Research On Removing Damage Of Optical Components Based On Magnetorheological Finishing Techniques

There are rigorous restrict to optical components used in Intense Optical System which requires excellent surface quality such as high surface precision, low surface roughness and better distributing of spatial frequency, and now the subsurface quality of these components are more and more important. When optical components are used in Intense Optical System, even though with very high surface quality, if there are subsurface damage existing, then these tiny neglected damage will be induced by the intense optics into huge breakage on the components like melt holes and burst stains which can lead these optical components perpetual invalidation. In addition, the surface and subsurface damage will badly reduce the threshold of laser damage of optical components. It is also to say that the threshold of laser damage of these tiny damage existing optical components is much smaller than that of the material used, which can make the component easier breakage at a low energy irradiation.The process of manufacturing optical components usually adopts traditional polishing as the last working procedure. Because of the mechanism of traditional polishing and some procedure problems, it is very difficult to produce non-damage or low damage optical components. At present the producing of non-damage optical components is becoming to an important problem which maybe restricts the development of high power laser system in our country.Under the fast development of high power laser system, a new polishing technology–Magnetorheological Finishing as the key technique is developed and techniques to produce non-damage optical components is researched in this thesis. It mainly contains the following portions:1. The research on damage removal mechanism of polishing optical components by using Magnetorheological Finishing (MRF). At first, this paper make the manufacturing in plastic region of hard and brittle material as an entrance, and analyze the bear forces of one polishing particle, as follow it conclude that MRF is an method which manufacture components in the material's plastic region. And then it compare MRF with traditional polishing in terms of the material's removing mechanism, polishing pad and so on to explain that MRF is much better in non-damage producing of optical components. At last we reach that MRF can produce the optical components which can meet with the demand of Intense Optical System that can be called as non-damage components.2. The research on damage removal technics using MRF. Because of the trait of polishing pad of MRF, not all of damage can be directly removed by MRF. At the same time, it should consider the cost and efficiency of manufacturing, so it is important to arrange all the procedures reasonable and realize the significance of pre-procedures. In addition, different machining parameters will produce different quality and efficiency, so the orthogonal experimental is introduced to get the optimal machining parameters.3. The research on post-procedure of damage removal using MRF. Considering the characteristic of MRF, there will be a thin layer of impurity and other ions on the optical components after MRF. These impurity and ions also can impact the application of components so this needs a next procedure to remove all of them and then two methods are mentioned in this paper for this purpose.