Deformation Analysis of the Glass Preform in the Progress of Precision Glass Molding for Fabricating Chalcogenide Glass Diffractive Optics with the Finite Element Method

Precision glass molding (PGM) technology is a cost-efficient process for the production of micro/nanostructured glass components with complex surface geometries. The stress distribution, surface profile, and reduced refractive index of the molded lens are based on the lens being fully formed. The process of the deformation of the glass preform is rarely discussed, especially in the case of multi-machining parameters in the experiment. The finite element method (FEM) was adopted to analyze the glass preform deformation. Due to the phenomenon of incomplete deformation of the glass preforms in the experiments, two groups of finite element simulations with different boundary conditions were carried out with MSC.Marc software, to reveal the relationship between the deformation progress and the parameters settings. Based on the simulation results, a glass preform deformation model was established. The error between the model result and the simulation result was less than 0.16. The establishment method of the glass preform deformation model and the established model can be used as a reference in efficiently optimizing PGM processing parameters when the designed lens has two different base radii of curvature.

Fabrication of a Chalcogenide Glass Microlens Array for Infrared Laser Beam Homogenization

Infrared (IR) microlens arrays (MLA) have attracted increasing interest for use in infrared micro-optical devices and systems. However, the beam homogenization of IR laser light is relatively difficult to achieve because most materials absorb strongly in the IR wavelength band. In this paper, we present a new method for the application of double-sided quasi-periodic chalcogenide glass (ChG) MLAs to infrared laser homogenization systems. These are non-regular arrays of closely spaced MLAs. The double-sided MLAs were successfully prepared on the ChG surface using a single-pulse femtosecond laser-assisted chemical etching technique and a precision glass molding technique. More than two million close-packed microlenses on the ChG surface were successfully fabricated within 200 min. By taking advantage of ChG’s good optical performance and transmittance (60%) in the infrared wavelength band (1~11μm), the homogenization of the IR beam was successfully achieved using the ChG quasi-periodic MLA.

A Comprehensive Review of Micro/Nano Precision Glass Molding Molds and Their Fabrication Methods

Micro/nano-precision glass molding (MNPGM) is an efficient approach for manufacturing micro/nanostructured glass components with intricate geometry and a high-quality optical finish. In MNPGM, the mold, which directly imprints the desired pattern on the glass substrate, is a key component. To date, a wide variety of mold inserts have been utilized in MNPGM. The aim of this article is to review the latest advances in molds for MNPGM and their fabrication methods. Surface finishing is specifically addressed because molded glass is usually intended for optical applications in which the surface roughness should be lower than the wavelength of incident light to avoid scattering loss. The use of molds for a wide range of molding temperatures is also discussed in detail. Finally, a series of tables summarizing the mold fabrication methods, mold patterns and their dimensions, anti-adhesion coatings, molding conditions, molding methods, surface roughness values, glass substrates and their glass transition temperatures, and associated applications are presented. This review is intended as a roadmap for those interested in the glass molding field.

Pre-Compensation of Mold in Precision Glass Molding Based on Mathematical Analysis

Precision glass molding is the most appropriate method for batch production of glass lenses with high surface accuracy and qualified optical performance. However, the form error caused by material expansion and contraction is the main factor affecting the precision of the molded lenses, thus the mold must be pre-compensated. In this paper, an effective method of mold pre-compensation based on mathematical analysis is established. Based on the thermal expansion curve of D-ZK3 glass, the freezing fictive temperature of the glass under the actual cooling rate is measured, and the mold pre-compensation factor can be quickly calculated. Experimental results show that the peak valley (PV) value of the surface form error of molded aspheric lens with an aperture of 5.3 mm is effectively reduced from 2.04 μm to 0.31 μm after the pre-compensation, thus meeting the geometric evaluation criterion.