Applications

Non-contact tachometers determine rotational speed by detecting reflected optical signals from a rotating target. Within the specified operating distance, measuring distance normally does not directly change the instrument’s stated accuracy. However, excessive or unsuitable distance can weaken the reflected signal, enlarge the detection area, increase interference, and lead to unstable, missed, or incorrect readings.

Non-contact tachometers typically determine rotational speed by detecting periodic reflected-light signals from reflective tape. Direct sunlight, high-intensity LED lighting, strobe lights, and welding arcs can increase background light and reduce signal contrast, resulting in fluctuating readings or detection failure. Proper alignment, shorter measuring distances, shielding from strong light, and correct use of reflective tape can significantly improve measurement stability.

Black rotating objects can be measured with a laser tachometer, but dark, matte, or low-reflectivity surfaces may return insufficient light to the optical sensor. This can result in no reading, fluctuating values, or poor repeatability. In most industrial applications, applying reflective tape to the rotating part provides a clear optical reference and improves measurement reliability.

Non-contact laser and optical tachometers typically work best with one effective reflective mark per revolution. If several reflective tapes are detected during each rotation, the tachometer may count multiple pulses and display an RPM value several times higher than the actual speed. This article explains how reflective mark quantity affects RPM measurement and when multiple marks may be used intentionally.

A difference between two infrared thermometer readings does not necessarily indicate a fault. Emissivity, measurement distance, spot size, viewing angle, reflected background radiation, instrument accuracy, and surface temperature distribution can all affect the result. Reliable comparison requires both instruments to be used under controlled and consistent conditions.

Over time, the optical system, infrared sensor, electronics, and temperature compensation of an infrared thermometer may change slightly. Regular performance verification helps confirm that measurement error, repeatability, and overall operating condition remain within specification. This article explains why verification is important, how often it should be performed, common verification methods, and situations that call for an earlier check.

Different areas of the same object are not necessarily at the same surface temperature. Local heating, heat dissipation, surface condition, emissivity, measurement spot size, and reflected background radiation can all cause temperature differences. This article explains the main causes and how to determine whether the observed difference is real or measurement-related.

When an infrared thermometer is used on a moving belt, conveyor, or rotating roller, the displayed temperature may continuously fluctuate. This does not necessarily indicate an instrument fault. Variations in surface temperature, emissivity, surface condition, measurement spot position, motion, and reflected radiation can all affect the reading. Stable distance, angle, and target area help improve measurement repeatability.

Most infrared thermometers can perform continuous scanning while the trigger is held, and some models also provide lock, continuous measurement, or data logging functions. However, suitability for extended operation depends on the instrument design, power supply, ambient conditions, and measurement setup. For unattended or long-term monitoring, a dedicated fixed infrared temperature sensor is usually more appropriate.

Infrared thermometers require a stable power supply for the infrared detector, signal-processing electronics, display, and other circuits. Under normal conditions, voltage regulation and low-battery detection help maintain reliable operation as battery voltage decreases. However, if the battery voltage becomes too low, unstable readings, abnormal response, display issues, or measurement failure may occur. Replacing the battery promptly helps maintain measurement reliability.

When an infrared thermometer displays “OL,” it does not necessarily indicate a malfunction. In most cases, the measured temperature or signal is outside the instrument’s valid measurement or display range. Excessively high or low target temperatures, as well as certain abnormal measurement conditions, may trigger this indication. This article explains the common causes of OL and how to troubleshoot them correctly.

When an infrared thermometer displays HI or LO instead of a normal temperature reading, it does not necessarily indicate a fault. HI usually means the detected temperature is above the instrument’s measurement range, while LO means it is below the range. On some models, HI and LO may also refer to high- and low-temperature alarm settings. This article explains the common meanings, causes, and troubleshooting methods.