With the recent increase in leisure time and wellbeing trends, the number of individuals who enjoy nighttime leisure activities has rapidly increased. Thus, the demand for luminous night safety clothing ensuring safety and that is also fashionable is increasing. Although higher visibility is important, studies on the influence of the backside elements of optical fiber materials on light emission are limited. The main components of the plastic optical fiber assembly in this study are the plastic optical fiber and backside elements, consisting of retroreflective material, and the backside sheet. The effects of the four types of retroreflective material, which are low, medium, high, and ultra-high luminance types, and the color of the backside sheet, white or black, on the luminance of the plastic optical fiber assembly are evaluated in bright, dusky, and dark environments. The results are analyzed using the statistical analysis software, SPSS 20.0. In the dusky environment, the plastic optical fiber assembly with prism material (80.78 ± 2.17) exhibits the highest luminance. However, there was no difference between the plastic optical fiber assembly with high- (38.52 ± 1.27) and medium-retroreflective material (36.76 ± 0.68). In the dark environment, the plastic optical fiber assembly with the prism material shows the highest luminance (66.83 ± 0.24), and there is no difference between the plastic optical fiber assembly with the low- (24.43 ± 0.42), medium- (24.63 ± 0.36), and high-retroreflective material (25.12 ± 0.42). Also, the luminance of the plastic optical fiber assembly with the white backside sheet is higher than that with the black backside sheet for all retroreflective material in dusky and dark environments. In summary, the optimal constitution of a plastic optical fiber assembly’s backside element is the retroreflective material of a prism type with the white backside color.
