Choosing the measuring device, be sure to read its main characteristics. Here we will examine the indicator thermometer sight and the focus. The term was introduced into the pyrometer to describe the optical system of the thermometer and compare them.
Under the sighting index refers to the ratio of the distance (D) between the device and the surface to be measured to the diameter (S) measured on the surface of the spot light. A mandatory rule is not the way the boundaries of the spots for the size of the measured area. If this happens, the indications of the pyrometer will not be stable. As the device determines the average temperature of the spots in this case will be issued “error”.
If you select the measuring device with the close, far or the standard focus for calculating the spot diameter, it is necessary to divide the distance to the measured object (the object) in the numerator of the index of sight, and then the obtained value is multiplied by its denominator.
the Example
Assume that you purchased the model thermometer BALTECH TL-0208C, sighting index which is 50:1. You need to know on a two-meter distance the measuring spot diameter. Divide 2 (the distance) to the numerator of the testimony of sight (50) and multiply the result by the denominator of (1) in this indicator. The result is 0,04 m:
2 : 50 x 1 = 0.04 m or 40 mm.
Note that this calculation will not give correct answer, because the light rays are sometimes not in proportion to diverge at a certain angle. It is often the case with a close focus. Rays from the instrument converge, then diverge. You are given a focus chart or reported distance to the measured surface at which the spot diameter is minimum.
But if you select the measuring device with a fixed type of focus, you will not have to count. Index of sight of these devices means that you should place the thermometer at the distance indicated in the figure. If you have a thermometer with a fixed housing and a sighting index is 203:6.9 mm, then the measuring device shall be placed exactly at a distance of 203 mm from the measured surface (no closer and no further). The size of the measured spots will grow 6.9 mm.
Remember: the Correct guidance of the measuring device for the selected dimension object will guarantee the correct measurements. It is very important to aim the thermometer perpendicular to the surface of the object, i.e. the direction of the normal should be ideally at an angle of 90 degrees to the object.
For temperature control concealed electrical equipment or internal components of electrical cabinets and safe electrical diagnostics we recommend to use the IR window (infrared window) BALTECH TR-055W.