Infrared LEDs with black packages meet industrial design criteria for surveillance cameras
20.09.2016 | Spotlights
Osram Opto Semiconductors presents infrared LEDs that make surveillance cameras much more discreet. The new Power TOPLEDs emit light with a wavelength of 850 nanometers (nm), which is virtually invisible to the human eye, from a package with a black surface. The black emitters give camera designers greater freedom because they are almost impossible to see in the surveillance systems that are used for example in foyers and museums.
The main applications for the new emitters are surveillance cameras (closed circuit TV, CCTV) which flood the area under observation with infrared light to ensure good image quality. The hemispherical housings for these dome cameras are a familiar sight in banks, museums and amusement arcades. The lighting units consist of several infrared LEDs (IREDs). Osram Opto Semiconductors serves this sector with extremely powerful Oslon emitters for long-reach systems and with Power TOPLEDs for medium brightness levels and reach. Most solutions operate with a wavelength of 850 nm because the camera sensors have good sensitivity around this wavelength. The new Power TOPLEDs also emit light in this spectral range.
Same package, different color
With the exception of the black color of the top of the package and lens, the new SFH 4278S and SFH 4279S are identical to their white counterparts, the SFH 4258S and SFH 4259S. All Power TOPLEDs with lenses have a footprint of 2.8 x 3.2 mm. They differ in height because of the lens geometry for the different emission angles. The SFH 4278S is 3.8 mm high and emits with a half-angle of ±15°, whereas the SFH 4279S has a somewhat broader emission angle of ±25° and is 0.3 mm shallower. The thermal resistance of 300 kelvin per watt has also remained the same, which means that the components can be operated at a current of 100 milliamperes (mA) even at high ambient temperatures.
Stack chip for more light from the same current
The optical output of the SFH 4278S / 4279S benefits from the use of chips with nanostack technology. These chips feature two emitting semiconductor layers so they produce more light from the same current. The SFH 4278S achieves a typical radiant intensity of 160 mW/sr at 100 mA. For the SFH 4279S the figure is 75 mW/sr. The total optical output for both emitters at 100 mA is typically 95 mW.
Simple switch from existing designs
On the whole, designs that already use Power TOPLEDs with lenses can be switched to the black versions without the need for any changes in the mechanics or electronics. The systems therefore comply with the industrial design requirements for surveillance cameras.