IR LED wavelength enhances image contrast

Article By : Vivek Nanda

Osram's IR LEDs increase contrast of camera images for license plate recognition at automatic barriers controlling traffic flow.

Osram Opto Semiconductors has introduced 810nm high-power infrared LEDs for illumination. The change in wavelength from the usual 850nm benefits camera systems, such as those used to read license plates.

Wavelengths of 850nm and 940nm typically used today have difficulty creating high-contrast images of certain colour combinations. The addition of the 810nm wavelength helps cameras improve image contrast making it easier to read patterns from recorded images.

Moreover, camera sensors have higher sensitivity at 810nm. That means, using a light source with the same optical output, an 810nm system will achieve a greater detection distance than was previously possible. Alternatively, designers can reduce the number of components while maintaining the same range. However, humans do perceive infrared light as a mild red glow and this is stronger at 810nm than at 850nm.

The SFH 4703AS is the 810nm addition to the companys' Oslon product family for infrared illumination. It's emitter generates 1W optical power at 1A with a beam angle of +/-45° and a radiant intensity of 630mW/sr. The component measures 3.85mm (W) by 3.85mm (D) by 2.29mm (H), including the lens.

The expansion in the portfolio means that you can now choose from mutually compatible emitters in three different wavelengths from Osram. They can be combined in a single illumination unit or used to convert existing systems to another spectral range without changing the layout.

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