CD is a general designation, it is divided into two kinds, one kind is read-only type optical disc, including CD Audio, CD - Video, cd-rom, DVD, Audio, DVD, Video, DVD cd-rom, etc.;Another kind is recordable compact disc, which includes cd-r, cd-rw, DVD - R, DVD + R, DVD + RW, DVD - RAM, Double layer DVD + R, and other various types.
with optical technology, laser technology, microelectronics technology, materials science, fine processing technology, the development of computer and automatic control technology, optical storage technology in the recording density, capacity, data rate, addressing time there will be the key techniques such as the huge development potential.At the beginning of the next century, CD storage will be in the functional diversification, intelligent operation will have significant progress.As the light quantum data storage technology, three-dimensional storage technology, near field optics technology, the development of optical integration technology, optical storage technology will become one of the backbone technology of information industry in the next century.
the principle of optical storage
both optical storage media such as CD, DVD, are the same as the floppy disk, hard disk storage way, in the form of binary data to store information.Rather than store data on the discs, transformed the computer need to use laser to the binary data with data model on flat, blanks with reflection ability.And in order to identify the data CD is defined on laser carved small pit is representing binary 1, and the margin represents the binary 0.Records of the DVD disc pits smaller than a cd-rom, and the distance between the spiral storage pits.The pit of DVD store data points is very small, and very close, minimum indentation length is only 0.4 & mu;M, the distance between each hole point is only 50% of the cd-rom, and track only 0.74 & mu;M.
CD drive, DVD drive and a series of optical storage devices, the main part is the laser generator and the monitor.Drive on laser generator is actually a laser diode, can produce the corresponding wavelength laser beam, and then after a series of processing on CDS, and then through the monitor to capture reflected light signal to identify the actual data.If the CD is not reflected laser represents where there is a small hole, then the computer will know that it represents a 1;If the laser is reflected, the computer will know that this point is a zero.Then the computer can put these binary code into the original program.When the disc in the drive for high speed rotating, moving, before and after laser under the control of the motor data continuously read out, just like that.