Thermometer determines wavelength range and response time
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 high-temperature areas, the optimal wavelength for measuring metal materials is near-infrared, and a wavelength of 0.18-1.0 μ m can be selected. Wavelengths of 1.6 μ m, 2.2 μ m, and 3.9 μ m can be selected for other temperature ranges. 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, select wavelengths of 10 μ m, 2.2 μ m, and 3.9 μ m (the measured glass must be very thick, otherwise it will pass through); Measure the internal temperature of the glass using a wavelength of 5.0 μ m; It is advisable to choose a wavelength of 8-14 μ m for low measurement areas; For example, when measuring polyethylene plastic films, a wavelength of 3.43 μ m is selected, while for polyvinyl chloride, a wavelength of 4.3 μ m or 7.9 μ m is selected. When the thickness exceeds 0.4mm, choose a wavelength of 8-14 μ m; For example, measuring C02 in flames uses a narrowband wavelength of 4.24-4.3 μ m, measuring C0 in flames uses a narrowband wavelength of 4.64 μ m, and measuring N02 in flames uses a wavelength of 4.47 μ m.
Determine response time:
The response time represents the reaction rate of the infrared thermometer to changes in the measured temperature, defined as the time required to reach 95% of the final reading energy. It is related to the time constant of the photodetector, signal processing circuit, and display system. The response time of Bytek's 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 it cannot achieve sufficient signal response and will reduce measurement accuracy. However, not all applications require fast responsive 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.
