Osram Opto Semiconductors has presented an infrared LED (IRED) for iris scanners at the Mobile World Congress. The SFH 4787S illuminates the eyes so evenly that the software identifying the iris pattern hardly needs to correct artefacts. Its direction of emission is slightly angled rather than vertical, thus simplifying the design process by eliminating the usual mechanical aids.

Iris recognition is among the reliable biometric identification methods. In short, iris scanners illuminate the eyes with infrared light and a camera. Special software detects the iris pattern that is unique to individual.

Two years ago, the company was first to introduce infrared LED and brought this technology to smartphones and other mobile devices. This was followed by a version with a slightly angled direction of emission, which meant that designers no longer need mechanical aids to tilt the entire LED. The angle of emission aligns with the camera’s field of view.

Even illumination simplifies processing

This third-generation Osram IRED for iris recognition meets another need in this application: the brightness differences in the camera images should ideally only originate from the iris pattern and not be additionally caused by a gradient in the illumination. This would mean that the software needs to correct fewer artefacts when determining the iris pattern. With the SFH 4787S, Osram has thus developed an emitter with a flat light, optimising the reflector and lens to ensure constant intensity across the emitted light beam.

The SFH 4787S is almost identical to its predecessor, the SFH 4786S. Both are based on the compact 3.5mm x 3.5mm x 1.6mm large Oslux package. A wavelength of 810nm delivers high-contrast images for all eye colours. The emission direction is tilted by 8 degrees, while the emission angle is ±18 degrees. The optical output of this highly efficient emitter is 720mW at a current of 1A, with a radiant intensity of 1,000mW/sr.