Lidar Evolution

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Maui/MALT Enterprise
Lidar Evolution
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Maui/MALT Investigators
Airglow Imagery Spectroscopy Mike Taylor,
Utah State U Gary Swenson, Alan Liu, U
Illinois Mike Kelley, Cornell U Jim Hecht,
Aerospace Corp Meteor Radar Steve Franke, U
Illinois Wayne Hocking, U Western Ontario Na
Wind/Temperature Lidar Gary Swenson, Alan Liu,
Chet Gardner Xinzhao Chu, U Illinois Rayleigh
Temperature Lidar Tim Kane, Penn State U John
Meriwether, Clemson U Program funded jointly by
NSF AFOSR
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Global Distribution of Gravity Wave Energy at
20-30 km in Northern Winter (1995-1997) Using
GPS/MET Data
The
Ep
value is averaged in an area extending 10 and 20
degrees in lat
itude
and longitude, and the center coordinates are
shifted every 1 an
d 2
degrees, respectively
Tsuda
et al., 2000
.
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Grad students Jeff Bruggemann (left) and
Chirantan Mukhopadhyay (right) operating the Na
wind/temperature lidar at Maui, January, 2004
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8/11/04
8/12/04
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Lidar Equation photons received from range
element
Receiving probability
transmitted photons
Scattering probability
System efficiency/ atmospherictransmission
Background
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Principles of Na Doppler Lidar (3)
Lidar Equations for Resonance Fluorescence
Effective Cross-section
Convolution
Doppler Width
Doppler Shift
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Lidar- Light Detection Ranging
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Costs (in K) 4 mirror starter receiver
system 205.2 (uses existing transmitter) Autono
my, and 1.8 m2 aperture area All up
system Vertical Receiver Array (Reflective) 710.5
Autonomy, and 7.2 m2 aperture area, GAIN
3-5X Upgraded Transmitter, with Chirp
meas. 499.5 Dual Wind Receiver Array
(Trans.) 583.5 Rayleigh (Density/Temp)
(Excimer) 301.3 Total 2,094.
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Plan to increase operations and ease of
maintenance of system Change to a bistatic
system (with transmitter) -Unrestricted access
allows much more operation time in zenith mode
to measure temperature, Na density, vertical
winds, heat flux, constituent flux (500-1000
hrs/yr -also daytime operations) -Enable
installation of Rayleigh lidar to obtain
temperature profile in the middle atmosphere.
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A Bistatic Lidar
RECEIVER
h?
2 x 8 Telescope Array (Area7.3 m2), directed to
Zenith
Each, 30 dia, f2 refelctive mirrors, with
motorized, computer controlled fiber alignment.
Fibers from all receiving telescopes
FOV 1 mr
Bore sighted alignment camera
h?
Spectral filtering and fiber relay
Sensor array
Optical Table
Mirror adjustable pointing
Note, there would be two systems of fiber,
spectral filtering, and sensors, for 589 and 355,
respectively.
Transmitter
Computer Control, Receive
Note, there would be two transmitters, one for
589 (Na resonance) and 355 nm (Rayleigh).
Maui MALT Enterprise
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Side View
Top View
Spider assembly with x,y positioning of fiber.
Position requirements lt .1 mm steps, gt12 mm
range.
Two fiber arrays, diameter 2 mm, one for 589
(Na resonance) and one for 355 nm (Rayleigh).
Cross Section of the reflector telescope, (1 of
16, directed vertically)
60 (focal length for f2 mirror)
Pyrex spherical mirror, f2, 30 diameter, lt100
um spot for PSF
Optical Table
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Cross Section of the sensor array in the image
plane
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Costs (in K) 4 mirror starter receiver
system 205.2 (uses existing transmitter) All
up system Vertical Receiver Array
(Reflective) 710.5 Upgraded Transmitter, with
Chirp meas. 499.5 Spectral Measurement, plus
Gain 4-6 Dual Wind Receiver Array
(Trans.) 583.5 Rayleigh (Density/Temp)
(Excimer) 301.3 Total 2,094.
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Principles of Na Doppler Lidar (2)
Doppler Width ? Temperature Doppler Shift ? Wind
Velocity
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Current Transmitter for Maui MALT
350mW
Verdi 4W
Ring Dye Laser
AOM AOM-
Z
N/S
E/W
200mW
NdYAG Laser 16.5W
PDA
2W
Scheme of current 50Hz transmitter
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Na Wind/Temperature Lidar _at_ Maui
AOM
Na Vapor Cell
Wavemeter
Verdi Laser
Ring Dye Laser
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Proposed New Transmitter (Plan 2)
1W
Verdi / Millennia 8-10W
Ring Dye Laser
375mW
AOM-
375mW
250mW
AOM
NdYAG Laser 1
2W
PDA 1
250mW
Z
NdYAG Laser 2
E
N
2W
PDA 2
250mW
NdYAG Laser 3
PDA 3
2W
Scheme of equivalent 150Hz transmitter
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Reflexite lens UVT acrylic
PSD as measured from an image of a star.
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Costs (in K) 4 mirror starter receiver
system 205.2 (uses existing transmitter) All
up system Vertical Receiver Array
(Reflective) 710.5 Upgraded Transmitter, with
Chirp meas. 499.5 Dual Wind Receiver Array
(Trans.) 583.5 Autonomous horizontal wind
capability Rayleigh (Density/Temp)
(Excimer) 301.3 Total 2,094.
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Two-2 x 8 Telescope Arrays (Area7.3 m2),
directed to acquire zonal and meridional informat
ion.
Horizontal Wind Receivers (2)
h?
Fibers from all receiving telescopes
Each, 30 dia, f2 refelctive mirrors, with
motorized, computer controlled fiber alignment.
FOV 1 mr
Bore sighted alignment camera
Spectral filtering and fiber relay
Sensor array
Tilted Optical Table
Note, there would be two systems of fiber,
spectral filtering, and sensors, for 589 and 355,
respectively.
Computer Control, Receive
Note, shown are reflector receivers, but fresnel
lenses have been costed.
Note, there would be two transmitters, one for
589 (Na resonance) and 355 nm (Rayleigh).
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An Optical Schematic of 1 element of a 16
element lens array for a lidar receiver.
FOV 2.6-4 mr
30 dia
Fresnel lens, UVT acrylic
fl30
2-3 mm dia fiber
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Fresnel Lens in Lab Test for Point Spread
Function (PSF)
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Costs (in K) 4 mirror starter receiver
system 205.2 (uses existing transmitter) All
up system Vertical Receiver Array
(Reflective) 710.5 Upgraded Transmitter, with
Chirp meas. 499.5 Dual Wind Receiver Array
(Trans.) 583.5 Rayleigh (Density/Temp)
(Excimer) 301.3 Temperatures, 30-120
km Total 2,094.
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There is a significant advantage in operating a
high power Rayleigh lidar in the proximity of a
metal (Na,Fe) Doppler lidar. Gravity and
Planetary wave as well as tides can be studied
from 30-gt105 km.
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Candidate
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Costs (in K) 4 mirror starter receiver
system 205.2 (uses existing transmitter) All
up system Vertical Receiver Array
(Reflective) 710.5 Upgraded Transmitter, with
Chirp meas. 499.5 Dual Wind Receiver Array
(Trans.) 583.5 Rayleigh (Density/Temp)
(Excimer) 301.3 Total 2,094.
Future considerations will include Rayleigh
Geostrophic Winds, and infusion of solid state
lasers which will eventually replace the Yags and
Excimers.
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Maui MALT Enterprise
1) We are motivated to become autonomous from the
large AF telescope. We believe that
by developing our own receiver, we can increase
our observing time to be consistent with the ISR
type facilities, i.e. 500-1000 hours per year.
As planned, we would have 75 the current light
gathering power (aperture) of the large AF
telescope. The zenith system would consist
of 16, near diffraction limited, f2 reflective
mirrors. In the process, we would eliminate
an approximate factor of 4 in tranmissive/receiver
optical losses associated with the coude path of
that system. Our system would be bistatic,
having minor losses through the bistatic
steering prisms. The net gain of our Enterprise
optical system would be 3. We would upgrade
sensor efficiencies, with anticipated quantum
efficiencies of 5-8, over our current system. 2)
Our plan includes an upgrade to the Na
transmitter to increase the average power a
factor of 4-5, using 3 Pulse Dye Amplifiers. We
would measure chirp in each of the tri
tranmitters. 3) Wind capabilities would follow
in development, with static receivers of equal
aperture directed to meridian and zonal
directions. These arrays are currently being
considered using fresnel optics. We currently
plan 16 diameter30" fresnel lenses, with fiber
receivers which would be used for the Na system,
at night. This is an approach similar to that
taken by CSU with their wind lidar. Note, the off
axis fresnel arrays are not shown on the
schematic. The net gain in this system is
conservatively a factor of 50 in signal to what
we currently have. 4) New Rayleigh capabilities
would be available. an added independent, 7.3 m2
aperture for zenith detection of Rayleigh
returns. Excimer lasers at 355 nm, with average
pulsed power of 50 watts are on the market along
with emerging solid state lasers. Currently, a
typical 5 watt yag system at 530 nm , with a 1 m
mirror, would have a power aperture of 5 wm2.
The new system would have a power aperture of
365, an improvement by a facter of 73. By going
to 355 nm instead of 530, the net increase in
cross section offers an additional signal
improvement a factor of 5, for a net improvement
potential of 365. (our new limit will be sensor
bandwidths).
Significant advantages include, in addition to
being autonomous from the AF mirror a) night and
daytime capability for the zenith. b) would
locate where we would have unrestricted access  
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Maui MALT Enterprise--Alignment
Calibration -Image the zenith star field and
identify zenith (McStronomy and Alignment
Camera) -Adjust laser steering so the beam is
directed to the zenith. (Alignment
Camera) -Adjust each telescope xy fiber
position (computer controlled) for a maximum
signal return. (Use the CCD camera in the
image plane and optimize brightness for each
telescope receiver. (Note, this scheme
requires the engineering of the
alignment calibration system to rely on both a
bore sighted alignment camera and a CCD in the
image plane of the fiber array.)
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Table Mountain
JPL makes DIAL Ozone measurements at Table Mtn,
CA and Maun Loa, HI. The BG channel at 355 nm has
quality Rayleigh information.
Steve Franke, UI, Thierry Lablanc, JPL, and
Stuart McDermid, JPL, July, 04