Laser measurement system for acrylic transmittance of JUNO central detector

Background During the research phase of acrylic panel for the Jiangmen Underground Neutrino Observatory (JUNO) central detector (CD), the darkroom transmittance measurement system (DTMS) was designed and built, and a massive amount of measurements were carried out to help determine the composition and processing techniques of the acrylic panel. Motivation The mass production of acrylic panels was started after the pilot production. The requirement of transmittance measurement put forward new demands on operation, and a new measurement system was considered to support removable and non-destructive measurement on site. Result After the accomplishment of design, development and verification were completed, the laser measurement system came into use in the acrylic workshop of Taixing Donchamp Acrylic Ltd, and the transmittance results of acrylic spherical panels met the requirement of JUNO. The optical design, tooling design, data processing interface and uncertainty analyses of the laser measurement system are discussed in detail, and the measured transmittance results are also introduced in this article.