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Broadband Microwave Phase Shift Detector

Patent Number: 10,247,814

Abstract

The detector senses very small phase shifts in a highly balanced microwave bridge. An electric field optimized microwave probe, in close proximity to a sample, serves to perturb the degree of bridge balance due to a .change in effective dielectric constant of the sample. The major innovation associated with the detector centers on the ability to balance the bridge to an extremely fine degree. In one embodiment the detector can be used to greatly increase the sensitivity of Fourier transform infrared spectroscopy. In another embodiment, the detector can be used to greatly increase the sensitivity and temporal resolution of thermometry measurements. In all cases, the probe dimensions define the spatial resolution and can be essentially arbitrary in geometry.

Patent Description

The new NIST detector senses very small phase shifts in a highly balanced microwave bridge.  An electric field optimized microwave probe, in close proximity to a sample, serves to perturb the degree of bridge balance due to a change in effective dielectric constant of the sample.  The major innovation associated with the detector centers on the ability to balance the bridge to an extremely fine degree.  The detector can be used to greatly increase the sensitivity of Fourier transform infrared spectroscopy (FTIR).  The detector can be used to greatly increase the sensitivity and temporal resolution of thermometry measurements.  In all cases, the probe dimensions define the spatial resolution and can be essentially arbitrary in geometry.  For example, the probe can be made longer to increase the overall sensitivity.  If spatial resolution is desired, the probe can be made smaller.  Since the measurement is non-contact, the high sensitivity lends itself quite nicely to scanned probe measurements.  The probe can be fabricated using standard silicon processing technology to produce low cost disposable probes and can greatly improve the repeatability of the measurement and reduce cross contamination.

In general, the strength of this detector invention is its ability to detect extremely minute changes in microwave phase shift.  Since this phase shift is directly proportional to sample temperature change, the detector can be used to greatly improve the sensitivity and utility of a wide variety of conventional measurement techniques.

Image of diagrams for the Classic Mach - Zehnder interferometer, Microwae transmission line based vserion, and guided wave probe tip interacts with sample

Features

In general, the strength of this detector invention is its ability to detect extremely minute changes in microwave phase shift. Since this phase shift is directly proportional to sample temperature change, the detector can be used to greatly improve the sensitivity and utility of a wide variety of conventional measurement techniques.

Created February 26, 2020, Updated April 15, 2020