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Infrared Tutorial |
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Infrared
Tutorial
Version 006
Copyright 2000-2003
www.ZyTemp.com / Radiant Innovation Inc.
--- All Rights Reserved ---
Reproduction of
this document in whole or in part is permitted if both of
the following conditions are satisfied:
This notice is included in its entirety at the beginning.
There is no charge except to cover the costs of copying.
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What
is the history of IR? |
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The Royal Astronomer Sir William
Herschel discovered "Dark Heat" radiation in
1800.
In 1880 the term "infrared" was coined. Samuel
Langley invented the bolometer that measures variations
of resistance when heated.
In 1901 a bolometer could detect a cow at 400 meters.
After World War II, many countries invest huge amounts
of money in IR for military application.
In 2002 Radiant Innovation, has designed the most compact;
most long battery life (70hours continuous use) and the
most affordable IR Thermometer by the proprietary SoC
& Infrared Technology, use MEMS based; advanced Thermal
Sensor. |
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What
is infrared radiation (IR)? |
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| IR
just like any light ray, is an Electromagnetic
Radiation, with lower frequency (or longer wavelength)
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| Anything above absolute zero (-273.15
degrees Celsius or 0 degrees Kelvin), radiates in the
infrared. Even ice cube, snow, your refrigerator emit
infrared. |
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Your eyes are design for Sunlight,
2 kinds of species are identified to be able to detect
IR: some rattle snake & beetle. But you still can
sense the IR by your skin:Beside a campfire, you can feel
the warmth from the IR.
When your car is baked by sun , you start the car, turn
on Air-Con, the air is cooled,
But you still feel Baking-Hot!, that's IR come from the
interior of the car, reaching your sensor (skin).
You may use IRT to learn that the radiation temperature
in your car can reach 80degC! |
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Believe or not, Quantum physics
is the key theory:
the total radiation energy is proportional to the fourth
power of the absolute temperature (Stefan-Boltzmann Law)
Wien Displacement Law: the product of the peak wavelength
and the temperature is found to be a constant.
Wien get the Nobel Prize for Physics for the year 1911.
These are the major earthquake in physics, after that
Classic Physics crashed, Quantum Physics flourish. |
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As
I remember, usually IRT are much larger than this one?
Accuracy is compromised? |
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IRT were much larger, but
ZyTemp is as small as the "battery of some large
IRT".
Accuracy is not compromised, each device has a test report
in our database, which is traceable by the serial number.
These test follow the disciplines of "ASTM E1256.Test
Methods for Radiation Thermometers (Single Waveband Type)"
Under Development:
COC on Web
You can check the accuracy test report of the very IRT
in your hand by visiting our web site www.ZyTemp.com and
entering the serial no.
Some model (TN1xx-tr) has a hardcopy test report right
in the package.
RII is the only manufacturer who can provide free test
report via internet.
In terms of accuracy, size doesn't
matter.
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Can
IRT measure air temperature? |
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No and Yes.
No, because Air do not emit infrared, the emissivity is
too low to be detected.
Yes, because you can pointing the IRT to anything that
has the SAME temperature as the air:
Outdoor: leaf , tree, grass (under sunshade) has the same
temperature as the air
Indoor: your desk, a piece of paper, has the same temperature
as the air.
The key to get "Air temperature" is to measure
"anything which should have the same temperature
as the air"
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Can
I measure the body temperature of an Ant by IRT? |
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You can pointing the IRT
to an Ant on your desk, but what you get is an average
temperature of the Ant & the Desk
because the Field Of View of the IRT is much larger than
the Ant.
But, if you can get 10,000 of ant, on your desk, which
can cover the whole FOV of the IRT,then
YES, you can measure the body temperature of Ant.
This FOV issue,
is a key to get correct reading from IRT.
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How
far ? |
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I can measure temperature of a
wall from 5meter? Temperature of a mountain from 1km?
We are using the 8um to 15um infrared, the atmosphere
is almost totally transparent for this band.
At 100meter, no rain, no fog condition, IRT is very accurate.
At 1km, you need some physics background to correct the
reading.
see [Theory and Practice of Radiation Thermometry] by
D.P. DeWitt, chapter 3. |
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Can
the IRT operated in complete darkness? |
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Yes, that's why DOD & military
are so interested in IR.
In fact, the early IR technology are developed by military
fund. |
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Can
the IRT penetrate a building, measure what's inside? |
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In real life, No. It can be done
only in the movie. |
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But
I remember IR can penetrate something? |
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IR can penetrate PE film (for
example: a complete dark garbage bag), Silicon, Gemanium.
You can hide something warm behind a PE film (your hand),
the IRT can detect the presence of the object. |
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Now
I can measure the body temperature of a fish in my aquarium? |
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No, water & glass is transparent
for visible light only, but for IR, it's completely "opaque",
all IR from the fish can't penetrate the water, so you
are only measure the temperature of the glass.
How about my pet's temperature? by pointing IRT to your
dog, you get the temperature of the fur. What you see
is what you got. |
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How
do I know, my IRT is still accurate? |
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Calibration of IRT is extremely
sophisticated, that's why IRT were so expensive. (not
any more!)
RII develop his own proprietary CCE(Continuous Calibration
Equipment), which can calibrate 96pcs of IRT at the
same time, at different temperatures, in a continuous,
high throughput operation.
The Cycle time is also reduced by a special prediction
algorithm.
RII are ISO9001 certified.
Our Infrared Ear Thermometer can conform with the ASTM
E1965's stringent requirement: +/-0.2degC
If still in doubt, you can try this DIY-Calibration:
- Fill a large polystyrene (e.g.,
Styrofoam) cup (10 oz or larger) (or any Thermos)
halfway to the surface with crushed ice.
- Add cold tap water to ? to
1 inch below the rim of the cup tip. Two cups, one
inside the other, will provide better insulation and
more stable temperatures throughout the test.
- Immerse the tip of an accurately
calibrated contact probe thermometer, that has been
calibrated, into the water and vigorously stir the
water's surface with the probe for one minute, or
until contact probe temperature stabilizes.
- When the probe temperature
has stabilized, continue stirring the water, while
taking simultaneous temperature measurements with
the IR thermometer.
- Hold the IR thermometer within
1 inches of the surface of the water for the most
accurate measurement. Infrared temperature
measurement should be within +/-1J (+2°F) of probe
reading at 0°C(32°F).
Warning: because such a testing
requires special technique; and for the follow reason,
RII has no guaranty on the result.
Advanced user may use a home
made triple-point (liquid; gas and solid co-exist) to
calibrate your Contact Thermometer,
see Scientific American, January 13, 1999, "Tackling
the Triple Point", By Shawn Carlson
This article provides an innovative way to maintain
a temperature standard about 0.0001 degree C, right
in your home and costs less than $50 to build.
Triple-point of water is a very accurate temperature
standard, much better than "Ice &Water coexist".
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What
else can I use IRT to measure? |
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You can measure the temperature
of almost anything, including the universe! to prove the
Big Bang theory.
In 1965, the remnant radiation from the Big Bang was discovered
by radio astronomers Arno Penzias and Robert Wilson. This
radiation, which peaks at 3 K (-270degC) can be found
in all directions in space.
Such a temperature is an evidence of the Big Bang (the
origin of this universe).
Well , you have to carry an IRT to outer space to get
a correct reading. Well, of course, you need some sophisticated
IRT and maybe a space shuttle to do this measurement.
Our IRT still can't operate in outer space. |
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So
this "Swiss Army Thermometer" can measure anything? |
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Yes, it's
a Swiss Army Thermometer. But there are still something
impossible to measure :
Gold, Shining Metal, or any low emissivity material.
For example: the reading of a 125degC gold, is only about
27degC.
For these material with high reflection in IR, what you
are measured is only the REFLECTION.
When IRT fail, try other contact type thermometers
Find..List..Learn About Temperature Sensors at: www.temperatures.com |
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Hint
to get accurate reading with IRT? |
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The target must cover the whole
FOV(Field Of View) of the IRT.
Avoid shining surface(metal), rough surface give better
accuracy.
add Electrical Insulating Tape (black is better) on the
metal surface, can solve the problem, give accurate result.
be sure the tape is large enough to cover to Field Of
View of the IRT.
be sure the tape will not BURN. use with caution!
Avoid temperature noise (avoid other High temperature
object is nearby)
for example: you are measuring an IC, with a solder-iron
nearby
Try to perpendicular to the target surface. |
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