We introduce a current development in optical design for vehicle forward lighting based on solid-state lighting, in particular, phosphor-converted white LEDs. The vehicles include bicycles, bikes, and automobiles. Although the requirements regulating different vehicles are different, the low beam always requires a high-contrast cutoff line. Three optical design approaches are discussed; these include a projection lens incorporated with a baffle or beam shaper, multisegment reflectors, and complex lenses. A new design approach called light field management technology for the multisegment reflector is introduced. In addition, the possible related manufacturing errors and the robustness of different optical approaches are analyzed. Finally, we introduce three approaches to adaptive forward lighting that provide a driver with brighter and clearer vision without inducing glare to people on the roadway. The application of video projection technology to roadway illumination could be a trend of vehicle forward lighting based on solid-state lighting. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

This paper presents the mid-field model for an ultraviolet C light emitting diode (UVC LED) of wavelength around 275±5 nm by comparison of the 2-dimension (2-D) gray-level image captured from a mono-CMOS sensor and simulated irradiance pattern. Because of UVC light, we propose using a fluorescent film to absorb UVC light and re-emit visible light so that the 2-D image could be captured. The analysis and calibration to obtain accurate gray level of image are performed. Finally, we achieve the mid-field model with high accuracy. Furthermore, this model is also applied for dome lens design and then compares the performance with fabricated samples in measurement to expertise its validity.

Great quantities of silicon wafers have been used in the semiconductor industry, resulting in a shortage of raw materials required for wafer production. Unfortunately, conventional wafer regeneration processes still have some issues of machining properties. In this study a precise abrasive jet machining (AJM) method with a novel composite abrasive is employed to reduce the surface roughness of recycled wafers. Experiments designed using the Taguchi method was conducted for removal of patterns from the wafer surface to explore the impact of different processing parameters on surface quality and to optimize the combination of processing parameters. Experimental results show that the optimal parameters for achieving a smooth surface with minimum subsurface damage are composite abrasive coated SiC mesh of # 3000, impact angle of 30, stand-off distance of 70 mm, jet pressure of 0.4 MPa, and platform revolution of 250 r/min. With these parameters, all surface patterns can be removed completely with machining for 5 min. The electronic data systems (EDS) results prove that no residual elements exist on silicon wafer and surface roughness is reduced to 0.118 μm Ra, which cntributes to surface improvement and shortens the post-processing time required for silicon wafer regeneration.

Phosphor-converted white light emitting diodes (pc-WLEDs) are used worldwide for an extensive amount of applications. The device is a complex combination of various components that introduce various technical issues: materials, electrical, chemical, thermal, and so on. All of these combined to obtain a targeted optical characteristic. While most of the pc-WLEDs are sufficient for basic illumination performance, there are still many issues to improve the pc-WLED performance. In this work, we deal with the incorporation of micron size particles of titanium oxide (TiO2) in silicone encapsulant that contains yttrium aluminum garnet (YAG) phosphor in remote phosphor pc-WLED. Based on the light output and the scattering spatial distribution measurements of the phosphor plates, we have found that several essential performance indices, like the color uniformity, the efficiency, and the amount of phosphor for the pc-WLEDs, can be adjusted by tuning the amount of TiO2 particles and thus be optimized. With a comprehensive model using a Monte-Carlo ray tracing process combined with the Mie scattering theory, two TiO2 loading conditions are revealed. The first one is the sparse condition that the TiO2 particles act as the scattering particles such as to increase the output flux to improve the efficiency of YAG. The second one is the dense condition that the TiO2 particles act more as barrier particles such so to decrease the output flux.

In this study, we proposed and demonstrated a circuit design for solving problems related to blue light leakage (e.g., eye damage) when phosphor-converted white light-emitting diodes (pcW-LEDs) overheat. This circuit only needs a positive thermal coefficient thermistor, resistor, and diodes in series and parallel; thus, it can easily be integrated into components. Simulations and corresponding experimental results show that this method can accurately suppress the overheating component’s injection current and allow for LEDs to work normally after returning to the operating temperature. It thus allows the user's eyes to be actively protected, e.g., to avoid exposure to the bluish light when overheating occurs. In addition, the quenching of luminous flux is a signal to remind the user to replace the LED. The proposed method is low-cost, effective, simple, and useful for increasing the quality of LED lighting and biological safety.