TInfrared pyrometers were non-contacting optical devices which intercepted and evaluated the visible radiation emitted by glowing objects.

What is an Infrared Thermometer?

An infrared thermometer, sometimes called an infrared pyrometer or radiation thermometer, is a device used for non-contact temperature measurement. Infrared thermometers are most often applied to measure the surface temperature of an opaque object. They are also used to measure a semi-transparent target such as high temperature combustion gas or molten glass that acquires the measurement into a depth of the target. Non-contact temperature measurement can be made over a wide range of distances, provided the sight path is free and clear of potential sources of error such as steam, dust, mechanical obstructions, dirty windows etc. 

Why should I use an infrared thermometer to measure temperature in my application?

An infrared pyrometer measures temperature in applications where it is not possible or practical to make contact with the target using a thermocouple or other contact sensor.
Non-contact temperature measurement is preferred or required under the following conditions:
The target is moving or is not accessible to a contact probe.
The target or the environment which encompasses the target is too aggressive, hazardous or would otherwise adversely influence the output signal of a contact probe.
Contact with the target would damage the surface or adversely influence the temperature measurement when in contact with the surface.
The temperatures to be measured are too high for the respective thermocouple or other type of contact probe. Infrared pyrometers can reduce maintenance costs dramatically due to their long life in contrast to the costly replacement of high temperature thermocouples which can fail, or are consumed frequently due to process conditions.

How does an infrared thermometer work?

Infrared thermometers detect radiation in the infrared portion of the electromagnetic spectrum which is adjacent to the portion where visible light exists.

The basic components of an infrared thermometer include a lens, filter(s) for the required infrared wavelength response, a detector, and electronics to process the received infrared energy into an output expressed as temperature. Mathematical principals developed in the 1800’s were completed by Max Planck in 1900 who gave us the formula that is still used today to convert infrared radiation into a temperature value.  

Is there a difference between a Pyrometer and a Thermometer?

The terms "infrared thermometer" and "infrared pyrometer" are often interchangeable terms used by end users and vendors alike.
Pyrometer comes from the Greek words meaning fire and measurement, which originally was used to describe an instrument that measured high temperatures, for both non-contact and contact instruments. Thermometers historically read lower temperatures. 
Today, infrared thermometers can measure both high and low temperatures.
The first non-contact pyrometer responded to visible light instead of infrared radiation. This pyrometer is known as an optical pyrometer or disappearing filament pyrometer, and is limited to measuring temperatures high enough for the object to emit visible light. The point at which an object begins to emit visible light is approximately 550 °C when no ambient light is present. A subset of available thermocouples which measure high temperature by contact are also referred to as pyrometers.
What other names are used by our customers to describe infrared pyrometers & infrared thermometers?
Radiation thermometer, infrared radiation thermometer, infrared temperature sensor, non-contact temperature sensor, non-contact thermometer, IR sensor, infrared radiometer, heat gun, IR gun and, although technically incorrect, an optical pyrometer.

Pyrometer for Machine Manufacturers – PyroMini OEM CALEX - UK. Save space and cut costs with the new PyroMini OEM from Calex. This infrared pyrometer has a miniature sensing head that can be used in ambient temperatures of up to 120°C with no need for cooling.

The sensor’s fixed emissivity setting of 0.95 makes it extremely simple to set up, and allows it to measure non-reflective non-metal surfaces with industry-leading accuracy and repeatability. A response time of just 240 ms provides a near-instant measurement of the surface temperature.

Materials such as rubber, paper, wood, thick plastics, textiles, asphalt, resins and organic materials can all be measured with the PyroMini OEM pyrometer, and other materials including metals can also be measured if an area of the surface is painted first. Other materials can also be measured using alternative sensors – contact Sensors Vietnam for more information.

A choice of analogue outputs is available: two-wire 4-20 mA, as well as four-wire Type J or K thermocouple, and 0-10 V DC.

The miniature sensing head with right-angled cable entry measures just 55 mm in length, including the sensor’s mounting thread. The separate electronics module has a small, lightweight housing that also fits into restricted spaces in machinery.

Example applications:

Paper and corrugated board manufacturing: web temperatures are measured quickly and accurately, and the 120°C ambient temperature capability allows the sensor to be installed near heated machinery such as calender rolls and single facers.

Curing: Resins, powder coatings, composite materials and printed textiles can all be measured with precise results and a near-instant response time. The non-contact sensor provides a non-invasive way to measure the surface temperature as the object cures. The sensing head can be installed inside ovens and dryers, and near infrared heaters, provided the ambient temperature is below 120°C.

Heated Rollers: Roll surface temperatures are easily measured provided the roll surface is non-reflective (e.g. silicone or rubber coated), or if a measurable band is painted around the roll. The PyroMini is ideal for machinery in the textile, food, rubber, plastic, laminating and converting industries among others.

Power Distribution: Measuring the temperature of electrical joints, transformers and batteries can provide early warning of deterioration, and help plan preventative maintenance.

This low-cost pyrometer can also be used in many more industrial applications than those described above.