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With advances in imaging software, there are many parameters that can be adjusted in a saved image whilst it is being optimising for reporting. However, one thing that cannot be changed after saving an image is focus. Focus is an optical adjustment, so can’t be changed in a saved image – getting the right focus is a critical aspect of thermal imaging.
Fluke LaserSharp® Auto Focus – improving efficiency and safety
An infrared field thermographer has many responsibilities whilst carrying out inspections.
Top priority is that they stay safe, followed closely by a requirement to bring back high-quality data for analysis.
With Fluke’s new LaserSharp® Auto Focus, which is available on Fluke Professional Series thermal imaging cameras, focusing the infrared camera is no longer one of the biggest challenges, meaning that operators reduce the time they spend focusing the camera on each subject or target while conducting inspections. If you consider that they can inspect literally hundreds of assets or thousands of components during an eight-hour shift, accurately and confidently focusing the camera at the first attempt can wipe hours off inspection time - allowing for additional assets to be inspected during the same time period.
LaserSharp® Auto Focus can also help to reduce or eradicate other challenges:
When working in bright or low-light conditions where image contrast on the LCD screen may not be optimal, LaserSharp® Auto Focus will assure the image is properly focused
Most industrial inspections are done wearing safety glasses and/or an arc flash face shield which often make it difficult to see clearly. A crisp focus can still be achieved with LaserSharp® Auto Focus
When following industry safety best practices for electrical applications, where high incident energy is present, operators need to optimize camera settings quickly, including focus, then move out of the flash protection boundary. Thermographers can do this while remaining confident the data they have collected is a suitable standard for analysis
Superior Image Quality
Which of the two halves in the picture above would customers prefer? In the left hand image it’s obvious that what’s being viewed is the exterior wall of a home. Despite the poor focus some details can be detected, including the abnormal heating pattern around the right hand window.
However, the right hand image is much clearer than the other image. More details are visible as well, such as the orientation of the siding and the location of framing. Even the reflections in the glass of the windows are nice and sharp.
Companies conducting infrared inspections want high quality images like the image on the right for better presentation and in-depth analysis.
More Accurate Temperature Measurement
Focus affects temperature measurement as well, a fact not fully understood by many thermographers. Just behind the lens, the imager has a detector array. Mounted on an electronic chip, the detector is a two dimensional array of elements that react electrically to the presence of thermal energy. Depending upon the resolution of the imager being used, there can be various numbers of individual elements. Imagine them like tiny little squares all of which are capable of detecting and measuring thermal energy.
The Fluke Ti400 (843-1540) for example is a 320x240 resolution detector, meaning that there are 76,800 individual detector elements that detect and measure thermal energy. With a sharply focused image, there is clear contrast between areas of varying thermal energy on the surface being inspected. This allows the individual detector elements to clearly report the intensity of the energy being focused on them. When the focus is poor, the incoming energy isn’t as distinctly concentrated on individual detectors, and their response is skewed. Think of it like smearing the energy together - averaging lower levels of energy with higher levels of energy.
Focus on Partially Obscured Objects
The Fluke Ti400 series of Fluke thermal imagers give thermographers the ability to choose the object or point of interest in the autofocus operation. A separate trigger allows initiation of the Laser-Sharp® Auto Focus feature. A laser then can be aimed precisely at the area of interest to the thermographer. The Ti400 imager senses the distance to the object of interest and the focus is adjusted to optimize the object.
This means that for the first time thermographers can focus precisely on objects that might be obscured by other obstructions or barriers, such as substation equipment behind a fence, disregarding the fencing material between the imager and the object of interest. Operators can get precise, focussed views of equipment sitting behind metal guards or in electrical cabinets with ventilation covers, because the Ti400’s LaserSharp® Auto Focus can be aimed through the guard to the focus object.
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Produced with the permission of Fluke Corporation, June 2016