IR Resolution
IR resolution refers to the detector pixel resolution, as opposed to the LCD display resolution. Pixel resolution is the maximum number of display points on a screen. The more pixels, the
better the resolution, and the sharper the thermal image.
Thermal Sensitivity
Since what a thermal imaging camera does is take radiant thermal emergy and convert it into a visible image, the best we can “see” the thermal energy is limited by the number of pixels and the sensitivity to temperature differences that the camera can pick up. Typical thermal imaging cameras have sensitivities of 0.25°C to 0.05°C. The visual defined by 256 colors or scales of gray, leading by division to 256 different possible temperatures that can be displayed. Often, this result in the camera attempting to pick up and display temperature differences of narrower range than its thermal sensitivity. Thus a block of pixels is shown to be a blotchy, uniform mass of temperature, however, this is not the reality and the image is inaccurate. This result is known as “noise”. Image quality improves and noise decreases proportionally to an infrared camera’s thermal sensitivity. The smaller the thermal sensitivity, the lower the noise and the better the image will be.
Field of View (FOV)
Field of view defines the size of the area that is seen in the thermal image. Typically this is given in horizontal degrees by vertical degrees. The lens has the greatest influence on what the FOV will be. Instantaneous field of view (IFOV) describes the capability of a thermal imager to resolve spatial detail (spatial resolution). It describes the smallest object that can be seen at a given distance.
Temperature Range
Be sure that the temperature range the camera operates in is within the range of temperatures of the targets you will be measuring. Some cameras feature a temperature range that is suitable to industrial applications, others are better suited for home inspections.
Accuracy
For thermal imaging cameras, accuracy is the temperature range within which the reported temperature is statistically likely to be. The industry standard for consistent accuracy is ±2% or ±2°C, whichever is greater. Beacuse temperature measurements are based on the detection of infrared radiation, and in order to produce accurate and repeatable results, adjustments should be made for the following factors: (1) emissivity values below 0.6; (2) temperature variations of ±30°C (54°F); (3) making measurements beyond the resolution of the system (target too small or far away); and (4) field of view.
Built-in Illuminator Lamp
Infrared cameras can see in total darkness but visual cameras require well lighted conditions and high resolution to generate clear, sharp pictures. Make sure the visual camera in the thermal imager has a built-in illuminator lamp, otherwise you could have a hard time comparing the thermal image to the visual image.
Image Fusion
Simultaneously capture and overlay pixel-for-pixel infrared and visible light images for full image optimization with 5 different viewing modes.
1. Full IR: For troubleshooting and analyzing equipment and installations with very high resolution IR imaging. For detecting the smallest temperature variations to track down the origin of problems and fully document the extent of remediation. Full IR images are automatically linked to full visible light images.
2. Picture-in-Picture: For creating an IR window surrounded by a visible light frame to easily identify thermal anomalies, while maintaining a frame reference with surroundings.
3. Alpha Bending: For combining visible and infrared images together in any ratio to create a single image with enhanced detail that will help in precisely locating problems.
4. IR/Visual Alarm: For displaying only temperatures that fall above, below, or in between a specified range as IR image, leaving the rest of the scene as a fully visible light image.
5. Full Visible Light: A bright, detailed pixel-for-pixel reference image of subject areas for documentation and reporting.
Thermal Palettes
A palette is a color scheme used to display the thermal variations and patterns in a thermal image. Whether inspecting or analyzing, the objective is to select the palette that best identifies and communicates the problem. Ideally a thermal imager that allows the user to select or change the desired palette both in the camera and in the software should be chosen.
A wide selection of available color palettes allows the thermographer greater flexibility in thermal inspection, analysis and reporting.
Laser Pointer
The laser pointer keeps your hands free and clear from danger while allowing you to point to the area of concern. Best of all, the laser pointer will allow you to see precisely where the infrared camera’s lens is focused.
http://www.itm.com/attachments/pdfs/TI_BROCH_ENG.pdf
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