Optronic Measurement, Testing and the Need for Valid Results Example of Infrared Measurements for Defence Countermeasures Azwitamisi E Mudau, C.J. Willers,
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Optronic Measurement, Testing and the Need for Valid Results Example of Infrared Measurements for Defence
Countermeasures
Azwitamisi E Mudau, C.J. Willers, M.J. Hlakola, F.P.J. le Roux, B. Theron, J.J. Calitz, M.J.U. Du Plooy
Defense, Peace, Safety and Security, Council for Scientific and Industrial Research
amudau@csir.co.za
© CSIR 2010 www.csir.co.za
Peace and Humanitarian Support
Heat Seeking Missiles and Infrared Countermeasures
Infrared Measurements at the Optronic Sensor Systems
Airborne Infrared Countermeasure Characterization
Strategy for Successful Measurement
Details of Experiments
Equipment used and Settings
Experimental layout
Understanding Infrared Temperature Measurements
Results
Reference Measurements
Flare Measurements
Conclusion
Overview
• South African Air Force transport aircraft are the platforms of choice to deliver humanitarian aid
• are used in rescue and support missions
• used to carry soldiers into countries for UN sanctioned peace support and stabilization efforts
• the core of the SANDF’s transport and lift capabilities acquired by the country at tremendous cost.
• If they are destroyed or attacked it seriously limits the ability for South Africa to perform the humanitarian role
Peace and Humanitarian Support
• Airborne IRCM flares are defensive mechanisms employed from military and civilian aircraft to avoid detection and attack by enemy infrared seeker missiles.
Airborne Infrared Countermeasure Characterization
• To model airborne IRCM flares effectively and correctly as missile countermeasures - Radiant intensity- Emissivity - Temperature
Strategy for Successful MeasurementD
etai
led
test
pro
cedu
res
Und
erst
and
the
proc
ess
Detailed test plan
Understand the test
Understand the sensor
Characteristics & Procedures
Test Cam
paignsMea
sure
men
ts
Sensors
Strategy is required for measuring the signatures of infrared countermeasure flares
Details of Experiment
© CSIR 2010 www.csir.co.za
Measurements were performed
using Cedip Jade LWIR thermal
imager
Fluke 574 Precision Infrared
Thermometer
A high temperature Electro Optics Industries extended-area blackbody
7 8 9 10 11 12 130
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Wavelength (microns)
No
rm
alized
Resp
on
se
(a) LWIR Imager Responsivity
3.5 4 4.5 50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Wavelength (microns)
No
rm
alized
Resp
on
se
(b) MWIR Imager Responsivity
0 1 2 3 40
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1(c) SWIR Imager Responsivity
Wavelength [micros]
No
rm
alized
Resp
on
se
Prior Infrared Measurements
The Jade IR thermal imagers need to
be CALIBRATED
The objective of the calibration is to
obtain a relationship between the
incident flux and the instrument output
(digital level).
They are calibrated over a broad
range of temperatures.
© CSIR 2010 www.csir.co.za
During Infrared measurement trials
Infrared Mobile Laboratory
Weather Station
Reference Measurements
Blackboy
Flare Launcher
420 m
Capture quality IR images of
the unit under test (UUT) and
two reference source
(blackbody)
Instrument settings and
meteorological data
Atmospheric Transmittance
• To account for the target radiation losses through the atmosphere
• MODerate spectral resolution atmospheric TRANsmission (MODTRAN) code
Parameter 2009/11/11 2009/11/12
Atmospheric Temperature [C] 20.7-28 25.3-29.4
Humidity [%RH] 51-77 35-58
Cloud Cover Partially Cloudy Cloudy
Visibility [km] Good Good
Atmospheric conditions during test
“The same as” measurement technique was used to calculate the
Pyrolysis flame temperature (Tm).
Understanding Infrared Temperature Measurements
© CSIR 2010 www.csir.co.za
Tc is determined from the calibration curves
by Tc = fcal(D), where D is the measured digital
level and fcal is the calibration curve
c is the calibration source emissivity
Lbb(T) is blackbody radiation of a source with
temperature T
S is the instrument spectral response
ac is the atmospheric transmittance during
calibration
Ta is the ambient environment temperature
ae is the spectral atmospheric transmittance
between the measured source and ambient
environment (near unity ) and Lpath is the
atmospheric path radiance (near zero) .
am is the spectral atmospheric transmittance
between the instrument and the object during
measurement
m is the measured source emissivity
Tm is the unit under test temperature
0 0
1c bb c ac m bb m am m bb a ae pathL T S d L T S d L T S d L
Reference Measurements
© CSIR 2010 www.csir.co.za
0 0.2 0.4 0.6 0.8 1 1.2695
700
705
710
715
720
725
730
Time [s]
Te
mp
era
ture
[K
]
(a) Blackbody Reference in the MWIR Spectral Band
0 0.2 0.4 0.6 0.8 1 1.2695
700
705
710
715
720
725
730
Time [s]T
em
pe
ratu
re [
K]
(b) Blackbody Reference in the SWIR Spectral Band
Blackbody Reference # 112
Blackbody Reference # 212
Blackbody Reference # 211
Blackbody Reference # 112
Blackbody Reference # 211
Blackbody Reference # 212
Test Point MWIR (K)
SWIR (K)
Fluke (K) Percentage Difference (%)
MWIR / SWIR
MWIR / Fluke
SWIR / Fluke
211 709.76 ± 2.13 709.34 ± 2.84 711.15 0.06 0.20 0.25
112 707.54 ± 3.14 718.98 ± 1.76 708.50 1.60 0.14 1.47
212 704.04 ± 5.97 709.36 ± 2.64 712.15 0.75 1.15 0.39
211 112 212704
706
708
710
712
714
716
718
720
Test Point
Te
mp
era
ture
[K]
Temperature vs Test Point
FlukeSWIRMWIR
Test Point MWIR (K)
SWIR (K)
Fluke (K) Percentage Difference (%)
MWIR / SWIR
MWIR / Fluke
SWIR / Fluke
211 709.76 ± 2.13 709.34 ± 2.84 711.15 0.06 0.20 0.25
112 707.54 ± 3.14 718.98 ± 1.76 708.50 1.60 0.14 1.47
212 704.04 ± 5.97 709.36 ± 2.64 712.15 0.75 1.15 0.39
© CSIR 2010 www.csir.co.za
Flare Measurements
0 0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
(a) Normalized Intensity at MWIR Spectral Band as a Function Burning Time
Normalized Burning Time
No
rma
lize
d In
ten
sit
y
0 0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
(b) Normalized Intensity at SWIR Spectral Band as a Function Burning Time
Normalized Burning Time
No
rma
lize
d In
ten
sit
y
0 0.2 0.4 0.6 0.8 12200
2250
2300
2350
2400
2450
2500
Normalized Burning Time
Te
mp
era
ture
[K
]
(a) Flare Temperature in MWIR Spectral Band
0 0.2 0.4 0.6 0.8 11800
1900
2000
2100
2200
2300
2400
2500(b) Flare Temperature in SWIR Spectral Band
Normalized Burning Time
Te
mp
era
ture
[K
]
The methodology used was developed over several field trials,
spanning several years.
The deep understanding of the instruments is essential in exploiting
the instrument and avoiding its weaknesses.
reference measurements are essential, during field trial to ensure
confidence in the measured data.
The results show that atmospheric corrections were done accurately
Conclusion
© CSIR 2010 www.csir.co.za
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