Hi,
Congratulations! For the big pile of BS.
I think it doesn't work, and will never work in the real world, maybe yours is different.
Have any idea of what percentage of IR radiation arrives to a deep buried target ???
ZERO. The soil will dump anything your ridiculos 10mW from the led!
The LED you'll not read any measurable variation.
Follow this thought: suppose you have a 23mm diameter/4.15cm^2 area coin buried at half a meter underground... and you're 10meters far from target on the horizontal plane...
OK the half-meter means 50cm of soil above the coin...
The soil will swamp any reading... or you're talking here that a target like a coin cause if the thermal gradient is what you're looking for you must know that heath transfers are related to the MASS of objects ...so considering a deep buried small target (50cm and a coin) you're trying to let people here think that the coin retains or delivers heath to/from the soil in a way that's detectable by a simple IR LED + amplifier ! Isn't it ?
Now... the heath radiation happens from/to coin isotropically, so in all direction from/to coin vs soil , right ?
So... a coin placed at 50cm will radiate or receive heath equally from a volume of 1m^3 soil if we consider soil temperature about flat constant in the 1st meter (a good approximation in most cases during the day).
1m^3=10,000,000 cm^3
Now look at the coin that is e.g. a 23mm diameter one, 1mm thick: you'll get a volume of around 4.15 cm^3 means something 4*10^-7 order to be clear... so the coin's volume is about 4/10,000,000 the volume of soil we are talking about...
About mass... soil mass for 1m^3 vary due to soil composition/density but in organic soil (farm soil in most places) is about roughly 1200kg/m^3 so 1200Kg mass for 1m^3 and for coin, say it's silver... with density of 10490Kg/m^3 , so 10490*0.000000415= 0.00435Kg or 4.35grams
Now look at energy transfer (heath) in ideal conditions between these 2 mass... in the case the silver coin is hotter than soil around it... with a temperature difference of 20°C = 20°K....with wide approximations it's something like this:
The energy release from silver coin is due to Qc= volume_of_coin*volumetric_heat_capacity_for_silver *delta_T(°K)...
so Qc= 4.15*2.44*20= 202.52 joules
... then we suppose the soil that's 20°K lower in temperature will get that heath by conduction mostly (an approximation close to reality) and so the temperature in soil will increase , but what's that increase in °K considering all energy will be transferred with no losses and no dispersions ?
here the energy Qs=volume_of_soil*volumetric_heat_capacity_soil(si lica,water)*delta_T_soil(°K)
Qs=Qc (perfect transfer)
delta_T_soil(°K) = Qs/(volume_of_soil_volumetric_heat_capacity_soil(sili ca,water)) = 202.52/(10,000,000*2.9)= 6.98*10^-6 °K
In other words... if your soil is humid, organic and hi content silica... say it's at 30°C and the 23mm silver coin buried at 50cm reach 50°C, so with gradient of +20°C at coin, and we approximate full heat transfer between coin and soil, you'll get just about 7u°K or 7*10^6 °C variation in the considered 1m^3 soil.
GUYS !? We consider having 20°C gradient at coin soil interface and end up with 7 MICRO CELSIUS variation at soil volume... so at surface.
Can you detect 7*10^-6 °C variations with a LED diode ???
From 10meters away ???
Consider also S/N... 7uCelsius variations will be swamped out by any e.g. wind movement... that will cause the soil to cool down at really faster rate than 7uCelsius!
Consider the evaporation of trapped water in soil... will that cool the surface or not ???
It's a themodynamic-hell for you PYROMETER OR LED... OR WHATEVER!
Is that the new LRL-science-fiction!
I'm sure you didn't realize any of these fairy-tales devices... otherwise YOU MUST KNOW that's impossible detecting something this way.
On the air... of course, things are quite different... but soil it's a well known dumping filler... that's cause e.g. an atomic bomb shelter is usually underground... (not only... there are other reasons too ) the heath is dispersed by soil/water volume... will not work at ground zero just under the bomb maybe... but at few distance the soil will shield from excess heath... not like painting white your room and wear your preferite sunglasses!
Kind regards,
Max