Modernization of the calorimetric method for temperature monitoring of material processing in microwave chamber based on parallel type of addressed fiber Bragg structure

Modernization of the calorimetric method for measuring the distribution of thermal fields in a closed microwave working chamber for monitoring the parameters of processing material heating by matrix of discrete thermos converters (TC) made of absorbing material is proposed. To solve the problem of reducing the cost of the TC interrogation system and improving its metrological characteristics, it is proposed to use addressable fiber Bragg structure (AFBS) built into each TC and microwave photonic systems for interrogating the obtained sequence of TC AFBSs connected by an optical fiber, which in addition to high sensitivity and high response speed to temperature changes, should provide the operator with information about the number of the interrogated matrix element (TC-address). Experimental results show that the accuracy of temperature measurements in this case increases by at least an order of magnitude comparing with classical fiber Bragg grating (FBG). In addition, the complexity of implementing the procedures and the methodological errors in measuring temperatures inherent in the basic calorimetric method are eliminated, which allows using the modernized method both at the design stage of working chambers and at the stage of their operation. Main problem which is decided in paper is extension of AFBS element length, because the length of TC is only 15 mm, and defined by processing wave length of electrical microwave field. Typical AFBS element length can be near 5 mm and common length of AFBS is 15 mm. But the error of measurements in this case will be low and defined by element length.