Howdy Paul,
You may try contacting Leupold & Stevens Instrument Company in
Beaverton/Portland, Oregon. They do some work in this area with night vision
scopes. They are good people.
Richard
----- Original Message -----
From: "Paul Lowrance" <[EMAIL PROTECTED]>
To: <vortex-l@eskimo.com>
Sent: Tuesday, March 13, 2007 4:40 PM
Subject: Re: [Vo]: Diodes capturing Ambient energy - BINGO!
That's an idea. It could be difficult to verify what type of active
material the FIR goggles use. I think public night vision goggles use InSb
or similar material. The very expensive military night vision goggles use
the expensive HgCdTe god material. Not sure, but perhaps the really cheap
goggles use photoelectric material? I know the photoelectric effect
generates DC voltage caused by temperature *differentials*.
Regards,
Paul Lowrance
Gibson Elliot wrote:
> Try buying surplus night vision goggles, or another
> component that has the device you want. You might be
> able to scavenge parts...
>
> Just a thought
>
> G
> --- Paul Lowrance <[EMAIL PROTECTED]> wrote:
>
>> More discoveries. It appears a HgTe photodiode is
>> just about the ultimate
>> material for this research. It has a band gap of
>> zero eV! Various amounts of Cd
>> (Hg[x-1]Cd[x]Te) increases the band gap to whatever
>> value you want. Here are
>> some interesting quotes -->
>>
>> Quote #1 from WikiPedia:
>> ---
>> Owing to its cost, the use of HgCdTe has so far been
>> restricted to the military
>> field and infrared astronomy research. Military
>> technology depends on HgCdTe for
>> night vision. In particular, the US air force makes
>> extensive use of HgCdTe on
>> all aircraft, and to equip airborne smart bombs. A
>> variety of heat-seeking
>> missiles are also equipped with HgCdTe detectors.
>> ---
>>
>> Quote #2 from WikiPedia:
>> ---
>> The main limitation of LWIR HgCdTe-based detectors
>> is that they need cooling to
>> temperatures near that of liquid nitrogen (77K),
>> ***TO REDUCE NOISE*** due to
>> thermally excited current carriers
>> ---
>>
>> Note the bold text in Quote #2. This material is so
>> noisy they need to cool it
>> to 77K, otherwise the voltage noise is incredible
>> ... bingo!
>>
>> This is so ironic. Why are most desirable things
>> come at such high cost?
>> Everyone loves ice cream, but the calories. I would
>> give just about anything to
>> experiment with a p-n HgTe photodiode, but it's
>> ridiculously expensive. Would
>> they even sell it to me?
>>
>> Furthermore, this material has ultra wide bandwidth.
>>
>> Mercury(II) cadmium(II) telluride (HgCdTe):
>> http://en.wikipedia.org/wiki/HgCdTe
>>
>> band gap image diagram:
>>
> http://en.wikipedia.org/wiki/Image:HgCdTe_Eg_vs_x.PNG
>>
>> Regards,
>> Paul Lowrance
>>
>>
>>
>>
>> Paul Lowrance wrote:
>> > Hi,
>> >
>> > The following is an important consideration for
>> those interested in the
>> > very real upcoming technology that will capture
>> significant continuous
>> > energy day or night from ambient temperature
>> (surrounding air and Earth).
>> >
>> > Silicon and Germanium are what is called
>> *Indirect band gap* material.
>> > This means Si and Ge are inefficient at emitting
>> and receiving
>> > radiation. Although recent technology has made
>> it possible to make Si
>> > LED's, but that's more complex.
>> >
>> > The following link contains a very nice table of
>> different
>> > semiconductors showing which materials are
>> Indirect and Direct band gap -->
>> >
>> >
>>
> http://www.chemistry.patent-invent.com/chemistry/semiconductor_materials.html
>> >
>> >
>> > Therefore, it seems highly advantageous to
>> perform experiments using the
>> > following materials -->
>> >
>> > * Indium Antimonide (InSb) 0.17 eV
>> > * Indium Arsenide (InAs) = 0.354 eV
>> >
>> > InSb is the best choice for capturing room
>> temperature black body
>> > radiation. I believe the above are direct band
>> gap materials, which
>> > means they are efficient at receiving and
>> emitting radiation.
>> >
>> > It's too bad Germanium is indirect band gap.
>> Sure glad I discovered
>> > this before heading out to buy various Ge diodes.
>> :-) Tom Schum placed
>> > 32 germanium diodes in series, which resulted in
>> ~1 uV. What would be
>> > terribly interesting is to see the vast
>> difference an InSb or InAs LED
>> > would make.
>> >
>> > It seems unrealistic to use a $108 to $175 MID-IR
>> LED for a replicable
>> > experiment. Very few people would spend $108
>> just to verify that
>> > ambient temperature energy is capturable. People
>> who already believe
>> > don't need it. One almost needs to pay a skeptic
>> to view an experiment
>> > that goes against their beliefs.
>> >
>> > There is one alternative, and that's the $10 1550
>> nm LED, made of
>> > InGaAsP, but I'm not sure present instruments
>> could measure the effect
>> > at room temperature. I calculate the effect would
>> be ~100 million times
>> > less than the $175 4900 nm LED. The presence of
>> Ga greatly increases the
>> > band gap, unfortunately, which is why this LED is
>> only 1550 nm.
>> >
>> >
>> >
>> > Regards,
>> > Paul Lowrance
>> >
>>
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