Method and system for calibrating a fiber optic gyroscope

A method for calibrating a fiber optic gyroscope comprising:

• propagating first and second portions of light from a first light source through a fiber optic line in respective first and second directions;
• directing the first and second portions of the light from the first light source onto a photo-detector;
• determining a first voltage operable to cause a predetermined phase shift between the first and second portions of the light from the first light source at the photo-detector;
• applying the first voltage to a modulator to cause the predetermined phase shift between the first and second portions of the light from the first light source;
• propagating first and second portions of light from a second light source through the fiber optic line in the respective first and second directions;
• directing the first and second portions of the light from the second light source onto the photo-detector;
• determining a second voltage operable to cause the predetermined phase shift between the first and second portions of the light from the second light source at the photo-detector;
• determining a difference between the first voltage and the second voltage;
• and determining a scale factor for the fiber optic gyroscope using the difference between the first voltage and the second voltage;
• and
• applying the second voltage to the modulator to cause the predetermined phase shift between the first and second portions of the light from the second light source.

A fiber optic gyroscope comprising:

• a fiber optic sensing coil configured to receive light and counter propagate first and second portions of the light received therein;
• a first light source operable to supply light;
• a second light source operable to supply light;
• a switch optically coupled between the first and second light sources and the sensing coil, the switch being moveable between a first position, in which light from the first light source is supplied to the sensing coil, and a second position, in which light from the second light source is supplied to the sensing coil;
• a processor in operable communication with the switch and configured to toggle the switch between the first and second positions, to thereby cause first and second portions of light from the first and second light sources, respectively, to counter propagating through sensing the coil, the processor further configured to determine a first voltage operable to cause a predetermined phase shift between the first and second portions of the light from the first light source, a second voltage operable to cause the predetermined phase shift between the first and second portions of the light from the second light source, and a difference between the first voltage and the second voltage;
• a modulator between the optical fiber sensing coil and the first and second light sources, the modulator operable to cause the predetermined phase shift between the first and second portions of the light from the first light source when the first voltage is applied to the modulator, and operable to cause the predetermined phase shift between the first and second portions of the light from the second light source when the second voltage is applied to the modulator;
• and
• a photodetector operable to receive light from the optical fiber sensing coil and operable to detect a phase shift between the counter propagating portions of light.