Electro-Optical Systems The last lecture of Weapons Class

What are we talking about? Optically guided weapons Night vision goggles Thermal Imaging Laser Guided Munitions

Electro-Optical Spectrum Electro-Optical Band 1011-1016 Hz Visible ~1015 Hz Infrared ~1011-1014 Hz Page 138

Sources Selective Emitters Narrowband – many be only a couple Hz. Only selective radiator we are interested in in Laser light.

Sources Thermal Radiates in proportion to the absolute temperature (Kelvin). Total power output is proportional to surface area. Many military applications

Lasers Narrow bandwidth Can operate in CW or Pulse modes Many different types Can damage skin or eyes based on relative intensity.

Infrared Passive system that collects thermal radiation emitted from the target. Used in military and law enforcement applications.

Characteristics of Thermal Energy Uneven spreading Attenuation / Absorption Scattering Spreading – Amount of energy leaving any one portion of the object will depend on the objects shape. Attenuation – Due to atmospheric conditions. A functions of frequency and range. Scattering – Energy can scatter just like other forms of energy.

Detectors Aperture Bandwidth Range Field of View Aperture – Determines the collected flux Bandwidth – There is an upper and lower limit to what the detector can collect and process

Detector Range Depends on: Attenuation due to atmosphere Source level Background levels Detector sensitivity and bandwidth

Detector Performance Resolution Spatial Thermal Ability to distinguish small objects or parts of objects Thermal Ability to distinguish temperature differences Spatial and Thermal resolution are inversely proportional. Combined performance measure - MRTD Spatial and Thermal resolution are inversely proportional because the farther away one gets from the target, the less heat they will “see” emanating from the target. MRTD – Minimum Resolvable Temperature Difference. Determined experimentally

Military Uses Laser guided munitions Thermal homing missiles Designated from air or ground Thermal homing missiles Optical Guidance Night Vision Thermal Missiles Stinger Sidewinder Optical Guidance Maverick TOW Low Level Light amplification systems – require some amount of light.

Weapons that use Optics

CIWS Blk IIA

Thermal Imaging

MIDN Ricks dancing at the Mil Ball

Johnson, Williams, Porter, Boyle lookin’ for a party……….

Night Vision Goggles (NVG’s)

LGB

TOW

Questions?