FIBER-OPTIC TACHOMETER Russian patent published in 2006 - IPC G01P3/36 G01P13/00 

FIELD: measurement engineering.

SUBSTANCE: tachometer can be used to measure speed of rotation and to inspect sign of rotation of self-moving objects. Coding unit in form of toothed disc is put onto shaft to be inspected. Shell aligned with shaft is mounted motionless around the disc. Signal coil is disposed inside shell and reference coil of fiber-optic tachometer is disposed outside shell. When disc rotates, pressure pulses act on signal coil of interferometer, which pulses are transformed by interferometer into photocurrent pulses. Frequency of photocurrent pulses carries information on frequency of rotation of shaft. To determine sign of rotation, the teeth of disc are disposed from axis of rotation to follow to monotonous dependence. Pulses at output of interferometer will have different amplitudes. Manner of change in pulses (increase or decrease in amplitude) gives information on sign of direction of rotation.

EFFECT: prolonged service life in aggressive medium.

3 cl, 2 dwg