The Application Of VT-DBR Laser In Transparent Media Structure Measurement

Float glass is currently the most efficient way to produce high quality flat glass.In order to improve the production efficiency of float glass,process parameters such as glass thickness need to be continuously monitored in real time.This is especially important when the production line is switching glass thicknesses.The traditional way of glass thickness monitoring is to measure the formed glass at the cold end of the production line.In this paper,a non-contact glass thickness measurement system based on white light interferometry demodulation method with VT-DBR(Vernier Tuned-Distributed Bragged Reflector)laser is developed according to the application requirements of float glass production industry and the limitations of existing technologies.By measuring the reflected interferometric laser signal from the glass surface and analyzing the data,the online high-precision measurement of glass thickness is achieved.The measurement probe has no electrical component and can be located outside the hightemperature region of the glass surface to achieve glass thickness measurement,reducing the requirement for probe cooling and high-temperature protection measures,which is suitable for the hot-end application of float glass production lines.This paper first analyzes the background of domestic and international research in the field of glass thickness measurement,discusses various laser detection methods such as geometric optical thickness measurement,laser interferometric thickness measurement,laser external aberration measurement and laser confocal thickness measurement,and compares the advantages and disadvantages of several laser detection methods before choosing white light interferometry based on wavelength phase-shift as the main research method in this paper.The VT-DBR laser stands out among many light sources and becomes the main research object of this paper due to its superior features such as wide wavelength tuning range(>40 nm),small tuning interval(pm),short wavelength switching time(<20 ns),fast tuning frequency(k Hz)and low cost.This paper uses Altium Designer to design the hardware of the thickness measurement system,which includes the laser driver circuit,photoelectric detection circuit,modulus acquisition circuit,communication circuit and temperature control circuit;uses Quartus II to write the control code of the thickness measurement system;uses Lab VIEW to write the upper computer control program of the thickness measurement system.This paper performs feasibility verification experiments on the system functions,such as laser lighting experiment,single wavelength stability experiment,modulus acquisition experiment,etc.The experimental results show that the self-researched thickness measurement system has good stability and practicality.In this paper static and dynamic thickness measurements of glass samples with thicknesses of 2 mm,7 mm and 12 mm were conducted using the thickness measurement system,and the performance was compared with the existing measurement equipment in the laboratory.The experimental results show that the system is competitive in terms of technical performance and product cost,and can be useful for improving the production efficiency of float glass.thickness measurements were also carried out on a three-layer structure sample,and the results show that the self-researched system is capable of performing measurements on transparent media structures.