‘Flatter’ IR LED improves iris recognition systems

16 Dec 2015

Developer Osram OS presents innovative thin, flat infrared LED design.

Iris recognition systems can be made less complex and with lower profiles since Osram Opto Semiconductors (Osram-OS) has developed a dedicated infrared for security systems. At 1.6mm thick, the so-called SFH 4786S is around one third shallower than its predecessor. The key to its improved suitability to iris recognition is that its direction of emission is slightly angled meaning that there is no further need for additional mechanical aids to ensure optimal geometric alignment.

Recognizing different iris patterns from one person to the next is one of the most reliable biometric identification methods. This technology has recently been adopted in smartphones and tablets to protect them against unauthorized access.

In 2014, Osram-OS launched the Oslux SFH 4780S, the first IRED which enabled compact and reliable iris scanners to be integrated in mobile devices. Whereas the 2.4 mm high SFH 4780S is optimized for maximum light extraction, the height of the new SFH 4786S has been reduced to 1.6 mm to meet growing demand for extremely low-profile emitters in designs where there is very little room for thick components.

Tilted emission

A new feature, which Osram-OS expects will be of interest to systems integrtors, is the 8° tilt in the LED’s emission direction. The slightly sideways emission characteristic is beneficial for the field of view of the camera mounted a little distance away. The performance of the overall system is also significantly better than a conventional source with an emitter emitting vertically upwards. Up to now, mechanical means have therefore been used in iris scanners to tilt the IRED slightly.

Bianka Schnabel, Marketing Manager at Osram O-S, commented, “This additional expense is no longer needed with the SFH 4786S. For our customers this also greatly reduces the level of complexity in designing iris scanners.” The application is also said to benefit from the somewhat 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 1,750 mW per steradiant at a current of 1 amp.

Like its predecessor the SFH 4780S, the SFH 4786S emits light with a infrared wavelength of 810 nm. In this spectral range it is possible to achieve high-contrast images for all iris colors. The chips are of nanostack design in order to provide two emission centers per emitter and therefore maximum optical output.

About the Author

Matthew Peach is a contributing editor to optics.org.