Vehicles have evolved into synthetic engineering systems owing to the developments in mechanical, electronic, and information technologies. Recently, driving assistance systems have gained considerable attention and are installed in vehicles under development by manufacturers. An important technology for the driving assistance systems is intervehicle distance measurement, for which several technologies have been proposed through hardware and software developments. The intervehicle distance measurement generally requires auxiliary sensor systems, complex algorithms, and high costs. An intervehicle distance estimation method is proposed, which calculates the distance using images obtained through a camera installed in the vehicle. For calculating the distance, the proposed method does not need any other physical sensors or information about the roads on which the vehicle moves. For estimating the intervehicle distance, the proposed method takes advantage of the fact that the width between two adjacent lanes on the road is constant. The difference in the distance calculated using the proposed method and the actual distance is <7 % .
We proposed a new structure for fiber lens to extend the working distance by applying polymer layer to the fiber lens.
The simulation result shows that the working distance can be extended to larger than 10 times than a fiber lens without a
coated layer. In simulation, the proposed structure extended the working distance to about 2,110 μm by using polymer
layer with a refractive index of 1.3.
For optical clock recovery of nonreturn-to-zero (NRZ) signals more than 40 Gb/s, we propose and experimentally demonstrate a simple clock recovery scheme using beat processing. Through the proposed scheme, we square the adjustment range of the variable optical attenuator (VOA) and achieved an enhanced clock-to-noise ratio (CNR) of more than 15 dB in the experiment, compared to a system without the proposed scheme.
Laser energy distributions of 20 μm and 40 μm glass microspheres were calculated with different laser wavelengths. Most simulation results show similar energy distributions in which laser energies are focused at the backside of the microsphere. Using time-resolved optical shadow images and Schlieren images, initial breakdown location and shockwave propagation from the breakdown were investigated for 20 μm glass microsphere which was ablated by Nd:YAG laser with a wavelength of 1.064 μm. Time-resolved imaging showed the location of the initial breakdown and the shockwave motion over its first 300 μm of expansion. Measured shockwave velocities were in the range of 1-10 km/s and showed a linear dependence on laser fluence within 30 ns.
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