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 Lana
Head Banana
Registered: 10/27/99
Posts: 3,109
Loc: www.MycoSupply.com
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 Misunderstanding on why IR is detected and how to 
#363393 - 07/30/01 04:34 AM (23 years, 1 month ago) |
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Hi Everyone,
Here's another post a friend sent to me. It was originally posted over on http://www.overgrow.com
http://www.overgrow.com/edge/showthread.php?threadid=31659&highlight
I'll copy and paste the first post from the thread and if you like, check out the link above to see the rest.
Lana
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Misunderstanding on why IR is detected and how to avoid detection
IR stands for Infra-Red light with a wavelength of over 7 nanometers... this means that this kind of "radiation" yes radiation, exists in the same form as visible light except that it has a lower amount of energy (longer wavelength EMF has less energy than a shorter wavelgth EMF), this "light" cannot be seen with the human eye. IR light although it can easily be passively picked up by IR Detectors/cameras, can easily be blocked. IR radiation/light is transmitted from a source(usually in this case a HID bulb) in 2 ways, it either passes through an object as radiation( this is why a material such as MYLAR which reflects ~97% of the spectrum of light from
IR -> UV that is incident to it's surface is used to shieldreflect IR and visible light) or it strikes an object and transfers its energy to the surface molecules of the object (dark black surfaces are excellent absorbers of light which is why you see an absence of light creating the apearrance of darkness/black, the absorbed is energy from the light is transferred to the struck molecules as heat, the heat is then reradiated as a lower energy EMF which is IR ). The Heat created at the surface of the object is now transferred through the object via conduction to the area of lower heat which is usually the other side of the wall/object(this is why foam / fiberglass insulators are necessary to prevent heat loss/transferrence.
I read in a previous thread http://www.hempcultivation.com/420/showthread.php?threadid=7197&pagenumber=2
that someone suggested using lead as an insulator from the IR. No Good as S2 previously pointed out. Lead is a great conductor of heat and the reason why an IR signature can still be seen by LEO is that the flux/flow of heat through a conductor is substantial enough to cause IR radiation to be emitted from the surface of the lead facing away from the light/heat source. Simple concept here from a physics class... allllll oscillating particles emit EMF (ElectroMagnetic Fields which is what IR is)... the greater the directional Flux of heat through a surface ((from the side of the surface facing the source of heat/radiation... I.E. from the Light bulb to the side of the surface fascing away from the lightbulb/heatsource since heat travels in a direction from highest to lowest concentration))the faster the particles of the material oscillate therefore the greater the energy transmitted by the IR... that is why in a previously posted thread/pic, a IR pic of a house's ceiling showed higher intensities of IR radiation than did the floor of the house.
http://www.x20.org/images/Vtherm_IR_scan.jpg
Ok i hope everyone is following b/c i am going to get to the point. To very efficiently prevent an IR signature of a grow room from being transmitted to the outside world where it can be passively picked up by IR detectors/cameras you should use multiple materials in conjunction with eachother... I will start from the inside of the room out proving my madness the entire way.
Layer 1: this is the first line of defense against IR leakage, this layer prevents a majority of radiation passing from the bulb... like amirror since mylar is an exceptional reflector
Mylar which is used to maximize internal reflection of light bulb to maximize amount of light supplied to plants.
Layer 2(optional): Waterproof Latex coated sheetrock
Layer 2a: Tuff-R foam insulation with double sided aluminum coated with Dry-Lock latex paint(the latex paint actually adds to the resistivity value to heat flow of the insulator) to prevent moisture condensation and mold mildew growth. this layer minimizes the flux of heat due to conduction
Layer 3: Air Space used in conjuction with Tuff-R Layer2a and Layer 4 to decrease conduction of heat
Layer 4: Tuff-R: double sided aluminum foil foam board insulation. final layer of conductive heat prevention
Layer 5: Mylar used to prevent remaining IR emitted from the foam board due to conductive heat ... remeber oscillating particles emit EMF...
[Edited by Pillsbury DroBoy on 05-14-2001 at 02:53 AM]
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Anonymous #1
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Re: Misunderstanding on why IR is detected and how to [Re: Lana]
#365626 - 08/02/01 01:52 PM (23 years, 1 month ago) |
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Excellent post Lana. But they usually don't look until they have been tipped off, and then the Heat signature is just one of the means by which a warrant is obtained. Usually just an informant alone is enough to warrant a search.
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