Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
  • G01C19/58—Turn-sensitive devices without moving masses
  • G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
  • G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
  • G01C19/721—Details, e.g. optical or electronical details
  • G01C19/722—Details, e.g. optical or electronical details of the mechanical construction

Definitions

• the present invention relates to the field of sensing coils for high-performance fiber optic gyroscopes. More specifically, the present invention pertains to an improved fiber optic gyroscope, which provides highly accurate rotation measurement with a sensing coil.
• Fiber optic gyroscopes are used for detection of rotation particularly in navigation systems such as those used in aircraft and spacecraft. Fiber optic gyroscopes are desirable due to the high-level of accuracy and reliability of sensing inertial rotation rate that they possess.
• Fiber optic gyroscope technology is well known in the industry.
• a fiber optic gyroscope light from a laser or some other light source is divided into two separate beams by means of a fiber optic coupler and then coupled into the two ends of a multi- turn coil of optical fiber.
• the fiber optic cable may consist of many of the standard types commercially available on the market.
• Light that emerges from the two fiber ends is combined by the fiber optic coupler and detected by a photodetector.
• the fiber optic gyroscope senses rotation rate by detection of a rotationally induced phase shift between the light beams that propagate in opposite directions around the coil of the fiber optic cable.
• the signal that is detected corresponding to the phase difference between the counter-propagating beams is typically subjected to some form of phase modulation.
• the photodetector converts the modulated light beam to an electrical signal that corresponds to the rate of rotation of the coil of optical fiber.
• the signal is processed to provide a direct indication of the exact rate of rotation of the coil of optical fiber that has occurred.
• FIG. 1 is a side view of a generic fiber optic coil showing multiple windings and an approximated jog zone.
• FIG. 2 is a perspective view of the generic fiber optic coil in Fig 1 emphasizing the portion of the multiple windings that comprise the jog zone portion of the coil.
• FIG. 3 is a top view of a fiber optic coil showing a detailed jog zone section that demonstrates the cross windings in the coil and the associated bend angles that occur in the jog zone. DESCRIPTION OF PREFERRED EMBODIMENTS
• Fig. 1 is a side view of a fiber optic coil 10.
• the coil 10 shows multiple windings 4 of a fiber cable 3 in the coil 10.
• the windings in the cable 3 may consist of any mode of fiber such as single mode or PM fiber.
• the windings may be wound in any configuration or pattern.
• Some of the standard winding patterns include the quadrupole, octupole or interleave patterns.
• the jog zone 6 comprises the area of the coil 10 wherein the windings 4 of the cable 3 transition from one wind or turn to the next successive wind or turn of windings. It is generally desirable to maintain the windings 4 of the cable 3 in an orthogonal position relative to the coil axis of the coil
• the fiber cable 3 is angled slightly to achieve a smooth transition to successive windings of the coil.
• the wound portions 12 and 13 experience a slight bend angle 14 that achieves the smooth transition from one wound turn to the next successive wound turn.
• Experimental results have shown that the jog zone angle 5 as shown in Fig. 1 achieves optimum performance for the coil 10 at an angle 5 that is a minimum of 45 degrees during the first layer turn 2 of the fiber cable 3. It is possible to allow the jog zone angle 5 to grow in size to a maximum of 90 degrees as additional layers are added to the coil 10 depending on the specific winding pattern of the coil 10.
• the bend angles 14 entering and leaving the jog zone 5 are reduced. This reduction also reduces the localized bend loss at each bend of 12 and 13 which can become significant with two bends on each turn with a jog zone 5 on the coil.
• the coil 10 will also experience a drop in induced birefringence, thereby lowering induced polarization performance errors in the bias output of the coil 10, and simplifying the coil winding automation due to reduction in the jog acceleration as the fiber coil 3 transitions from one turn to the next.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Optics & Photonics (AREA)
• Electromagnetism (AREA)
• Power Engineering (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Gyroscopes (AREA)

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Citations (2)

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• 1998
  • 1998-12-29 US US09/222,606 patent/US6005665A/en not_active Expired - Lifetime
• 1999
  • 1999-11-10 DE DE69920968T patent/DE69920968T2/de not_active Expired - Lifetime
  • 1999-11-10 JP JP2000591381A patent/JP2002533704A/ja active Pending
  • 1999-11-10 CA CA002358121A patent/CA2358121A1/en not_active Abandoned
  • 1999-11-10 WO PCT/US1999/026500 patent/WO2000039527A1/en not_active Ceased
  • 1999-11-10 EP EP99963879A patent/EP1144949B1/en not_active Expired - Lifetime

Patent Citations (2)

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