A seemingly contradictory statement
that may nonetheless be true.
Active & Passive Light Sensor
The APLS started life as a light sensor, but as it is to be used in a totally dark location I realized it needed its own light source, pulsed ultraviolet and infrared LEDs were added for the light source.
The switchable LED's are pulsed so as to distinguish the emitted light from other external sources.
APLS is designed to detect and indicate the presence of an object able
to reflect the projected pulsed light, responses are indicated on a
LED display giving an optical response and from an audio tone generator
which pulses relative to the proximity of an object, both change relative
to light intensity change.
When I added pulsing LED emitters it became a useful tool, the addition
of switched ultraviolet and infrared allows various uses.
The APLS is potentially able to detect and illuminate unseen objects
(to the naked eye) at up to approximately 5 meters.
Paul Rowland for further information.
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