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The fiber optic sensors measuring accuracy depends on such destabilizing factors influence, as light emitter power variations, different research surface reflecting and scattering properties, photoreceiver parameters alterations and etc. Sometimes it is necessary to transform the measuring displacement into time interval, which duration is in proportionality to measurement value and is independent to destabilizing factors influence also. The mathematical model of the invariant transformation method of measuring displacement into time interval was elaborated for two channel fiber optic sensor. Using two measuring channels with mutual involuting adjustment permits to compensate the error components of the transfer functions and time dependences errors, gives the opportunity to becomes more simile, because frequency instability of excitation voltages doesn't influence at the transformation results. Considered method permits to increase of the device quick-action, to simplify of displacement analog-digital conversion and to decrease of the comparator's error on account of contrary changing voltages comparison. The two-channel fiber optic sensor with modulated emission for precision positioning was elaborated in which research object surface is illuminated by modulated emission with the help of semiconductor laser, laser pulses duration is chosen divisible to 1/50 Hz. The two-channel fiber optic sensor with modulated emission for precision positioning operates in the structure of laser microscope positioning system. The device output signal sign is defined identically by fiber optic guide face plane shift direction. Its value is in proportionality to deflection value. Schematic diagrams of method realized devices are shown and the main concerned to these method and devices correlations are discussed.
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