Mini infrared LED provides highest radiant intensity of its size class

July 10, 2012 // By Christoph Hammerschmidt
The infrared Mini Midled from Osram Opto Semiconductors is only 0.9 millimeters high but it produces a narrow and intense beam of infrared light. With its radiant intensity of 60 milliwatts per steradian (mW/sr) at 100 milliamperes (mA) it outperforms other comparable devices. This low-profile surface-mountable emitter is particularly suited for proximity sensors in devices where space is limited and for light barriers.

In many sensor applications it is not only the optical power of an emitter that is important but also whether the available light is widely spread or concentrated in a narrow high-power beam. This is characterized by the half-angle. The radiant intensity (measured in watts per steradian) indicates the optical power within a solid angle and therefore defines the intensity of the emitted light beam. 

The advantage of the new Mini Midled is its half-angle of 17°, producing a narrow light beam and a radiant intensity of 60 mW/sr at 100 mA. This is achieved by focusing the light with a metalized reflector integrated in the device. The new infrared LED offers a high output despite its exceptionally small dimensions of just 2.3 x 1.95 x 0.9 mm. 

The Mini Midled is the second SMT device from Osram Opto Semiconductors in MID (Molded Interconnected Device) technology, following the 1.6 mm high Midled. Thanks to new package technologies, Osram has managed to reduce the total height of the new infrared emitter to less than one millimeter but the new device can still be processed in the usual way. 

Small and powerful infrared diodes with a wavelength of 850 nm, such as the low-profile narrow-beam Mini Midled, offer major benefits in applications where there is little space but high radiant intensity is needed. Typical applications include light barriers, smart phones and optical touch screens. Thanks to its design, it also considerably reduces optical crosstalk so no optical shielding is required. 

Proximity sensors are a combination of an emitter and a detector. The emitter illuminates an approaching object, and the light reflected from the object is received by the detector. For proximity sensors to operate properly it is crucial that no light from the emitter should reach the detector directly (crosstalk). This is what often happens with devices that are not equipped with a metalized reflector. With the Mini Midled there is no