# Enhancement of ECE SuperPin Curved Reflex Reflector by the Use of Double Pins with Corner Cubes
## 5 Conclusions and Discussions  
A new optimal CCCR design which improves the performance and working area of the previous commercial one is proposed. We have demonstrated that the parameter of height difference between pin groups in a CCCR unit has an impact on the reflected light performance. In experiments, the curved retroreflector with a 120 \(\times\) 28 mm reflecting area was built by 15 arrays of double-pin groups, and each pin cross-section size is 5.56 mm. It is demonstrated that a SuperPin CCCR can retro-reflect one incident beam as six beams, as shown in Figure 5c. If a CCCR has a curved region, the height between each group of pins due to surface curvature would affect optical characteristics, leading to lower reflection efficiency and even failing to pass ECE regulations. By using double-pin groups to build the primary SuperPin CCCR, reflection efficiency can be improved. Through using OptisWork software to find out the optimized SuperPin CCCR, \(\mathbf{R_{I}}\) can be increased further, but by sacrificing reflection efficiency \(\mathbf{R_{A}}\), as shown in Figures 18 and 19. Using an efficient working area ratio, reflection efficiency \(\mathbf{R_{A}}\) and coefficient of luminous intensity \(\mathbf{R_{I}}\) as the evaluation indices of CCCR to compare a commercial SuperPin CCCR with the proposed new design, it can be inferred that the optimized SuperPin CCCR redistributes the reflected light beam energy of the primary SuperPin CCCR, which shares more energy into the 0.33\({}^{\circ}\) up-reflected beam by taking energy from the other five reflected beams. After computer simulations and optical experiments, it is demonstrated that the proposed SuperPin CCCR is not only above the ECE standard but also has a 33% larger working area and much better reflection efficiency than the commercial one, whose posterior region is not effective at all, as shown in Figures 18 and 19. Based on the data in Figure 22, it can be computed that the ratio of averaged \(\mathbf{R_{I}}\) of the optimized SuperPin CCCR to that of the commercial CCCR is (14929/8930, 0\({}^{\circ}\)), (12689/5983, 10\({}^{\circ}\)U), (10450/4822, 10\({}^{\circ}\)D), (9704/5715, 20\({}^{\circ}\)L) and (10152/5894, 20\({}^{\circ}\)D), which means 40.1% (0\({}^{\circ}\)), 52.85% (10\({}^{\circ}\)U), 53.05% (10\({}^{\circ}\)D), 41.1% (20\({}^{\circ}\)L), and 42% (20\({}^{\circ}\)R) higher retro-reflection efficiency can be accomplished by the proposed SuperPin CCCR. One of the most important advantages of this research outcome is that the new design of the SuperPin CCCR can enhance transportation safety. On the other hand, to produce our proposed design  
Figure 22: Comparison of the coefficient of luminous intensity \(\mathbf{R_{I}}\) between the commercial sample and the optimized prototyped sample (region by region). with the highest accuracy and optimal efficiency, it is essential to have an advanced CNC (computer numerical control). Consequently, the commercial price of this design will be slightly higher than previous ones. In conclusion, we proposed a curved reflex reflector with a new cube-corner structure. By using genetic algorithms for optimization, the angles and the positions of the pins considered as building elements of corner-cube reflectors can enhance the performance of a curved reflex reflector. Compared with conventional retro-reflectors, it is found that a 46% higher retro-reflection efficiency and 33% larger working area can be accomplished with our optimized design. The yield rate of the mold production of the optimized design is less than the commercialized design because, through the pin composition method, the precision of the pin height control is even more necessary. In order to overcome the technical problems, we are conducting a study into molding by ultra-high precision casting. The authors of the present work made equal contributions to all of its parts. This research received no external funding.