Lens dirt and protective window cleaning: invisible causes of image quality degradation

How does dirt affect the picture

Dirt on the lens or protective window will cause local scattering, which manifests as:

• Overall fogging: A uniform thin gray or oily film, the contrast is reduced, and the picture seems to be separated by a layer of gauze.
• Halos and glare: This is especially noticeable at night, with large halos appearing around point light sources.
• Partial white spots: water stains and insect marks after the raindrops have dried. The fixed position does not change with the picture.
• Infrared reflection: In night vision mode, dust on the inside of the protective window will be illuminated by infrared light. The screen is completely white - this is the most common cause of "night vision deterioration", but it is often misjudged as an equipment failure.

Cleaning cycles for different environments

Key points of homework

• Turn off the power first or switch to maintenance mode to avoid hot-swapping damage to the device (especially when the infrared lamp is hot).
• Use an air blower or soft brush to remove floating dust, then use a lens cloth and a small amount of cleaning fluid to wipe spirally from the center outward.
• Do not use hard fiber materials such as clothing, paper towels, etc., as they will leave fine scratches.
• Check whether the sealing strip of the protective cover is aged. Dust entry often indicates seal failure. Clean the seal at the same time.
• After cleaning, compare the screenshots before and after cleaning to confirm the effect and record it in the maintenance ledger.

Prevention during the design phase

Instead of frequent cleaning in the later stage, it is better to avoid it in the early stage: give priority to models with sunshades to avoid rain stains; For fume environments such as kitchens, use special shields with wipers or air blowers; for coastal environments, use corrosion-resistant coating models; The installation location should be as far away as possible from lamps directly facing sources of dust and insects.