Thermographic camera & Thermal Imaging for Buildings

Thermographic camera (Thermal Camera)

Thermal Camera, is used normally for Militery/ Security Purpose only. But is now started using in Industrial surveillance across the Globe. Before knowing or using the product we must know what it is and how it is working. Some Information herewith

A thermo graphic camera or infrared camera is a device that forms an image using infrared radiation, similar to a common camera that forms an image using visible light. Instead of the 450–750 nanometer range of the visible light camera, infrared cameras operate in wavelengths as long as 14,000 nm (14 µm).

 

 

R.D. Parker patented the IR iceberg detector in 1914. In 1929, Hungarian physicist Kálmán Tihanyi invented the infrared-sensitive (night vision) electronic television camera for anti-aircraft defense in Britain.[1][2] The first conventional IR camera, the "Evaporograph", was declassified around 1956

 

 

Infrared energy is just one part of the electromagnetic spectrum, which encompasses radiation from gamma rays, x-rays, ultra violet, a thin region of visible light, infrared, terahertz waves, microwaves, and radio waves. These are all related and differentiated in the length of their wave (wavelength). All objects emit a certain amount of black body radiation as a function of their temperatures. Generally speaking, the higher an object's temperature is, the more infrared radiation is emitted as black-body radiation. A special camera can detect this radiation in a way similar to an ordinary camera does visible light. It works even in total darkness because ambient light level does not matter. This makes it useful for rescue operations in smoke-filled buildings and underground.

 

 

 

 

 

Thermo graphic image of a ring-tailed lemur

Images from infrared cameras tend to have a single color channel because the cameras generally use a sensor that does not distinguish different wavelengths of infrared radiation. Color cameras require a more complex construction to differentiate wavelength and color has less meaning outside of the normal visible spectrum because the differing wavelengths do not map uniformly into the system of color vision used by humans. Sometimes these monochromatic images are displayed in pseudo-color, where changes in color are used rather than changes in intensity to display changes in the signal. This is useful because although humans have much greater dynamic range in intensity detection than color overall, the ability to see fine intensity differences in bright areas is fairly limited. This technique is called density slicing.

 

 

 

 

 

View of woman's body temperature

For use in temperature measurement the brightest (warmest) parts of the image are customarily colored white, intermediate temperatures reds and yellows, and the dimmest (coolest) parts blue. A scale should be shown next to a false color image to relate colors to temperatures. Their resolution is considerably lower than of optical cameras, mostly only 160x120 or 320x240 pixels. Thermographic cameras are much more expensive than their visible-spectrum counterparts, and higher-end models are often deemed as dual-use and export-restricted.

 

In uncooled detectors the temperature differences at the sensor pixels are minute; a 1 °C difference at the scene induces just a 0.03 °C difference at the sensor. The pixel response time is also fairly slow, at the range of tens of milliseconds.

 

Thermal imaging photography finds many other uses. For example, firefighters use it to see through smoke, find persons, and localize hotspots of fires. With thermal imaging, power line maintenance technicians locate overheating joints and parts, a telltale sign of their failure, to eliminate potential hazards. Where thermal insulation becomes faulty, building construction technicians can see heat leaks to improve the efficiencies of cooling or heating air-conditioning. Thermal imaging cameras are also installed in some luxury cars to aid the driver, the first being the 2000 Cadillac DeVille. Some physiological activities, particularly responses, in human beings and other warm-blooded animals can also be monitored with thermographic imaging. Cooled infrared cameras can also be found at most major astronomy research telescopes.

Thermographic cameras can be broadly divided into two types: those with cooled infrared image detectors and those with uncooled detectors.

 

 

 

Uncooled thermal cameras use a sensor operating at ambient temperature, or a sensor stabilized at a temperature close to ambient using small temperature control elements. Modern uncooled detectors all use sensors that work by the change of resistance, voltage or current when heated by infrared radiation. These changes are then measured and compared to the values at the operating temperature of the sensor. Uncooled infrared sensors can be stabilized to an operating temperature to reduce image noise, but they are not cooled to low temperatures and do not require bulky, expensive cryogenic coolers. This makes infrared cameras smaller and less costly. However, their resolution and image quality tend to be lower than cooled detectors. This is due to difference in their fabrication processes, limited by currently available technology.

 

Uncooled detectors are mostly based on pyroelectric and ferroelectric materials [1] or microbolometer technology. The material are used to form pixels with highly temperature-dependent properties, which are thermally insulated from the environment and read electronically.

 

Thermal image of steam locomotive made by Sonel KT-384 IR camera

Ferroelectric detectors operate close to phase transition temperature of the sensor material; the pixel temperature is read as the highly temperature-dependent polarization charge. The achieved NETD of ferroelectric detectors with f/1 optics and 320x240 sensors is 70-80 mK. A possible sensor assembly consists of barium strontium titanate bump-bonded by polyimide thermally insulated connection.

 

Silicon microbolometers can reach NETD down to 20 mK. They consist of a thin film vanadium(V) oxide sensing element suspended on silicon nitride bridge above the silicon-based scanning electronics. The electric resistance of the sensing element is measured once per frame.

Current improvements of uncooled focal plane arrays (UFPA) are focused primarily on higher sensitivity and pixel density.

Some of the materials used for the sensor arrays are e.g.: [2]

 vanadium(V) oxide (metal insulator phase change material, for microbolometer arrays)

 lanthanum barium manganite (LBMO, metal insulator phase change material)

 amorphous silicon

 lead zirconate titanate (PZT)

 lanthanum doped lead zirconate titanate (PLZT)

 Cooled infrared detectors

 

Thermographic image of several lizards

Thermal imaging camera & screen, photographed in an airport terminal in Greece. Thermal imaging can detect elevated body temperature, one of the signs of the virus H1N1 (Swine influenza).

Cooled detectors are typically contained in a vacuum-sealed case or Dewar and cryogenically cooled. The cooling is necessary for the operation of the semiconductor materials used. Typical operating temperatures range from 4 K to just below room temperature, depending on the detector technology. Most modern cooled detectors operate in the 60 K to 100 K range, depending on type and performance level. Without cooling, these sensors (which detect and convert light in much the same way as common digital cameras, but are made of different materials) would be 'blinded' or flooded by their own radiation. The drawbacks of cooled infrared cameras are that they are expensive both to produce and to run. Cooling is power-hungry and time-consuming. The camera may need several minutes to cool down before it can begin working. The most commonly used cooling systems are rotary Sterling engine cryocoolers. Although the cooling apparatus is comparatively bulky and expensive, cooled infrared cameras provide superior image quality compared to uncooled ones. Additionally, the greater sensitivity of cooled cameras also allow the use of higher F-number lenses, making high performance long focal length lenses both smaller and cheaper for cooled detectors. An alternative to Sterling engine coolers is to use gases bottled at high pressure, nitrogen being a common choice. The pressurized gas is expanded via a micro-sized orifice and passed over a miniature heat exchanger resulting in regenerative cooling via the Joule–Thomson effect. For such systems the supply of pressurized gas is a logistical concern for field use.

 

Materials used for cooled infrared detection include photo detectors based on a wide range of narrow gap semiconductors including:

 Indium antimonite (3-5 μm)

 Indium arsenide

 Mercury cadmium telluride (MCT) (1-2 μm, 3-5 μm, 8-12 μm)

 Lead sulfide

 Lead selenide

 

Infrared photo detectors can be created with structures of high band gap semiconductors such as in Quantum well infrared photo detectors.

A number of superconducting and non-superconducting cooled bolometer technologies exist.

In principle, superconducting tunneling junction devices could be used as infrared sensors because of their very narrow gap. Small arrays have been demonstrated. Their wide range use is difficult because their high sensitivity requires careful shielding from the background radiation.

Superconducting detectors offer extreme sensitivity, with some able to register individual photons. For example ESA's Superconducting camera (SCAM). However, they are not in regular use outside of scientific research.

 

Thermal imaging is a technology which allows people to take pictures of heat energy. This is a noninvasive and convenient way to inspect certain areas of a home. For example, thermal imaging cameras can detect the heat signatures of pests or help map piping without tearing apart a wall

Thermal Imaging for Buildings

Everything around us, including ourselves constantly emits thermal energy to the environment in the form of invisible infrared radiant energy. As an object heats up, it will radiate more and more energy from its surface. We are often able to feel this infrared radiation, but cannot see it with our unaided eyes, but the lens in an advanced building infrared camera has the capability to sense a difference in temperature of less than 0.06 DegC. Today’s lightweight and rugged infrared cameras can not only see in real-time, but can also record infrared images and measure the temperatures of target objects quite accurately-to within 1/10 of a Fahrenheit degree or better.

Thermal Imaging allows the user to see anomalies in the building fabric that in turn identify problems in buildings and their component electrical, mechanical, plumbing, and waterproofing systems. The thermal image can be recorded onto videotape or stored on an onboard digital device such as a hard disk or memory card for later analysis using appropriate computer software. Infrared thermography provides an effective method to show areas of air leakage, pathways in a building envelope, particularly when used in conjunction with building pressurization / depressurization tests (Air pressure testing).

Building infrared survey applications can be divided into categories such as heat loss, moisture intrusion, insulation quality assurance, structural and pest surveys.

Design flaws, entrained moisture in roofs and walls and water leaks can cause thousands of euro worth of damage. In wet Irish climate, poorly installed insulation and vapor barriers can lead to condensation problems and the degradation of the building itself. This can cause rot, mold and mildew and all of these problems lead to the building being devalued. Because our winters are relatively mild condensation and its side effects–mold and mildew, become a real threat to the building owners and managers. Mold is a microscopic fungus known to destroy building materials and cause health problems for many individuals. Infrared thermography cannot be used to detect mold itself, because mold does not exhibit an exothermic reaction strong enough to be seen by an infrared camera walking around a building. But building infrared thermographers can help find moisture and without moisture, mold grow is limited. Roof moisture detection can be accomplished on almost any type of system either by looking up at the roof or down onto the roof. In roofs with attics, the thermographer looks for the evaporative cooling effect of water. In flat or low-sloped roofs, IR imagery can pinpoint areas that contain moisture.

Disputes is another area where we use Thermal Imaging. The costs of construction, repairs and renovation are increasing dramatically as owners bring construction lawsuits against the contractors. “Getting what you paid for” is not a new concept, but perspective building owners are increasingly concerned the costs and about the quality and efficiency of their investments. Infrared thermography can be used as a building quality assurance tool during construction, so that repairs can be made without destroying the building or delaying the building process.

We can use the date collected during thermography for advisory reports, energy audits and in cases involving controversy. Contact us today to find out more about the services we offer and get a free quote.

Did you know?

Infrared imagery is often a grayscale picture whose scales (or shades of gray) represent the differences in temperature and emissivity (opposite of reflectivity) of objects in the image.

As a general rule, No object is detected in visible light wavelengths (400-700nm) rather, it detects infrared wavelengths (3000-5000nm < 8000-14000nm).

Lights and other relatively hot objects are evident, but as a result of their heat -not light emissions. When an image is taken with an infrared camera, it is often recorded onto videotape and/or digitally saved to an on-board storage device. The images are downloaded, opened in specialized software and modified in a number of ways to enhance their value to the end user, like colorizing the images or adjusting the span and temperature to highlight a particular object in the image.