A holographic interferometer senses vapor-induced optical path length changes in polymer or other chemically sensitive films. The interferometer is inherently sensitive to changes in chemical vapor content, self-compensates for drifts, and accommodates a large array of sensor elements. A sniff-locked-loop synchronous detection method takes advantage of the interferometer's rapid response to achieve vapor concentration sensitivity in the parts-per-billion (ppb, parts in 10^9) range. We demonstrate, for example, 40 ppb sensitivity to ethyl alcohol using poly(N-vinyl pyrrolidone) with a measurement time of 5 s.
© 2005 Optical Society of America
(090.2880) Holography : Holographic interferometry
(120.2880) Instrumentation, measurement, and metrology : Holographic interferometry
(160.5470) Materials : Polymers
(190.5330) Nonlinear optics : Photorefractive optics
Hongke Ye, Oyvind Nilsen, Victor M. Bright, and Dana Z. Anderson, "Holographic chemical vapor sensor," Opt. Lett. 30, 1467-1469 (2005)