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The color of an object will change according to its temperature. Infrared Radiation is invisible allows us to see objects that are hotter than the background. Infrared Radiation is used in weather prediction. The pit viper uses infrared radiation to find its prey.
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The color of an object will change according to its temperature.
Infrared Radiation is invisible allows us to see objects that are hotter than the background.
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.
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.
This is the data taken by ALPIS that was found to be a false positive.
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
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
An AOTF allows us to tune the filter in front of the detector. Cold Filter It is expected that the AOTF will enhance ALPIS by … increasing signal-to-noise eliminating many false positives enabling the equipment to operate over water allowing the helicopter to increase its altitude AOTF
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. We have ideas that could resolve this problem, but they are proprietary and only those working on the project can know about them. First Order Beam Zeroth Order Beam