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Title: Broad Band Intra-Cavity Total Reflection Chemical Sensor

Abstract

A broadband, ultrahigh-sensitivity chemical sensor is provided that allows etection through utilization of a small, extremely low-loss, monolithic optical cavity. The cavity is fabricated from highly transparent optical material in the shape of a regular polygon with one or more convex facets to form a stable resonator for ray trajectories sustained by total internal reflection. Optical radiation enters and exits the monolithic cavity by photon tunneling in which two totally reflecting surfaces are brought into close proximity. In the presence of absorbing material, the loss per pass is increased since the evanescent waves that exist exterior to the cavity at points where the circulating pulse is totally reflected, are absorbed. The decay rate of an injected pulse is determined by coupling out an infinitesimal fraction of the pulse to produce an intensity-versus-time decay curve. Since the change in the decay rate resulting from absorption is inversely proportional to the magnitude of absorption, a quantitative sensor of concentration or absorption cross-section with 1 part-per-million/pass or better sensitivity is obtained. The broadband nature of total internal reflection permits a single device to be used over a broad wavelength range. The absorption spectrum of the surrounding medium can thereby be obtained as amore » measurement of inverse decay time as a function of wavelength.« less

Inventors:
 [1]
  1. Gaithersburg, MD
Issue Date:
Research Org.:
DEPARTMENT OF COMMERCE
OSTI Identifier:
879725
Patent Number(s):
5835231
Application Number:
09/962171
Assignee:
The United States of America as represented by the Secretary of Commerce (Washington, DC)
Patent Classifications (CPCs):
G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
G - PHYSICS G01 - MEASURING G01J - MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED, VISIBLE OR ULTRA-VIOLET LIGHT
DOE Contract Number:  
AI07-97ER62518
Resource Type:
Patent
Country of Publication:
United States
Language:
English

Citation Formats

Pipino, Andrew C. R. Broad Band Intra-Cavity Total Reflection Chemical Sensor. United States: N. p., 1998. Web.
Pipino, Andrew C. R. Broad Band Intra-Cavity Total Reflection Chemical Sensor. United States.
Pipino, Andrew C. R. Tue . "Broad Band Intra-Cavity Total Reflection Chemical Sensor". United States. https://www.osti.gov/servlets/purl/879725.
@article{osti_879725,
title = {Broad Band Intra-Cavity Total Reflection Chemical Sensor},
author = {Pipino, Andrew C. R.},
abstractNote = {A broadband, ultrahigh-sensitivity chemical sensor is provided that allows etection through utilization of a small, extremely low-loss, monolithic optical cavity. The cavity is fabricated from highly transparent optical material in the shape of a regular polygon with one or more convex facets to form a stable resonator for ray trajectories sustained by total internal reflection. Optical radiation enters and exits the monolithic cavity by photon tunneling in which two totally reflecting surfaces are brought into close proximity. In the presence of absorbing material, the loss per pass is increased since the evanescent waves that exist exterior to the cavity at points where the circulating pulse is totally reflected, are absorbed. The decay rate of an injected pulse is determined by coupling out an infinitesimal fraction of the pulse to produce an intensity-versus-time decay curve. Since the change in the decay rate resulting from absorption is inversely proportional to the magnitude of absorption, a quantitative sensor of concentration or absorption cross-section with 1 part-per-million/pass or better sensitivity is obtained. The broadband nature of total internal reflection permits a single device to be used over a broad wavelength range. The absorption spectrum of the surrounding medium can thereby be obtained as a measurement of inverse decay time as a function of wavelength.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {11}
}

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