| 摘要 |
A grating sensor (15, 45, 75) and method for optical interrogation (11, 41, 71) of that sensor uses a lock- in technique to achieve simultaneous measurements of strain (and related temperature) and ultrasonic stress wave signals, as well as other environmental conditions that affect a reflection spectrum of the grating sensor. It achieves this by using a lock-in amplifier (21) or a software demodulator (53, 83) to detect slight shifts in the grating reflection spectrum with high sensitivity and accuracy. A dynamic feedback loop based on the lock-in error signal output (29, Verror) retunes the light wavelength of the light source (e.g., a tunable laser) (11, 41) or of a wavelength filter (76) in the reflection path to maintain it relative to a specified reflection point of the grating reflector. The lock-in error signal serves as a measure of temperature /strain changes and of ultrasonic vibrations. |
