We use stochastic resonance to measure weak transmittance amplitudes that are below the instrumental detection limit. Gaussian noise is added to the subthreshold (chopped) transmittance signal T(t) before detection by a crossing detector that uses a dc reference signal B>0. Without noise, no measurement is possible because T(t)<B. A fourfold improvement has been obtained in the detection limit, permitting the measurement of amplitudes that are as small as 0.25B.
© 1998 Optical Society of America
(120.1880) Instrumentation, measurement, and metrology : Detection
(120.3930) Instrumentation, measurement, and metrology : Metrological instrumentation
(120.7000) Instrumentation, measurement, and metrology : Transmission
A. Palonpon, J. Amistoso, J. Holdsworth, W. Garcia, and C. Saloma, "Measurement of weak transmittances by stochastic resonance," Opt. Lett. 23, 1480-1482 (1998)