How to choose the best infrared lens for your application

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How to choose the best infrared lens for your application

In addition to the standard infrared lens that comes with thermal imagers, some infrared cameras provide a choice of optional lenses. These macro, telephoto, and wide angle lenses make it possible to inspect targets that—due to their size and distance—would be challenging to see with a standard lens.

Germanium is the material of choice for quality infrared lenses because the element is transparent in the infrared spectrum and has a high index of refraction. Along with an engineered coating, Germanium provides the most efficient material to transmit energy to the detector to produce high quality infrared images.

Better macro and telephoto add-on lenses are called “smart lenses” because they do not need to be calibrated to a specific camera and are interchangeable among compatible cameras. Fluke offers a line of such add-on lenses for certain infrared cameras.

The following chart offers guidelines for selecting add-on lenses for your applications.


Use to scan


Wide Angle

Large targets, viewed from a relatively close distance

  • Maintenance, electrical, and process technicians – when working in a tight space or needing to view a large area
  • Building inspectors – for roofing and industrial building inspections, save time by seeing a much greater area at once 

2x telephoto

Small to medium sized targets, viewed from a distance

  • Maintenance, electrical, and process technicians–when equipment is too high, difficult to reach, or unsafe to approach
  • Building inspection–see fine detail from a distance

4x telephoto

Small targets, viewed from a great distance

Most relevant to those working in

  • Petrochemical–tall stacks
  • Power utilities generation and transmission–long distances
  • Metals refinement—too hot to approach; may have equipment near refinery that needs inspection


Tiny to microscopic targets, viewed from extremely close

Engineers and scientists working in

  • Research and development
  • Electronics design and validation
  • Microscopic thermography

Audience can be found in universities and research organizations, process development, and micro-electronics design companies.

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Infrared Cameras

Fundamental information about using thermal imagers for inspection and diagnosis.