The x-ray interferometer is not a joke. In about 1974, Gerd Materlik built one for his thesis and inserted it in front of my beamline at the DESY synchrotron. The beam splitters and "mirrors" were all carved out of a single block of perfect single crystal silicon. He inserted a wedge of plastic in one arm acting as a phase shifter and produced dark and white bands in a film. I was really, really impressed.
As for the three-beam experiments by Edgar Weckert and K. Hümmer, carried on by Bob Sweet, as impressive it is to get precise phase measurements for a reflection, there is a practical downsided: the radiation dose for measuring one reflection to a few % is as high as the dose for a whole data set from which we conventionally extract the phases of all reflection though only at about 30% but still good enough to solve the structure. I have the inkling that Bernhard's phase retrieval would suffer the same death: only the ultra-parallel fraction of the x-ray beam passes through the interferometer cutting down tremendously the intensity of reflections from macromolecular crystals which tend to be far from parallel. Gerd On 01.04.2020, 16:02, "CCP4 bulletin board on behalf of Tim Gruene" <[email protected] on behalf of [email protected]> wrote: Dear Bernhard, your paper is actually not so much of a joke. Are you aware of K. Huemmer's and E. Weckert's three-beam experiments? See e.g. https://link.springer.com/chapter/10.1007/978-1-4615-5879-8_24 Best regards, Tim On Wednesday, April 1, 2020 4:00:19 AM CEST Bernhard Rupp wrote: > Hi Fellows, > > > > just in time for a little reading during quarantine-induced boredom here > preprint pages > > (embargoed until 04.01) from my recent Phys. Rev. paper with a different > take on phasing > > https://tinyurl.com/Phys-Rev-2020 > > > > Enjoy, BR > > ------------------------------------------------------ > > Bernhard Rupp > > <http://www.hofkristallamt.org/> http://www.hofkristallamt.org/ > > <mailto:[email protected]> [email protected] > > +1 925 209 7429 > > ------------------------------------------------------ > > Department of Genetic Epidemiology > > Medical University Innsbruck > > Schöpfstr. 41 > > A 6020 Innsbruck > > <mailto:[email protected]> [email protected] > > +43 676 571 0536 > > ------------------------------------------------------ > > Many plausible ideas vanish > > at the presence of thought > > ------------------------------------------------------ > > > > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 -- -- Tim Gruene Head of the Centre for X-ray Structure Analysis Faculty of Chemistry University of Vienna Phone: +43-1-4277-70202 GPG Key ID = A46BEE1A ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
