Hi Esteban,
I would not worry about what Max claims about infrared. Everybody who read his posts knows he does not know what he is talking about for infrared emissions. You cannot expect him to read any science reports about this. He already established in a different post that he is a real busy guy and he does not have time for reading lots of science reports. I think maybe he don't care what you show the Caltech professor says.
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Originally Posted by Esteban
You emit a IR-laser or IR modulated in audio beam, NO A FIX BEAM in wich you insert the tone via a capacitor. No, you ON and OFF the IR diode at this tone frequency, can be 400 Hz. This tone (modulation) appears as a phase shift in a receiver system. I only try with IR, but sure IR-laser will be better, but much more expensive in comparation. Not for to measure temp, but this beam is like a precisse antenna in wich beam "travel" the phenomenom (because I try it only for old buried items, no for new) and dislocates the system. Also all bodies emit IR, metals in major quantity. But the question is: why I can't detect a person (wich emit IR) but yes a metal buried? What is the associated phenomenom inherent to this? Atomic vibration also? Is very complex!
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This is a very interesting thing you talk about. Let me see if I understand correctly:
You say I should take an inrfared LED or an infrared laser, and pulse it on and off with a square wave, not sine wave at maybe 400HZ. This beam should be aimed at an old buried metal target. Correct?
If I understand your idea correctly for sending a beam to the long time buried metal, then my question is: How do I measure phase shift? Do I look for a change in the phase of the transmitted light beam frequency? or do I look for a diffenrence between the transmitted and the reflected beam? I would think a reflected beam will show very close to the same time as the beam sent when the target is at close distance.
In order to measure a phase shift, I would think it is necessary to use a very fast IC to see the small shift in a light beam time. Am I correct? Do we need to use methods similar to radar ranging techniques? What kind of circuit do you use to see the phase change?
Also, has this phenomena been seen in different light frequencies besides the usual infrared diodes and lasers? Do you know of any experiments with the red lasers or the 532nm high power green lasers?
Best wishes,
J_P