A simple method for determining surface emissivity to improve infrared camera temperature measurements

Abstract An experimental study was conducted to determine surface emissivity, in a sense, adjust an infrared (IR) camera for temperature determination at approximately 70.0 °C. Because of the importance of emissivity in engineering, many studies have examined emissivity calibration and measurement. However, existing methods are often complex, labor-intensive, and time-consuming, limiting their practicality in both laboratory and real-world applications. To address this issue, we propose a frugal installation consisting of a flat plate of aluminum material in combination of a flat heater and a temperature controller, and an IR camera for in-situ emissivity adjustment and measurement. This setup was experimentally tested to adjust the normal emissivity of the surface, which serves as an approximation of hemispherical emissivity under the assumption of isotropic emission. The evaluation was conducted on a thin aluminum layer deposited via cold spray coating on a flat aluminum sample. In the measurement procedure, the measured temperature in the surface of the thin aluminum layer utilizing the proposed approach closely matched the set temperature, whereas the tape approach resulted in a 2.1 °C deviation. The adjusted IR camera (operating within a spectral range of 7.5–13.0 μm) was then employed to measure the surface temperature of an aluminum coated fused deposition modeled (FDM) flat specimen under heating using a far-IR ceramic heater, which emits radiation across a broader spectral range of 2.0–20.0 μm, where direct contact measurement was impractical and other conventional non-contact approaches, such as reference materials with known emissivity, introduced significant errors. The experimental results aligned well with theoretical determinations, validating the effectiveness of the proposed process of tuning the emissivity parameter input on the IR camera. This approach offers a simple, low-cost, and time-efficient solution for emissivity tuning and measurement, making it suitable for both laboratory and practical applications.