METHOD AND CIRCUIT FOR SIGNAL PROCESSING, AND INTERFERENCE SENSOR, AND PHYSICAL QUANTITY DETECTING METHOD

Japanese Patent JPH03252521

A

PURPOSE:To realize the small-sized, high-accuracy interference sensor and a vehicle control system which do not deteriorate in the resolution of phase difference detection due to a decrease in light intensity by imposing phase modulation upon light beams which are propagated in a fiber loop clockwise and anticlockwise and then multiplexing them into interference light. CONSTITUTION:The light beam from a light source 10 is propagated through a light beam fiber coupler 21 and a polarizer 30 to reach a fiber coupler 22, where the light is branched to become two light beams propagated in the fiber loop 40 clockwise and anticlockwise. Those light beams have light phases modulated by a phase modulator 50 according to the modulating signal generated by a phase modulator driving circuit 60 and then reach the fiber coupler 22, which multiplexes them into the interference light. This interference light travels backward from the fiber coupler 22 and returns to the fiber coupler 21 through the polarizer 30. The interference light is branched at the fiber coupler 21; and one light beam returns to the light source 10 and the other reaches a photoelectric converting circuit 70 using a photodiode and is outputted as an interference signal. This interference signal is sent to a signal processing circuit 100 and processed here to extract the angular velocity of rotation.

OBO SHIGERU
SONOBE HISAO
MAKINO JUNICHI
KAJIOKA HIROSHI
KUMAGAI TATSUYA

JP4939690A

November 11, 1991

March 02, 1990

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HITACHI LTD (JP)
HITACHI CABLE (JP)

G01C19/72; H01S3/083; (IPC1-7): G01C19/72; H01S3/083

Katsuo Ogawa (2 outside)

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