| Low coherent interference technique is using coherent degrees lower broadband illuminant, whose amplitude was separated by couplers spectral equipment. The light enters the corresponding interference light path and makes up of the low coherent system. Through testing interference fringes which was reflected by the interference system two arms the interference fringes and picking up related information, the system can absolutely measure any quantity in physics which was converted to the displacement of arms. The resolution of measurement can is vary high by using this technique of coherent systems. Therefore, the technology is widely applied in all kinds of precision measurement. However, there is lack of application in low coherent interferometry of interference fringes calculation, processing algorithms and analysis of noise.In this dissertation, we researched the details on low coherent theory and technique, especially for typical low coherent system the interference fringes analysis and numerical simulation. The function expression was established by analyzing the results of beat noise, thermal noise, shotgun noise. We have designed and established an experimental system to study the beat noise. The survey of experimental results was obtained from corresponding measurements. The results were simulated by advanced optical communication software and photonics design software of the experimental system. The theory results are well agreed with experimental results.According to the characteristics of interference signals, the beat noise was identified to be the system's main noise. Based on the analysis of signal frequency band, we considered that the beat noise and useful signal frequency position interlaced. We also analyzed the experimental data of time domain and frequency domain analysis of noise forward based on coherent function method and power spectral estimation methods respectively. Finally, the results will provide reference for the studies in related fields. |
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