Reprogrammable meta-hologram for optical encryption

Abstract Meta-holographic encryption is a potentially important technique for information security. Despite rapid progresses in multi-tasked meta-holograms, the number of information channels available in metasurfaces is limited, making meta-holographic encryption vulnerable to some attacking algorithms. Herein, we demonstrate a re-programmable metasurface that can produce arbitrary holographic images for optical encryption. The encrypted information is divided into two matrices. These two matrices are imposed to the incident light and the metasurface, respectively. While the all-dielectric metasurface is static, the phase matrix of incident light provides additional degrees of freedom to precisely control the eventual functions at will. With a single Si metasurface, arbitrary holographic images and videos have been transported and decrypted. We hope that this work paves a more promising way to optical information encryption and authentication.

Download Full-text

Encrypted Fourier holographic data storage with variable data reference wave for optical information security

10.1117/12.758340 ◽

2007 ◽

Cited By ~ 1

Author(s):

M. K. Sheeja ◽

P. T. Ajith Kumar ◽

Achuthsankar S. Nair

Keyword(s):

Information Security ◽

Data Storage ◽

Reference Wave ◽

Holographic Data Storage ◽

Optical Information ◽

Variable Data

Download Full-text

Coordinating movement at two joints: a principle of linear covariance

Journal of Neurophysiology ◽

10.1152/jn.1996.75.4.1760 ◽

1996 ◽

Vol 75 (4) ◽

pp. 1760-1764 ◽

Cited By ~ 65

Author(s):

G. L. Gottlieb ◽

Q. Song ◽

D. A. Hong ◽

G. L. Almeida ◽

D. Corcos

Keyword(s):

Degrees Of Freedom ◽

Sagittal Plane ◽

Linear Scaling ◽

Joint Movement ◽

Zero Crossings ◽

Linear Dynamic ◽

Important Principle ◽

Linear Covariance ◽

At Will ◽

Scaling Rule

1. Six subjects performed fast, "single-joint" flexions at either the elbow or shoulder over three angular distances in a sagittal plane. Movement endpoints were located to require flexion of only a single, "focal" joint, without any external, mechanical constraint on the other, "nonfocal" joint. Three subjects performed another series of movements between two targets while moving along different paths and in which both joints were flexed. 2. We compared the torque patterns that were produced at the two joints. For single-joint movements, they were both biphasic pulses that accelerated and then decelerated the limb. 3. The torque at the nonfocal joint of a single joint movement was very close to linearly proportional to that at the focal joint throughout the movement. Elbow and shoulder torques differed by a linear scaling constant and went through extrema and zero crossings almost simultaneously. 4. In contrast, during movements in which subjects were explicitly instructed to use a hand path they would not naturally, use the linear interjoint torque scaling rule did not apply. This demonstrated that when we wish to move along a path between two targets that is not produced by linear torque covariation, we are able to modify that rule at will. 5. We speculate that linear, dynamic covariation of the torque patterns across two joints may be an important principle for reducing the number of degrees of freedom that the nervous system must independently control in performing unconstrained limb movements over naturally chosen paths.

Download Full-text

Kinematic Synthesis of a Spatial 3-RPS Parallel Manipulator

Journal of Mechanical Design ◽

10.1115/1.1539505 ◽

2003 ◽

Vol 125 (1) ◽

pp. 92-97 ◽

Cited By ~ 67

Author(s):

Han Sung Kim ◽

Lung-Wen Tsai

Keyword(s):

Parallel Manipulator ◽

Degrees Of Freedom ◽

Parallel Manipulators ◽

Point Of View ◽

Dimensional Synthesis ◽

Kinematic Synthesis ◽

End Effector ◽

Solution Methods ◽

Moving Platform ◽

At Will

This paper presents the design of spatial 3-RPS parallel manipulators from dimensional synthesis point of view. Since a spatial 3-RPS manipulator has only 3 degrees of freedom, its end effector cannot be positioned arbitrarily in space. It is shown that at most six positions and orientations of the moving platform can be prescribed at will and, given six prescribed positions, there are at most ten RPS chains that can be used to construct up to 120 manipulators. Further, solution methods for fewer than six prescribed positions are also described.

Download Full-text