RESUMO
We report a novel process technology of hemispherical shaped microlenses, using isotropic wet etching of silicon in an acid solution to produce the microlenses molds. Governed by process parameters such as temperature and etchant concentration, the isotropic wet etching is controlled to minimize various defects that appear during the molding creation. From the molds, microlenses are fabricated in polymer by conventional replication techniques such as hot embossing and UV-molding. The characterization of molds and measurements of replicated microlenses demonstrate high smoothness of the surfaces, excellent repeatability of mold fabrication and good optical properties. Using the proposed method, a wide range of lens geometries and lens arrays can be achieved.
Assuntos
Lentes , Silício/química , Anisotropia , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Miniaturização , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , MolhabilidadeRESUMO
An extensive study of the single-step replication of form-birefringent quarter-wave plates is presented. Using rigorous diffraction theory, the fabrication parameters and tolerances are carefully studied in order to obtain ideal conditions for successful replication. The design considerations are then applied to fabricate a master element by electron-beam lithography, and to replicate quarter-wave plates using the UV-moulding process. The measurements show that the replicas behave as high-performance quarter-wave plates for the design wavelength.
Assuntos
Desenho Assistido por Computador , Desenho de Equipamento/métodos , Modelos Teóricos , Dispositivos Ópticos , Refratometria/instrumentação , Birrefringência , Simulação por Computador , Análise de Falha de Equipamento , Luz , Espalhamento de RadiaçãoRESUMO
Waveguiding in periodical structures of the size of the wavelength is applied to increase the functional spectral band of diffractive optics. The deviation of the effective refractive index between waveguides as a function of the wavelength is utilized to compensate the strong wavelength dependence of the efficiency of diffraction gratings.
Assuntos
Desenho Assistido por Computador , Modelos Teóricos , Refratometria/instrumentação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Espalhamento de RadiaçãoRESUMO
Four-level transmission-type surface relief grating profiles with nearly flat efficiency over a spectral octave are designed by rigorous electromagnetic diffraction theory. Parametric optimization of the relief depths and transition points of the profile steps of these leads to efficiencies in the range 50-60% over the entire octave if the ratio of the grating period and the mean spectral wavelength is greater than ~ 3.
