History of infrared measuring technology

Up until 1960, radiation thermometers are primarily used to measure high temperatures. However, after that time, various types of radiation detectors that are also receptive to wavelengths larger than 8 µm are developed, enabling reliable and accurate temperature measurement right down to below the freezing point of water.

• 1800    Herschel discovers the IR spectrum through tests with a liquid thermometer with IR-absorbing ball
• 1900 Planckian radiation laws
• 1938    Book “Optical Pyrometer” (measuring technology application)

Guidelines for infrared measuring techniques

Infrared temperature measuring instruments are particularly suitable for...

• ...poor thermal conductors, such as ceramic, rubber, plastics, etc. A probe for contact measurement can only display the correct temperature if it can take on the temperature of the measurement body. With poor thermal conductors, this is generally not the case or response times are extremely long.
• ...for determining the surface temperature of rough surfaces (e.g. plaster, textured wallpaper, etc.). Measurement with probes can only sometimes be carried out due to the poor thermal contact.
• ...for moving parts, e.g. running paper webs, rotating tyres, running sheet metal webs, etc.
• ...for parts that must not be touched, e.g. food, painted parts, sterile parts or aggressive media.
• ...for live parts, e.g. electrical components, busbars, transformers, etc.
• ...for small and low-mass parts, e.g. components and all measurement objects where a contact probe draws too much heat, thereby causing incorrect measurements.
• ...for the measurement of extremely small or extremely large surfaces through the selection of various lenses.

Advantages of infrared measuring technology

There has been a huge increase in applications involving infrared measuring systems in recent years. The following factors undoubtedly play an important part in this trend.
Infrared measuring technology offers easy temperature capture and quick, dynamic processes. This is enhanced by the short response time of the sensors and systems. 
The systems offer sophisticated, modern technology with reliable sensors and modern microprocessor electronics. 
Their absence of interaction, i.e. they do not influence the measurement object, permits online measurements of sensitive surfaces and sterile products, as well as measurements in hazardous or inaccessible areas. 
Another factor in this trend that should not be ignored, over and above the technical advantages, is that these systems are attractively priced for customers as a result of cost-optimized production processes, which place the emphasis on high unit totals.

Thermal radiation

It is common knowledge that all bodies, depending on their temperature, emit electromagnetic waves, i.e. radiation. Energy is transported along with this radiation, ultimately permitting non-contact measurement of the body's temperature with the help of the radiation.
The radiated energy and its characteristic wavelengths primarily depend on the temperature of the radiating body.
Ideally, a measurement object will take on all the energy (absorption) and convert it into its own heat radiation (emission). In such cases it is referred to as a “black body radiator”. Such behavior virtually never occurs in nature; rather, additional reflection and transmission of the radiation at or through a body occurs.
However, in order to nevertheless obtain reliable measurements with infrared measurement systems in practice, it is necessary to identify this emission, reflection and transmission behavior (also see 1.4) accurately or to eliminate this influence by suitable means.
This can be achieved with the aid of reference measurements using contact thermometers or by deliberately modifying the measuring area to make it suitable for infrared measuring technology, e.g. by applying lacquer coatings, adhesive and glue, plastic coatings or paper stickers.

Whether and how these measures are to be performed depends ultimately on the measurement object and the measurement environment. Classifying applications according to the appearance of the measurement objects and their surface helps when assessing this.

Current, Voltage, Resistance

• Clamp Meter to facilitate measurement of current without interrupting the connection
• Multimeter & Insulation Tester for measuring voltage, current and resistance

Testo India Pvt. Ltd., a 100% subsidiary of Testo AG, Germany was founded in 2006 in Pune. The company has established thirteen home offices in major metros and a dealers’ network covering this enormous country.

Flue Gas Analysis

• Flue Gas Analyzer testo 310 optimizes the combustion efficiency by monitoring O2 and CO levels in flue gas of boilers, furnaces etc
• Also calculates CO2 percentage excess air level and efficiency

Testo India Pvt. Ltd., a 100% subsidiary of Testo AG, Germany was founded in 2006 in Pune. The company has established thirteen home offices in major metros and a dealers’ network covering this enormous country.

Temperature Analysis

• Testo 830 T1, IR Temperature Measuring Gun measures temperature from a distance using infrared technology
• Thermal Imager testo 870 creates a heat profile of components & assemblies and detects even the smallest temperature differences to identify anomalies in time

Testo India Pvt. Ltd., a 100% subsidiary of Testo AG, Germany was founded in 2006 in Pune. The company has established thirteen home offices in major metros and a dealers’ network covering this enormous country.