Compound x-ray refractive lenses made of polyimide

Theoretical considerations of the parameters that enable the construction of compound refractive lenses are treated in this writing. The best performing compound refractive lenses (CRLs) that have been constructed to date were made by Adelphi Technology Inc. stacking individual paraboloidal lenses made of polyimide (Kapton(R)). Polyimide lenses are capable of focusing photon with energies between 4 keV and 60 keV with focal lengths below 60 cm. They are not affected much by small misalignment of the individual lenses. Surface finish is less stringent than for visible light lenses. The increase in intensity in the image plane relative to the intensity that would have been obtained without a lens or gain measured at the experimental station of a bend magnet beam line was found to be 5.5 at 9 keV x-rays with transmission of 10% at that same energy. The measured values were in good agreement with the theoretical predictions at all wavelengths tested. Because of smaller source sizes and more collimated beams the gain of Kapton(R) CRLs scales about three orders of magnitude higher on undulator beam lines at third generation x-ray sources compared to the results obtained at the bending magnet x-ray source, with dimensions 445 mum by 1700 mum placed at 16m from the lens, used in this work. Even more dramatic gains of 10(6) will be obtained at coherenyt x-ray sources such as the LCLS. Gain and transmission of polyimide CRLs have been improved and their performance enhanced to surpass any CRLs previously developed and permitting focusing and imaging at lower energies. There is still much room for improvement of these lenses in all aspects of their development particularly increasing their aperture and transmission and improving their surface quality. Because of the source characteristics, synchrotron facilities in particular those with considerable production of coherent x-ray photons, will greatly benefit from the development of refractive lenses such as those being demonstrated in this writing.