Measurement Bench Research Articles

Improvements to the variable aperture method for measuring the mode-field diameter of dispersion-shifted fibers

The variable aperture system for measuring single-mode fiber mode-field diameter is modified to provide accurate measurements of dispersion-shifted fibers. The system's numerical aperture (NA) is increased by using a spherical mirror and a large aperture wheel with 23 apertures out to 0.556 NA. Petermann's second mode-field diameter (MFD) definition is calculated with Simpson's rule numerical integration. The industrialized high-NA variable aperture method in the far field (VAMFF) system is accurate to within 1%, with a measurement standard deviation of less than 0.5%. Flexibility for measuring various fiber designs over a range of wavelengths is also a key feature. It is concluded that the industrialized high-NA VAMFF system is an excellent MFD measurement bench because of its precision, accuracy, and versatility.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In-Pile Gamma-Ray Spectrometry to Follow OSIRIS Irradiations

A description is given of a gamma-ray spectrometry facility located in the immediate proximity of the OSIRIS reactor core. This device is used to examine nuclear fuel elements in loop or rig throughout the period of irradiation, with no more than a few minutes required to transfer the fuel from the irradiation point to the measurement bench. This internal reactor gamma-ray spectrometry device of original design eliminates corrections for radioactivity decrease and avoids any risk of overlooking relevant data.