Effect of scattering noise on the data fidelity of holograms recorded in photorefractive crystals

2001 ◽  
Vol 674 ◽  
Author(s):  
Mingyan Qin ◽  
Shiquan Tao ◽  
Guoqing Liu ◽  
Xiaohong Ding ◽  
Dayong Wang
Keyword(s):  
Lithium Niobate ◽  
Data Storage ◽  
Signal To Noise Ratio ◽  
Low Noise ◽  
Holographic Storage ◽  
Photorefractive Crystals ◽  
High Data ◽  
Iron And Zinc ◽  
Data Fidelity ◽  
Scattering Noise

ABSTRACTIn this paper a method is proposed to investigate how the scattering noise of photorefractive crystals influences the quality of an input data page in holographic storage. By illuminating the crystal under investigation with an intense coherent light beam, and measuring the signal-to-noise ratio (SNR) of an image formed through the crystal before and after the exposure, the loss of SNR provides a good assessment for the suitability of the crystal for data storage. A variety of doped lithium niobate crystals were investigated. The results show that the intensity of fanning light increases with increase of the doping concentration, but there is no strict correlation between the fanning strength and the fidelity degradation. Owing to the low noise and high data fidelity, iron-and- zinc co-doped lithium niobate crystal is a potential material for high-density holographic data storage.

scholarly journals Automatic Detection Technology of Sonar Image Target Based on the Three-Dimensional Imaging

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Wanzeng Kong ◽  
Jinshuai Yu ◽  
Ying Cheng ◽  
Weihua Cong ◽  
Huanhuan Xue
Keyword(s):  
Data Storage ◽  
3D Imaging ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Automatic Detection ◽  
Classification Model ◽  
Image Detection ◽  
Practical Applications ◽  
Sonar Image ◽  
Detection Technology

With 3D imaging of the multisonar beam and serious interference of image noise, detecting objects based only on manual operation is inefficient and also not conducive to data storage and maintenance. In this paper, a set of sonar image automatic detection technologies based on 3D imaging is developed to satisfy the actual requirements in sonar image detection. Firstly, preprocessing was conducted to alleviate the noise and then the approximate position of object was obtained by calculating the signal-to-noise ratio of each target. Secondly, the separation of water bodies and strata is realized by maximum variance between clusters (OTSU) since there exist obvious differences between these two areas. Thus image segmentation can be easily implemented on both. Finally, the feature extraction is carried out, and the multidimensional Bayesian classification model is established to do classification. Experimental results show that the sonar-image-detection technology can effectively detect the target and meet the requirements of practical applications.

Some features of data storage in and retrieval from lithium niobate

1980 ◽  
Vol 10 (2) ◽  
pp. 247-248
Author(s):  
É S Vartanyan ◽  
É Kh Gulanyan ◽  
R K Ovsepyan
Keyword(s):  
Lithium Niobate ◽  
Data Storage

Miniature Two-Axis Actuator for High-Data-Transfer-Rate Optical Data Storage System

2002 ◽  
Vol 41 (Part 1, No. 3B) ◽  
pp. 1804-1807 ◽  
Author(s):  
Gakuji Hashimoto ◽  
Hiroki Shima ◽  
Kenji Yamamoto ◽  
Tsutomu Maruyama ◽  
Takashi Nakao ◽  
...  
Keyword(s):  
Data Storage ◽  
Transfer Rate ◽  
Data Transfer ◽  
Storage System ◽  
Optical Data Storage ◽  
Optical Data ◽  
Data Transfer Rate ◽  
High Data ◽  
Data Storage System

High-density large-capacity nonvolatile holographic storage in photorefractive crystals

2005 ◽  
Author(s):  
Shiquan Tao ◽  
Zhuqing Jiang ◽  
Wei Yuan ◽  
Yuhong Wan ◽  
Ye Wang ◽  
...  
Keyword(s):  
High Density ◽  
Holographic Storage ◽  
Photorefractive Crystals ◽  
Large Capacity

MIMO Detectors: A Comprehensive Performance Analysis

2021 ◽  
Vol 16 (3) ◽  
pp. 24-27
Author(s):  
E. Obi ◽  
B.O. Sadiq ◽  
O.S . Zakariyya ◽  
A. Theresa
Keyword(s):  
Error Rate ◽  
Mimo Systems ◽  
Signal To Noise Ratio ◽  
Minimum Mean Square Error ◽  
Multiple Input Multiple Output ◽  
Symbol Error Rate ◽  
Signal To Noise ◽  
High Data ◽  
Noise Ratio ◽  
Better Than

Multiple-input multiple-output (MIMO) systems are increasingly becoming popular due to their ability to multiply data rates without any expansion in the bandwidth. This is critical in this era of high-data rate applications but limited bandwidth. MIMO detectors play an important role in ensuring effective communication in such systems and as such the performance of the following are compared in this paper with respect to symbol error rate (SER) versus signal-to-noise ratio (SNR): maximum likelihood (ML), zero forcing (ZF), minimum mean square error (MMSE) and vertical Bell laboratories layered space time (VBLAST). Results showed that the ML has the best performance as it has the least Symbol Error Rate (SER) for all values of Signal to Noise Ratio (SNR) as it was 91.9% better than MMSE, 99.6% better than VBLAST and 99.8% better than ZF at 20db for a 2x2 antenna configuration., it can also be deduced that the performance increased with increase in number of antenna for all detectors except the V-BLAST detector.

scholarly journals Theoretical Study of a Surface Collinear Holographic Memory

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 70
Author(s):  
Hirayama ◽  
Fujimura ◽  
Umegaki ◽  
Tanaka ◽  
Shimura
Keyword(s):  
Data Storage ◽  
Transfer Rate ◽  
Data Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Storage System ◽  
Reconstructed Image ◽  
Data Transfer Rate ◽  
Holographic Memory ◽  
High Data ◽  
Volume Holograms

Holographic memory is currently attracting attention as a data storage system capable of achieving a data transfer rate of about 105~106105~106 times that of an optical disc such as Blu-ray disc. In conventional holographic memory, data is generally recorded by optical writing using volume holograms. However, a volume hologram has the problem not only that it is required to have high mechanical accuracy of a system and low coefficient of thermal expansion of a recording medium, because reconstruction tolerance is extremely low, but also that duplicating time efficiency is poor because whole data cannot be recorded at once. In this paper we proposed surface holographic memory that achieved a high data transfer rate, stable readout performance, and collective duplication by expressing holograms with fine surface asperity. Furthermore, the theoretical formulas of recording and reconstruction processes in the proposed system were derived and the reconstruction characteristics of the hologram were evaluated by numerical simulation. As a result, the proposed method generated reconstructed image readout with sufficient signal for a single page recording. However, the reconstructed image had noise, which was particular to a surface holographic memory.

Methods for the robust computation of the long-period seismic spectrum of broad-band arrays

2020 ◽  
Vol 222 (3) ◽  
pp. 1480-1501
Author(s):  
Ross C Caton ◽  
Gary L Pavlis ◽  
David J Thomson ◽  
Frank L Vernon
Keyword(s):  
Signal To Noise Ratio ◽  
Spectral Band ◽  
Broad Band ◽  
Low Noise ◽  
Small Aperture ◽  
Transient Signals ◽  
Seismic Arrays ◽  
Low Snr ◽  
Long Period ◽  
Student’S T

SUMMARY We describe array methods to search for low signal-to-noise ratio (SNR) signals in long-period seismic data using Fourier analysis. This is motivated by published results that find evidence of solar free oscillations in the Earth's seismic hum. Previous work used data from only one station. In this paper, we describe methods for computing spectra from array data. Arrays reduce noise level through averaging and provide redundancy that we use to distinguish coherent signal from a random background. We describe two algorithms for calculating a robust spectrum from seismic arrays, an algorithm that automatically removes impulsive transient signals from data, a jackknife method for estimating the variance of the spectrum, and a method for assessing the significance of an entire spectral band. We show examples of their application to data recorded by the Homestake Mine 3-D array in Lead, SD and the Piñon Flats PY array. These are two of the quietest small aperture arrays ever deployed in North America. The underground Homestake data has exceptionally low noise, and the borehole sensors of the PY array also have very low noise, making these arrays well suited to finding very weak signals. We find that our methods remove transient signals effectively from the data so that even low-SNR signals in the seismic background can be found and tested. Additionally, we find that the jackknife variance estimate is comparable to the noise floor, and we present initial evidence for solar g-modes in our data through the T2 test, a multivariate generalization of Student's t-test.

Optimum conditions for high-fidelity holographic storage in photorefractive crystals

1995 ◽  
Author(s):  
Shiuan-Huei Lin ◽  
Pochi Yeh ◽  
Mei-Li Hsieh ◽  
Ken Y. Hsu ◽  
Tai Chiung Hsieh
Keyword(s):  
High Fidelity ◽  
Optimum Conditions ◽  
Holographic Storage ◽  
Photorefractive Crystals
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