Thermometer, Fiber Optic, Probes
Wednesday, September 20, 2006
A Fiber Optic Thermometer has been designed and developed capable of measuring temperatures of minute test samples without disturbing or heat sinking the test sample. The small photodetector mass of the thermometer allows rapid response and high sensitivity transient sensing levels. The probes are nonmetallic, electrically nonconducting, and unaffected by EMI.
The Thermometer uses a temperature sensitive phosphor fixed to the end of quartz Fiber Optic. The Fiber Optic is connected back to the Thermometer. Blue-violet light pulses are sent down the Fiber Optic, causing the phosphor to glow. Decay of the fluorescence after each pulse varies precisely with temperature. This variation provides the basis for temperature measurement at the photodetector with an absolute accuracy of ±0.1 °C. The temperature range is -200 °C to 450 °C. The fluorescent decay time is measured by multipoint digital integration of the decay curve. The Fiber Optic transmits the excitation pulses and returns the fluorescent signal.
A four photodetector array is used for thermal mapping. The array is made from non-fragile 250 μm plastic Fiber Optic in a Teflon sheath. The total outside diameter is less than 0.9 mm and can fit into a specially designed 19 gauge catheter needle.
There are two Thermometer configurations for surface measurement; 1) Phosphor coating on the test sample surface for non contact measurement and 2) Elastometer tipped probe for contact measurement, where the elastometer is clear and can operate as a lens.
Source: None Available
Reference: D. R. Wickersheim, Luxtron, Mountain View, CA;
posted by JD52 @ 8:53 PM,