Agar-made biodegradable ball lens

This work proposes the fabrication and characterization of ball lenses made of agar, a biodegradable and renewable material. Pouring a boiled solution of food-grade agar, glycerol, and water into cooled vegetable oil under agitation by a magnetic stirrer produces transparent and manipulable spheres. The glycerol concentration and rotation speed define the refractive index and size distribution, respectively, yielding lenses with diameters between 1 and 8 mm and indices ranging from 1.33 to 1.46. Experiments also characterized the output beam profile with 632 nm laser illumination. The results corroborate with the focal length simulated for a Gaussian beam model, suggesting controllable optical properties and anticipating potential applications of the agar ball lens as a biodegradable optical device for biomedical imaging, illumination, and sensing.