유한요소해석법을 이용한 자유곡면 반사경의 조립부 형상에 따른 초정밀 가공 특성

Demand for precision optical system is increased due to the rapid development of aerospace, defense, and imaging fields. Research to produce high precision reflector mirror is being carried out. In particular, confocal off-axis reflecting optical system can be applied to various fields due to the advantage of beingable to implement a short focal length and a large field of view. The axis of freeform reflector is asymmetrical, so ultra precision machining which is possible to accurately controls over three-axis is required for the reflector. Precision machining of free-form reflectors is more difficult than precision machining of symmetrical reflector. In this study, effect of mirror mounting structure on cutting characteristics was researched by finite element analysis(FEA) to set the reference plane using the machining and measurement of the freeform mirror. The mirror mounting has been divided into four types of squares, hexagons, octagons, and dodecagon. This study of FEA shows that there are not much difference in stress on the surface of the mirror for rotating and cutting forces. It was confirmed that deflection have great different over 5 times according to mounting structure. The analysis results are expected to be useful in the assembly part design and production to minimize the manufacturing tolerances of the freeform mirror.