A highly responsive design that even detects a single finger moving at five meters!

The most basic problem with regard to standard light sensors is that these frequently trigger at a specific light level, while what happens in real life is that ambient light levels fluctuate all the time. Therefore a standard light sensor will function correctly only in a controlled environment, or under highly predictable conditions.

The Super Motion Sensor described here, on the other hand, auto-adjusts over the range of about 50 lux to 60,000 lux (that is, a 40W incandescent light-bulb in a 10-meter-square room to direct sunlight). It really “shines”, dare we say, in the mid-range of about 100 lux to 10,000 lux (that is, a modestly lit room to bright shade).

It is what is called a “passive” system, in that it does not generate the light which it detects, nor does it use any additional circuitry for this purpose. At the same time, it may be used in the same way as both “active” and “passive” systems.

In daylight, the Super Motion Sensor will typically detect a single finger moving at a distance of 5 metres – without the use of any lenses. It will detect a person crossing a path at 20 metres’ distance – without lenses. Under a.c. lighting, it will typically detect a person walking in front of an ordinary light source (e.g. a 60W incandescent light-bulb) at 20 metres – also without the use of any lenses. Note, however, that in this case the sensor is pointed directly at the light source, and its range as a “passive” system under a.c. lighting will typically be only eight metres or so.

Generally speaking, a single lens will double these distances, while the use of two lenses, if an “active” system is used, will multiply the basic range by six or seven. Furthermore, if the system is augmented with an inexpensive laser diode, a range of hundreds of meters may be achieved.