On the transport of intensity technique for phase retrieval.
The Transport of Intensity technique is becoming a viable alternative to electron holography for phase retrieval in Transmission Electron Microscopy. However, several issues are still to be clarified in order to ascertain the applicability of the technique; among them, the controversy regarding its geometrical or wave-optical nature, as related to the phase detection limit. We show here that the Transport of Intensity is a wave-optical technique that works in a special regime of small defocus where the image intensity is linear with the defocus parameter. By a simple analytical example we show that the Transport of Intensity correctly reconstructs the electron optical phase shift even when the phase is smaller than pi, a value defining the boundary between the geometrical and wave approaches. Another example is given, the reconstruction of a phase jump, accompanied with experimental support showing that phase retrieval by Electron Holography and Transport of Intensity techniques yields results in good agreement.
Beleggia
M
M
Brookhaven National Laboratory, Center for Functional Nanomaterials, Building 480, Upton, NY 11973, USA. beleggia@bnl.gov
Schofield
M A
MA
Volkov
V V
VV
Zhu
Y
Y
D000465:Algorithms; D006696:Holography; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D046529:Microscopy, Electron, Transmission; D008858:Microscopy, Phase-Contrast / Q000379:methods