Papers by Keyword: Diffractive Optical Elements

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Authors: Chao Chang Arthur Chen, Shi Chi Kao
Abstract: This research aimed to develop a novel two-stage micro injection compression molding (μ-ICM) process for fabrication of plastic diffractive optic elements (DOE). The DOE was designed with the spherical coefficients and the Fresnel lens. A piezo actuator was installed inside the mold plate for activating the mold insert for the second compression motion for micro ICM of the DOE lens. The first experiment proceeded to find the operation window of Fresnel lens and then compare the product weight of flat spherical lens by injection molding (IM), injection compression molding (ICM) and μ-ICM. The second experiment was to investigate the effectiveness of micro compression activated by the piezo actuator by the transfer ratio of grooves (TRG) of the DOE lens with spherical lens and Fresnel lens. Results showed that the μ-ICM of the DOE can obtain the highest TRG than that of IM and conventional ICM processes. Therefore, results of this research can be explored to related aspheric optical elements with micro features, such as fine lens used in the zoom lens of camera.
Authors: Cheng Huan Chen, Po Chou Chen, Chin Ju Hsu, Chia Jen Ting
Abstract: A diffractive laser beam shaper has been proposed as a lossless approach to transfer a Gaussian laser beam into a thin line beam with a uniform distribution along the line direction for scanning material processing or illumination application. With the consideration for the feasibility of fabrication, the optical performance of the diffractive beam shaper with its surface relief quantized at different levels has been analyzed with scalar diffraction theory, which shows that an 8 level solution is sufficient for keeping the uniformity in the line direction while the focusing function in the orthogonal dimension needs to be performed by an extra cylindrical lens.
Authors: Seung Yub Baek
Abstract: Diffractive optical elements (DOE) can be used to simplify optical systems such as lightening its mass, reducing elements numbers and so on. Single-crystal diamond is considered as the preferred tool materials in ultra-precision and nanometer-scale cutting operation. Due to the well known and exceptional difficulty in shaping, the fabrication of diamond cutting tools requires special processing method. As a highly efficient and cost-effective solution, the mechanical lapping process has been extensively applied in tool-making industry. In this paper, the key enabling technologies to design and fabricate the diamond-cutting tools for ultra-precision and submicronic machining are presented and reviewed. The paper describes the shape of micro cutting tool that is based on the finite element method of calculation of relief angle and rake angle.
Authors: Chia Jung Chang, Choung Lii Chao, Wen Chen Chou, Yu Kun Chen, Kung Jeng Ma, Chun Chieh Chen
Abstract: Driven by the huge market demand, the glass lenses made of various optical glasses are required to be more diversified in sizes/shapes, to have better form accuracy/ surface roughness, to be more environmental durable, and to be more competitive in price. In comparison to conventional refractive lens, diffractive lens (diffractive optical element, DOE) has the advantages of being thinner and lighter, and is widely used in optical systems such as lighting and photovoltaic systems. Glass moulding process(GMP) is regarded as a very promising technique for mass producing high precision optical components such as spherical/ aspheric glass lenses and free-form optics. However, only a handful of materials can sustain the chemical reaction, mechanical stress and temperature involved in the glass moulding process. Besides, almost all of these mould materials are classified as hard-to-machine materials. This makes the machining of these materials to sub-micrometer form accuracy and nanometer surface finish a rather tough and expensive task. As a result, making service life of mould longer has played a critical part in the GMP industry. The excessive stress and/or temperature involved in the moulding process are amongst the main reasons for pre-matured mould failure. This research aimed to analyze the stress/strain conditions and the obtained dimensional accuracy under various molding parameters by simulations. Molding experiments were subsequently carried out to verify the simulated results. A glass DOE of 14.8 mm in diameter and 3.36 mm in thickness are successfully produced in this research and the difference between the simulated and the molded DOE is around 15μm.
Authors: V.K. Parashar, A. Sayah, M.A.M. Gijs
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