As all infrared temperature sensors, pyrometers and infrared thermometers have a distance to spot ratio D:S (optical resolution), it is important to know the measuring distance from the sensor to the measured object and how large the measuring spot of the measured object should be.

A laser sighting aid or a laser pointer function can be helpful for correctly aligning the pyrometer with the measurement object.
Once the ratio of measuring distance to measuring spot is known, it is important to select a suitable sensor with the correct optical resolution in order to achieve accurate temperature readings.

When selecting the appropriate sensor optics, it should be ensured that the measurement object completely fills the measurement spot of the sensor.