KEYWORDS: Fiber optic gyroscopes, Photodetectors, Interference (communication), Signal to noise ratio, Dark current, Photovoltaics, Photodiodes, Temperature metrology, Signal detection, Relative intensity noise
The photodetector module is a key optoelectronic device that converts the optical signal of the sensing optical path of FOG (Fiber Optic Gyroscope) into electrical signal and amplifies the weak signal, which greatly affects the accuracy and performance of FOG. High precision FOG requires detector components with low noise, high sensitivity, high responsiveness and wide dynamic range. In this paper, the zero voltage and the noise voltage of the traditional detector module are analyzed, and a new detector design scheme is proposed. The photovoltaic operating mode is selected and the signal is processed by difference. At the same time, the noise such as dark current is suppressed by controlling the temperature. The test results show that the variation of the zero voltage at full temperature (- 50°C~75°C) of the new detector assembly is reduced from 50 mV to no more than 3 mV, and the noise voltage is reduced from 0.8mV to 0.5mV. In practical application, the random walk coefficient of the high-precision FOG is reduced by 17.3%, and the full temperature bias stability is improved by 32.6%. The new detector assembly is of great significance for improving the accuracy and full temperature performance of the high-precision FOG.
In view of the demand of space application field for long-life and highly reliable fiber optic gyroscopes, a life evaluation method for fog in space is presented in this paper. The effect of various physical fields on the performance of fiber optic gyroscope is analyzed in this paper. The temperature field and irradiation are the main environmental factors affecting the operating life of fiber optic gyroscope on orbit. The acceleration test method of temperature field and irradiated double stress double temperature point is carried out, and the performance of fiber optic gyroscope under the action of multi physical field is built. An accelerated life test evaluation method for fog is put forward. The life assessment method of fog in space can provide technical support for the design, selection and verification of the long life fiber optic gyroscope.
For fiber optic gyroscope(FOG), the bias stability is an important index to measure its performance level , which directly affects the accuracy of FOG , and affects the initial alignment accuracy and navigation accuracy of FOG inertial navigation system. Therefore, the requirement of the high precision FOG on the bias stability is rising. Due to the conduction of power and the space electromagnetic radiation of circuit, there is unavoidable cross-coupling between the forward channel circuit, the backward channel circuit and the light source driving circuit in the FOG, and these cross-coupling have a certain extent influence on the performance of the FOG. As the cross-coupling coefficient changes in different environments, the FOG bias bring out drift. In this paper, the internal cross-coupling model of FOG is established. Aiming at the bias drift caused by cross-coupling, a suppression method was proposed, which eliminate the bias drift by periodically converting the polarity of Y-waveguide and the corresponding modulation and demodulation algorithm. A large number of tests were carried out at high temperature and low temperature. The experimental results show that the bias drift of FOG is reduced from 0.31°/h to 0.07°/h at different temperature points.
In this paper, factors of fiber coil winding asymmetry, winding tension, non-ideal fiber type, adhensive glue type,and bonding way in fiber optic gyroscope could lead to fiber coils have different temperature distribution, and thermal induced nonreciprocity errors(Shupe errors). The influence of fiber coil temperature distribution in different wingding states on the fiber optic gyrocope temperature performance is studied in this paper, a temperatue distribution measure system of fiber coil is established, and the different wingding states coils are tested. Compared to the truly temperature distribution, the temperatue distribution measure model is exact relatively. The measure system can give more symmetrical and more uniform wingding state of fiber coil by meausure the temperatue distribution. Finally, the contrast experiment of fiber optic gyrocope is progressed, the experimental results agree well with the theory
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