Dynamic microforce measurement by distortion detection with a coupled-cavity laser displacement sensor stabilized in a mechanical negative-feedback loop

摘要

A small displacement sensor for dynamically measuring small forces is presented. Employing a coupled-cavity laser configuration constructed with a moving external mirror, this sensor provides high sensitivity with a minimum detectable displacement of 0.8 nm, independently of the lasing wavelength, while the lasing state is mechanically stabilized by a negative-feedback loop to maintain a constant external-cavity length. The sensor is shown to be of great use for detecting extremely small distortions in a stiff cantilever, reflecting transient variations in small friction forces in mechanical systems. (C) 1998 Optical Society of America. OCIS codes: 030.1670, 280.3420. [References: 15]