Domains of application

The association of «electronics» and «optics» leads to a large number of terms :

for example, « electro-optic » materials are materials with properties (such as transmittance, refractive index, birefringence,...) that may be modified under application of some electrical field.

"Optoelectronics" covers the domain of components that transform photons into electrons, or vice-versa (detectors, lasers, light emitting diodes, laser diodes,...), or those that carry light (optical fibers), amplify it, or modulate it.

As for the term «electro-optical», it is not so much related to components, but rather to the sensors, devices, instuments, equipments or systems which are made up of optical, optoelectronic, electro-optic and electronic components. These sensors are utilized in quite many domains, amongst which :

• Defense : electro-optical equipments are more covert than radars, to which they are often associated, because many of them are completely passive (they emit no radiation) and the ones that emit, radiate much narrower beams than radars ; on the other hand, a traditional strong point of optics is its angular precision, which allows EO sensors to greatly improve the quality of observation on the battlefield, and to be of prime interest in target recognition and identification, or in terminal missile guidance. EO countermeasure sensors ar also on the rise in order to neutralize these highly efficient equipments.

• Space : electro-optical sensors intervene in space applications as satellite navigation aids (horizon and star sensors), in earth and space observation, in vegetation monitoring, in astronomy,...There also exist research programs in space telecommunications by means of lasers, that could greatly optimize long range transmissions, for example between geostationary and low orbit satellites.

• Telecommunications : there are many reasons that explain the increasing use of optical fibers in telecommunications : low losses, high bandwidths, low weight and volume, possible exposure to high voltages, absence of electrical flashes, of ground loops, very little influence of optical or electrical perturbations, .... Very high rate fiber optics terminals are now available, at relatively low cost.

• Industry : More and more laser equipments can be found in industrial fabrication processes, such as cutting, soldering, marking. Quite many electro-optical sensors are utilized in industrial controls, in order to measure, among other parameters : temperatures, flow rates (fluids), displacements, velocity, acceleration, pressure (fluids, acoustic), humidity, stress, forces, charges, gas, pollution, level (liquids), vibrations, shocks, couples, surface shapes...These contactless sensors do not perturb the parameters to be observed, and they may operate in the presence of agressions, either chemical (corrosion), mechanical (vibrations, pressure, shocks), thermal, electrical, magnetic, or radiative (nuclear environment), because of the possibility of locating the sensor far from the measurement area.. Their usage is growing in robotics (shape, object, defect recognition by means of image processing), industrial and environnemental surveillance, chemical analysis, metrology,...They are invading the transportation and automotive industries, particularly as driving aids and for anticollision purposes.

• Mass Media : Images are taking more and more room in everyday life, and EO sensors are accompanying this explosion, as well at the image production level as in image display : digital still or movie cameras, projection screens, displays, minicameras for portable phones, compact discs readers, ...

• Scientific research : Quite a number of electro-optical sensors are being integrated in scientific projects of national and international importance, such as those of several Atomic Energy Commissions (MegaJoule Laser project of CEA in France, National Ignition Facility in the United States), in astronomy (large telescopes), as well as in numerous research laboratories, either in industry or at Universities.

• Medical : Medicine is utilizing more and more electro-optical sensors, be it for diagnosis (thermography, laser imagery) or for medical care (laser surgery).