Near field millimeter wave microscopy with conical Teflon probes

Abstract

We demonstrate 260 GHz (λ=1.15 mm) near field imaging using a conical Teflon probe whose tip protrudes through an aperture in a tapered aluminum holder. The imaging system is based on a quasioptical millimeter wave vector network analyzer. We present a variety of different imaging examples of dielectrics and metals, in both reflection and transmission modes, as well as an analysis of interesting diffraction and scattering effects observed in some of the images. The probe has an approximate tip diameter of 0.17 mm and an aperture size of about 1 mm. We observe horizontal resolution ranging from 0.2–0.5 mm depending on the sample being imaged.

Sub‐THz complex dielectric constants of smectite clay thin samples with Na+/Ca++ ions

“…At Colorado school of Mines (CSM) we use 3 mm wave (or sub‐THz) modalities to extract material properties: (1) a quasioptical system, [ Scales and Batzle , , ; Greeney and Scales , ] to study bulk properties; (2) a near‐field scanning system [ Weiss et al , ], to measure local properties; and (3) the open hemispherical cavity resonator [ Rahman et al , ; Dudorov et al , ], for samples that are too thin or too low loss for quasioptical techniques. In this work, using cavity resonance perturbation (Figure ), we extract the complex dielectric constants of clay‐thin films in 100–165 GHz and investigate electrical properties in the presence of Ca ++ /Na + ions.…”

“…(2) a near-field scanning system [Weiss et al, 2009], to measure local properties; and (3) the open hemispherical…”

Millimeter-Wave Single-Pixel Imaging Using Electrically-Switchable Liquid-Crystal Mask

“…A classical MMW imaging method is the raster scan [1], [21], [22], which uses an MMW detector in which a certain position in a measuring plane corresponds to one measured data in a one-to-one relationship. An arrayed antenna combined with a dielectric lens [23], [24] can reduce the data acquisition time.…”

Apertureless near-field microscopy using a knife blade as a scanning probe at millimeter wavelengths

“…[10][11][12] In the millimeter-wave region, tapered dielectric waveguides are used. 13,14 Slit-type probes [15][16][17][18][19][20][21] featuring no cutoff, having a slit-like aperture in a rectangular or a parallel plate waveguide, are suitable for use in the millimeter and terahertz wave regions because of the simplicity of their structure. In comparison with optical waves, the benefit of using radio waves such as microwaves, millimeter waves, and terahertz waves in scanning near-field microscopy lies in the promise of new types of material contrast.…”