Revealing climatic and groundwater impacts on the spatiotemporal variations in vegetation coverage in marine sedimentary basins of the North China Plain, China.

The North China Plain (NCP) is one of the three great plains in China and also serves as a vital region for grain, cotton, and oil production. Under the influence of regional hydrothermal changes, groundwater overexploitation, and seawater intrusion, the vegetation coverage is undergoing continuous alterations. However, a comprehensive assessment of impacts of precipitation, temperature, and groundwater on vegetation in marine sedimentary regions of the NCP is lacking.

An optimization method coupled the index-overlay method with entropy weighting model to assess seawater intrusion vulnerability.

Seawater intrusion poses a serious threat to coastal areas around the world. The purpose of this study was to develop a comprehensive approach to assess the vulnerability of saltwater intrusion. The powerful decision-making technique GALDIT was firstly selected, and its inherent weights are the origin of the subjective method.

Autofocusing of digital holographic microscopy based on off-axis illuminations.

An auto-focusing method for digital holographic microscopy has been proposed by employing two off-axis illumination beams. When specimens are illuminated by two plane waves in different directions, it is found that the farther the reconstruction plane is from the image plane, the wider the two reconstructed images are separated from each other. Thus, the image plane can be determinated by finding the minimum of the variation between the two reconstructed object waves on both the amplitude and phase distributions.

Autofocusing based on wavelength dependence of diffraction in two-wavelength digital holographic microscopy.

An autofocusing method for two-wavelength digital holographic microscopy (TWDHM) based on the wavelength dependence of the diffraction process is proposed. Red and green lights are employed for the illumination of the TWDHM, and the generated holograms are recorded simultaneously by a color CCD camera. Due to the wavelength dependency of the diffraction process, the farther the reconstruction plane is from the image plane, the larger the difference is between the red and green light distributions.

Dual-wavelength slightly off-axis digital holographic microscopy.

We propose dual-wavelength digital holographic microscopy with a slightly off-axis configuration. The axial measurement range without phase ambiguity is extended to the micrometer range by synthesizing a beat wavelength between the two wavelengths with separation of 157 nm. Real-time measurement of the specimen is made possible by virtue of the high wavelength selectivity of the Bayer mosaic filtered color CCD camera.

Improvement of the performance of the twisted-nematic liquid-crystal display as a phase modulator.

A twisted-nematic liquid-crystal display (TN-LCD) placed between two linear polarizers (P) generally produces coupled intensity and phase modulations. For the purpose of phase-only modulation, quarter-wave plates (QWPs) are often used in front of or behind the LCD. In this paper, we demonstrate theoretically and experimentally the QWPs' effect on the modulation properties of the TN-LCD based on the general Jones matrix descriptions for all the devices, which circumvents the inconvenience of the traditional method on the basis of the TN-LCD's internal parameters.