Factors of influence on far-infrared thermometers
The principle of far infrared thermometer
Infrared thermometer consists of optical system, photoelectric detector, signal amplifier, signal processing, display output and other parts. The radiation from the measured object and the feedback source is modulated by the modulator and then input to the infrared detector. The difference between the two signals is amplified by the inverse amplifier and controls the temperature of the feedback source so that the spectral radiance of the feedback source is the same as the spectral radiance of the object. The display indicates the brightness temperature of the object being measured
Factors affecting far infrared thermometer
1. The relationship between the size of the temperature measurement target and the temperature measurement distance: At different distances, the effective diameter D of the measurable target is different, so when measuring small targets, pay attention to the target distance. The definition of the distance coefficient K of the infrared thermometer is: the ratio of the distance L of the measured target to the diameter D of the measured target, that is, K=L/D
2. Select the emissivity of the material to be measured: Infrared thermometers are generally classified according to black bodies (emissivity ε = 1.00), but in fact, the emissivity of materials is less than 1.00. Therefore, when the true temperature of the target needs to be measured, the emissivity value must be set. The emissivity of a substance can be found in the "Data on the Emissivity of Objects in Radiation Thermometry".
3. Measurement of targets in a strong light background: If the target to be measured has a bright background light (especially if it is directly exposed to sunlight or strong lamps), the accuracy of the measurement will be affected. Therefore, objects can be used to block the strong light directly hitting the target. Eliminate background light interference.
4. Measurement of small targets
⑴The thermometer should be fixed on a tripod (optional accessory)
⑵ It is necessary to adjust the focus accurately, that is: use the small black dot in the eyepiece to align the target (the target should be filled with small black dots), adjust the lens back and forth, and shake your eyes slightly. If there is no relative movement between the small black dots to be measured, adjust the focus. The focus is complete
5.Temperature output function
(1) Digital signal output - RS232, RS485, temperature signal remote transmission
(2) Analog signal output - 0~5V, 1~5V, 0~10V, 0/4~20mA, which can be added to closed-loop control.
(3) High alarm and low alarm - If the temperature is required to be controlled within a certain range during the production process, high and low alarm values can be set. High alarm: When the high alarm setting is turned on, when the temperature is higher than the high alarm value, the corresponding LED light flashes, the buzzer sounds, and the AH normally open relay is connected.
