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Almost half of the X-ray beamlines at the Cornell High Energy Synchrotron Source (CHESS) are based on multilayer optics. ;Traditional' multilayers with an energy resolution of DeltaE/E approximately 2% are routinely used to deliver X-ray flux enhanced by a factor of 10(2) in comparison with standard Si(111) optics. Sagittal-focusing multilayers with fixed radius provide an additional factor of 10 gain in flux density. High-resolution multilayer optics with DeltaE/E approximately 0.2% are now routinely used by MacCHESS crystallographers. New wide-bandpass multilayers with DeltaE/E = 5% and 10% have been designed and tested for potential applications in macromolecular crystallography. Small d-spacing multilayers with d < or = 20 A have been successfully used to extend the energy range of multilayer optics. Analysis of the main characteristics of the Mo/B4C and W/B4C small d-spacing multilayer optics shows enhancement in their performance at higher energies. Chemical vapour deposited SiC, with a bulk thermal conductivity of a factor of two higher than that of silicon, has been successfully introduced as a substrate material for multilayer optics. Characteristics of different types of multilayer optics at CHESS beamlines and their applications in a variety of scattering, diffraction and imaging techniques are discussed.

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We are developing depth-graded, multilayer-coated mirrors for astrophysical hard X-ray focusing telescopes. In this paper, we discuss the primary technical challenges associated with the multilayer coatings, and report on progress to date. We h a v e sputtered constant d-spacing and depth-graded W Si multilayers onto 0.3 0.5 mm thick DURAN glass AF45 and D263 and 0.4 mm thick epoxy replicated aluminum foils ERAFs, both of which are potential mirror substrates. We have characterized the interfacial roughness, uniformity, and stress of the coatings. The average interfacial roughness of each multilayer was measured from specular re ectivity scans i = r using Cu K X-rays. The thin lm stress was calculated from the change in curvature induced by the coating on at glass substrates. Thickness and roughness uniformity w ere measured by taking specular re ectivity scans of a multilayer deposited on the inside surface of a quarter cylinder section.We found that interfacial roughness in the multilayers was typically between 3.5 and 4.0 A on DESAG glass, and between 4.5 and 5.0 A on the ERAFs. Also, we found that coatings deposited on glass that has been thermally formed into a cylindrical shape performed as well as at glass. The lm stress, calculated from Stoney's equation, for a 200 layer graded multilayer was approximately 200 MPa. Our uniformity measurements show that with no ba es to alter the deposition pro le on a curved optic, the layer thickness di ers by 20 between the center and the edge of the optic. Interfacial roughness, however, remained constant, around 3.6 A, throughout the curved piece, even as the layer spacing dropped o .