Write once read many data storage

The main interest in this book is the use of laser addressable dyes in optical data recording, specifically WORM (write once read many times) used in the industrial and institutional arena for the mass storage of data, and CD-R used in smaller scale computing, educational and entertainment outlets. 

Heat. As mentioned above most molecules lose energy from the excited state as heat. The most efficient molecules for converting electromagnetic radiation into heat are those that absorb in the near-IR region, i.e., infrared absorbers (IRAs). There has been much interest in IRAs because of their use in laser thermal transfer, optical data storage [the older write-once read-many (WORM) and the newer compact disc recordable (CD-R) and digital versatile disc recordable (DVD-R) systems], computer-to-plate printing, and as solar screens for car windscreens and windows. 

Optical data storage media fall into three main classes [26] (Figure 6.9). Read only media comprise the CD in its audio and CD-ROM formats and DVD, also of the CD format but having about six to ten times the data capacity of a CD-ROM, depending upon whether one or two recording layers are used. These read only media are mainly dedicated to entertainment. As seen from Figure 6.9, the systems which use organic dyes are WORM (write-once-read-many), CD-R, and DVD-R. 

Write once, read many, or WORM systems, are a bit more complicated than ROM systems. Though they have essentially the same optical system for data retrieval, for writing operations they require a more powerful laser and a modified storage disk. 

Write once read many (WORM) is data storage device in which information, once written, cannot be modified and the data caimot be tampered with once it is written to the device. In ordinary data storage devices, the number of times data can be modified is limited by the device. The read many aspect is unremarkable, as modern storage devices permit unlimited reading of data once written. 

Write Once Read Many (WORM) mass data storage. 

Data storage devices based on gold nanorods are necessarily limited to the write-once/read-many paradigm as the structural change responsible for the spectral modification is irreversible. However, these ideas can be extended to patterning and encryption applications [98], Polymer films doped with nanorods could be patterned with characteristic or coded features to prevent counterfeiting of documents or currency. 

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