| The marine studies center around three major issues:the maritime rights and interests, ocean resources and marine environments. The protection of the rights to exploit and occupy marine resources is bringing about more conflicts among countries, and the deep-ocean technology is coming to the forefront in the competition.The Deep Ocean Compact Automatic Raman Spectrometer can be widely applied in various kinds of deep ocean environments, both normal and extreme. When carried by the underwater vehicles, the Spectrometer is capable of analyzing the components of such media as seabed rocks, mineral deposits and interstitial water, so the rapid in-situ detection of solid, liquid and gaseous undersea objects is available. Based on the national 863 project "The Deep Ocean Compact Automatic Raman Spectrometer", this thesis studies the mechanical structure design of the spectrometer and critical issues in sea tests, in order to provide valuable reference to the construction, testing and sample releasing of this spectrometer in related researches.The thesis firstly introduces the main structure, function and specifications of the Deep Ocean Compact Automatic Raman Spectrometer, and focuses on several key technologies such as the frame structure design, sample release system design and sea trial testing.In chapter three, the equipment cabin and the frame structure of a prototype that can work in the shallow sea are designed, and some key parameters about the cabin size and internal devices are fixed, which serves as good preparations for the prototype design targeted at deep-sea activities. On this basis, according to the technical specifications of the deep-sea prototype, more analyses are made on the functionality, structure, size and load-bearing of the carrying platform, and the integration of the Spectrometer and the platform is further studied. An equipment cabin of the prototype designed for deep-sea environment is constructed through modularization, integration and innovation on the original prototype. In addition, the thesis also discusses the standby wake-up device as well as length and tension adjustment of the wire rope, which are crucial to the normal functioning of the system.In the performance evaluation process, the sample release device is an important link, and it is indispensible to the practical application of the Spectrometer. In order to evaluate the system's performance in rapid in-situ deep-sea detection, a sample release mechanism is developed in the forth chapter to cooperate with the Spectrometer. It uses a standard air cylinder to hold samples, and releases the sample into the testing area with the force of mechanical spring. This mechanism satisfies the requirements of resistance to pressure, simple release action, reusability and low cost. Additionally, accommodating the SBE's release action, this scheme avoids the concerns on pressure-bearing and sealing in deep-sea environment, and successfully deals with sample release problem in high-pressure surroundings. According to the property that the amplitude of Raman Peaks varies with the spread of samples and with the help of the sample cache device, the variation of density with time can be deduced, and thus the correctness and reliability of the sample release system are proved. Moreover, a sample cache device is invented to ensure that the sample spreads to the detection window again after blending with sea water. The device also restricts the spread area, so extends the time that the Spectrometer is exposed to the Raman spectroscopy of the self-prepared sample.Carrying an ROV to conduct undersea in-situ detection and even long-term observation is one of the future development of the System. In this situation, the equipment cabin needs to be placed stably under the sea, or to adjust its own posture after reaching the bottom of the sea, so the precise measurement of the cabin's posture (three dimensional dip angle) becomes one of the most essential technological task. The measurement of the angle is also of great importance to the lifting and placing of other undersea long-term workstations, as such data provides reference to on-deck operations to ensure the safety and accurate location of the placement of devices. The fifth chapter discusses the pre-researches on how to optimize the dip angle measurement of the deep-sea in-situ observation station. With the differential-input operational amplifier and A/D conversion in separate domains, the resolution is greatly improved, making possible the precise acquisition of dip-angle data in all ranges. The lab observation is very satisfactory especially when the sensitive axis is approximately parallel with 1g (gravity), where the resolution can be improved to better than 0.5°. With sufficient energy supply, the observation station adjusts its posture based on the dip-angle data acquired, so as to maintain the best working status of the in-situ detection.The last part of the thesis summarizes the discussions above and proposes some topics worth further researches from three perspectives:miniaturization of engineering prototypes, time difference between sample release and detection, and gaseous sample release. New materials shall be used to optimize the structure and pressure resistance design. In order to precisely and automatically control the time and dose of sample release, and to reduce the time difference of in-situ detection to zero, an automatic mechanism should be adopted. Moreover, the degassing technique in the deep-sea environment should be further studied. Keywords:laser Raman spectroscopy; in-situ detection in deep-sea; pressure test; seal; sample release; sea trial...
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