Implementation and assessment of a low-cost 3D laser platform controlled by open software for printing polymeric micro-structures

Abstract

A low-cost 3D opto-mechatronic platform controlled by free-source software with optical and mechanical resolutions of 120 m and 10 m, respectively, was developed to fabricate micro-pedestals in grid presentation and diffractive optical elements such as micro-square and micro-slits. Direct laser writing (DLW) and low-one photon absorption (LOPA) were employed as the fabrication protocol and the physical phenomena involved in the platform control and development of the micrometric structures. A laser pointer, one of the lowest-cost lasers in the market, centered at 532 nm with an intensity of 65 mW, was used to polymerize the SU8-2050 photoresist through the DLW procedures. The printing process was carried out by using 5X and 10X microscope objectives with numerical apertures of 0.13 and 0.25, respectively. The point spread function demonstrated the geometrical variations and the field intensity distribution about the focal plane, where the Debye–Wolf approximation is valid, which were used for comparison purposes. In addition, ray tracing simulations were presented to demonstrate how light interacts with the SU8-film and how out of focus condition plays a fundamental role in the final size of the printed micro-pattern. Finally, two optical diffractive elements and their diffraction patterns in the Fraunhofer regime were presented.