06-12-2012, 04:02 PM
OPTICAL DATA SECURITY
optical data security.pptx (Size: 96.5 KB / Downloads: 25)
INTRODUCTION
Optical data storage is an alternative to magnetic disk data storage.
Currently data access times are extremely slow for magnetic disks when compared to the speed of execution of CPUs so that any improvement in data access speeds will greatly increase the capabilities of computers, especially with large data and multimedia files.
OPTICAL DATA STORAGE PRINCIPLE
Holographic method was a two step coherent image forming process in which a record is made of the interference pattern produced by the interaction of the waves diffracted by the object and a coherent background or a reference wave.
When this hologram is illuminated, the original wave front is reconstructed.
LASER
Laser is a device for the generation of coherent, nearly monochromatic and highly directional electromagnetic radiation emitted.
Fundamental attributes of a laser are directionality, mono chromaticity, coherence and brightness.
To record holograms on the crystals usually argon ion lasers, krypton lasers and diode lasers are used.
SPATIAL LIGHT MODULATORS
SLM is an optical device that is used to convert the real image or data into a single beam of light that will intersect with the reference beam during recording.
It basically consists of an array of pixels which are usually microscopic shutters or LCD displays. Each pixel of the SLM corresponds to bit of data.
Depending on whether the bit is a 1 or a 0 the pixel will go dark or transparent in the case of a LCD.