RADIATION THICKNESS METER AND MEASURING METHOD OF THICKNESS BY USING RADIATION

摘要

PURPOSE:To dispense with a radiation detecting element and thereby to simplify construction and to facilitate manufacture and maintenance by using a pressure gauge and a thermometer measuring the pressure and temperature of a gas respectively. CONSTITUTION:A radiation detector 4 disposed opposite to a radiation source 2 at a prescribed gap G detects a radiation 2a and outputs a first detection signal 4a. A preamplifier 6 converts this signal into a voltage signal and outputs a second detection signal 6a having a voltage E. A pressure gauge 18 detects the pressure P of a gas 12 in a measuring space 5, while a thermometer 19 detects the absolute temperature T thereof, and they output a pressure signal 18a and a temperature signal 19a respectively. A signal processing element 20 receiving the signals 6a, 18a and 19a as inputs stores a value Eoa of the voltage E, a value Pa of the pressure P and a value Ta of the temperature T obtained by input of a first control signal 20a, at the time t1 in a state wherein a substance 11 to be measured is not inserted into the space 5. Besides, it computes the right member of an equation by using a voltage value Ex, a pressure value Pb and a temperature value Tb obtained by input of a second control signal 20b at the time t2 later than the time t1 and also the values Eoa, Pa and Ta, and outputs a thickness signal 20c showing X as a result. According to this constitution, the measurement of a thickness is enabled.