Method and device for measuring the thickness of a layer of material

A method for measuring the thickness of a layer of first material, the method comprising:

• acquiring at least one frequency response of the layer of first material via a microwave sensor;
• setting the microwave sensor on a plurality of specimens of second materials for different temperature values to obtain reference data;
• calibrating the microwave sensor as a function of the electrical conductivity of the first material using the reference data;
• measuring the temperature of the layer of first material via a temperature sensor;
• determining measurement parameters of the layer of first material from the frequency response;
• and
• processing the reference data with the measurement parameters and the measured temperature to obtain a measurement of the thickness of the layer of first material, in which said processing the reference data envisages processing second ones of said reference data, in which said second reference data comprise data of thickness of said specimens of second materials having one and the same electrical conductivity, for a plurality of given temperature values, in which said data of thickness are obtained as the working frequency of the microwave sensor varies for each of said plurality of temperature values, in which said measurement parameters comprise a first intercept frequency determined by processing a first range of values of working frequency of the microwave sensor corresponding to a first range of values of amplitude of said frequency response of the layer of first material, in which said range has a given extension of value and is centred around a value of amplitude equal to said calibration parameter, in which said measurement parameters comprise a second intercept frequency determined by processing a second range of values of working frequency separate from said first range of values of working frequency and corresponding to said first range of values of amplitude;
• and a value of minimum amplitude of the same frequency response, said value of minimum amplitude being obtained by processing a second range of values of amplitude corresponding to a third range of values of working frequency comprised between the first and the second intercept frequencies, in which said processing the reference data with the measurement parameters envisages processing said first and second intercept frequencies together with said value of minimum amplitude of the layer of first material by means of an artificial neural network in such a way as to increase the precision on said measurement of thickness.

A device for measuring the thickness of a layer of first material;

• the device comprising control means, and read means connected to the control means and designed to be set in contact with the layer of first material;
• the control means comprising a storage unit, an interface unit for communication with the read means, and a processing unit connected for communication with the storage unit and the interface unit;
• the read means comprising a microwave sensor and a temperature sensor;
• the processing unit being loaded with a control program designed for implementing, when run, operations comprising:
• acquiring at least one frequency response of the layer of first material via a microwave sensor;
• setting the microwave sensor on a plurality of specimens of second materials for different temperature values to obtain reference data;
• calibrating the microwave sensor as a function of the electrical conductivity of the first material using the reference data;
• measuring the temperature of the layer of first material via a temperature sensor;
• determining measurement parameters of the layer of first material from the frequency response;
• and processing the reference data with the measurement parameters and the measured temperature to obtain a measurement of the thickness of the layer of first material, wherein calibrating the microwave sensor comprises determining a calibration parameter as a function of the electrical conductivity of the first material and of first ones of said reference data.