The emissivity and surface characteristics of the target material determine the spectral response or wavelength of the thermometer. For high reflectivity alloy materials, there is a low or varying emissivity. In the high-temperature zone, the optimal wavelength for measuring metal materials is near-infrared, which can be selected from 0.18-1.0 μ M wavelength. Other temperature zones can be selected as 1.6 μ m. 2.2 μ M and 3.9 μ M wavelength. Due to some materials being transparent at a certain wavelength, infrared energy can penetrate these materials, and special wavelengths should be selected for this type of material. If measuring the internal temperature of glass, choose 10 μ m. 2.2 μ M and 3.9 μ M (the measured glass must be very thick, otherwise it will penetrate) wavelength; Selecting 5.0 for measuring the internal temperature of glass μ M wavelength; Selection of low measurement area 8-14 μ The appropriate wavelength is m; For example, selecting 3.43 for measuring polyethylene plastic film μ M wavelength, 4.3 for polyvinyl chloride μ M or 7.9 μ M wavelength. 8-14 for thicknesses exceeding 0.4mm μ M wavelength; Similarly, measuring C02 in flames using narrowband 4.24-4.3 μ M wavelength, narrow band 4.64 for measuring C0 in flames μ M wavelength, measuring N02 in flames using 4.47 μ M wavelength.
The response time represents the reaction speed of the infrared thermometer to the temperature change being measured, defined as the time required to reach 95 percent of the final reading (only 5 percent energy is required for dual color optical fibers). It is related to the time constant of the photodetector, signal processing circuit, and display system. The response time of the new infrared thermometer can reach 1ms. This is much faster than the contact temperature measurement method. If the target's movement speed is very fast or when measuring rapidly heated targets, a fast response infrared thermometer should be selected, otherwise insufficient signal response will be achieved, which 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.
