Influence of wind shear on laser
propagation
Joe Watkins
Reza Malek-Madani
Svetlana Avramov-Zamurovic
Experimental set up to measure the influence of
wind shear on laser light propagation
Wind shear refers to the variation of wind speed over horizontal distances.
 Laser source: HeNe red laser 2 mW
 Laser propagated through a tunnel
 Target was observed using beam splitter and camera with 12 bit
resolution (possibility to measure 4095 different light intensities)
 A phase screen was inserted in the tunnel in order to introduce
wind shear perpendicular to the propagation of the laser beam
 Three experiments were carried out:
NO wind
Wind 3m/s
Wind 5m/s
 Each experiment was monitored for three minutes using camera
that recorded changes in the laser light intensities at the target, at
the rate of 20 frames per second
Comparison between the 5 m/s wind
and no wind conditions
Wind 5 m/s
No wind
20
20
All of the frames
added together
Only one location
indentified for ‘hot’
pixel
40
60
80
100
120
140
160
180
200
1600
40
1500
60
1400
80
100
1300
120
1200
140
160
1100
180
20
40
60
80
100
120
140
160
180
1000
200
200
50
200
200
180
180
Locations for the
maximum intensity
for each of 3700
frames
160
140
120
100
80
60
40
100
150
200
160
140
120
100
80
60
40
20
20
20
40
60
80
100
120
140
160
180
200
20
40
60
80
100
120
140
160
180
200
Comparison between the 5 m/s wind
and no wind conditions
Wind 5 m/s
Intensity values for all of the frames
Very little variation : mean 1651.8
std = 9.1614
averaging radius 10 pixels
No Wind
Intensity values for all of the frames
Very little variation : mean 1647.9
std = 9.7914
averaging radius 10 pixels
1690
1680
1700
1670
1690
1660
1680
1650
1670
1640
1660
1630
1650
1620
1640
1630
1620
0
500
1000
1500
2000
2500
3000
3500
4000
0
500
1000
1500
2000
2500
3000
3500
4000
Data Histogram Comparison for Wind
Influence Experiments
From each experiment 5 runs were
averaged and histograms are presented
300
No wind
Wind 3 m/s
Wind 5 m/s
250
Mean light intensity for each run for
all of the experiments
Data Frequency
200
NO wind
Experiment
1525
150
1520
3 m/s wind
Experiment
100
1515
50
0
1200
5 m/s wind
Experiment
1510
1300
1400
1500
Light Intensity
1600
1700
1800
1505
1500
1495
1490
1485
0
5
10
15
20
Data Histogram Comparison for Heat
Influence Experiments
# of occurrences
* No heat
* HEAT Phase Screen
Discussion
The wind perpendicular to the beam propagation does not have
major influence on light intensity fluctuations, compared to the
influence the heat phase screen.
•
We were able to establish slight shift in mean value and the shape
of the histogram for the three experiments with variable wind velocities
•
Individual Probability Density Functions for each run did not
demonstrate reliable differentiation between the experiments.
•