Shopping cart

Live Chat

Infrared Pyrometers and the Science of Radiation Thermometry.

In the realm of precision temperature measurement, AST (Accurate Sensors Technologies) has emerged as a pioneering force, offering advanced infrared pyrometers that redefine the way industries monitor and control temperature. Pyrosales distributes AST products to many different industries.

Ast El50 3 ImageRadiation Thermometry: The Foundation of Infrared Thermometers

Infrared thermometers, often referred to as pyrometers or radiation thermometers, belong to subset of devices known as “thermal radiation thermometers.” These non-contact thermometers measure the temperature of an object based on the thermal radiation it emits. AST infrared pyrometers excel in this domain, offering precise readings without physical contact.

Origins of Thermometer: A Historical Perspective

Screenshot 2023 12 21 131414 ImageThe journey of the thermometer traces back to 1612 when Santorii published the earliest account of this temperature-measuring device. Gabriel Fahrenheit’s invention of the first mercury thermometer in 1714 marked a significant milestone in thermometer evolution. Meanwhile, the origins of infrared energy can be attributed to Sir William Herschel, an astronomer credited with discovering infrared energy in the 1800’s.

Herschel’s groundbreaking experiment involved using a prism to spread sunlight into the colour spectrum. By employing thermometers with blackened bulbs, he measured temperatures across different colours, discovering an increase temperature beyond the visible red range. This led to the term “calorific rays,” now known as “infrared” energy. Over time, advancements in technology have refined and shaped the contemporary infrared pyrometer, such as AST innovating offering.

How Infrared Thermometers Work.

Screenshot 2023 12 21 132016 ImageInfrared pyrometers measure temperature from a distance, ranging from kilometres to a fraction of an inch. These thermometers operate on the principle of black body radiation, where objects above absolute zero emit infrared radiation. The higher the temperature, the more rapidly molecule within the object move, emitting infrared radiation. The higher the temperature, the faster the molecules move. As they move, the molecules emit infrared radiation, a type of electromagnetic radiation below the visible spectrum of light. As they get hotter, they emit more infrared, and even start to emit visible light. That is why heated metal can glow red or even white. Infrared thermometers detect and measure this radiation. Infrared light works like visible light it can be focused, reflected, or absorbed. Infrared thermometers usually use a lens to focus infrared light from one object onto a detector called a thermopile. The thermopile absorbs the infrared radiation and turns it into heat. The more infrared energy, the hotter the thermopile gets. This heat is turned into electricity. The electricity is sent to a detector, which uses it to determine the temperature of whatever the thermometer is pointed at. The more electricity, the hotter the object is.

Infrared Pyrometers utilise lenses to focus infrared light onto detector called a thermopile. This component absorbs the infrared radiation, converting it into heat. The amount of electricity generated correlates with the temperature of the objects being measured. This process enables AST infrared pyrometers to provide accurate and rapid temperature readings.

Glass 8 ImageApplications and Uses of Infrared Thermometers.

The applications of infrared thermometers are extensive and diverse. Industries such as steel, glass, and electrical frequently utilise these instruments for temperature monitoring. AST infrared pyrometers, including fixed, portable, and high-temperature variants, cater to the specific needs of various industrial processes.

Advantages of Using AST Infrared Pyrometers.

Pyrometers offer a host of advantages, making them indispensable in industrial applications:

  • Remote temperature measuring without physical contact.
  • Availability in different spectral ranges tailored for specific applications.
  • Digital and robust features with compact electronic components.
  • Minimal maintenance due to durability in harsh environments.
  • Rapid response time within milliseconds.
  • Easy operation and handling.
  • Economic with high accuracy.
  • Capability to measure a wide variety and high temperature ranges.
  • Remote mounting options for hot targets.
  • Suitable for hazardous or inaccessible areas.
  • Immune to electromagnetic fields, ensuring accurate readings.


What to consider when setting up a pyrometer system?

Setting up a pyrometer system in your industrial process there are a few crucial factors to consider, we have set up a few pointers on how to select what you require for your system.

Factor 1. You need to know what temperature range you need to measure, the distance between the pyrometer and the targeted object and any other specific requirements for your industrial measurement application.

Factor 2. Once you have determined your measurement requirements you need to select the correct pyrometer. There are many options with different configurations each one suited to different industrial applications. It is better to use a specialist like us Pyrosales to assist you in your selection with our expertise who can assist you in the correct selection.

Factor 3.  The installation of the pyrometer system will require a specialist to ensure the pyrometer or pyrometers are mounted correctly and securely so there is no chance of vibration. Aligned with the targeted objects is crucial to have accurate temperature measurement.

Factor 4. The plant control system needs to be installed or connected to the pyrometer or pyrometers so monitoring can commence. You will need to configure your control system to receive the pyrometers signal and use it to control your temperature process.

Pyrosales works very closely with our distributor of pyrometers Accurate Sensor Technologies (AST). An example of an AST system being used.

Example of Pyrometers for a Lab Grown Diamond.

Screenshot 2023 12 21 133042 ImagePlasma Chemical Vapour Deposition (PCVD) is a technique by which lab growing diamonds can be grown from a hydrocarbon gas mixture. In the CVD process, a thin slice of diamond seed (often an HPHT produced diamond) is placed in a sealed chamber at high temperature and high pressure. The chamber is then filled with a carbon rich gas (usually methane) along with other gases. Then, the gases are ionised into plasma using microwaves, lasers, or other techniques. The Ionisation breaks the molecular bonds in the gases and the pure carbon adheres to the diamond seed and slowly builds up into up into a crystal, atom by atom and layer by layer form.

The method for producing diamonds includes positioning a diamond in a holder such that a thermal contact is made with a side surface of the diamond adjacent to an edge of a growth surface of the diamond, measuring temperature of the growth surface of the diamond to generate temperature measurements, controlling temperature of the growth surface based upon the temperature measurements and growing single crystal diamond by microwave plasma chemical vapour deposition on the growth surface, wherein the growth rate of the diamond is greater than 1μm per hour. In this entire process temperature plays a critical role. We need to measure the temperature of the target diamond rather than the plasma.

Temperature Measurement by Infrared Pyrometers.

Screenshot 2023 12 21 133109 ImageA non-contact temperature measurement device is positioned to measure the temperature of the diamond across the grown surface of the diamond. The pyrometer is mounted on a glass window of a chamber to read the temperature of target diamond. The challenging part of the application is Plasma emits IR energy at specific wavelengths and we need to measure consistent temperature of the target through the plasma. AST offers non-contact type IR based Pyrometer which works in selected wavelength where plasma is transparent.

Key Features

  • Temperature Range – 350°C to 1800°C
  • Fast response time in millisecond
  • Laser sighting
  • Connectivity via USB 2.0, Bluetooth V2.0 and RS-232 or RS-485 Serial interface
  • Measure the temperature of target through plasma at specific wavelength.


Pyrosales offer all AST models of Infrared Pyrometers. Pyrosales engineers are available to consult on various stages of any project, from the development and planning of a new project to modifying or upgrading an existing facility. Our staff is here to provide you with assistance and recommendations to ensure the best outcome and value. We are happy to visit our clients on-site or conduct meetings from one of our offices.

Contact Us