A small self-contained "transmitter" module, consisting of a modulated optical retro-reflector, and an optical receiver module, consisting of a laser diode light source and a photodetector, is proposed. These modules together comprise a retro-communications data readout system which can easily meet the objectives of data transmission from remote parts of a test aircraft or missile to a central acquisition system without the need for connecting wiring, without the need for supplying power to the remote location, and while operating in the environment of a modern jet fighter aircraft. The retro-transmitter can be made very small, say the size of a rivet or smaller, and can be thin and flat if desired enabling easy integration into or onto the aircraft or missile skin. The power required on the remote transmitter is small, consisting only of the power needed to modulate the retro-return of the retro-reflector. A battery comparable to a wrist watch battery should suffice. Ruggedness obtains as a result of the small size and compactness of the device and because of its insensitivity to alignment and displacement. EMI immunity is obtained because of the use of a narrow band of optical wavelengths to effect data transmission.
