Mie scattering theory was shown in this paper to be suitable for analyzing the forward scattered light intensity distribution of micro-sized air bubble defects in glass, shining by a monochrome laser with a wavelength of 532um. The scattered light was measured by a high definition CCD camera. The scattering process can be classified as uncorrelated single scattering according to the properties of optical media. After calculating and smoothing the gray value of split rings of picture, Chahine algorithm was applied to reverse the size of defects. This technique was accurate to within 5% for defects with radii of <50um.
Two liquid level sensors based on different long-period fiber gratings are proposed and compared. The long-period
gratings have the same characteristics (length, grating period) but are fabricated in different optical fibers (photosensitive
B-Ge codoped optical fibers with different dopants concentrations). The principle of this type of sensor is based on the
refractive index sensitivity of long-period fiber gratings. By monitoring the resonant wavelength shifts of a given
attenuation band, one can measure the immersed lengths of long-period fiber gratings and then the liquid level. The
levels of two different solutions are measured. The maximum shift (7.69 nm) of the investigated resonance wavelength
was observed in LPG1 (fabricated in Fibercore PS1250/1500). By controlling the fiber dopants concentrations one can
improve the readouts of a fiber-optic liquid level sensor based on long-period fiber gratings.
Water optical properties are important factors that affect phytoplankton biomass, carbon formation and carbon output of
the upper body. Water spectral absorption properties are among the most important inherent optical properties. This
paper was a preliminary analysis on spectral absorption properties of water suspended particle, de-pigmented particle,
pigment particle and chromophoric dissolved organic matter (CDOM) in main channel of Hangzhou Xixi Wetland
National Park phase I. The results indicate that the absorption spectrum of suspended particle is similar to the
de-pigmented particle, while the absorption spectrum of pigment particle is almost submerged in the de-pigmented
particle; The absorption spectrum of de-pigmented particle and CDOM follows the exponential decay law, the former
slope S<sub>d</sub> average value of the exponential function in the range of 400-700nm is 9.56±0.86μm<sup>-1</sup>, the latter slope S<sub>g</sub>average value of the exponential function in the range of 400-500nm is 14.28±1.23μm<sup>-1</sup>. The absorption peak of
chlorophyll a of pigment particle near 440nm is virtually not existent and also very weak at 675nm. According to the
absorption contribution rate of each component to the total absorption, de-pigmented particle is the greater contributor
than pigment particle and CDOM in this field campaign. In addition, according to water mass classification based on the
contribution rate of absorption coefficient at 440nm, vast majority of the water body in study area could be classified
into the most optical complex water mass type.