A low-cost infrared sensor that uses room temperature pyroelectric detectors integrated with bandpass filters to provide low-resolution spectral scans of the absorption characteristics of hazardous chemicals was developed for fixed security applications. The sensor provides fast (1 s) and continuous monitoring, detection, and identification capabilities. A unique detection and identification algorithm that uses non-linear computation techniques to account for the exponential nature of optical absorption was developed. Chemical detection and identification is achieved by matching the recorded sensor response vector to an updatable signature library that currently includes the signatures of 14 chemicals. The sensor and algorithm were tested by introducing methanol vapor at optical depths between 225 - 270 ppm-m. Using 1 s signal samples obtained during approximately 20 min. test, resulted in no false positive alarms and 3.4% of false negatives. All false negatives were shown to be due to misidentification of methanol as isopropanol, which is spectrally similar to methanol. By grouping isopropanol with methanol the rate of false negatives was reduced to 0%. Results of the same test using a 30 s signal integration time resulted in no false positive and no false negative alarms.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
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.