A method for the fabrication of highly ordered superhydrophobic dual micro- and nanostructures on silicon by direct laser interference lithography (LIL) is presented. The method offers its innovation that the superhydrophobic dual micro- and nanostructures can be fabricated directly by controlling the process of four-beam laser interference and the use of hydrofluoric acid (HF) to wipe off the silica generated during the process. Different laser fluences, exposure durations, and cleanout times have been investigated to obtain the optimum value of the contact angle (CA). The superhydrophobic surface with the CA of 153.2 deg was achieved after exposure of 60 s and immersion in HF with a concentration of 5% for 3 min. Compared with other approaches, it is a facile and efficient method with its significant feature for the macroscale fabrication of highly ordered superhydrophobic dual micro- and nanostructures on silicon.
On-axis tracking technology is an ideal tracking mode with high tracking precisions. The author constructed an on-axis tracking system through assuming the target maneuvers with equal acceleration model, filtering and predicting the position and velocity with Kalman fiter. The analysis results show that the constructed on-axis system not only improves tracking precision dramatically, but also decreases the noise simultaneously.