850nm and 940nm infrared LED are two commonly used light sources in the near-infrared field, with the main differences reflected in wavelength characteristics, optical performance, and application scenarios. Here is a specific comparison:
Table of Contents
1. Wavelength and Visual Visibility
-850nm infrared LED
-The wavelength is relatively short, close to the visible red light band (760nm is the boundary between visible light and infrared light). At close range, the naked eye may perceive weak red light (similar to dark red), but invisible light dominates.
-Poor concealment, suitable for scenes with low requirements for concealment.
-940nm infrared LED
-Longer wavelength, far from the visible light range, completely invisible, difficult to detect by the human eye and ordinary camera sensors.
-Strong concealment, suitable for applications that require a “no light” environment.
2. Light output efficiency and power consumption
– 850nm infrared LED
-Semiconductor materials such as AlGaAs have higher luminous efficiency and stronger optical power at the same current (for example, under the same driving conditions, the radiation intensity at 850nm may be more than 30% higher than that at 940nm).
-Lower power consumption, suitable for scenarios that require high brightness and long-distance illumination.
– 940nm infrared LED
-The material efficiency is low and requires higher current to achieve the same optical power, resulting in relatively higher power consumption.
-If high brightness output is required, more complex heat dissipation design may be needed.
3. Penetration ability and transmission characteristics
– 850nm
-Short wavelength, strong scattering effect in air (such as Rayleigh scattering), but energy concentration, high light intensity within a short distance (such as within 10 meters), suitable for high brightness illumination at close range in clear environments.
-Easy to be scattered by particles such as water vapor and dust, and significantly attenuated in hazy and humid environments.
– 940nm
-Long wavelength, weak scattering effect, stronger penetration ability in haze, smoke or water vapor, suitable for medium to long distances (such as over 20 meters) or complex environments (such as outdoor monitoring, foggy scenes).
-The energy distribution is more uniform, and the attenuation of light spots is smoother when irradiated from a distance.
4. Application scenarios
-Typical Applications of 850nm Infrared LED
-Security monitoring: Infrared camera fill light (such as night vision goggles), strong light is required but slight red light leakage is acceptable.
-Infrared communication: such as home appliance remote controls (some early products), data transmission (such as IrDA protocol).
-Stage lighting/special lighting: Use weak red light to achieve a “pseudo infrared” effect (such as invisible ink excitation).
-Typical Applications of 940nm Infrared LED
-Concealed monitoring: Bank and home security cameras require completely invisible light compensation.
-Biometric recognition: Mobile Face ID, fingerprint recognition module (to avoid visible light interference).
-Medical equipment: pulse oximeter (using 940nm and 660nm red light to compare and detect blood oxygen concentration).
-Automotive electronics: In car driver monitoring (DMS) to avoid interfering with the driver’s line of sight.
5. Environmental light interference and signal-to-noise ratio
– 850nm
-The wavelength is close to visible light and is susceptible to interference from sunlight (including near-infrared components) or indoor lighting. When used during the day, the signal-to-noise ratio may be low and additional filtering is required.
– 940nm
-Far away from the visible light band, with less ambient light interference, especially during the day or in complex lighting environments, the signal stability is better, suitable for scenarios with high anti-interference requirements.
6. Cost and Process
– 850nm
-Mature technology, large mass production scale, low cost, suitable for cost sensitive large-scale applications (such as consumer grade cameras).
– 940nm
-The material and process requirements are higher (such as InGaAs materials), and the cost is slightly higher, but as the demand for biometric recognition increases, the price gap gradually narrows.
Summary: How to choose?
-Choose 850nm infrared LED: high brightness, low power consumption, short distance, and can accept slight visible red light (such as ordinary monitoring and infrared lighting).
-Choose 940nm infrared LED: It needs to be completely concealed, strong anti-interference, long-distance or complex environments (such as security, biometric, medical).
According to the concealment, distance, environmental conditions, and cost requirements of specific scenarios, each has its own advantages. For example, outdoor monitoring at night may prioritize 940nm (penetrating haze+concealed), while low-cost indoor night vision lights can choose 850nm.
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