Analysis Of Impact Of RTV Bond On The Surface Shape In The Assembly Of High-precision Optical Lens

With the emergence and development of modern adhesives, more and moreengineers use a variety of structural adhesives in the production and assemblage ofoptical instruments, which take place of mechanical fastening screw, platen, and otherforms of fasteners. However, the adhesive bond is often simplified or even completelyignored in the finite element analysis of the optical mechanism, owing to the thicknessof adhesive bond connected with the mirror and cellis generally0.05~1mm, andmaterial properties of adhesive are difficult to completely obtained through experiment.In the analysis of high-precision optical systems, it’s necessary to consider the impact ofthe bond on the optical glass, since there will be shrinkage stress during the curingprocess of structural adhesive, and there will be thermal stress when temperaturechanges for the mismatch of the coefficient of thermal expansion of the cell, the mirrorand the bond. In order to predict the impact of the bond on the shape accuracy of opticalglass, this paper is mainly focus on the impact of the shrinkage stress of the bond on theoptical glass, specifically undertaken in the following aspects in the paper:1) Experimental studied of the mechanical properties of a silicone rubber material.2) Established the viscoelastic model of the silicone rubber material based on theexperimental data by the viscoelastic theory.3) Since curing stress cannot be directly measured by experiment, throughcomparison of experiment and finite element method(FEM) analysis, made theequivalent of the adhesive curing stress.4) Finally, made the opto-mechanical structure analysis of the lens by the finiteelement method, considering the impact of gravity and curing stress on the surfacedeformation. Then fit the surface of the optical glass by Zernike polynomial methodbased on the node displacement data of the surface of the optical glass calculated byFEM.5) For a given size of the lens, considering the impact of the thickness and the area of adhesive bond, found out the relationship between surface shape and the thicknessand the area of adhesive bond, which could provide a reference for the assemblage ofoptical lens with the structure adhesive.