New Osram IR LEDs provide better camera image contrast
810nm high power LEDs aid smooth traffic flow through automatic barriers and optimise license plate recognition
Osram Opto Semiconductors is expanding its offering of high-power infrared LEDs for illumination solutions to include a new wavelength (810 nm) for camera systems, such as those used to read license plates.
The additional wavelength can be used to improve image contrast making it easier to read patterns from recorded images, says Osram. Moreover, camera sensors have higher sensitivity at 810 nm. At the same optical output, the new device therefore extends the range of camera systems as compared to 850 nm.
Greater image contrast for easier analysis
The newly available wavelength is said to be particularly advantageous for applications requiring superior image contrast. Wavelengths of 850 nm and 940 nm typically used in today have difficulty creating high-contrast images of certain colour combinations.
Camera systems supporting automatic license plate recognition at toll stations or entrances to parking garages are a perfect example. The SFH 4703AS gives these cameras higher-contrast images for many types of license plates, making it easier to retrieve the license plate numbers. As a result, automated barriers function more smoothly, reducing waiting times for drivers. And other camera applications also stand to benefit from the new component, such as traffic monitoring and CCTV systems.
Increased range
This new wavelength comes with the added bonus that the spectral sensitivity of typical camera sensors is higher in this range than it is for 850 and 940 nm. Using a light source with the same optical output, an 810 nm system will achieve a greater detection distance than was previously possible. Alternatively, this also allows designers to reduce the number of components if they wish to maintain the same range. However, designers should bear in mind that humans do perceive infrared light as a mild red glow, and this is stronger at 810 nm than at 850 nm.
Osram Opto Semiconductors already provides 810 nm emitters for iris scanners in mobile devices. For the SFH 4703AS, developers mounted the highly efficient chip manufactured in nanostack technology in the tried-and-tested Oslon package for illumination applications.
At 1 amp current, the emitter generates 1 watts optical power. The beam angle of +-45° allows for broad illumination, with a resulting radiant intensity of 630 milliwatts per steradian (mW/sr) at 1A. The component measures 3.85 by 3.85 mm, and is 2.29 mm high including the lens.
With this new device, designers can now choose from mutually compatible emitters in three different wavelengths. These can be combined within a single illumination unit or used to convert existing systems to another spectral range without the need for layout changes.
