ABSTRACT
A new type of all-fiber frequency shifter is demonstrated. It is capable of operation at lower frequencies than traditional approaches based on surface acoustic waves and is believed to be unique in not requiring the removal of the fiber buffer coat. For 2.3-W electrical drive the prototype achieved a 2.5% conversion efficiency and greater than 20-dB unwanted sideband suppression.
ABSTRACT
A simple, inexpensive fibre optic spectrophotometric cell has been developed for clinical use. The system may employ one of two indicator reagents for the measurement: phenol red and BDH universal indicator. The spectrophotometer uses two ultrabright LED sources and a PIN diode photodetector. The fibre is of the plastic type with a core diameter of 1.0 mm. Two alternative analytical methods are available: electronic or computer processing. In the case of phenol red the measuring range using computer processing is between 6.0 and 8.0 pH units, with an accuracy of 0.015 pH units. The range for electronic circuit processing is from 6.8 to 8.0 pH units with an accuracy of 0.02 pH units. Using a BDH universal indicator, the range for computer processing is between 5.5 and 8.5 pH units with an accuracy of 0.05 pH units, while with electronic processing the range is between 6.0 and 8.0 pH units with an accuracy of 0.03 pH units. A description of the optoelectronics, an analysis of the indicator reagents and the calibration procedure are presented here, together with some example results.
