Thermal Effects in Single-Point Curing Process for Pulsed Infrared Laser-Assisted 3D Printing of Optics

Abstract

Additive manufacturing (AM) process is an ideal way to rapidly prototype freeform optics. We present a new precision additive freeform optics manufacturing (AFOM) method using pulsed infrared laser to thermally cure optical silicones. To achieve the tight optical surface requirements, the curing volume pixel (voxel) of the AM process should be precisely controlled. We have developed an opto-thermal-chemical-coupled multiphysics model to simulate the curing process and predict the shape and size of cured polymer. Single-point curing experiments were conducted using a Q-switched fiber laser with an average power of 10 W and a repetition rate at 30 kHz. Numerical simulation shows a good agreement with the experiments, showing a path for a theoretically guided design of a high-precision AFOM process.

Laser‐Assisted Direct Ink Writing for High‐Fidelity Fabrication of Elastomeric Complex Structures

“…[ 23 ] The transmission valleys denote the strong absorption of the incident energy at the corresponding wavelengths. According the previous study, [ 22 ] at the laser wavelength where the transmittance is almost 0, the temperature at the center of the spot ascends dramatically, which is not conducive to the adjustment of laser energy. While at the laser wavelength where the transmittance is close to 100%, there is almost no heating effect.…”

“…Polymers, such as PDMS, experience an absorption loss, mainly caused by the vibrational overtone and combination bands of the CH 3 ‐groups of the polymer. According to the research of Li et al., [ 22 ] different infrared laser wavelengths have great influence in the heating effect of materials. The FT‐IR measurement of PDMS material was carried out to confirm the suitability of the laser wavelength applied for material heating.…”

“…The Gaussian distribution of laser energy was adopted from reference. [22] Data Measurement: The cross-linking reaction of the silicone material was determined by differential scanning calorimetry (DSC 2500, TA Instruments, America). The test was performed with air gas and increased from room temperature to 300 °C at a ramp rate of 10 °C min −1 .…”

“…However, this method was mainly researched for the annealing of silver nanowires. [ 21 ] Although the fabrication of optic silicone lenses using infrared laser has been studied, [ 22 ] the material's low viscosity limits the fabrication of complex structures such as large spans and thin wall features. Thus, it is necessary to study infrared laser‐assisted in situ curing for commercial high‐viscosity PDMS for fabricating complex spatial structures.…”