| Laser interference measurement technology is widely applied in the ultraprecise processing and equipment-manufacturing industry, as it is featured by non-contact, traceability, and high accuracy. However, with the fast development of scientific technology, the interference measurement technology needs to be improved so that it could measure in a more precise and faster way as well as a larger range. For this, the bandwidth of interference measurement has been put bigger and bigger, while the signal becomes weaker and weaker. Therefore, there comes a great challenge of the technology in the fields of photoelectricity signal examining and signal processing.This dissertation is derived from the project of the 100m Bi-frenquency Laser Interferometer, which is the key scientific and technological project in Heilongjiang Province. First, the author states the current photoelectricity examining situation and analyzes the pros and cons of this technology; then designs a new method of photoelectricity examining to overcome the present technological difficulties, such as the big bandwidth, the weak of the signal, and the phase difference excursion. This new method has low-noise, high-frequency big-gain, and low phase difference excursion.The main tasks accomplished in this dissertation are as follows:(1) There exist the problems of high-frequency and weak-signal in current photoeletricity examining system as a result of the application of multi-wavelength spliting and compounding technique. The author analyzes the electrocircuit technology parameters such as circuit Gain-Bandwidth-Product and slew rate, uses the method of multilevel-magnifying structure to magnify the micro signal;(2) It is hard to prohibit the noise of the simulated electrocircuit because of the high-frequency and large-bandwidth of photoelectricity examining system. The author analyzes the source and features of the noise, uses noise impedance matching, designs a more proper negative feedback amplifier circuit, chooses appropriate magnifier and applies the method of narrowband-division in order to restrain the noise. In addition, the simulated channel with a high signal-noise ratio is provided to improve the detecting ability of photoelectricity examining system;(3) As to the problem of electrocircuit phase difference excursion brought by the turbulence of environmental temperature, the author designs a digital temperature-controlling system based on DSP. It controls the temperature of the photoelectricity detecting module by the small-sized constant tempetature trap and fast-and-high-precise tempetature-control arithmetic;(4) As to the problem of phase difference excursion brought by the electromagnetism interference of high-frequency electrocircuit, the author analyzes the reason and mechanism, improves the design of high frequency PCB electromagnetism compatibility in combination with the feature of electrocircuit in this project, solves the difficulties of high frequency transmission line impedance matching, harass among lines and space electromagnetism interference in order to improve the performance of electrocircuit;In this dissertation, the author designs the related experiments on the basis of above designing projects and hardware electrocircuit. The result of experiments proves the followings: the detecting ability of photoelectricity of this system comes to 0.050mW; the signal-noise ratio of the electrocircuit reaches 60dB; the difference of tempetature between two boards is controlled to less than 0.1℃; phase difference precision between two boards processed the 100MHz high frequency signals is as tiny as 0.05°.
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