The development of the real-time Michelson interferometer for the measurement of thermal expansion coefficients of dental composites nanofiller

This study aims to design a thermal time-based expansion coefficient sensor system using a nickel interferometer that uses a 6 Watts heater to produce a similar oral cavity temperature of 30°C to 60°C. The light source used was the He-Ne Laser, with a wavelength of 632.8 nm. Hollow cylindrical samples with an outer diameter of 1.1 cm, an inner diameter of 1 cm, and a height of 1.5 cm were placed in the sample box behind one of the Michelson Interferometer mirrors. The interference pattern (fringes) formed was recorded using a webcam and counted using the principle of motion detection in the Delphi program. The temperature sensor used was LM 35 with LM 358 amplifier. The resulting voltage output was converted to a temperature value with Arduino. The data were then displayed on a PC with the Delphi interface. The purposely written Delphi program has four functions: recording and counting fringes, displaying temperature, and calculating the thermal expansion coefficient of acrylic resin and nanofiller composite. The generated data in the study included the heating time for 25,421 seconds to produce a temperature of 60°C, delay of (0,802 ± 0,006) second with the sensor performance of 99,76%, and software performance of 98,18%. In three data collections, the average thermal expansion coefficient of resin acrylic was (111.37 ± 10.93). 10-6 / ° C with an error percentage of 23.74% from the literature, while for the composite nanofiller samples, we obtained (49.6 ± 0.95). 10-6 / ° C with an error percentage of 6.9% from previous studies.