Optronic Measurement, Testing and the Need for Valid Results Example of Infrared Measurements for Defence Countermeasures Azwitamisi E Mudau, C.J. Willers,

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

[email protected]

© 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


Heat Seeking Missiles

Infrared Countermeasures

• Airborne IRCM flares are defensive mechanisms employed from military and civilian aircraft to avoid detection and attack by enemy infrared seeker missiles.

The Infrared Signature of the Aircraft

The engine hot parts

Exhaust plume

The skin of the airframe

Infrared Measurements at the Optronic Sensor Systems

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


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.


During Infrared measurement trials

Infrared Mobile Laboratory

Weather Station


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


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



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






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


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


No

rma

lize

d In

ten

sit

y

0 0.2 0.4 0.6 0.8 12200

2250

2300

2350

2400

2450

2500


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


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


Thank you

Optronic Measurement, Testing and the Need for Valid Results Example of Infrared Measurements for Defence Countermeasures Azwitamisi E Mudau, C.J. Willers,

Documents

temperature slide

test slide

prior infrared measurements

infrared signature

airframe slide

humanitarian support

area blackbody slide

precision infrared thermometer