Annealing of Compression Molded Aspherical Glass Lenses

Tao, Bo; He, Peng; Shen, Lianguan; Yi, Allen Y.

doi:10.1115/1.4025395

Cited by 11 publications

(6 citation statements)

References 22 publications

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“…In the peripheral region, larger Δ Z is found in the range of −3.52 to 4.96 µm, but is still below the pixel dimension of 7.1 µm and the layer thickness of 5 µm. The experimentally measured manufacturing accuracy is comparable with conventional methods for fabricating aspheric lenses . Therefore, the ultrasmooth optical surface together with the subvoxel precision of surfaces make it possible for the rapid 3D printing of high‐quality optical lenses.…”

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confidence: 70%

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

et al. 2018

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Advancements in three-dimensional (3D) printing technology have the potential to transform the manufacture of customized optical elements, which today relies heavily on time-consuming and costly polishing and grinding processes. However the inherent speed-accuracy trade-off seriously constrains the practical applications of 3D-printing technology in the optical realm. In addressing this issue, here, a new method featuring a significantly faster fabrication speed, at 24.54 mm h , without compromising the fabrication accuracy required to 3D-print customized optical components is reported. A high-speed 3D-printing process with subvoxel-scale precision (sub 5 µm) and deep subwavelength (sub 7 nm) surface roughness by employing the projection micro-stereolithography process and the synergistic effects from grayscale photopolymerization and the meniscus equilibrium post-curing methods is demonstrated. Fabricating a customized aspheric lens 5 mm in height and 3 mm in diameter is accomplished in four hours. The 3D-printed singlet aspheric lens demonstrates a maximal imaging resolution of 373.2 lp mm with low field distortion less than 0.13% across a 2 mm field of view. This lens is attached onto a cell phone camera and the colorful fine details of a sunset moth's wing and the spot on a weevil's elytra are captured. This work demonstrates the potential of this method to rapidly prototype optical components or systems based on 3D printing.

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confidence: 70%

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

et al. 2018

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“…Given the complexity of interface friction and glass material properties, finite element analysis is an effective alternative to analyze the glass molding process [29][30][31][32][33] and evaluate the friction coefficient. 10,12 In this paper, FEA models were developed to predict the axial displacement history and sample's final dimensions when different friction coefficient values were used.…”

Section: B Finite Element Analysis Resultsmentioning

confidence: 99%

Investigation on the friction coefficient between graphene-coated silicon and glass using barrel compression test

Zhou

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Articles you may be interested inResidual stress modeling of density modulated silicon thin films using finite element analysis J. Vac. Sci. Technol. A 33, 021503 (2015); 10.1116/1.4902953Thermo-mechanical characterization of glass at high temperature using the cylinder compression test. Part I: Viscoelasticity, friction, and PPV Graphene-coating on silicon wafer can prevent adhesion between silicon and glass in precision glass compression molding. The main goal of this research is to evaluate the graphene/glass interface friction coefficient, which dictates the flow behavior of glass and the durability of the silicon mold. In this research, barrel compression tests using BK7 glass were conducted at different molding temperatures. The purpose of the tests was to obtain the glass cylinder's axial displacement history and the final dimensions after pressing, both of which were decided by the friction coefficient. First, the friction coefficients were estimated by the empirical equations. Then, finite element analysis was implemented to simulate the friction behavior in the pressing stage. The roles of friction coefficient, molding temperature, and applied force were discussed separately. By comparing the experimental and numerical simulation results, both the axial displacement history plots and friction calibration curves show that the best matching friction coefficient is between 0.20 and 0.25 in the temperature range of 660-700 C. Furthermore, the specific friction coefficient values in the same temperature range were calculated using linear interpolation of the friction calibration curves, and showed good agreement with the results from the empirical equation. This study also demonstrated that the friction in the graphene/glass interface has no direct correlation with test temperature. In summary, this study revealed graphene coating's extraordinary low and stable friction behavior at high molding temperatures.

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“…The simulation results indicated that the liquid thermal expansion coefficient had a great influence on the predicted refractive index change of the lens and the residual stress distribution. Tao [18] clarified that the annealing process significantly affects the refractive index, residual stress distribution, and shape of the lens. Pallicity et al [19] used the photoelasticity of the glass to measure the residual birefringence of the formed lens by a six-step phase shift method after considering the stress relaxation, structural relaxation characteristics, and friction characteristics.…”

Section: Introductionmentioning

confidence: 99%

Effect of Elastic Modulus on the Accuracy of the Finite Element Method in Simulating Precision Glass Molding

Yao

Zhang

et al. 2019

Materials

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Precision glass molding is a revolutionary technology for achieving high precision and efficient manufacturing of glass aspheric lenses. The material properties of glass, including elastic modulus and viscosity, are highly dependent on temperature fluctuations. This paper aims to investigate the effect of elastic modulus on the high-temperature viscoelasticity of glass and the accuracy of the finite element simulation of the molding process for glass aspheric lenses. The high-temperature elastic modulus of D-ZK3L glass is experimentally measured and combined with the glass cylinder compression creep curve to calculate the high temperature viscoelasticity of D-ZK3L. Three groups of viscoelastic parameters are obtained. Based on this, the molding process of the molded aspheric lens is simulated by the nonlinear finite element method (FEM). The surface curves of lenses obtained by simulation and theoretical analyses are consistent. The simulation results obtained at different initial elastic modulus values indicate that the elastic modulus has a great influence on the precision of the FEM-based molding process of glass aspheric lenses.

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Annealing of Compression Molded Aspherical Glass Lenses

Cited by 11 publications

References 22 publications

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

Investigation on the friction coefficient between graphene-coated silicon and glass using barrel compression test

Effect of Elastic Modulus on the Accuracy of the Finite Element Method in Simulating Precision Glass Molding

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