Generally, nano-scale patterned sapphire substrate (NPSS) has better performance than micro-scale patterned sapphire substrate (MPSS) in improving the light extraction efficiency of LEDs. Laser interference lithography (LIL) is one of the powerful fabrication methods for periodic nanostructures without photo-masks for different designs. However, Lloyd’s mirror LIL system has the disadvantage that fabricated patterns are inevitably distorted, especially for large-area twodimensional (2D) periodic nanostructures. Herein, we introduce two-beam LIL system to fabricate consistent large-area NPSS. Quantitative analysis and characterization indicate that the high uniformity of the photoresist arrays is achieved. Through the combination of dry etching and wet etching techniques, the well-defined NPSS with period of 460 nm were prepared on the whole sapphire substrate. The deviation is 4.34% for the bottom width of the triangle truncated pyramid arrays on the whole 2-inch sapphire substrate, which is suitable for the application in industrial production of NPSS.
According to the technical features and requirements of the television imaging system for tracking and measuring, we
designed a TV system with focal length of 2800mm, F/11.7 and 2ω(FOV) of 14.2′. The system is compact and easy to
fabricate and align, with good image quality. Meanwhile, we performed stray light analysis with ASAP optical software,
described stray light suppression techniques used in the TV for tracking and measuring, proposed a method to determine
optical properties of the system components and parameters of the scattering model reasonably. We calculated the PST
curve of the system for incident angle from -45° to 45°. The results show that when the off-axis angle is larger than the
critical incident angle of the sun, PST value is less than 10<sup>-8</sup>.