Optical countermeasures against CLOS weapon systems

Abstract

There are many weapon systems in which a human operator acquires a target, tracks it and designates it. Optical countermeasures against this type of systems deny the operator the possibility to fulfill this visual task. We describe the different effects that result from stimulation of the human visual system with high intensity (visible) light, and the associated potential operational impact. Of practical use are flash blindness, where an intense flash of light produces a temporary "blind-spot" in (part of) the visual field, flicker distraction, where strong intensity and/or color changes at a discomfortable frequency are produced, and disability glare where a source of light leads to contrast reduction. Hence there are three possibilities to disrupt the visual task of an operator with optical countermeasures such as flares or lasers or a combination of these; namely, by an intense flash of light, by an annoying light flicker or by a glare source. A variety of flares for this purpose is now available or under development: high intensity flash flares, continuous burning flares or strobe flares which have an oscillating intensity. The use of flare arrays seems particularly promising as an optical countermeasure. Lasers are particularly suited to interfere with human vision, because they can easily be varied in intensity, color and size, but they have to be directed at the (human) target, and issues like pointing and eye-safety have to be taken into account. Here we discuss the design issues and the operational impact of optical countermeasures against human operators.

Laser Safety—What Is the Laser Hazard Distance for an Electro-Optical Imaging System?

“…The central lobe is approximated by using [17] ( ) = ( ) exp −8 (6) where the peak irradiance of the diffraction pa ern is given by [23] (…”

“…Incapacitation means that the imaging system can no longer fulfill its intended task, either due to reversible (dazzle) or irreversible (damage) effects. The result of dazzling and/or damaging of imaging systems by laser radiation can be irritating to an observer but may be of less importance in the civilian sector, unlike in military operations, where laser attacks pose a severe threat [ 4 , 5 , 6 , 7 , 8 , 9 ] and may disrupt operations. In order to inform people about laser hazards, it would be beneficial to have the ability to perform laser safety calculations for imaging systems that ideally follow the existing concepts of laser eye safety.…”

Review and prospects of optical countermeasure technologies

“…A laser beam is an ideal effector for an OCM system: The optical energy is generated within a narrow spectral range and with a beam quality which allows for the concentration of the energy within a small solid angle providing a high spectral radiant intensity (W/µm/sr). A simple order of magnitude calculation illustrates this fact: A MTV flare radiates as a black body of 2000 K approximately 25 kW over 3 sec omnidirectional in the 3-5 µm spectral band [11]. An infrared laser releases photons (quasi-) continuously with 1 W output power in the band 3.9 to 4.0 µm and with a full (1/e 2 ) divergence of 3.7 mrad after the beam director.…”

“…As analysed in Ref. [11], there are three possibilities to disrupt the visual task of an operator with optical countermeasures such as flares, lasers or a combination of both: by an intense flash of light, by an annoying light flicker or by a glare source. In all cases, the rules of engagement require that the Protocol IV of the Geneva Convention [12] will be respected.…”

Estimation of Lens Stray Light with Regard to the Incapacitation of Imaging Sensors—Part 2: Validation

“…Unlike in the civilian sector where the occurrence of dazzle or detector damage to cameras from laser radiation can be disruptive, in military operations, laser irradiation poses a real threat [ 5 , 6 , 7 , 8 ] since safety aspects are concerned. Thus, it would be of advantage to be able to perform laser protection calculations for cameras, following the well-established laser safety concepts that exist for the human eye.…”