A new wake bubble processing method based on standard images is developed. The distribution, size, population, movement of bubbles in ship wakes are most important characteristic influencing the sonic, optical, conductive and other signatures of ship wakes as information sources for detecting and tracing moving target in sea. The intuitive and effective method to get the parameters of wake bubbles is optical imaging. Standard bubble images can be one of the means of evaluating the performance of imaging processing method. The standard sequence bubble images are generated which the size, velocity, position of bubbles and the width of laser sheet are known and can be changed. The effectiveness and accuracy of the wake bubble image processing method can be evaluated by standard images.
The performance of mitigated site coated with antireflective (AR) coating is investigated, and its
discrepancy is also investigated by comparing the bare site with substrate from surface morphology and
profile, transmittance and laser induced damage threshold (LIDT). The results indicated that more SiO2 sol
will be deposited in the crater of mitigated site during the dipping process, while the coated site does not
seriously influence the performance of the entire sample. The LIDT results indicate that both the coated
substrate and mitigated site are lower than that of un-coated substrate and mitigated site.
Keywords: fused silica; mitigated site; coating; sol-gel.
A three-dimensional model of the field in the vicinity of a spherical inclusion in fused silica illuminated by a laser beam is established based on Mie scattering theory, and intensity distributions of the scattered field modulated by the inclusion are studied. The effects of refractive index and the radius of inclusion on light intensity enhancement factor (LIEF) and the position of the maximum intensity are analyzed. The results show that modulation effect of inclusion can be considered ineffective when inclusion radius is below 40 nm. When the radius is above 40 nm, inclusions (voids, Al, Fe, ZrO2) act as positive or negative lenses for the incident laser. Maximum light intensity is two orders of magnitude larger than the incident wave intensity in some parts distance away from inclusion. For a non-dissipative inclusion, maximum LIEF increases with the increasing difference between refractive index of inclusion and fused silicon. With the increasing of refractive index, the point of the maximum intensity moves from the backward to the forward of the inclusion. For a dissipative inclusion, with the increasing of the imaginary part of the refractive index, real part of the refractive index has less effect on LIEF. LIEF increases with increasing radius, and the points of maximum intensity move from the forward to the backward of the inclusion.