Study On Manufacturing Technology Of Diffraction Elements Based On Ultraviolet Curing Organic-inorganic Materials

Diffractive optical elements were based on the diffraction theory of light.They were designed by computer and processed by various processing techniques on the surface of traditional optical elements.They were a kind of optical elements with the functions of convergence,imaging,beam splitting and so on.Because of the use of diffractive optical elements,the number of optical elements in the system was reduced,compact,small size,light weight and so on,it has been widely used in various optical systems.At present,the materials used for diffractive optical elements were mainly optical glass and optical plastics.If the optical glass was used to process the diffractive optical elements,the processing error had a great influence on the diffraction efficiency.If optical plastics were used as substrates to process diffractive optical elements,the surface microstructures would be very high due to the limited types of materials,which would easily lead to shielding effect.In order to achieve high diffraction efficiency of diffractive optical elements in wide band,it was necessary to find optical materials,reduce the height of their microstructures and reduce the shielding effect.Organic-inorganic nanocomposites had high refractive index,high dispersion and other optical properties.It also had good toughness and easy processing.Using organic-inorganic nanocomposites to fabricate diffractive optical elements can also improve the degree of freedom of design.By considering the limitations of material selection and shielding effect associated with the manufacturing of diffractive optical elements,this study introduces the fabrication of diffractive optical elements based on the rapid prototyping technology of the ultraviolet(UV)-cured organic-inorganic nanocomposites.Thus we can obtain diffractive optical elements exhibiting a high refractive index and a high dispersion.Further a composite formulationsuitable for manufacturing diffractive optical elements is obtained based on an experiment on the organic-inorganic nanocomposite preparation.The formulation contains 57.97wt% aliphatic polyurethane acrylate(2PUA),38.64wt% pentaerythritol triacrylate(PETA),1.45wt% Irgacure 184,1.93wt% disperbyk 163 and ITO nanoparticles with controllable mass fraction.Diffractive optical elements were fabricated by this method.Measuring the average microstructural height of the mold surface of diffractive optical elements by step instrument was 13.26 micron.The UV curable diffractive optical elements were fabricated.And the average surface microstructural height of diffraction optical elements using UV curing organic-inorganic nanocomposites was 12.58 microns.The relative error between the diffraction optical elements and the mold microstructures fabricated by UV curing organic-inorganic nanocomposites was 5.141%.The manufacturing technology of diffractive optical elements for UVcurable organic-inorganic nanocomposites breaks through the limitation of material selection and reduces the occlusion error.It was of great significance to rapid prototyping of refractive-diffractive hybrid optical systems in wide band.