Reduce size semiconductor ring laser gyroscope including a sensor coil made of a multilayer wound optical fiber

1. A semiconductor ring laser gyroscope comprising:

a semiconductor laser for emitting two lights from both end surfaces thereof;

an optical fiber ring through which the two lights emitted from the both end surfaces of the semiconductor laser propagate in respective opposite directions, and which, in association with the semiconductor laser, constitutes a laser resonator;

an optical detection unit for detecting a rotational angular velocity based on beat frequencies of the two lights propagating through the optical fiber ring in the respective opposite directions; and

a sensor coil made of an optical fiber wound in a multilayer manner, the sensor coil constituting a part of the optical fiber ring;

wherein the optical fiber ring is structured to satisfy an expression (1):

F rlg ≦10 ΔF beat — min   (1)

in which F rlg =C/nL, where F rlg is a ring resonance frequency, ΔF beat — min is a beat frequency corresponding to a lower limit of an angular velocity measuring range of the optical detection unit, C is a light speed, n is a refractive index of the optical fiber, and L is an overall length of the optical fiber.

2. A semiconductor ring laser gyroscope according to claim 1 , wherein the optical fiber ring is structured to satisfy an expression (3):

2 ΔF beat — max <F rlg ≦10 ΔF beat — min   (3)

in which F rlg =C/nL, where ΔF beat — max is a beat frequency corresponding to an upper limit of an angular velocity measuring range, F rlg is a ring resonance frequency, ΔF beat — min is a beat frequency corresponding to a lower limit of the angular velocity measuring range, C is a light speed, n is a refractive index of the optical fiber, and L is an overall length of the optical fiber.

3. A semiconductor ring laser gyroscope according to claim 1 ,

wherein the optical detection unit comprises: an optical splitter for extracting part of each of the two lights propagating through the optical fiber ring in the respective opposite directions; a multiplexing prism for causing the two lights extracted by the optical splitter to interfere with each other; a sectioned photodiode comprising a plurality of light receiving faces for receiving an interfered light produced by the multiplexing prism; and a mask disposed between the multiplexing prism and the sectioned photodiode and comprising a plurality of slits having their respective phases shifted from one light receiving face to another.

4. A semiconductor ring laser gyroscope according to claim 1 , wherein the semiconductor laser is a Fabry-Perot semiconductor laser.

5. A semiconductor ring laser gyroscope according to claim 3 , wherein the semiconductor laser is a Fabry-Perot semiconductor laser.

6. A semiconductor ring laser gyroscope comprising:

a semiconductor laser for emitting two lights from both end surfaces thereof;

an optical fiber ring through which the two lights emitted from the both end surfaces of the semiconductor laser propagate in respective opposite directions, and which, in association with the semiconductor laser, constitutes a laser resonator;

an optical detection unit for detecting a rotational angular velocity based on beat frequencies of the two lights propagating through the optical fiber ring in the respective opposite directions; and a sensor coil made of an optical fiber wound in a multilayer manner, the sensor coil constituting a part optical fiber ring;

wherein the optical fiber ring is structured to satisfy an expression (2):

2 ΔF beat — max <F rlg   (2)

in which F rlg =C/nL, where ΔF beat — max is a beat frequency corresponding to an upper limit of an angular velocity measuring range of the optical detection unit, F rlg is a ring resonance frequency, C is a light speed, n is a refractive index of the optical fiber, and L is an overall length of the optical fiber.

7. A semiconductor ring laser gyroscope according to claim 6 , wherein the semiconductor laser is a Fabry-Perot semiconductor laser.

8. A semiconductor ring laser gyroscope comprising:

a semiconductor laser for emitting two lights from both end surfaces thereof;

an optical fiber ring through which the two lights emitted from the both end surfaces of the semiconductor laser propagate in respective opposite directions, and which, in association with the semiconductor laser, constitutes a laser resonator;

an optical detection unit for detecting a rotational angular velocity based on beat frequencies of the two lights propagating through the optical fiber ring in the respective opposite directions; and a sensor coil made of an optical fiber wound in a multilayer manner, the sensor coil constituting a part of the optical fiber ring;

wherein the optical detection unit comprises: an optical splitter for extracting part of each of the two lights propagating through the optical fiber ring in the respective opposite directions; a multiplexing prism for causing the two lights extracted by the optical splitter to interfere with each other; a sectioned photodiode comprising a plurality of light receiving faces for receiving an interfered light produced by the multiplexing prism; and a mask disposed between the multiplexing prism and the sectioned photodiode and comprising a plurality of slits having their respective phases shifted from one light receiving face to another.

9. A semiconductor ring laser gyroscope according to claim 8 , wherein the semiconductor laser is a Fabry-Perot semiconductor laser.