A low-absorption x-ray energy filter for small-scale applications.
We present an experimental and theoretical evaluation of an x-ray energy filter based on the chromatic properties of a prism-array lens (PAL). It is intended for small-scale applications such as medical imaging. The PAL approximates a Fresnel lens and allows for high efficiency compared to filters based on ordinary refractive lenses, however at the cost of a lower energy resolution. Geometrical optics was found to provide a good approximation for the performance of a flawless lens, but a field-propagation model was used for quantitative predictions. The model predicted a 0.29 E/E energy resolution and an intensity gain of 6.5 for a silicon PAL at 23.5 keV. Measurements with an x-ray tube showed good agreement with the model in energy resolution and peak energy, but a blurred focal line contributed to a 29% gain reduction. We believe the blurring to be caused mainly by lens imperfections, in particular at the periphery of the lens.
Fredenberg
Erik
E
1Department of Physics, Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm, Sweden. fberg@mi.physics.kth.se
Cederström
Björn
B
Nillius
Peter
P
Ribbing
Carolina
C
Karlsson
Staffan
S
Danielsson
Mats
M
D000465:Algorithms; D004867:Equipment Design / Q000295:instrumentation; D007089:Image Enhancement / Q000295:instrumentation; D007909:Lenses; D008855:Microscopy, Electron, Scanning / Q000379:methods; D015233:Models, Statistical; D055095:Optics and Photonics; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation; D012031:Refractometry / Q000295:instrumentation; D017356:Synchrotrons; D014965:X-Rays