Characterization of high-reflectance diffuse coatings for 3D-printed optics

Authors

DOI:

https://doi.org/10.21014/actaimeko.v15i2.2253

Keywords:

diffuse reflectance, high-reflectance coatings, Lambertian behaviour, 3D-printed optics, BRDF

Abstract

Low-cost diffuse reflectance coatings were characterized for use on 3D-printed optical assemblies. Barium sulfate (BaSO4) and titanium dioxide (TiO2) suspensions were deposited on polylactic acid (PLA) substrates through a multilayer drop-casting process with an acrylic binder, and compared to commercial white paints and Spectralon® standards. Hemispherical reflectance was measured using an integrating sphere over the 300 nm to 1000 nm range, while angular scattering was assessed from −85° to 85° using a collimated xenon source. BaSO4 achieved the highest broadband performance, with a mean hemispherical reflectance of 98.9 % and a mean angular deviation of 6.3 % from the ideal cosine law. TiO2 showed slightly lower reflectance (96.6 %) and stronger angular directionality, consistent with its smoother and glossier surface finish. Commercial acrylic coatings exhibited markedly lower reflectance (70 % to 86 %) and large deviations from cosine behaviour, while office paper provided good diffusivity but insufficient spectral uniformity. The results demonstrate that a simple BaSO4-based coating can deliver stable, broadband, and highly diffuse reflectance when applied to 3D-printed substrates, enabling the fabrication of low-cost optical diffusers and reflectance references for custom laboratory setups.

Author Biographies

Giovanni Gibertoni, Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Italy

Giovanni Gibertoni is a Tenure Track Researcher (RTT, since October 2024) in Bioengineering (IBIO-01/A) at the University of Modena and Reggio Emilia, Department of Biomedical, Metabolic and Neurosciences. He received his MSc in Electronics Engineering with honors in 2019 and his PhD in Information and Communication Technologies in 2023. His doctoral work focused on optoelectronic methods and instrumentation for ophthalmic diagnostics and visual perception.

His research investigates innovative optical systems for non-invasive eye diagnostics, integrating optics, electronics, embedded hardware, and advanced image and signal analysis. He has developed a Maxwellian-view pupillometer based on silent substitution for photoreceptor-specific stimulation, an automated anterior chamber angle assessment system for glaucoma risk evaluation (currently under clinical testing with IRCCS Fondazione G.B. Bietti, Rome), hyperspectral imaging methods for anterior segment analysis, near-infrared wearable sensors for prosthetic control within the FIT4MedRob PNRR program, and a photoacoustic prototype for breath-based diagnostics within the PRIN 2022 PNRR project.

His experience in optical design and prototyping has led to collaborations with academic, clinical, and industrial partners. He has contributed to the development and calibration of a commercial pupillometer with Oculox Technologies SA and is a co-inventor on two patent applications in ophthalmic instrumentation. He also contributes to an international project funded by the Velux Foundation focused on non-contact screening for narrow anterior chamber angles.

He has authored peer-reviewed articles in journals including IEEE TIM, Diagnostics, Sensors, and Electronics, and has presented at major international conferences such as SPIE Photonics West and IEEE I2MTC. He collaborates with research groups at SUNY College of Optometry and the University of Applied Sciences and Arts Western Switzerland. Through his role at OptoLAB, he coordinates interdisciplinary work bridging optical engineering, biomedical sensing, and clinical validation to develop low-cost and clinically relevant tools for early detection of ocular disease.

Luigi Rovati, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy

Full Professor of Electronic Instrumentation and Measurement Science, received his first-class honours degree in Electronic Engineering in 1989 and PhD in Electronic Engineering and computer science in 1994, both at the University of Pavia, Italy. From 1995-2001, he was a researcher and Assistant Professor at the University of Brescia. He joined the Department of Information Engineering at the University of Modena and Reggio Emilia in 2001. His research activities have been towards the study and the development of low-noise, high-performance, innovative biomedical instrumentation. The published papers production (more than 200 publications) testifies to the level of the developed activity.

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Published

2026-05-18

Issue

Vol. 15 No. 2 (2026)

Section

Research Papers

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Copyright (c) 2026 Giovanni Gibertoni, Luigi Rovati

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