Is 940nm better than 850nm?

Comparing 940nm and 850nm Wavelengths in Infrared Applications

When looking at the infrared spectrum, the 940nm and 850nm wavelengths are commonly used for a variety of applications. The choice between the two wavelengths depends on specific use cases and requirements. Here we will discuss some of the key differences and considerations for choosing between 940nm and 850nm infrared light.

Visibility

850nm: This wavelength is closer to the visible spectrum and can produce a faint red glow when used in infrared LED applications. This may be undesirable in situations where stealth or unobtrusiveness is required.

940nm: The 940nm wavelength is less visible to the human eye, making it a better option for covert operations where the light should remain undetected, such as wildlife observation or security applications.

Penetration and Range

850nm: Generally provides better penetration and range for the same amount of power compared to 940nm. This makes it a popular choice for surveillance cameras and night-vision equipment where distance viewing is important.

940nm: While offering increased stealth, the 940nm wavelength tends to have a shorter range and less penetration ability due the higher absorption rates in the atmosphere and certain materials.

Sensor Sensitivity

Many cameras and sensors that are sensitive to infrared light are more responsive to the 850nm wavelength. This increased sensitivity can lead to better performance in low-light conditions and improved overall efficiency of the system.

Biological Effects

There is also a difference in biological impact, particularly concerning eye safety. Prolonged exposure to 850nm light can cause more damage to the human eye than 940nm, which is considered safer because it is further away from the visible spectrum and less likely to cause photochemical damage.

Applications

The choice between 850nm and 940nm will typically be dictated by the application:

• For covert surveillance, wildlife monitoring, or applications where visibility of the IR light source is an issue, 940nm would likely be the more appropriate choice.
• For applications requiring higher range and better sensor responsiveness, such as night-vision devices or active IR systems needing superior penetration, 850nm would be more suitable.

Ultimately, whether 940nm is 'better' than 850nm cannot be answered definitively, as 'better' is contingent upon the requirements of the specific application. Each wavelength has its own advantages and trade-offs, and the ideal choice will depend on a careful balance of factors including visibility, range, sensor compatibility, and safety concerns.