Phase Imaging and Detection in Pseudo-Heterodyne Scattering Scanning Near-Field Optical Microscopy Measurements
When considering the pseudo-heterodyne mode for detection of the modulus and phase of the near field from scattering scanning near-field optical microscopy (s-SNOM) measurements, processing only the modulus of the signal may produce an undesired constraint in the accessible values of the phase of the near field. A two-dimensional analysis of the signal provided by the data acquisition system makes it possible to obtain phase maps over the whole [0, 2π) range. This requires post-processing of the data to select the best coordinate system in which to represent the data along the direction of maximum variance. The analysis also provides a quantitative parameter describing how much of the total variance is included within the component selected for calculation of the modulus and phase of the near field. The dependence of the pseudo-heterodyne phase on the mean position of the reference mirror is analyzed, and the evolution of the global phase is extracted from the s-SNOM data. The results obtained from this technique compared well with the expected maps of the near-field phase obtained from simulations.
C. Moreno et al., "Phase Imaging and Detection in Pseudo-Heterodyne Scattering Scanning Near-Field Optical Microscopy Measurements," Applied Optics, vol. 56, no. 4, pp. 1037-1045, Optical Society of America (OSA), Feb 2017.
The definitive version is available at https://doi.org/10.1364/AO.56.001037
Mechanical and Aerospace Engineering
Keywords and Phrases
Data acquisition; Data handling; Heterodyne detection; Heterodyning; Optical data storage; Optical microscopy; Co-ordinate system; Data acquisition system; Maximum variance; Post processing; Pseudo-heterodyne; Quantitative parameters; Reference mirrors; Two-dimensional analysis; Near field scanning optical microscopy
International Standard Serial Number (ISSN)
Article - Journal
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