Directed Infrared Countermeasures (DIRCM) Principles
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This document contains slides from a professional development course on Directed Infrared Countermeasures (DIRCM) taught by John L. Minor. It outlines the course structure, covering topics such as the electromagnetic spectrum, infrared threats, missile systems, and DIRCM principles, aimed at enhancing technical professionals' understanding and skills in infrared technologies. The training offered by ATI focuses on current state-of-the-art technologies to improve effectiveness and productivity in competitive environments.
Directed Infrared Countermeasures (DIRCM) Principles
- 1. Slides From ATI Professional Development Short Course Directed Infrared Countermeasures (DIRCM) Principles Instructor: John L. Minor ATI Course Schedule: http://www.ATIcourses.com/schedule.htm ATI's DIRCM: http://www.aticourses.comDirected_Infrared_Countermeasures_DIRCM_Principles.htm
- 2. www.ATIcourses.com Boost Your Skills 349 Berkshire Drive Riva, Maryland 21140 with On-Site Courses Telephone 1-888-501-2100 / (410) 965-8805 Tailored to Your Needs Fax (410) 956-5785 Email: ATI@ATIcourses.com The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly competitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presented on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training increases effectiveness and productivity. Learn from the proven best. For a Free On-Site Quote Visit Us At: http://www.ATIcourses.com/free_onsite_quote.asp For Our Current Public Course Schedule Go To: http://www.ATIcourses.com/schedule.htm
- 3. Course Overview 0. Intro, Administrative, and Course Overview 1. Electromagnetic Spectrum & Infrared Fundamentals 2. The Infrared Threat 3. Missile Warning Receivers 4. Aircraft Signatures 5. Infrared Missile System Principles 6. DIRCM Systems – Increasing J/S Requirement – Legacy DIRCM (Broadband and Flash Lamp) Systems – Laser Jam (Closed Loop) DIRCM Systems 7. Test and Evaluation of DIRCM Systems © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 4. End of Module 0 QUESTIONS? © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 5. Next Up 1. Electromagnetic Spectrum & Infrared Fundamentals © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 6. Module 1 The Electromagnetic Spectrum & IR Fundamentals © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 7. Course Overview 1. Electromagnetic Spectrum & Infrared Fundamentals 2. The Infrared Threat 3. Missile Warning Receivers 4. Aircraft Signatures 5. Infrared Missile System Principles 6. DIRCM Systems – Increasing J/S Requirement – Legacy DIRCM (Broadband and Flash Lamp) Systems – Laser Jam (Closed Loop) DIRCM Systems 7. Test and Evaluation of DIRCM Systems © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 8. Module 1 Overview • Electromagnetic (EM) Wave Basics • Properties of EM Waves and Light • Regions of Interest in the EM Spectrum • Infrared Basics • Blackbody Radiation Physics and Terminology © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 9. Propagation of Light as EM Waves • ALL Electromagnetic radiation consists of an electric (E) field and a magnetic (H) field • The wave propagates at the speed of light, at right angles to the E/H field planes • If you cross the E Field vector with the H Field vector, you get the direction of travel of the EM wave (known as the right hand rule) © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 10. The Speed of Light • Light, like all electromagnetic waves, travels at the same fixed velocity (in a vacuum) 186,000 miles/second = 3 X 108 meters/second • C = the speed light = 3 X 108 meters/second • C = f or you can always remember the 2 Greeks >> C = © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 11. EM Wave Terminology • The amplitude is related to the intensity of the light in Volts/Meter. • The period (T) is the time between crests of the wave in seconds. • The wavelength ( ) is the physical distance between wave crests • The frequency (or f ) is the inverse of the period, and vice-versa. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 12. Polarization Direction of E field determines the E polarization of an EM wave. With E field in vertical direction wave is said to be vertically polarized Direction of travel by the right hand rule crossing the E vector into the H vector H Horizontal Circular Can be right or left E hand circularly polarized © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 13. EM Wave Polarization Video © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 14. Diffraction • When light passes through a narrow opening, it tends to spread out as if the opening itself were a very small point source of light •The bending of light when it passes through a narrow opening or along the edge of a barrier is known as diffraction Note: Diffraction limits the resolution of an optical system © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 15. The Electromagnetic Spectrum © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 16. Optical Band of the Electromagnetic Spectrum ROYGBV Optical frequencies, or light can be both visible and invisible to the unaided eye Note: Boundaries, UV, & IR Band Nomenclature are somewhat arbitrary and are author/text dependent © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC. Red, orange, yellow, green, blue, violet
- 17. Electromagnetic Spectrum Charts (cont.) This is the IR Threat X-Band Radar Older IR Modern FLIR 10 GHz, 3 cm UV MWS NVG Missiles IR Missile 3-5, 8-12 0.1-0.4 (0.65-0.95) Near IR Threat 3-5 EO Wavelengths shown in microns (m) CCD TV 0.55-0.95 © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 18. Diffraction Limited Resolution ~ 1.22 R D © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 19. Phase Angle Properties © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 20. Interference Properties of Light • When two or more light waves meet at the same place and time, their amplitudes will add by the principle of superposition • If crests meet crests they add together to produce a larger amplitude and this is constructive interference • If crests meet with troughs they add together to produce a smaller amplitude and this in know as destructive interference © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 21. The Interaction of Light With Matter When light (EM energy) strikes the boundary of some type of matter, three things can happen: 3 1 Medium 1 Medium 2 2 Boundary between two different media such as air/glass or air/water 1. REFLECTION - Radiation is turned back into the first medium () 2. REFRACTION - Radiation is passed or transmitted into the second media (also called transmission). If the index of refraction is different between the two medium, the light will be bent or refracted () according to Snell’s Law 3. ABSORPTION - Process in which the energy of the incident photons are absorbed and changed into molecular energy & heat ( ) Note: The sum of these three coefficients ( must = 1 © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 22. The Discovery of Infrared On 11 February 1800, Sir William Herschel was testing filters for viewing the sun so he could observe sun spots When using a red filter he found there was a lot of heat produced Herschel discovered infrared radiation by passing sunlight through a prism and holding a thermometer just beyond the red end of the visible spectrum This thermometer was meant to be a control to measure the ambient air temperature in the room He was shocked when it showed a higher temperature than the visible spectrum Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 23. The Infrared Spectrum When we speak of infrared, we mean that portion of the electromagnetic spectrum that lies between visible light on one side and microwaves on the other. Quantitatively, is is expressed as the region extending from a wavelength of ~ 0.7 microns to ~1000 microns ~0.7-1000 microns IR © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 24. Radiometry • A source at the origin radiates optical power such that P0 is radiated into a cone as shown A2 • Other powers may be radiated in other directions. R1 A1 P0 • For the first cone, the power per R2 unit area at a distance R1 away is… P0/A1 and is called the “Irradiance” • The Irradiance at distance R2 is P0/A2 • Since the illuminated area increases as the square of R, i.e. A2/A1=(R2/R1)2, in a non-absorbing medium the Irradiance produced by the source varies as inverse R-squared. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 25. Radiometry (cont.) • Irradiance is given the symbol “E” and is expressed in the units W/cm2. A2 • Missiles care about the quantity “Irradiance” because the power R1 A1 they receive Pr is determined by P0 that value and by the missiles’s R2 collection area Am. That is… Pr2=E2 x Am =(P0/A2) x Am is the power the missile receives when it is at the range R2 • Since the Irradiance increases as the inverse-square of R, the missile receives greater and greater power as it flies toward the source. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 26. Radiometry (cont.) • The angular region contained in the cone is called the “solid angle” of the A2 cone, and is given by R1 A1 =A/R2. P0 • This definition is true for any arbitrary R2 angular region which can differ from that of a cone. • Since the illuminated area varies as R- squared, the solid angle of the illuminated region does not change with range. • A radiometric quantity called “Radiant Intensity” has been defined and is calculated using the expression P/.. Since the power P0 uniformly fills the solid angle region, in a non-absorbing medium, the Radiant Intensity does not vary with range. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 27. Radiometry (cont.) • Radiant intensity is given the symbol “I” and is expressed in the units W/sr. • IRCM engineers care about the A2 quantity “Radiant Intensity” because that value describes the R1 strength of target and jammer A1 P0 sources without specifying range * R2 • Irradiance can be found from Radiant Intensity by dividing by the range-squared. That is… E2=I/(R2)2 Is the Irradiance produced at a range R2 by a source of Radiant Intensity “I”. * This is true for a non-absorbing medium. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 28. Radiometry (cont.) • Aircraft targets and jamming transmitters are optical sources whose radiation strengths may be expressed in terms of Radiant Intensity or Irradiance. • Whatever radiometric quantity is used, IRCM engineers refer to the aircraft radiation strength as “S” for signature, and to the Jammer strength as “J”. The IRCM system’s J/S is then determined as the ratio. • Since aircraft and jamming systems can radiate different amounts in different directions, the apparent values of S, of J, and of J/S, can vary with the observer’s viewing perspective. • As an example, a fixed-wing aircraft signature may be 1000 W/sr at a tail perspective where aircraft engines are unobscured, but may be only 100 W/sr when viewed nose-on. • Since the atmosphere will typically remove power from any radiating cone through absorption, values of J and S may change with range beyond the standard R-squared multiplier. © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 29. RADIOMETRIC UNITS Watts • The watt is the fundamental unit of optical power and measurement, and is defined as a rate of energy of one joule per second • It is a function of both the number of photons and the wavelength of the photons • Each photon carries an energy = h = hc/ where h = Planck’s constant = 6.623 x 10 -34 Joule-sec c = speed of light = 3 x 10 8 meters / sec wavelength of the photons © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 30. Radiator Response Curves Emissivity () = 1 (black body at 300° (Watt/cm3 - micron) = 0.9 (gray body) = varies as wavelength Energy Density Monochromatic (Selective Radiator) 0 10 20 30 (m) Need to specify the for the spectral band of interest • Usually specified as an average over a given spectral band • For example: = 0.3avg at 8-12 microns © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 31. Important Laws of Radiation • Inverse Square Law • Lambert’ s Cosine Law • Stefan-Boltzman’s Law • Wien’s Law • Planck’s Law © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 32. Inverse Square Law Defines the relationship between the irradiance (illuminance) from a point source and the distance to it The intensity per unit area varies in inverse proportion to the square of the distance -- why? © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 33. Inverse Square Law Inverse Square Law & Divergence © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 34. Stefan-Boltzman’s Law (Thermal Radiation Law) The amount of radiation emitted by a body is proportional to the emissivity and to the fourth power of the absolute temperature of the body 4 W T = Stefan Boltzman’s Constant W 5.670 x 10-8 cm2 k4 = Emissivity T= Temperature (absolute) Note that if T is doubled, the FOR A BLACKBODY radiated emittance is increased sixteen times = 1.0 © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 35. Wien’s Displacement Law The wavelength at which the maximum radiance occurs is inversely proportional to the absolute temperature of the body (Kelvin): 9.6m max 2900/T microns 300 8 12 © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 36. Planck’s Law • In physics, Planck's law describes the spectral radiance of electromagnetic radiation at all wavelengths from a black body at temperature T. As a function of frequency ν, Planck's law is written as: © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 37. Planck’s Law Weins Law Solar All bodies emit radiation at all wavelengths as a function of the bodies absolute temperature Rocket Exhaust Jet Engine Exhaust Earth (terrain) © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 38. Lambert’s (Cosine) Law • The irradiance or the illuminance falling on any surface varies as the cosine of the incident angle • Maximum at 90 degrees to the surface (shown as 0 degrees here) The perceived measurement area orthogonal to the incident flux is reduced at oblique angles causing the light to spread out over a wider area than it would if perpendicular to the measurement plane © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 39. IRCM Terminology © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 40. Common IRCM Terms • IR spectrum • Open loop IRCM • Band pass • Closed loop IRCM • Radiant intensity • Optical break lock • Watts per steradian • Guidance suppression • Watts per cm2 • J/S ratio • IR signature © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 41. Module 1 Questions? © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 42. Next Up 1. Electromagnetic Spectrum & Infrared Fundamentals 2. The Infrared Threat 3. Missile Warning Receivers 4. Aircraft Signatures 5. Infrared Missile System Principles 6. DIRCM Systems – Increasing J/S Requirement – Legacy DIRCM (Broadband and Flash Lamp) Systems – Laser Jam (Closed Loop) DIRCM Systems 7. Test and Evaluation of DIRCM Systems © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 43. Module 5 Infrared Missile Systems © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 44. Course Overview 0. Intro, Administrative, and Course Overview 1. Electromagnetic Spectrum & Infrared Fundamentals 2. The Infrared Threat 3. Missile Warning Receivers 4. Aircraft Signatures 5. Infrared Missile System Principles 6. DIRCM Systems – Increasing J/S Requirement – Legacy DIRCM (Broadband and Flash Lamp) Systems – Laser Jam (Closed Loop) DIRCM Systems 7. Test and Evaluation of DIRCM Systems © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 45. Module 5 Overview • How IR Missiles Work • Video – Basics of How IR Missiles Work • Threat Development Timeline & History • Missile Guidance Basics • Intro to IRCM Basics to Defeat IR Missiles © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 46. IR Missile Guidance Loop Description Detector Steering Commands Spin To Fins Carrier AMP Band Pass Envelope Band Pass Guidance Processing Precession Pointing Commands To Seeker Gyro Reticle, Mirror/Gyro MODULATION • Tracks small targets (points sources) more efficiently than large sources • Has problems with extended sharply defined edges (horizon line) © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 47. IR Missile Threat Evolution © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 48. Threat Development Timeline vs. Band 1960s 1970s 1970/80s 1980s 1990s 2000 Scanning Imagers Cooled Pseudo- Spin Scan Con Scan FRCCM Seeker Imagers 2005 reticle-based seekers 1st Gen Staring Imagers Stgr-POST SA-7 SA-14 Redeye Stgr-BASIC SA-18 HN-5 SA-16 Mistral 2010 Band I Band II Band IV 2nd Gen (hot metal) (hot metal) (jet engine plume) Spectral Imagers © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 49. Rosette Detector IFOV • Pseudo Imaging • Small Field-of-View Detector Target Petal Scanning a Rosette Pattern Using Image Two-Counter-Rotating Optical A Rosette Scanning Pattern Elements • Small IFOV – Provides Greater Sensitivity Petal Scan – Resistant to Jammers S(t) Time – Resistant to False Targets 1 0 t Normalized Signal Pulse Sequence for On-Axis Image © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 50. Imaging • Produces an Image • Takes Advantage of State-of-the-Art Technology – Processing Capability – Software Track Algorithms Rectangular Detector Arrays Linear Detector Array Target Scene Image Target Scene Linear Detector Array Scanning Rectangular Detector Array of a Target Scene and Target Scene Illustration of Imaging Detectors © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.
- 51. Flare Decoy Objective: Present a more attractive IR target to the missile • Shortcomings -Flares operate at higher temperatures than aircraft, emitting primarily in Bands 1 & 2 (versus modern Band 4 threats) -Very effective against Band 1 & 2 (1st and 2nd Generation) missiles -Limited performance against newer Band 4 missiles due to output energy limitations and inclusion of flare CCM techniques in missile design © Copyright 2010 by John L. Minor, American Eagle Aerospace LLC.