLL having 728 layers made at the APS. These same techniques were used to achieve a partial linear zone plate structure having a 5-nm outer most zone width and consisting of 1588 total layers as discussed below. Achromatic focusing to 80 nm of x-rays in the range {approx}7 to 22 keV by an elliptically figured K-B mirror has been demonstrated at the APS with a mirror coated at the APS. The mirror was made by profile coating a substrate with Au to achieve the elliptical surface shape. The elliptical mirror was made starting from a flat substrate. To make further progress, non-x-ray-based metrology data for real mirrors will need to be incorporated into simulations. This is being done using Fourier Optics methods as detailed below. Multilayer Laue Lens with 5-nm outermost zone - A scanning electron micrograph of a cross section of a 5-nm MLL structure is shown in Fig.1, below. The bilayer structure was WSi{sub 2}/Si and a total of 1588 layers were sputter deposited at the APS. The micrograph was read to obtain the data plotted in Fig. 2. Here the d-spacing as a function of position in the lens is shown, where the d-spacing is twice the individual layer spacing A linear behavior in 1/d vs. position is needed to satisfy the zone plate law. (Owing to limited SEM resolution, the thinnest layers were subject to greater uncertainty.) This lens was used to obtain a linear focus of 19.3 nm at 19.5 keV at beamline 12-BM at the APS. Kirkpatrick-Baez mirrors and Fourier Optics Simulations - Elliptically shaped mirrors have been made by profile coating at the APS. A program to simulate the performance of such mirrors by means of Fourier Optics has recently been started. Mirror aberrations away from a perfect ellipse will be incorporated into a complex pupil function. In the absence of any aberrations, spherical waves emanating from a point source will be reflected to produce spherical waves directed to a focus. The resultant Fraunhofer diffraction pattern near the focal plane is shown in Fig. 3. Subsequent introduction of mirror aberrations will be simulated with this procedure.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 991605
- Report Number(s):
- ANL/XSD/CP-118784; TRN: US1007516
- Resource Relation:
- Conference: 5th International Conference on Synchrotron Radiation in Materials Science (SRMS 5); Jul. 30, 2006 - Aug. 2, 2006; Chicago, IL
- Country of Publication:
- United States
- Language:
- ENGLISH
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