A compact fiber-optic magnetometer employing an amorphous metalwire transducer

A compact fiber-optic magnetometer constructed using a short piece of amorphous metal wire (5-cm long×100-μm diameter) as the magnetostrictive transducer is discussed. The inherently large ratio of length to cross-sectional area results in a low demagnetization along the axial direction. A magnetostrictive constant of 5×10^-5 /Oe², which is 10-50 times larger than the reported values for transducers made from Metglas ribbons, was measured. Minimum detectable magnetic fields on the order of 10^-5 Oe/Hz^1/2 at 1 Hz were achieved using a 5-cm-long sensing fiber     

Response to comment on Rayleigh-Scattering Calculations for the Terrestrial Atmosphere

Rayleigh optical depths that were calculated by Bucholtz represent an improvement over previous calculations (from 1.4% to 20%) because an updated depolarization factor that varied with the wavelength was used. These optical depths were obtained by integrating standard atmospheric model temperature and pressure profiles over height. This integration is a valid method for obtaining an estimate of the column density and therefore the Rayleigh optical depth, given that small errors (less than 0.7%) will be introduced because of quadrature and inaccuracies in any given model.     

Sideband noise of a large phase carrier in interferometric sensors

Interferometric sensors using balanced detectors and phase stabilisation schemes remain susceptible to laser intensity noise if phase carrier techniques are employed. An intensity stability of 4 × 10?6 is required for the low-frequency side-band noise to be equivalent to microradian phase shift sensitivity if the phase carrier has a peak phase shift of ?/2 rad.     

New nonlinear phase transduction method for DC measurand interferometric fibre sensors

A new approach to the measurement of displacement using optical fibre interferometry is described. The technique is based on a geometrical arrangement in which linear displacement is transposed nonlinearly into axial fibre strain. The technique can be used in the development of true DC sensors for the displacement, acceleration, pressure and other variables. A displacement sensitivity of ?4 ? is demonstrated.     

DC fibre-optic accelerometer with sub-?g sensitivity

We describe a fibre-optic accelerometer, based on the technique of nonlinear displacement-to-strain conversion (NDSC), suitable for use at DC and low frequencies. The sensor exhibits a minimum detectable acceleration of less than 1 ?g RMS (g = 9.8 m/s2) at 0.5 Hz and a linear dynamic range greater than 106.     

Effect of external perturbations on fiber-optic magnetic sensors

The effects of external nonmagnetic perturbations on a fiber-optic magnetic sensor are analyzed theoretically. It is shown that the deleterious effects of these perturbations can be controlled by maintaining the DC magnetic field at prescribed levels. Experiments have been performed with externally applied stresses and accelerations (vibrations) that validate the theory and yield values for the stress and acceleration responsivities of the sensors studied in this investigation. The analysis and techniques given apply equally well to any interferometric sensor using nonlinear transduction mechanisms     

Analysis of the response of long period fiber gratings to externalindex of refraction

This paper demonstrates that the change in wavelength of a long period fiber grating attenuation band with changes in external index of refraction can be enhanced by proper selection of the grating period. We calculate and experimentally verify that the wavelength shift caused by changing the external index from n=1 to n=1.44 of the attenuation band which appears in the 1400-1600 nm region in a 200-μm period grating is four times that in a 350-μm period grating. Changes in the spectrum over a wavelength range from 1100 to 1600 nm and 1相似文献