Complex point receiver formulation of spherical near-field scanning of acoustic fields using higher-order probes

Wave Motion ◽  
2009 ◽  
Vol 46 (8) ◽  
pp. 498-510 ◽  
Author(s):  
Thorkild B. Hansen
Keyword(s):  
Near Field ◽  
Higher Order ◽  
Acoustic Fields ◽  
Complex Point ◽  
Near Field Scanning

scholarly journals Numerical Investigation of the System-Matrix Method for Higher-Order Probe Correction in Spherical Near-Field Antenna Measurements

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Thorkild B. Hansen
Keyword(s):  
Condition Number ◽  
Matrix Method ◽  
Near Field ◽  
Higher Order ◽  
Normal Matrix ◽  
Identity Matrix ◽  
System Matrix ◽  
Higher Order Modes ◽  
Near Field Scanning ◽  
Least Squares Approach

The system-matrix method for higher-order probe correction in spherical near-field scanning is based on a renormalized least-squares approach in which the normal matrix closely resembles the identity matrix when most of the energy of the probe pattern resides in the first-order modes. This method will be “stressed-tested” in the present paper by employing probes for which up to 49% of the pattern energy resides in the higher-order modes. The condition number of the resulting normal matrix will be computed, and its “distance” from the identity matrix displayed. It is also shown how the condition number of the normal matrix can be further reduced.

scholarly journals Probing polarization and dielectric function of molecules with higher order harmonics in scattering–near-field scanning optical microscopy

2009 ◽  
Vol 106 (11) ◽  
pp. 114307 ◽  
Author(s):  
Maxim P. Nikiforov ◽  
Susanne C. Kehr ◽  
Tae-Hong Park ◽  
Peter Milde ◽  
Ulrich Zerweck ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
Dielectric Function ◽  
Near Field ◽  
Higher Order ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

Near-field scanning optical microscopy

1986 ◽  
Vol 44 ◽  
pp. 642-643
Author(s):  
E. Betzig ◽  
A. Harootunian ◽  
M. Isaacson ◽  
A. Lewis
Keyword(s):  
Near Field ◽  
Optical Microscope ◽  
Visible Radiation ◽  
Field Methods ◽  
Optical Elements ◽  
Optical Region ◽  
Order Of Magnitude ◽  
Nondestructive Imaging ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

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