# Enhancement of ECE SuperPin Curved Reflex Reflector by the Use of Double Pins with Corner Cubes
## 4 Optics Design and Verification
Based on the lengthwise extent and bend of the curved surface, dual pins had 15 groups that comprised 15 variables of _di_ (from _d1_ to _d15_). This is illustrated in Figure 13. The constraints of each variable of _di_ are determined by the curvature of the contact surface. Each variable has a non-identical limitation of height values and is contingent on the situation of the surface that merit should fluctuate from 0.01-0.81 mm. The territory of a CCCR which has extreme curvature will have the highest altitude value. Our optimal goal should focus on the posterior area, where the lowest reflectivity is achieved, and improve the reflectivity of light. As shown in Figure 8, the restriction was determined by the location of each region. In order to set the target value of the optimization, the simulation experiment with a flat regulated CCR was exercised to find the reflected light power as the reference by a 1000 lumen incident beam. The resulting power was 850 lm and was used as the target for the subsequent searching of the optimized CCCR. By running the scheme in optimization steps, manually limited to 500 searching steps to quickly find a better solution, the best results were determined in step 139, as shown in Figure 14. The final intensity sensor value was shown to be 810.27 lm, which was also the output power reflected by the optimized CCCR. Figure 14: The recorded value for the intensity sensor versus running cycles. In the initial optimization process, the mathematical equation for the intensity distribution of reflected light entered into the program is expressed in the measurement value of the intensity sensor. The luminous intensity \(\mathbf{R_{I}}\) is defined by I(\(\phi\), a, b, c) at the polar angle of \(\phi\), shown in Equation (8). The target of the optimization process was defined as a value corresponding to the retroreflective light intensity on the retro-reflector plane. During the optimization, to have the CCCR meet the requirement of the ECE standard at 0.33\({}^{\circ}\) and maximum reflection efficiency, the values of \(\delta\) and \(\mathrm{d_{i}}\) were found through the workflows shown in Figures 15 and 16, respectively. As the optimization is terminated by the program, the optimized CCCR with the same curve as the commercial one was obtained. After the optimization process, the optimized CCCR was analyzed for comparison with the commercial reflector by simulations. The distance from the light source to the CCCR is set as 30.5 meters and the diameter of laser beam is 25 mm. The CCCR is kept with its car driving direction at 0\({}^{\circ}\), 10\({}^{\circ}\) (up, down) vertically, and 20\({}^{\circ}\) (left, right) horizontally with the incident light, respectively, to perform the optical tests of ECE regulations. The resulting intensity distributions by 0\({}^{\circ}\) incident light to the anterior, central and posterior regions sequentially are shown in Figure 17. The results showed that the optimized CCCR can contribute much greater effective light intensity than that of the commercial design (no effective retro-reflection at 0.33\({}^{\circ}\) up), as shown in Figure 17c,f. The candela values shown in Figure 17 showed that the light reflection intensity of the optimal design is 4.36% (anterior area) and 16.7% (central area) higher than the commercial design at 0\({}^{\circ}\) light incidence. In addition, it was demonstrated that \(\mathbf{R_{I}}\) and \(\mathbf{R_{A}}\) are also increased significantly in all regions, and a larger retro-reflection working area is accomplished through the optimal design. With 0\({}^{\circ}\), 10\({}^{\circ}\) (up, down) vertical, and 20\({}^{\circ}\) (left, right) horizontal incident light, the retroflection results data \(\mathbf{R_{I}}\) and \(\mathbf{R_{A}}\) achieved by the optimized CCCR, the primary CCCR, and the commercial CCCR are calculated and shown in Figures 18 and 19 individually for comparison. Figure 16: Flow chart of optimization process.