developments in synchrotron X-ray generation allows for the produced X-ray beam
to be virtually coherent. To preserve the coherence of the X-ray beam the current
available refractive optics are not ideal due to the inherent grainy structure
of Be, Al and Ni that represent the lens materials presently offered. This
project focuses on fabricating and characterizing a refractive lens in a single
crystal diamond. A lens in single crystal diamond has the potential of being
distortion free to the beam coherence while still focusing the beam.
A large part of the project will be to
optimize the fabrication process of the lenses. The lens form is ablated into
the diamond using a pico second laser and is subsequently treated in various
plasma etches. Both the laser ablating and the plasma etching processes have
several parameters and due to interdependence and non-linearities it is not a
trivial exercise to determine the ideal settings. Once a batch of lenses have
been produced, they will be inspected using a confocal optical microscope and
there will be iterations to improve on the lens form and the lens roughness.
See  and  for further information on diamond lenses.
To estimate the
performance of the made lenses ray tracing simulations is to be conducted. The
ray tracing tool will be McXtrace that is partly developed at DTU, see  and http://www.mcxtrace.org/. The measured
height error and roughness of the diamond lenses will be superimposed onto a
lens shape in the software and the detrimental effects of these will be
evaluated with respect to coherence preservation and focusing capability.
later stage of the project the student will take the best of the lenses to the
APS synchrotron in Chicago, USA. At the APS the produced lenses will be
characterized using the synchrotron X-ray beam and the coherence degradation of
the X-rays can be established, along with characteristics such as focusing and
The project is
suitable for 1 to 2 students. We suggest the project to be 35 ECTS.
learning goals of the project are listed below:
Learn to structure an extended
Get familiarized with the
physics governing Compound Reflective Lenses, CRLs
Optimize the laser ablation of
single crystal diamonds to attain a small height error and a small surface
Optimize the plasma etch
process (the plasma etching is done in the Nanolab cleanroom)
Characterize the diamond lenses
using a confocal optical microscope (the microscope is in Nanolab cleanroom)
Learn to use McXtrace and do
ray tracing simulations on the produced lenses incorporating the measured
height error and roughens.
Learn to organize large data
sets and extract trendlines of any parameter space
Go 2-3 week to the APS in
Chicago to do X-ray characterization of the lenses, particularly using Talbot
interferometry for coherence measurements
Write a concise rapport on a
large set of experimental and simulated data
Main supervisor: Henning Friis Poulsen, DTU PHYSICS
Co-supervisor: Jesper Hanberg, DTU NANOLAB
Co-supervisor: Erik Bergbäck Knudsen, DTU PHYSICS
Co-supervisor: Paw Kristiansen, JJ X-Ray
 Terentyev, Sergey, et al.
"Parabolic single-crystal diamond lenses for coherent x-ray imaging."
Applied Physics Letters 107.11 (2015): 111108. https://aip.scitation.org/doi/abs/10.1063/1.4931357
 Antipov, S., et al.
"Single-crystal diamond refractive lens for focusing X-rays in two
dimensions." Journal of synchrotron radiation 23.1 (2016): 163-168. http://scripts.iucr.org/cgi-bin/paper?S1600577515020639
 Bergbäck Knudsen, Erik, et al.
"McXtrace: a Monte Carlo software package for simulating X-ray optics,
beamlines and experiments." Journal of Applied Crystallography 46.3
(2013): 679-696. https://scripts.iucr.org/cgi-bin/paper?he5585
Structured approach to experimental work. Some simulation/coding experience will be advantageous.