5 Things to Know Before Buying Industrial thermal inspection lenses

26 May.,2025

 

7 factors to consider when choosing a thermal imaging camera

1. Temperature range / value to be measured

The highest and lowest temperature required to be measured defines the temperature range required by the thermal camera. The range is the set of temperatures that the camera is capable of measuring.

Please visit our website for more information on this topic.

It is very important when selecting a infrared camera to first know the range of temperatures that we are going to get in our application and that we need to measure.

2. Spectral range

The spectral range is the range of wavelengths that the thermal camera sensor is able to detect.

The spectral range is an important factor to consider when selecting a thermal camera and will depend on the target material and its emissivity. Emissivity is the parameter that determines the proportion of thermal radiation emitted by a surface or object due to its temperature.

To minimize errors and increase the accuracy of the measurement we have to choose the thermal camera with the shortest wavelength that can measure the temperature range of our application.

For example, if we want to measure 600°C and we do not need to measure values less than 450°C, then we will choose a 1 micron camera (NIR camera). Although we can use an LWIR (7 to 14 microns), the temperature measurement will be more accurate with the shorter wavelength.

According to the temperature ranges we want to measure, the most commonly used industrial thermal cameras are of the following:

  • LWIR for “low” temperature measurements between -50°C and 900°C (exceptionally up to °C)
  • NIR-SWIR for high temperature measurements (450°C to °C)
  • MWIR for measuring low and intermediate temperatures with high precision (the vast majority refrigerated and expensive)

3. Sensitivity (NETD)

The thermal sensitivity (Noise Equivalent Temperature Difference, NETD) is equivalent to the smallest differential in temperature that is able to measure the infrared camera without being attributed to its own noise. Thermal sensitivity is equivalent to the thermal resolution of the camera (it is the minimum measurement value between two consecutive temperatures).

The more sensitive the detector (lower NETD), the finer the temperature details the thermal camera is able to display.

Conventional cameras have a NETD between 80mK and 100mK, while the cameras with the highest sensitivity can have 40mK at competitive prices or at 20mK or even 10mK for those with the highest performance (usually cooled and with high cost).

If you want to learn more, please visit our website IRLENS.

If the objectives to be measured have large temperature differences, a camera with a low NETD is probably not necessary.

4. Resolution

The resolution of the thermal camera sensor, also called detector, determines the quality of the rendered image. The resolution indicates the number of pixels in the detector. More pixels means higher resolution.

The higher the resolution of the detector, the sharper and more accurate each individual point in the image will be, allowing for more precise measurements and better decisions.

Higher resolution infrared cameras can measure smaller targets at a greater distance and create sharper thermal images for more accurate and reliable measurements.

The most widely used resolutions in the industry are 80×80, 160×120, 382×288 and 640×480 pixels in LWIR and 764×480 pixels in NIR.

5. Optics / Field of View (FOV)

The field of view (FOV) is determined by the thermal camera lens and refers to the extent of the scene that the camera can capture. The greater the field of view, the greater the area or space that can be captured with the thermal camera.

Some cameras are available with multiple lenses for different types of applications. A camera that allows you to change the lens increases its versatility.

Knowing the distance at which the camera can be installed and the size of the smallest detail that we want to measure in the scene, allow us to identify the ideal optics for our application.

10 Things You Need To Know About Thermal Imagers | Fluke

10 things you need to know about thermal imagers

Whether you choose a simple point-and-shoot model or a high-end thermal camera with all the bells and whistles, here are some key features and specs you should consider:

Contact us to discuss your requirements of Industrial thermal inspection lenses. Our experienced sales team can help you identify the options that best suit your needs.

  1. Resolution
    • Detector resolution indicates the number of detector pixels on the camera. More pixels, means higher resolution thermal imaging.
    • Spatial resolution is based on detector pixels and the field of view (FOV) spec, combining them to define the area the imager sees at any given moment. Spatial resolution can be used to help define the smallest object size that can be detected. A lower spatial resolution value means better detail and image quality.
  2. Focus 
    With a variety of focus mechanisms to choose from, it is important to take into account your skill level as well as the application in selecting a focus type. Here are the common focus mechanisms:
    • Fixed: Point and shoot simplicity
    • Manual: Precise incremental focus
    • Auto focus: Automatically focuses on a target but may require manual adjustment.
    • Laser-assisted auto focus: Uses a built-in laser distance meter to calculate distance to the target.
    • Multifocal: Captures and stores multiple images of the target from varying focal distances and uses software to blend them into one image with ultra-sharp depth of field detail. Fluke Corp., for example, calls its implementation of this technology MultiSharp™ Focus.
  3. Temperature range 
    The highest and lowest temperature you encounter in your inspection determines the temperature range you need from your thermal imager. Or, select a camera with a wide temperature range that automatically selects the range based on your scene, or allows you to manually select the temperature range.
  4. Lens options
    A camera that lets you change lenses increases your versatility, allowing you to inspect many more types of equipment and situations. There are lots of choices for lots of applications—standard, wide angle, telephoto, and macro.
  5. Saving images and additional data
    Save infrared and digital images and in some cases voice notes to internal memory, a removable SD card, or to a USB flash drive. It’s important to have the flexibility to save images and additional related data to different media for backup or sharing.
  6. Color palettes 
    Slight differences are easier to see with a monochromatic palette, such as grayscale or amber. High contrast palettes can make it easier to quickly find obvious anomalies. You should be able to change the palette in the camera or in the software.
  7. Color alarms
    Use these to quickly highlight areas outside your normal temperature ranges.
  8. Emissivity and reflected temperatures
     Low emissivity surfaces, such as shiny metals, can reflect infrared energy from other objects and throw off your image and your measurement accuracy. So, look for the option to adjust parameters when choosing an imager.
  9. Spot markers
    Mark specific temperatures on your image to compare simultaneous temperatures from multiple points on the same image.
  10. Battery type and life
     Look for a battery with useful features such a charge level indicator. Nothing is worse than starting an inspection with no idea of the battery status. Also consider long battery life and quick charging ability.

Featured resources

  • Best Fluke thermal cameras
  • Five tips for taking quality thermal images
  • Why thermal imaging is essential for detecting moisture damage