The Dual Optical Comb Ranging (DCR) method has the advantages of large range, fast speed and high precision, which has a wide application prospect in the field of absolute ranging. In this paper, the Mie scattering theoretical model and the key parameters of atmospheric refractive index which affect the ranging accuracy of the DCR system are studied numerically. The effects of the relative size and refractive index of the Mie scattering particles on the ranging accuracy are simulated. The numerical results show that with the increase of the relative size and refractive index, the loss of light energy is greater, resulting in the reduction of the Signal to Noise Ratio (SNR) of the ranging results. The influence of atmospheric refractive index on ranging results is also simulated, and the influence of atmospheric temperature jitter on ranging is 2.9033 μm/(m∙°C), atmospheric pressure jitter on ranging is 8.203 μm /(m∙kPa), atmospheric humidity on ranging is 3.7676 μm for 1m ranging target with 1% humidity jitter, and atmospheric carbon dioxide on ranging is 1.45×10-4 μm /(m∙ppm).
The rapid development of modern science and technology puts forward higher and higher requirements for displacement measurement. As a non-contact measurement technology, laser ranging has played an important role in various fields for the unique advantages and has become a hot topic in the field of measurement research. At present, there are little research on high-precision displacement measurement at medium and long distance, the needs of which are widespread in practical application, so this work has important value. Among various laser ranging technologies, the laser triangulation method has the advantages of high-speed, high precision, simple structure, etc. Therefore, this paper chooses the direct laser triangulation method to carry out the research after analyzed the common types of laser triangulation system. In view of the requirements of high-precision displacement measurement requirements at medium and long distance, this article discussed the design of laser triangulation measuring system and the selection of structural parameters. Then we proposed a direct laser triangulation measurement structure under Scheimpflug conditions. This system selects PSD displacement transducer to collect the position information of the scattered light spot. After that, this paper discusses the principle of laser triangulation distance measurement and simulates the system. Then the influence of different parameters on high-precision displacement measurement and the relationship between them are investigated. Based on the research talked above, we got a set of structural parameters of the displacement measurement system. The measurement accuracy can be ~micron with the working distance of 500mm.
In this paper, a novel optical method is proposed to effectively double the sensitivity of FOGs. Two fiber polarization combiner/splitters (PCS) are added in the traditional FOG optical path, which are able to either combine two orthogonal polarizations transmitting at two different PM fibers into the two orthogonal axes of one PM fiber respectively or split two polarizations transmitting at the two orthogonal axes of one PM fiber into two polarizations to transmit at two different PM fibers respectively. Through the specific placement and coupling of these two fiber polarization combiner/splitters, the incident light can transmit twice along the light path of FOG. The experimental setup is established and the method is verified experimentally. The results show that the proposed method will effectively improve the sensitivity and the signal-to-noise ratio (SNR) of FOG without increasing the length of fiber coil, which is very benefit to improve the technology of FOGs, as well as the miniaturization of FOGs.
Previous studies have shown that there exists a large nonreciprocal phase error in the single-mode fiber coil of a depolarized interference fiber optic gyroscope (De-IFOG) under time-varying temperature and magnetic field, which evidently weakens its environmental adaptability. A real-time software compensation method considering the coupling effect of time-varying temperature and magnetic field is first proposed and verified experimentally. After compensation, the error of De-IFOG decreases from 50 deg / h to 6 deg / h when the magnitude of the magnetic field is 10 G and temperature uniformly increases from 10°C to 60°C with time-varying rate of 36 ° C / h. The compensation method is of great significance in De-IFOG engineering applications.
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