6 Mar 2023
by Ben Watson

infocus #69 March 2023 Investigating the liquid Characterising the surface quality of 3D printed optical elements using interference reflection microscopy

Optical microscopy has used the same manufacturing methods for milling and sanding glass elements to produce high-quality optics for over a century. Recent developments in 3D printing have opened the possibility of printing optical components, but the surface quality of these 3D prints remains unknown.

10.22443/rms.inf.1.246

To address this, I designed and printed several planoconvex lenses using a consumer-grade 3D printer, and then experimented with various post-processing methods to improve the quality of the lens surface. I then used a confocal microscope set up in reflection mode to image the topology of the lens surface following different post-processing methods.

This method produced constructive and destructive interference patterns on the lens, displayed as fringes corresponding to the axial position of the lens surface. I wrote my own code to reconstruct a 3D visualisation of the lenses using the interference fringe data and then calculated the radius of curvature of the 3D printed lens. This data was compared to the specifications of the CAD model that was printed.

By the end of my studentship, I had developed a workflow for manufacturing 3D printed lenses and written a custom analysis script that was used to characterise and quantify their surface quality.