Lasers & Sources

Osram IR LED is intended for eye tracking in mobile devices

Dec. 4, 2015

Blinking can replace the conventional double-click.

With a height of 0.6 mm, a footprint of 5.4 mm2, and a typical optical output of 1200 mW, the SFH 4770S is currently the most-compact high-power LED with a wavelength of 850 nm, according to Osram, its maker.

Osram Opto Semiconductors has introduced a compact infrared LED (IRED) that is intended for integration into smartphones and other devices, to be used in facial recognition and eye-tracking systems that can activate applications in response to eye blinking instead of the usual double-click. The SFH 4770S emits a typical 1200 mW at an 850 nm wavelength.

The basis for the emitter is the Synios package, which Osram introduced some time ago for LEDs in the visible spectral range for automotive applications. The package measures 2.7 x 2.0 x 0.6 mm and provides optimum light extraction, according to Osram. The SFH 4770S is the first component in which this package has been used for infrared emitters.

Installed in the IRED is a 1-mm²-emitter chip in which two 850-nm-wavelength emission centers are provided with the aid of nanostack technology; the two emitters are epitaxially stacked in one chip. Overall, the component delivers a typical optical output of 1200 mW at a current of 1 A from the one chip.

The height of only 0.6 mm makes the LED attractive for designs that call for broad homogeneous illumination in a limited space. This is particularly true for applications in mobile devices such as smartphones and tablets. "The SFH 4770S takes up very little space," says Chris Goeltner, product marketing manager at Osram Opto Semiconductors. "Compared to the Oslon, previously our most compact high-power IRED, we have managed with Synios to reduce the footprint by almost one-third and the height by around one quarter."

The emission angle of 120° ensures even illumination of the target area, and the device achieves a typical radiant intensity of 375 mW per steradian (mW/sr). Both these factors make the LED well-suited for for facial recognition and eye-tracking systems, which need the user’s face to be brightly and uniformly illuminated. The LED's thermal resistance (R_th) is a maximum of 9 kelvin per watt (K/W).

The Synios package can also be used for injecting light into external optics or light guides.

The Synios SFH 4770S is available on request for first customer projects, says Osram; volume startup is planned for the end of January 2016.

For more information, see osram-os.com.

Source: Osram Opto Semiconductors

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.