A laser-pumped temperature sensor using the fluorescent decay time of alexandrite

In this work a simple intensity-independent fiber-optic temperature sensor using alexandrite crystal was constructed. The sensor uses the change in the characteristics of the fluorescence of the material to sense the parameter required and operates using light from an electrooptically modulated He-Ne laser at 633 nm. Microprocessor control and signal processing is used to achieve an accuracy of
\sim \pm1\deg
C with a 3-s response.