Infrared Cameras: Technical Issues and Selection Considerations
1. Overview
With the increasing demand for night vision monitoring in security video systems, infrared (IR) cameras have become mainstream, with sales rising steadily. However, technical issues in IR night vision applications are gradually emerging. This article briefly discusses technical issues and selection considerations, for sharing insights with industry professionals.
2. Selection of LED Infrared Light Sources
The LED infrared lights on surveillance cameras function like flashlights. A narrow beam angle reaches farther but covers a smaller area; a wide angle covers more area but with a shorter distance. Currently, high-quality IR cameras in China often use LED modules from Taiwanese manufacturers, such as Dingyuan, Hongbai, and Lite-On.
Many users assume that the number of LEDs determines camera quality, but this is not entirely accurate. LEDs are generally built-in or external, and their size and power affect detection distance. Built-in LEDs have limited space, reducing monitoring range. Industry experts emphasize that LED power is the primary factor affecting infrared illumination distance.
For optimal performance, the design of the LED assembly and its alignment with the lens are crucial. Key considerations include:
- High-power, low-current LEDs to prevent overheating
- Aluminum substrates for heat dissipation to avoid waterproofing issues and fog/dust accumulation
- Metal partitions between LED and lens to prevent light interference
- Strengthened waterproofing to reduce fogging
- Lens improvements (ED glass) to ensure proper night focusing
Minimizing attenuation and extending IR camera lifespan can be achieved through:
- Using high-quality LEDs
- Metal-film reflective technology
- High-efficiency optical lenses (5% higher transmittance than standard glass)
- Constant current and voltage circuit design
- LED circuit protection systems
- Independent power for each LED group to prevent cascading failure
- Redundant designs to ensure longevity of individual LEDs
3. Application Analysis of LED Infrared Light
Infrared LEDs in remote controls emit mostly IR light, with a small visible red component. Beam angles are typically around 30 degrees, allowing effective operation without perfect alignment. Without external IR interference, the effective range can reach 5 meters; under normal ambient light, it is usually within 3 meters. Doubling emission power increases range by roughly 40%.
Surveillance cameras also use IR LEDs sensitive to infrared light. Single LEDs generally cover no more than 2 meters, with low brightness at that distance. Therefore, multiple LEDs are often used in a row. More LEDs increase effective range, following the 100%-to-40% approximate relationship between power and distance.
High-power IR LEDs (1W–5W) are now widely available. A 1W IR LED is sufficient for standard cameras with a 5-meter effective range. High-power IR LEDs are used in surveillance, outdoor search, and military or civilian applications.
