The Aurificusian Hypothesis

[Aurificus]

PULSING IR LED DETECTORS - Theory & Practice

Background : IR remote sensing

Common uses currently include: Satellite weather imaging, crops and land clearing studies, monitoring river, dams & lake levels. etc, etc.

Movement sensors to operate security, lights, alarms, cameras,etc.

For less than $50 you can purchase a quite accurate, IR, remote sensing, digital pyrometer (thermometer), (pay the extra and get the one with the laser pointer).

These detection systems rely on receiving “black body” IR radiation emitted by objects.

ATTENTION: A pulsing LED detector DOES NOT use this method.

What we are attempting to detect is far more subtle and is the type of effect that is considered inconsequential noise in standard EE practice.
In fact, standard theories & practices are designed to dampen, cover-up, ignore or over-power these effects.

The LED emits energy as IR radiation.
When it contacts matter this energy can be transmitted, absorbed or reflected.
Standard theory assumes that the matter involved has a constant temperature and therefore the rate of transmission, absorption or reflection is constant.
In a real world, (the one I’m in, maybe not yours!!) matter is constantly changing
its temperature. The rate of change depends on the introduction or removal of an energy source (radiation, let’s call it ‘heat’) and the composition and physical properties of the object in question and the medium it is in.

i.e. What size is the object?, what is it made of?, what it is buried in?, how deep is it?, is heat from the sun warming it?, is it cooling down?, etc, etc, etc, etc,…….

The zone around a buried object will therfore have a thermal energy gradient, except for brief periods where equilibrium might exist. Depending on conditions the gradient could extend to the air space above a buried object ( phenomenal!)

So what?!!! The emission from an IR LED is tiny and will have a negligible effect on any of “that BS” at any sort of distance!!!!!

True…..but what if a remote energy level change has an effect on the LEDs?

An LED will have a “rise time” from the application of power to its full IR emission level. Energy is required to excite (don’t say heat) a diode each time it is triggered.
The amount of energy needed will depend on how much energy the LED has dissipated whilst switched off. If the pulse is constant the LED’s start-up power requirement will change according to how much energy it is transferring to the environment while it is emitting.

Monitoring these undoubtedly very small voltage and/or current fluctuations might best performed with a sensitive ‘amplitude’ detector or similar that is separated from the power circuit to minimise any effect on it.

In conclusion, the theory is this: The pulsed beam is a ‘detection probe’ or a ‘transmitting antenna’, the zone around the target absorbs or rejects ‘additional’ energy at a greater rate than ‘ambient’ and the response is measured as power fluctuations at the transmitter not in reflected signals from the target.

No magic, No mumbo Jumbo. Just science and physics and not letting “the big stuff over-power the small stuff”. May I have a Patent, please? Plenty granted for a lot less than that!! I’ll share it with Esteban, we’ll be rich and retire and go treasure hunting.

P.S. For practical use, the variables involving real targets are so numerous that results might be “Very Hit & Miss”. When it works, it works, when it doesn’t……..try again, under different conditions……try again…… (more system development and/or control of the variables is required)

P.P.S The concept, however, has a lot of value. This type of sensing of seemingly insignificant, but quite measurable “side effects” can be applied to many different real world problems.

P.P.P.S. My deep RESPECT to Esteban, who politely and patiently shares elements of his years of work on Remote Detection equipment. The good, the bad & the otherwise. Without his input this thread would be little more than sceptics teasing novices & stroking their own and each others……prejudices.

Cheers, Aurificus