Ronchigram

{{Short description|Shadow image mainly used to correct aberrations}}

Ronchigram (after Italian physicist Vasco Ronchi [ˈroŋki]{{Cite journal |last=Ronchi |first=Vasco |date=1964-04-01 |title=Forty Years of History of a Grating Interferometer |url=https://opg.optica.org/ao/abstract.cfm?uri=ao-3-4-437 |journal=Applied Optics |language=EN |volume=3 |issue=4 |pages=437–451 |doi=10.1364/AO.3.000437 |issn=2155-3165}}{{Cite journal |last=Ronchi |first=Vasco |date=1923-07-01 |title=Due nuovi metodi per lo studio delle superficie e dei sistemi ottici |url=https://doi.org/10.1007/BF02959347 |journal=Il Nuovo Cimento (1911-1923) |language=it |volume=26 |issue=1 |pages=69–71 |doi=10.1007/BF02959347 |s2cid=122620904 |issn=1827-6121}}) is the convergent beam diffraction pattern{{cite journal | last1=Kossel | first1=W. | last2=Möllenstedt | first2=G. | title=Elektroneninterferenzen im konvergenten Bündel | journal=Annalen der Physik | publisher=Wiley | volume=428 | issue=2 | year=1939 | issn=0003-3804 | doi=10.1002/andp.19394280204 | pages=113–140 | language=de}} of a known object with features comparable to the diffracting wavelength. In the case of electron Ronchigrams amorphous materials are used. The structure of the Ronchigram encodes information about the aberration phase field across the objective aperture.{{cite book | last=Kirkland | first=Earl J. | title=Advanced Computing in Electron Microscopy | publisher=Springer US | publication-place=Boston, MA | year=2010 | isbn=978-1-4419-6532-5 | doi=10.1007/978-1-4419-6533-2| s2cid=62171402 }} As such, Ronchigrams have become increasingly important with the invention of aberration corrected scanning transmission electron microscopy.{{cite journal | last1=Schnitzer | first1=N. | last2=Sung | first2=S.H. | last3=Hovden | first3=R.H. | title=Introduction to the Ronchigram and its Calculation with Ronchigram | journal=Microscopy Today | volume=3 | year=2019 | issue=3 | pages=12–15 | doi=10.1017/S1551929519000427 | s2cid=155224415 | doi-access=free }}