Osram Opto Semiconductors GmbH of Regensburg, Germany says that its new Oslux SFH 4786S infrared LED (IRED) enables iris recognition systems to be made less complex and with lower profiles. At 1.6mm high, the new IRED is about a third thinner than its predecessor. Also, its direction of emission is slightly angled, so there is no need for the usual mechanical aids to ensure correct geometrical alignment.
Recognizing different iris patterns from one person to the next is one of the most reliable biometric identification methods, says Osram Opto. The technology has recently been adopted in smartphones and tablets to protect them against unauthorized access.
In 2014, Osram Opto launched the Oslux SFH 4780S (claimed to be the first IRED that enabled compact and reliable iris scanners to be integrated into mobile devices). The 2.4mm-high SFH 4780S is optimized primarily for maximum light extraction whereas the new SFH 4786S features the same high light extraction performance but its height has been reduced to only 1.6mm (while maintaining the same footprint) to meet the demand for extremely low-profile emitters in designs where very little height is available.
A completely new feature is the 8° tilt in the emission direction of the SFH 4786S. The slightly sideways emission characteristic is beneficial for the field of view of the camera mounted a slight distance away. The firm say that the performance of the overall system is significantly better than one with an emitter slightly emitting vertically upwards. “Up to now, mechanical means have been used in iris scanners to tilt the IRED slightly,” says Chris Goeltner, product marketing manager, IR. “However, this additional expense is no longer needed with the SFH 4786S. This greatly reduces the level of complexity in designing iris scanners.”
Designers also benefit from the broader emission angle of +13°, which allows a larger area to be illuminated at the customary working distance for iris scanners in mobile devices. The radiant intensity of the SFH 4786S is typically 1750 milliwatts per steradian (mW/sr) at a current of 1A.
Like the SFH 4780S, the SFH 4786S emits light with a wavelength of 810nm. In this spectral range, it is possible to achieve high-contrast images for all iris colors. The chips are of Nanostack design, which provides two emission centers per emitter, resulting in maximum optical output.
Both IREDs are based on the highly efficient Oslux package, which focuses the light tightly with its reflector and an appropriate internal lens. Osram Opto says it is capable of providing high radiant intensities and also of being easy to process due to its flat surface. Also, the thermal resistance of the package is just 25K/W.
The SFH 4786S is available now upon customer requests. Volume production is planned to start at the end of January.
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