Care and Feeding of Infrared Lenses and Other Optics
Sponsored by:
Care and Feeding of Infrared Lenses and Other Optics
Tip provided by
Wayne Swirnow – Infrared Imaging Services LLC
Like all fine optics, the lens of an infrared camera must be treated with special care to maintain the integrity of the image and accuracy of the information you are expecting it capture.
As with most lenses, an infrared camera lens has a spectrally selective coating on its front surface that is specifically designed to be the transmissive in the frequencies of infrared energy.
Damage to the coating on the lens surface can change the bandpass and rejection of the selective coating modifying the amount of infrared energy transmitted through the lens and onto the detector chip, thereby changing the amount of infrared energy the camera sees and therefore the cameras calibration.
In fact, a large degradation in a specific area such as a deep scratch on the surface of the lens could require a re-recalibration of the camera because the pixels behind that area will receive a different amount of infrared energy than the other pixels on the chip where the lens is not damaged will.
To properly clean an optical surface, first all dust and grit or other abrasive material must be removed. This is done usually with some type of air blower or puffer and a specially designed very soft brush. If using a can of compressed air be sure to not allow the cold liquid to strike the surface of the lens. Never wipe any lens with a cloth or lens tissue without first removing any dust and grit from the lens with an air stream and fine brush. Wiping a lens before removing any dust and dirt that is like using sandpaper on the fine and fragile optical coating.
Once the lens surface has been cleaned of any grit, is then permissible to use a soft cloth to remove smudges or fingerprints. Never use any cleaning liquids on the lens unless it is approved for use by the camera lens manufacturer.
In general, good camera hygiene would be to wipe the entire camera down with a soft cloth removing any exterior dust and dirt after each days use. When charging batteries look at the contacts to ensure they are clean, not bent, and free of any dirt or grease.
Occasionally it may be necessary to use a vacuum cleaner on the camera’s carrying case to remove dirt and dust which can accumulate over time in the case. Wipe dust off the battery charger, cables, and any components that go in the case with the camera. Periodic cleaning of your camera and optics can help to ensure proper operation and a long life.
