Fibre loop for fibre gyroscope with 3 x 3 coupler - contains depolarised component with spliced doubly refractive fibres preventing contrast fading

摘要

A fibre loop for a fibre optic gyroscope with a 3 X 3 coupler contains a depolarised component contg. at least two pieces of doubly refracting glass fibres spliced together with their main axes enclosing approximately 45 deg. The loci of the natural polarisation states of the fibre loop combined with the component are represented on a Poincare sphere so that a contrast fluctuating by 0.5 is achieved irrespective of the loop alignment. ADVANTAGE - Prevents contrast reduction and uses fibre configuration of optimum efficiency.