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Optimal tolerance allocation in the optical head of near-field recording system

In this paper, error analysis and tolerance allocation methods for the optical head of NFR (Near Field Recording) system are presented. We fabricate the NFR system and test the reading & writing performance of the NFR system. The test results show that the performance is not good enough. In order to find the cause of the performance drop in the NFR system, assembly and manufacturing tolerances in the optical head of NFR system are simulated. The tolerances analysis result shows that it needs to allocate the tolerances of the optical head of NFR system. So we proposed optimal compound tolerance allocation method using WOW (worst on worst) method and Monte-Carlo method base on sensitive analysis of the optical system. We used two tolerance allocation methods to allocate the compound tolerance in the optical head of NFR system. The results show that WOW method is an over-design method and the Monte-Carlo method is the optimal method of tolerance allocation in optical system.