Product Details Supplier Info More products
Download document:

Full Technical Article - .PDF file.

NIR cameras, which are sensitive to the near-infrared spectrum (0.9 to 1.7um), are increasingly found in research laboratories, design departments and factory production lines, according to Flir ATS.

Used to view phenomena that cannot be observed with ’thermal’ (MWIR/LWIR) imaging systems, NIR cameras have many advantages.

For example, they do not require cryogenic cooling and are therefore lighter, smaller and less expensive.

Most NIR cameras use an InGaAs (Indium Gallium Arsenide) detector that can be used without cooling or combined with a Peltier effect module.

Since these cameras have no mobile parts, they are particularly robust and capable of withstanding harsh use conditions such as continuous 24/7 operation.

NIR cameras are very similar to traditional CCD cameras.

Key components include an optical lens that concentrates light flow on the surface of the detector and contributes to the formation of the image.

Optics corrected over the entire 0.9-1.7um spectrum are best for optimal image quality.

For applications requiring spectrum selectivity, it should be possible to use an interferential filter.

Some applications are based on the rejection of a major part of the spectrum in order to maximise the useful information provided.

Detectors, also called FPA (Focal Plane Array), are the core of the camera’s detection system.

Although most NIR camera detectors are made of InGaAs photovoltaic cells, some are HgCdTe (mercury cadmium telluride) in cases where extended sensitivity (up to 2.35um) is required.

It should be noted that a modified version of the InGaAs detector, known as VisGaAs, has a sensitivity extending into the visible spectrum: it covers the 0.4 to 1.7um spectrum.

The 320 x 256 pixel detector with a 30um pitch is currently the most common.

An electronics module is used to apply a certain number of operations and process the signal from the detector (uniformity corrections, synchronous triggering and so on).

NIR cameras available today commonly connect with Gigabit Ethernet.

Other types of connections, in addition to communications and control, are also available, such as trigger in/out when the camera must control or be controlled by an outside source, lock-in for applications requiring synchronous demodulation, video output for viewing on a video display and so on.

NIR and SWIR cameras are used in so many applications that it would be impossible to list them all, so a conclusion should be reached that their use is limited to just these applications.

There are, however, a number of applications sufficiently well known and integrated in various industrial processes or areas of research that they can be cited as good examples of the potential of these imaging systems.

NIR/SWIR cameras are often chosen by research laboratories because of the physical and chemical properties of certain materials (solids, liquids or gases) at these wavelengths.

Infrared reflectography is a method used to investigate drawings beneath easel paintings that was developed in the 1970s.

In addition to providing documentary evidence for archives, this technique also helps settle issues relating to the attribution of works of art.

This non-destructive expert investigative technique, used by many museums and art research centres, is based on the optical properties (diffusion and absorption) of pigments in the near-infrared range.

NIR/SWIR cameras with a focal plane array can be used to determine the spectrum of an object or extended component with spatially variable spectral properties (variable composition, localised active components and so on).

For rapid results and greater versatility, the camera should be used with an acousto-optics tunable filter (AOTF) or liquid crystal tunable filter (LCTF), or with an interferometer, depending on the precision of measurement required.

Each mono-element in the array (pixel) in this case acts as a multi-spectral detector.

A three-dimensional reconstruction can then be made as a function of the wavelength and transmission.

NIR/SWIR spectroscopy can be used to measure humidity in a solvent (ethanol, for example) or to determine concentrations of OH-, CO32- and HS- ions in an aqueous solution.

In pharmacology, these imaging systems can be used to carry out non-destructive investigations on tablets, to determine the presence or absence of an active ingredient, for example.

Industrial applications are those in which the imaging system, often an integral part of a more complex system, has a direct or indirect impact on a process (research and development, production, quality control) within a company.

The applications mentioned above are dependent on the reflective properties of the objects under consideration.

Thermography, for its part, makes use of emissions from the objects themselves; it is based on the theory of the black body introduced by Gustav Kirchhoff.

Traditionally, infrared thermography uses imaging systems operating in the middle-wave (2.5-5.1um) or long-wave (7.7-14um) range depending on the naming systems commonly used by manufacturers.

Thermography in the NIR or SWIR range has a number of advantages, including smaller investment in the camera (no cryostat); very high sensitivity to temperatures above 800C, with measures beginning at 400C also possible; and the possibility of measuring through windows made of standard glass (BK7, among others).

NIR and SWIR cameras are often used in laboratories, R and D departments and up to some extent, on process control lines.

Their high quantum efficiency between 900 and 1,100nm (greater than 75 per cent), makes them the best choice compared to EMCCDs, for which quantum efficiency at these wavelengths is very low (less than 20 per cent).

Easy to integrate and easy to run, these cameras have opened a world of investigation.

The range of applications is large and is getting broader every day.

With almost 10 years of experience in the design and fabrication of InGaAs detectors and cameras, Flir has grown an extensive knowledge in this technology and is able to offer advice on developing applications.

FLIR Systems specialises in technologies that enhance perception and awareness.  The company brings innovative sensing solutions into daily life through its thermal imaging and visible light imaging technology and systems for measurement, diagnosis, location and advanced threat detection.  Its products improve the way people interact with the world around them, enhance productivity, increase energy efficiency and make the workplace safer.

FLIR Systems has six operating segments – surveillance, instruments, OEM and emerging markets, maritime, security and finally, detection. Of these six, ‘instruments’ is of greatest interest to trade and industry and the second largest segment in the company’s portfolio. This division provides devices that image, measure and assess thermal energy, gases and other environmental elements for industrial, commercial and scientific applications.

These products are manufactured across five production sites, three in the USA and two in Europe; Sweden and Estonia.

A model to suit every application and budget
The options that FLIR Systems provides for measuring temperature and studying thermal performance have never been greater.  Not only does the company offer a huge range of models to suit all thermal application needs but the technology is also affordable and very easy to use.  Thermal cameras now come in various shapes, sizes and degrees of sophistication and FLIR continues to invest heavily in the development of new and complementary technologies to differentiate itself from competitors.

An important milestone in the development of thermal imaging has been the introduction of the FLIR Lepton® core, a micro longwave detector, the size of a mobile SIM.  This has allowed thermal imaging to be repackaged to meet the needs of an even wider audience and, in combination with another new technology called Infrared Guided Measurement – IGM™ – has led to the development of a range of test and measurement meters with imaging capability.

Another important growth area for FLIR thermal imaging is in continuous monitoring to assure quality and safety.  Through its introduction of discrete fixed mounted thermal cameras which are fully compliant industry standard plug-and-play protocols, FLIR Systems has provided industry with infrared machine vision which is instantly ready for quick and easy network installation.

Protecting assets and people from fire is an area for which thermal imaging is least known but, thanks to FLIR Systems’ development, it is now one of the most cost-effective methods available.  Its application flexibility and rapid return on investment present an attractive proposition for any site or safety manager.

View full profile