scholarly journals Resolving the Alignment Problem in Visual Cryptography

2018 ◽  
pp. 321-351
Author(s):  
Feng Liu
Keyword(s):  
Visual Cryptography ◽  
Alignment Problem

The alignment problem of visual cryptography schemes

2008 ◽  
Vol 50 (2) ◽  
pp. 215-227 ◽  
Author(s):  
Feng Liu ◽  
Chuan Kun Wu ◽  
Xi Jun Lin
Keyword(s):  
Visual Cryptography ◽  
Alignment Problem

Security Concern and Countermeasures for Cheating in Visual Cryptography

2018 ◽  
Vol 6 (8) ◽  
pp. 277
Author(s):  
Ekta Y
Keyword(s):  
Communication System ◽  
Visual Cryptography ◽  
Detection Methods ◽  
Information Communication ◽  
New Approach ◽  
The World ◽  
Visual Cryptography Scheme ◽  
Prevention Methods ◽  
Security Concern

As IT sector is ruling the world now,confidentiality and security of information has become the most important inseparable aspect in information communication system. Keeping in view the same, a new approach called Visual Cryptography (VC) has been suggested by many researchers but there are some limitations with this scheme and cheating is one of the main problem among them. This paper intends to show the basis of cheating in VC in terms of cheating process, its detection methods and its prevention methods suggested by various researchers along with their merits and demerits. Finally, a good Cheating Immune Visual Cryptography Scheme (CIVCS) has been discussed which states the properties to be adopted by every Visual Cryptography scheme to make it immune to cheating attacks.

scholarly journals Integrated Double-Sided Random Microlens Array Used for Laser Beam Homogenization

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 673
Author(s):  
Wei Yuan ◽  
Cheng Xu ◽  
Li Xue ◽  
Hui Pang ◽  
Axiu Cao ◽  
...  
Keyword(s):  
Laser Beam ◽  
Microlens Array ◽  
Energy Utilization ◽  
Utilization Rate ◽  
Periodic Lattice ◽  
Lattice Distribution ◽  
Speckle Field ◽  
High Laser ◽  
Alignment Problem ◽  
In Series

Double microlens arrays (MLAs) in series can be used to divide and superpose laser beam so as to achieve a homogenized spot. However, for laser beam homogenization with high coherence, the periodic lattice distribution in the homogenized spot will be generated due to the periodicity of the traditional MLA, which greatly reduces the uniformity of the homogenized spot. To solve this problem, a monolithic and highly integrated double-sided random microlens array (D-rMLA) is proposed for the purpose of achieving laser beam homogenization. The periodicity of the MLA is disturbed by the closely arranged microlens structures with random apertures. And the random speckle field is achieved to improve the uniformity of the homogenized spot by the superposition of the divided sub-beams. In addition, the double-sided exposure technique is proposed to prepare the rMLA on both sides of the same substrate with high precision alignment to form an integrated D-rMLA structure, which avoids the strict alignment problem in the installation process of traditional discrete MLAs. Then the laser beam homogenization experiments have been carried out by using the prepared D-rMLA structure. The laser beam homogenized spots of different wavelengths have been tested, including the wavelengths of 650 nm (R), 532 nm (G), and 405 nm (B). The experimental results show that the uniformity of the RGB homogenized spots is about 91%, 89%, and 90%. And the energy utilization rate is about 89%, 87%, 86%, respectively. Hence, the prepared structure has high laser beam homogenization ability and energy utilization rate, which is suitable for wide wavelength regime.

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