Turning on the interior lighting without pressing a switch? This could soon be possible with the high ambient light independent optical sensor (HALIOS) electro-optical system developed by automotive supplier Hella (www.hella.com). It reacts as soon as a hand is placed near it.
The special feature of this solution developed by Hella is a compensation function that makes the system relatively insensitive to external disturbances. Although sunlight or stray light caused by scratches in the glass cover, dirt or temperature fluctuations can change the useful light signal, in the HALIOS system a second light diode transmits the same infrared signal once more but phase-shifted through 180°. After the two light impulses have been processed the sum total of the two sinusoidal signals must be zero.