Thermoforming mechanism of precision glass moulding

Intelligent evaluation for lens optical performance based on machine vision

Optical performance evaluation is a critical process in the production of collimating lenses. However, the current visual inspection of lens light-spot images is inefficient and prone to fatigue. Intelligent detection based on machine vision and deep learning can improve evaluation efficiency and accuracy. In this study, a dual-branch structure light-spot evaluation model based on deep learning is proposed for collimating lens optical performance evaluation, and a lens light-spot image dataset is built, containing 9000 images with corresponding labels. Experimental results show that the proposed model achieves accurate classification of lens optical performance evaluation. Combined with the proposed weighted multi-model voting strategy, the performance of the model is further improved, and the classification accuracy successfully reaches 98.89%. Through the developed application software, the proposed model can be well applied to the quality inspection in collimating lens production.

Optical elements from 3D printed polymers

3D printing belongs to the emerging technologies of our time. Describing diverse specific techniques, 3D printing enables rapid production of individual objects and creating shapes that would not be produced with other techniques. One of the drawbacks of typical 3D printing processes, however, is the layered structure of the created parts. This is especially problematic in the production of optical elements, which in most cases necessitate highly even surfaces. To meet this challenge, advanced 3D printing techniques as well as other sophisticated solutions can be applied. Here, we give an overview of 3D printed optical elements, such as lenses, mirrors, and waveguides, with a focus on freeform optics and other elements for which 3D printing is especially well suited.

Mechanisms and optimization for the rapid fabrication method of polymeric microlens arrays

This paper presents a simple and cost-effective rapid method to make defect-free polymeric microlens arrays at room temperature without applying external pressure. This method uses an optically clear and high-transparency Norland Optical Adhesive (NOA) monomer solution. This is realized by using a combination of a mold and an ultraviolet (UV) polymerization technique. NOA can cross-link in a tenth of a second upon UV exposure. The uniformity and surface quality of the manufactured microlens arrays are investigated through atomic force microscopy and optical microscopy techniques. Experimental results show that the microlens arrays manufactured by the polymerization process are of very high quality without any defects. Further, the surface quality of the lenses can be significantly enhanced by increasing the viscosity of the photosensitive monomer solution.

Quality improvement of collimating lens produced by precision glass molding according to performance evaluation

Precision glass molding technology is one of the most important approaches to produce optical glass lenses. However, the high fidelity and repeatability of optical performance be sometimes achieved even though the lenses meet the requirements of geometric assessments. The surface errorform errors transferred from mold surface with a complicated combination of components of different spatial-frequencies greatly influence the optical lenses performance. An optical model is built to investigate the impact of form errors with various frequencies on the optical performance of the lens. The mid-spatial frequency error is proved to be the factor that results in the most serious surrounding circle phenomenon. Based on the diffraction theory of the sinusoidal grating, numerical calculation is carried out to analyze their relationship. Experiments are conducted to validate the analysis and a mold polishing procedure is provided as a method to improve the quality of lenses according to performance evaluation.

Numerical optimization platform for precision glass molding by the simplex algorithm

Precision glass molding (PGM) can fabricate aspherical lens and irregular optical products in a single step, but its applicability is currently limited by the thermally induced residual stresses and lens shape derivation after molding. To remove this barrier, this paper develops a numerical optimization platform for PGM based on a simplex algorithm and finite element simulation. It was found that the platform can effectively reduce the residual stress in a molded lens through cooling process optimization and minimize the lens shape derivation by die shape compensation. The platform established can improve the lens quality by PMG and make molded lenses have better quality than those manufactured by ultraprecision machining processes.