Non-contact temperature measurement based on Wien’s displacement law using a single webcam in the infrared spectrum region

摘要

The objective of this study is to design a temperature measurement system based on a non-contact method using a sensor camera from a webcam. The material being measured is nickel wire given an electrical current of 4.5 A–6.5 A with an interval of 0.5 A. The temperature measurement is based upon the measurement of the average pixel value distribution of infrared (IR) electromagnetic waves emitted by the measured material, i.e.: the nickel wire. The IR waves are passed through a diffraction grating and then captured by the sensor camera consisting of red, green, and blue layers. Calculation of the temperature is conducted by way of Planckian distribution as a model for the average pixel value distribution in the IR regions producing Wien’s displacement law. Results show that the IR wavelength at maximum average pixel value shifts to a shorter wavelength as the nickel wire is heated in accordance with Wien’s displacement law. Moreover, the Wien’s constant is recovered for the temperature calculation of the red and green layers, which shows the best model for the non-contact measurement system. However, the temperature measurement still contains a systematic error that shifts the calculated temperature in contrast to the true temperature. This systematic error may be reduced by adjusting the measurement system set-up.