Study On Optical Non-planar Detection Technology Of Trplg Ring Resonator

Laser gyro is one of the core components of strap-down inertial navigation system,which has advantages as quick start,high precision,large dynamic range and low loss.It has played an important role in the fields of missile guidance,aircraft flight control and the remote sensing satellite attitude control.The ring resonator is the core of the laser gyro,and the ring optical path is formed by four total reflection prisms in prisms laser gyro,hence it has the advantages such as non-coating and small backscattering.However,for the prism ring resonator,light travels comparatively longer in the total reflection prisms,the numbers of light reflection and refraction are more than that in the traditional mirror resonator.Prism laser gyro easily cause the light path non-planar of ring cavity by the disturbance of external environment,which affects the gyro operating stability.In this thesis,according to the structure of ring resonator with four total reflection prisms,the relationship between the elliptic polarization degree of the oscillation light in the ring cavity,the magnetic sensitivity of the laser gyros and the optical path non-planar has been analyzed using Jones matrix.A novel method has been proposed to detect light path non-planar of ring cavity.he main contents of this thesis include as follows:First,the operating principle of the laser gyros and light path non-planar detecting techniques have been introduced,and the structure and working characteristics of the prisms laser gyros have been introduced emphatically.Second,according to the structure of the ring resonant environment factor being considered,the transmission matrix of the refraction and reflection on the prism surfaces have been modified.Hence,the temperature,machining tolerance of the prism and the cavity,tower differential have been considered as perturbations,the old 2-by-2 matrix has been modified to the new 3-by-3 matrix.Third,according to the self-consistent theory of the laser ring resonator,the theoretical model of the intra-cavity light transmission has been established by the modified optical path transmission matrix.The distance and angle offsets of the light path by such error perturbations have been analyzed.Fourth,the influence of light path non-planar on the elliptic polarization degree of the oscillation light in the ring cavity has been analyzed qualitatively.According to the self-consistent theory,the relationship between light path non-planar and the elliptic polarization degree of the oscillation light has been analyzed by Jones matrix and its eigen-vector.The results have shown that the elliptic polarization degree of the light increased with the non-planar angle of the light path.Fifth,by the Jones matrix eigen-value,the relationship between the light path non-planar and magnetic sensitivity of laser gyro with total reflection prism has been analyzed.The results have shown that the magnetic sensitivity is positively correlated with the light path non-planar angle.Using a Helmholtz coil as a magnetic field generator,the magnetic sensitivity test has accomplished.The experimental results are consistent with that of the theoretical analysis.And a method of detecting the light path non-planar has been proposed based on the detection of laser gyros magnetic sensitivity and the elliptic polarization degree of the light oscillating in the ring cavity.