Chemical sensing of in situ extracted organics by direct detection of mode-filtered light

Robert E. Synovec; Carsten A. Bruckner; Lloyd W. Burgess; M. D. Foster

doi:10.1117/12.190966

21 October 1994 Chemical sensing of in situ extracted organics by direct detection of mode-filtered light

Robert E. Synovec, Carsten A. Bruckner, Lloyd W. Burgess, M. D. Foster

Proceedings Volume 2293, Chemical, Biochemical, and Environmental Fiber Sensors VI; (1994) https://doi.org/10.1117/12.190966
Event: SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, 1994, San Diego, CA, United States

Abstract

A novel chemical analyzer is described in which an optical fiber is inserted into a transparent capillary tube, such that the inner diameter of the tube is only a few microns larger than the outer diameter of the fiber cladding. This configuration is referred to as a torus column. When a sample volume is introduced to the torus column at a low flow rate, propagated light is mode-filtered due to a change in the critical angle at the core/clad interface, as a result of in-situ extracted chemical species. Conventionally, chemical species extracted into the cladding are sensed as a change in the transmitted light at the end of the fiber. An alternative approach, measuring this mode-filtered light directly along the side of the fiber, is reported. The new approach has a signal-to-noise advantage over the conventional approach. The result is a low volume sensor that temporally separates, as well as detects, chemical species that partition into the fiber cladding. The temporal information enhances sensor performance, providing first order information for subsequent data analysis. We have examined the modulation of the critical angle by chemical species of interest at steady-state concentrations, and as transient concentration profiles that were shifted in time. In summary, the analyzer has chemical selectivity provided by differences in the refractive index, distribution coefficient, and transient time of the concentration profile of each chemical species in a sample. The chemical analyzer should be a promising tool for process and environmental monitoring.

Citation Download Citation

Robert E. Synovec, Carsten A. Bruckner, Lloyd W. Burgess, and M. D. Foster "Chemical sensing of in situ extracted organics by direct detection of mode-filtered light", Proc. SPIE 2293, Chemical, Biochemical, and Environmental Fiber Sensors VI, (21 October 1994); https://doi.org/10.1117/12.190966

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available