Research Of Making Micro-optical Devices By Optical Plastic Molding Technology

Along with the rapid development of optics and especially binary optics in recentyears, huge changes have taken place in optical elements and instruments. Opticalelement is developing in the direction of multi-step. Diffractive optics element, arecently developed type of optical element, is more and more widely applied to variousoptical instruments. That contributes a lot to the miniaturization, array and integration ofoptical instruments and related spare parts.The paper proposes to apply masking alignment and injection molding to makingdiffractive optical elements. Purpose is to find an effective production process, so thatthe production of diffractive optical elements in the small, the array of basis, towardsthe rapid, mass, low cost direction.As the first step, make masking figures of binary raster, Fresnel’s zone plate andother basic diffractive optical elements with ATUOCAD, input them into a computer,and produce photolithography mask on a chromium plate. As the second step, apply thechrome mask to touch photo etching system, manufacture with the alignment techniquethe array of diffractive optical elements on positive photo resist coated nickel base alloy,and then sculpture nickel base alloy with electrochemical etching so that the pattern canbe transferred from photo resist to alloy. After twice of masking alignment and etching,the production of stamper core would be completed.Copy stampers were mainly adopted injection molding, and also tried a modifiedhot-pressing method. The design and manufacture of injection mold was the key ofusing injection molding to complete copy. Mold drawing was designed by ATUOCADto copy the array pattern and discrete component, and corresponding mold was made.The molds were applied to the transferring of diffractive optical elements from nickelbase alloy to optical plastics. The paper presents the design of injection mould for themain advantage is that facilitate replacement mandrel. If the mandrels have the samedimensions, that change mandrel engraved with different design can create all kinds ofpattern of the diffractive with the same injection mould.As to the selecting of optical plastics, two optical resins were chosen for theirthermoplastic nature, namely PC and PMMA. PC, with a refractive index of1.586, is one of the three top refractive index materials. What’s more, it is featured by excellentresistance to impact, dimensional stability, mechanical property, heat-resisting andhygroscopicity. PMMA is endowed with great light-admitting quality. During theexperiment, PC was chosen as the replicating material for injection moulding method,while PMMA for hot embossing method.On the basis of plentiful experiments, the paper concludes with the technologicalparameters in diffractive optical element making process as well as reasons for certainexperimental errors. And have manufactured optical plastics elements.