Bullet-shaped LEDs are commonly used in self-luminous traffic signs as LED-dotted matrices due to their low cost, simplicity, robustness, and ease of installation. We proposed a simple low-cost method that creates a model suitable for the high manufacturing tolerance found in bullet-shaped LEDs. The method starts from measuring multiple one-dimensional angular intensity patterns at interested distances from multiple LEDs to form a database, including distances at 10, 15, 20, 25, 35, 50, and 100 mm. Their normalized cross-correlations are then calculated to find the batch that has the most similarity and base our model off that batch. Finally, we validate the model via Monte Carlo simulations in comparison to the original one-dimensional angular intensity patterns in the database. The platform demonstrated to obtain an average of 99% in normalized cross correlation between different batches of the same model LED, and a model of that LED is currently under development.
In this study, a low glare and high-efficient tunnel lighting design which consists of a cluster light-emitting diode and a
free-form lens is presented. Most of the energy emitted from the proposed luminaire is transmitted onto the surface of
the road in front of drivers, and the probability that the energy is emitted directly into drivers’ eyes is low. Compared
with traditional fluorescent lamps, the proposed luminaire, of which the optical utilization factor, optical efficiency, and
uniformity are, respectively, 44%, 92.5%, and 0.72, performs favorably in traffic safety, energy saving, and glare