Rencnt measurements with Ru~(2+) oxygen sensors, using doped sapphire crystals, both as a calibration aid and an integral emperature sensor

摘要

Recnet measurements are presented, using an improved, real-time, all-optical snesor for simultaneous measurement of dissolved oxygen and temperature. The sensor has a small Cr~(3+) -doped sapphire (ruby) thermal monitoring crystal mounted at the probe tip, to hwich is bonded a Ru~(+) -based oxygen-indicator membrnae. The probe may be interrogated in real-time, using, for both temperature and oxygen monitoring, the same combination of blue LED, light source, optical filter set, photomultiplier detector and digital processor. The ruby crystal also provides a fluorescent intensity reference, for possible on-line self-testing of the interrogation hardware. By examining the relative intensitites from ruby and the membrane, mechanical damage, detachemnt or photo-bleaching of the sensing membrane may also be recognised. Recent developments of our novel, Ti~(3+) -doped sapphire fluorescence-lifetime caliration probe are reported. These confirm that the fluorescence lifetime of the probe can e thermally controlled in a reliable manner. This calibration probe then allows multi-point calibration of Ru~(2+)-chemical sensors.