www.fizoptika.com FIZOPTIKA Fiber Optic Gyroscopes. VG910 series. Information Guide Version #8 of 25/05/2018 Page 9 of 20
2. Mounting Guidelines
The VG910 is typically screw mounted.
2.1. Screw Mounting Guidelines
•The mounting surface should be clean, smooth and flat.
•Torque screws M3 max to 3-7 Ncm limits.
•Special consideration is required when there is a high frequency vibration. Eigen-frequencies (resonances) of
the mating frame should exceed vibration frequencies. Otherwise a noisy signal is possible as a result of gyro
mechanical distortion.
2.2. Cable Routing
Use high flexibility cables with a low weight per length. It is strongly recommended that the cable be secured by fastening
it at some point in the vicinity of the output pins. Make sure that cable bending does not result in contacts stress. Avoid
routing cables near high-voltage wires and also ground the shield at the signal conditioner to minimize ground loops.
3. Open-loop Fiber Optic Gyroscope
3.1. Principle of Operation
An FOG is a gyroscope that uses the interference of light to detect mechanical rotation. The sensor is a coil of 100 m of
optical fiber. Two light beams travel along the fiber in opposite directions. Due to the Sagnac effect, the beam travelling
against the rotation experiences a slightly shorter path than the other beam. The resulting phase shift affects how the
beams interfere with each other when they are combined. The intensity of the combined beam then depends on the
angular rate of the device. The broadband SLD together with beam splitting components launch the light so that photons
travel simultaneously in clockwise and counterclockwise directions through the fiber. The FOG provides extremely
precise rotational rate information, in part because of its lack of sensitivity to vibration, acceleration, and shock. Unlike
the classic spinning-mass gyroscope, the FOG has virtually no moving parts and no inertial resistance to movement.
Hence, FOG technology is one of the most reliable gyroscope technologies.
3.2. Embedded Design
The Fizoptika gyro is a complete gyro system which comprises a fiber optic sensing assembly and analog processing
electronics (refer to the Assembly drawings presented below). The sensing assembly (open-loop minimum configuration)
is fabricated from a single length of optical fiber by a fusion-tapering technique. Industrial silicone compounds are used to
mount optical components on quartz substrates. The substrates are placed into a miniature plastic container filled with
soft silicone gel for protection and mechanical stabilization. A connecting board is used to connect a processing PCB to
external power sources and instrumentation. The connecting board includes a temperature sensor. When the gyro
experiences mechanical, thermal or electrical shock that exceeds its specifications, the resultant failure is most often
traced to SLD electrical/mechanical damage or to fiber and wire breakage. To ensure the gyros are in good working
order prior to leaving the factory, each gyro runs at an elevated temperature while scale factor, bias and current
consumption are measured. Every unit is shipped with a certificate specifying major parameters.
For demanding applications additional specific ATP (burn-in test, vibration mapping, screening, etc) may be conducted
with correspondent certificates provided.
