1. Fog mainly forms in two areas: on the internal lens of the camera and on the outer cover glass.
2. Fogging generally occurs in low-temperature and high-humidity environments. When infrared LEDs activate at night, the internal temperature of the camera rises. Saturated water vapor cools down and condenses into fog or frost, adhering to the housing glass or internal lens and resulting in blurred images.
   A key question arises: can fog be better prevented by fully sealing the camera, or by enabling proper ventilation to avoid water vapor condensation on the internal lens? Judgement must be made according to specific conditions.

a. Internal Fogging: Excessive Moisture Inside the Camera

1. Short-term countermeasures: install defrost circuits, open vent holes, equip cooling fans or place desiccants. For fundamental resolution, strict factory inspection is required to eliminate volatile substances.
2. Adopt well-manufactured PCBs, mainboards, lamp boards and lenses free from impurities and volatile materials.
3. Ensure tight fit between the aperture ring and cover glass to avoid light leakage. Light leakage from poorly fitted aperture rings causes infrared light refraction into the lens.
4. Extend aging testing to maintain dryness inside the camera; control humidity in the production workshop.

• Install waterproof rubber sleeves and gaskets on cable interfaces;
• Apply waterproof sealant on wiring screw holes to boost waterproof performance.
  Most infrared cameras adopt aluminum alloy housings. Improving machining precision of interfaces and using high-quality silica gel for bonding achieves satisfactory waterproof results.

b. External Fogging

• Equip the housing with a wiper to clean the glass surface;
• Adopt invisible wiper coated window glass, which repels water and dust.