Experimental study on polarization holographic storage in genetic mutant BR-D96N film

Recording with both parallel and orthogonal linearly polarized lights, polarization holographic storage in genetic mutant BR-D96N film is reported with both transmission type geometry and reflection type geometry. Polarization properties of diffraction light and scattering light are discussed for two different cases, parallel polarization recording and orthogonal polarization recording. It shows that, compared with recording with parallel polarization lights, orthogonal polarization holography can separate the diffraction light from the scattering noise, therefore improving the signal-to-noise ratio. It also shows that, compared with reconstruction with reference light, reconstruction with phase conjugated wave of the reference light can improve the signal-to-noise ratio of the reconstructed diffraction image, and also the wave-front aberration of the object light introduced by irregular phase object in the optical pass-way can also be corrected effectively, which ensures that the reconstructed diffraction image has a better fidelity. The preliminary angle-multiplexed volume holographic storage multiplexed by transmission type geometry and reflection type geometry is demonstrated in the BR-D96N film. Experiment shows that there is no cross-talk between the two pages of images except for some scattering noises.

Anisotropy analyses of population distribution patterns

Direction-dependence,or anisotropy,of spatial distribution patterns of vegetation is rarely explored due to neglect of this ecological phenomenon and the paucity of methods dealing with this issue.This paper proposes a new approach to anisotropy analysis of spatial distribution patterns of plant populations on the basis of the data resam-pling technique(DRT)combined with Ripley’s L index.Using the ArcView Geographic Information System(GIS)platform,a case study was carried out by selecting the popula-tion of Pinus massoniana from a needle-and broad-leaved mixed forest community in the Heishiding Nature Reserve,Guangdong Province.Results showed that the spatial pattern of the P.massoniana population was typically anisotropic with different patterns in different directions.The DRT was found to be an effective approach to the anisotropy analysis of spatial patterns of plant populations.By employing resam-pling sub-datasets from the original dataset in different direc-tions,we could overcome the difficulty in the direct use of current non-angular methods of pattern analysis.