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.


Mechanical and Aerospace Engineering

Research Center/Lab(s)

Intelligent Systems Center


Ministerio de Economía y Competitividad (MINECO) (PR201500063, TEC2013-40442); University of North Carolina at Charlotte.

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)


Document Type

Article - Journal

Document Version


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© 2017 Optical Society of America (OSA), All rights reserved.

Publication Date

01 Feb 2017