Infrared thermometer signal processing function explains how to determine the wavelength range:
The emissivity and surface characteristics of the target material of the online thermometer determine the spectral response or wavelength of the thermometer. For high reflectivity alloy materials, there is a low or varying emissivity. In high-temperature areas, the optimal wavelength for measuring metal materials is near-infrared, which can be selected as 0.18-1.0 μ m wavelength. Other temperature zones can use wavelengths of 1.6 μ m, 2.2 μ m, and 3.9 μ m. Due to some materials being transparent at certain wavelengths, infrared energy can penetrate these materials, and special wavelengths should be selected for these materials. If measuring the internal temperature of glass, wavelengths of 1.0 μ m, 2.2 μ m, and 3.9 μ m (the measured glass should be very thick, otherwise it will pass through) should be selected; Measure the internal temperature of the glass using a wavelength of 5.0 μ m; It is advisable to use a wavelength of 8-14 μ m for measuring low areas; For example, when measuring polyethylene plastic film, a wavelength of 3.43 μ m is used, while for polyester, wavelengths of 4.3 μ m or 7.9 μ m are used. Select wavelengths of 8-14 μ m for thicknesses exceeding 0.4mm; For example, CO2 in flames is measured using a narrowband wavelength of 4.24-4.3 μ m, CO in flames is measured using a narrowband wavelength of 4.64 μ m, and NO2 in flames is measured using a narrowband wavelength of 4.47 μ m.
Explanation of signal processing function of infrared thermometer to determine response time: Response time represents the reaction speed of the infrared thermometer to changes in the measured temperature, defined as the time required to reach 95% energy of the final reading. It is related to the time constant of the photodetector, signal processing circuit, and display system. This is much faster than contact temperature measurement methods. If the target is moving at a fast speed or when measuring rapidly heated targets, a fast response infrared thermometer should be selected, otherwise it will not achieve sufficient signal response and will reduce measurement accuracy. However, not all applications require fast response infrared thermometers. When there is thermal inertia in a stationary or target thermal process, the response time of the thermometer can be relaxed. Therefore, the selection of response time for infrared thermometers should be adapted to the situation of the target being measured.
