[Study of Spectral Property and Measurement of Linear Variable Filters].

Linear variable filters (LVF) are widely used in a variety of small rapid spectrometric detecting devices. In the present paper, the splitting property of LVF was studied, and the spectral-property expression in Gaussian form was given, and the relationship between indexes of expression and LVF center transmission, width of spectrum, and linear dispersion was specified. Measurement based on monochromator for imaging spectrometers calibration was introduced, the sensitivity for detection system was discussed, and the tolerance was analyzed. It was shown that the slit displacement of monochromator relative to the optical axle and the slope of LVF affect the detecting accuracy most, and the tolerance can be reduced by adjustment of optical path and structure to reach requirement. System was built and the detection for spectral property of sample LVF was made. The result of data processing indicates that MSE for center transmission detection was lower than 0.05%, and the accuracy of this method was proved. Reference-parameters of relevant system designing and calibrating based on the LVF can be provided by this method.

[Manufacture tolerance analysis of solid Mach-Zehnder interferometer in large aperture static imaging spectrometer (LASIS)].

The principle and instrumental structure of large aperture static imaging spectrometer (LASIS) were briefly described in the present paper, the principle of the Mach-Zehnder imaging spectrometer was introduced, and the Mach-Zehnder interferometers' working way in the imaging spectrometer was illustrated. The structure of solid Mach-Zehnder interferometer was analyzed, and discussion was made based on the requirements of field of view (FOV) in image space and single sided interferogram with a small portion around zero path difference (ZPD). The additional optical path difference (OPD) created by manufacturing and matching tolerance of two asymmetrical pentagonal prisms will lead to the displacement of shearing and OPD nonlinearity. It was showed that the additional OPD from non-common optical path structure of solid Mach-Zehnder spectrometer implies more requirements on the manufacture of this element, compared with Sagnac interferometer, for the matching tolerance of two asymmetrical pentagonal prisms to br lower than 0.02 mm. The recovery spectrum error caused by the OPD nonlinearity is lower than 0.2% and can be ignored.

[A wide-field push-broom hyperspectral imager based on curved prism].

A wide-field pushbroom hyperspectral imager covering short-wavelength infrared range is presented, which can be carried by space borne or airborne platform for remote sensing, acquiring hyperspectral data cube, and analyzing substance compositions and physicochemical properties. Curved prism which simultaneously possesses the functions of dispersion and imaging is used as the prismatic element, and the combination with Offner relay configuration substantially simplifies the design of spectrometer. Compared to conventional dispersive spectral imagers, this design is compact, light-weighted, and small-sized, and can efficiently correct unavoidable spectral line curve (smile) and spectral band (keystone or frown) by prismatic dispersion Compared to grating spectral imagers of the same configuration, the energy utilization efficiency of this design is much higher. The paraxial aberration theory and imaging characteristics of Offner relay configuration is briefly described. The optical layout and image evaluations, including spatial and spectral dimensions, are illustrated respectively, according to Monte Carlo ray-tracing results of seven principal wavelengths.

Occurrence and phase distribution of polycyclic aromatic hydrocarbons in riverine runoff of the Pearl River Delta, China.

The occurrence and phase distribution of polycyclic aromatic hydrocarbons (PAHs) in waters at the eight riverine outlets of the Pearl River Delta (China) were examined based on a monthly sampling program from March 2005 to February 2006. The total concentrations of PAHs in the aqueous phase and suspended particulate matter (SPM) combined ranged from 55.5 to 522 ng/L, at the mid level of the global values in rivers and estuaries. No clear temporal and spatial trends of PAH concentrations were found. However, the concentrations of PAHs associated with SPM coincided with the monthly precipitation of Guangzhou, indicating the importance of atmospheric deposition. The PAHs found in the region were likely derived from a combined pyrolytic and petrogenic origin, as suggested by the molecular indices of PAHs. Normalized partition coefficient (K(oc)) between water and SPM was correlated with octanol-water partition coefficient (K(ow)) to understand the environmental behavior of PAHs.