Phase shifting microscopy

Powerful methods that have been developed more recently, and are currently used to observe surface micro topographs of crystal faces, include scanning tunnel microscopy (STM), atomic force microscopy (AFM), and phase shifting microscopy (PSM). Both STM and AFM use microscopes that (i) are able to detect and measure the differences in levels of nanometer order (ii) can increase two-dimensional magnification, and (iii) will increase the detection of the horizontal limit beyond that achievable with phase contrast or differential interference contrast microscopy. The presence of two-dimensional nuclei on terraced surfaces between steps, which were not observable under optical microscopes, has been successfully detected by these methods [8], [9]. In situ observation of the movement of steps of nanometer order in height is also made possible by these techniques. However, it is possible to observe step movement in situ, and to measure the surface driving force using optical microscopy. The latter measurement is not possible by STM and AFM. 

At this point it is worth comparing the different techniques of contrast enliancements discussed so far. They represent spatial filtering teclmiques which mostly affect the zeroth order dark field microscopy, which eliminates the zeroth order, the Schlieren method (not discussed here), which suppresses the zerotii order and one side band and, finally, phase contrast microscopy, where the phase of the zeroth order is shifted by nil and its intensity is attenuated. 

Tamayo, J. and Garcia, R., Relationship between phase shift and energy dissipation in tapping-mode scanning force microscopy. Appl Phys. Lett., 73(20), 2926-2928 (1998). Gotsmann, B., Seidel, C., Anezykowski, B. and Fuchs, H., Conservative and dissipative tip-sample interaction forces probed with dynamic AFM. Phys. Rev. B Condens. Matter, 60, 11051-11061 (1999). 

The sizing methods involve both classical and modem instrumentations, based on a broad spectrum of physical principles. The typical measuring systems may be classified according to their operation mechanisms, which include mechanical (sieving), optical and electronic (microscopy, laser Doppler phase shift, Fraunhofer diffraction, transmission electron miscroscopy [TEM], and scanning electron microscopy [SEM]), dynamic (sedimentation), and physical and chemical (gas adsorption) principles. The methods to be introduced later are briefly summarized in Table 1.2. A more complete list of particle sizing methods is given by Svarovsky (1990). 

KeUing, S., Paoloni, R, Huang, J., Ostanin, V. R, and Elliott, S. R. 2009. Simultaneous readout of multiple micro cantilever arrays with phase-shifting interferometric microscopy. Rev Set Instrum 80, 093101. 

ISO 25178- 71 2012 Geometrical product specifications (GPS) -Surface texture Areal - Part 71 Software measurement standards ISO/NP 25178- 603 Geometrical product specifications (GPS) - Surface texture Areal - Part 603 Nominal characteristics of non-contact (phase-shifting interferometric microscopy) instruments... 

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