physics 110g invisible light toc 1 the color of an object will change according to its temperature
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Physics 110GInvisible Light
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The color of an object will change according to its temperature.
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Infrared Radiation is invisible allows us to see objects that are hotter than the background.
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Physics 110GInvisible Light
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Infrared Radiation is used in weather prediction.
Physics 110GInvisible Light
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The pit viper uses infrared radiation to find its prey.
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TitleAOTF DIAL LIDAR Detector System
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ALPIS uses DIAL LIDAR in the Infrared Spectrum.
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Methane absorbs certain wavelengths of light and transmits others.
DIAL LIDAR sends light at a wavelength that methane absorbs – online
DIAL LIDAR also sends light at a wavelength that methane transmits - offline
If the difference in intensity between online and offline is large enough , then the presence of methane is indicated.
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The Lidar is mounted to the bottom of a helicopter.
A variable source is used that can switch between online and offline wavelengths at a frequency great enough to assure that the online and offline are taken with a spatial location difference that is very small.
A detector that has a wide bandwidth receives both the online and offline light.
A cold filter that whose bandwidth is slightly larger than the wavelength difference between online and offline is used to eliminate as much background as possible.
An onboard computer receives the data and controls the system through DAQ cards.
The onboard computer then communicates the data to an operator’s console so that the information can be tracked for errors.
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This is the data taken by ALPIS for an actual leak.
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This is the data taken by ALPIS that was found to be a false positive.
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This is a picture of the area where the false positive occurred and another area close by where no indication is given.
Can you tell from these pictures why one absorbed the online and the other did not?
<- This is the false positive
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There are many objects that can absorb the online or cause a saturation in the detector.
Both can cause false positives.
Roads
Water
Rock Formations
Highly Reflective Buildings
Changes in Terrain
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Cold Filter
AOTF
It is expected that the AOTF will enhance ALPIS by …
increasing signal-to-noiseeliminating many false positivesenabling the equipment to operate over waterallowing the helicopter to increase its altitude
An AOTF allows us to tune the filter in front of the detector.
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One of our biggest hurdles is the detector field-of-view needed to cover the entire footprint on the ground.
The circle on the ground is approximately 40 feet in radius.
The first order diffraction beam overlaps the zeroth order.
First Order Beam
Zeroth Order Beam
We have ideas that could resolve this problem, but they are proprietary and only those working on the project can know about them.