The size of the target and the optical resolution of the two-colour infrared thermometer
Infrared thermometer according to the principle can be divided into monochrome pyrometer and two-colour pyrometer (radiation colourimetric pyrometer). For single-colour pyrometer, when the temperature measurement, the measured target area should be full of pyrometer field of view. It is recommended that the target size exceeds 50% of the field of view size. If the target size is smaller than the field of view, the background radiant energy will enter the pyrometer's visual acoustic signature and interfere with the temperature reading, resulting in an error. Conversely, if the target is larger than the pyrometer's field of view, the pyrometer will not be affected by background outside the measurement area.
In the case of a two-colour pyrometer, the temperature is determined by the ratio of the radiant energy in two separate wavelength bands. Therefore, when the measured target is small, not filled with the site, the measurement path there is smoke, dust, obstruction to the radiant energy attenuation, will not have an impact on the results of the measurement. Even in the case of energy attenuation of 95%, can still ensure that the required temperature measurement accuracy. For the target is small, and in motion or vibration of the target; sometimes in the field of view of the movement, or may be partially out of the field of view of the target, under these conditions, the use of two-colour pyrometer is the best choice. If the pyrometer and the target between the possibility of direct aiming, measurement channel bending, narrow, obstructed, etc., dual-colour fibre optic pyrometer is the best choice. This is due to its small diameter and flexibility, which allows it to transmit optical radiation energy over curved, obstructed and collapsed channels, thus allowing measurement of targets that are difficult to access, in harsh conditions or close to electromagnetic fields.
Optical resolution of two-colour infrared thermometers
Optical resolution (distance and sensitivity) is determined by the ratio of D to S. It is the ratio of the distance D from the pyrometer to the target to the diameter of the measured spot S. If the pyrometer must be installed far from the target due to environmental conditions, and to measure small targets, you should choose a high optical resolution pyrometer. The higher the optical resolution, i.e. the larger the D:S ratio, the higher the cost of the pyrometer.
