The Development Of The Optical Fiber High-tempertature Thermometer

The measurement of high-temperature is the emphasis and the difficult point in temperature measurement fields.There are many kinds of theory method and practical application of the high-temperature measurement.The working characteristics include high temperature,changing quickly,bad conditions, large technical difficulties, unrepeatable one-time process.In order to measure the high-temperature of the medium accurately,this paper puts forward the contact and non-contact method of temperature measurement that includes sensing probe of Sapphire optical fiber and conveying medium of normal quarz optical fiber.The theoretical basis of high-temperature measurement is the blackbody radiation laws,like Planck law and Lambert law etc.The calculation method of emission rate is Gouffe radiation law.The method of the temperature measurement is the color-comparing method.Using the color-comparing method is able to measure the high temperature effectively,but the temperature measurement exist certain temperature deviation due to the influence of the whole system structure and On-site environment.In the different links of temperature measurement system,there are two aspects at reducing deviation.They are the optical fiber loss deviation,the radiant heat deviation between sapphire optical fiber and air around.Using the color-comparing method,the real temperature of medium can be gave and measured.The whole optical fiber high-temperature thermometer consists of sapphire optical fiber blackbody cavity,tapered fiber,ordinary transmissive fiber,narrowband filter, low noise photoelectric detector, data processing system and upper computer.The low noise photoelectric detector consists of the Si-diode and the two stage amplifier circuit.Use the ARM Cortex-M3processor as the core processor to complete the temperature conversion, display,storage and transmission.Use the IAR Embedded Workbench software to debug and load program.Use the LabVIEW software as the upper computer interface to diplay and analyse the temperature signal.