Manufacture and characterization of a 3D-printed integrating sphere

Abstract

3D printers are more accessible in both academic and research groups, becoming instruments to facilitate the construction of high-quality scientific equipment for laboratories. In the present study, a 3D printed integrating sphere was validated to acquire diffuse reflectance and transmittance on turbid samples in order to compute optical absorption and reduced scattering through the inverse adding doubling algorithm. The 3D printed integrating sphere was validated in three stages: analysis of the integrating sphere coating reflectance using two possible coating materials (barium sulfate powder and a mixture of barium sulfate and paint), the sphere wall reflectance, and using two accurate optical polyurethane phantoms to measure the absorption and reduced scattering coefficients. The results indicate that the system developed with this methodology shows satisfactory reflectance compared to commercial models and is able to acquire experimental diffuse reflectance and transmittance measurements to compute the optical coefficients of turbid samples due to the use of an inverse adding doubling (IAD) algorithm. However, this system is limited to the region from 500 to 1300 nm due to a decrease in the reflectance of the coating.

Keywords:

• 3D printing
• double integrating sphere
• inverse adding doubling (IAD)

Additional information

Funding

This study was partially funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. This work was supported by the São Paulo Research Foundation (FAPESP) grant\# 2017/25923-5 and 2011/07960-4. The authors thank Cynthia Maria de Campos Prado Manso for linguistic advice.