 Welcome to the session of Blu-ray player, learning outcome of the session. Before proceeding, let me ask you one question. What is the capacity of CDs and DVDs? You may pause the video, think about the question, write down your answer in your notebook and resume the video to see the answer. Let me give you the answer. The CD has a maximum capacity of 650 to 900 MB and the DVD have the capacity of 1.4 to 8 GB. The Blu-ray player is a digital player that plays the Blu-ray disc. So, what is a Blu-ray disc? A Blu-ray disc is also known as BD. It is a digital optical disc which is used for storage of the information. The Blu-ray disc is invented in 2006. The name Blu-ray refers to the Blu laser that is actually the violet laser which is used to read the disc which allows the information to be stored at the greater density than is possible with the longer wavelength red laser which is used for the DVDs. With their high storage capacity, the Blu-ray disc can hold and play the large quantities of high definition video and audio. As well as they can store a photo, data and other digital content. The figure shows the photograph of the typical Blu-ray player. The evolution of the consumer optical disc. In earlier, the CDs are invented. These are the compact disc which is operated on the infrared laser. The infrared laser is used to read the disc. The maximum capacity of the CDs are 780 MB which is used in order to record the two-channel pulse-coded modulated audio for up to 74 minutes. Next the DVD player is invented. The DVD player uses the red laser in order to read the information. The maximum capacity of DVD is 4.7 GB which is needed to record the movie in MPEG 2, up to the maximum of 2 hours and 15 minutes. Then the Blu-ray disc is invented. The Blu-ray disc operates on Blu laser which has the capacity of 22 GB which is used for the recording of the digital broadcasting. We can have up to the 50 GB capacity for a dual layer disc, we will see it later. The interactive feature of the Blu-ray disc. Blu-ray disc not only have a more storage capacity than the traditional DVDs but they can also offer a new levels of the integrity. The users will be able to connect to the internet and instantaneously download the subtitles and other interactive movie features. They can record the high definition television that is HDTV videos. They can instantaneously skip to any spot on the disc. They can record one program while watching the another program on the disc. They can create the playlist. They can edit or record the programs which are recorded onto the disc. Automatically search for the empty space on the disc to avoid the recording over the program. They can access the web to download the subtitles or other extra features are also available in case of the Blu-ray player. The Blu-ray disc size comparison. So let us compare the Blu-ray size with the DVD. The single layer DVD have 4.7 GB of the data maximum. So the average 2 hours of the standard definition movie without any extra feature can be recorded onto the DVD where the Blu-ray is a next generation digital video disc. It can record, store, play the high definition video and digital audio signal as well as the computer data. The advantage of Blu-ray disc is that the large amount of the information can be recorded onto the Blu-ray disc. A single layer Blu-ray disc which is roughly of the same size of the DVD can record up to the 27 GB of the data. So it is more than the 13 hours of the standard video recording and more than the 2 hours of the high definition video recording. So the double layer that is dual layer Blu-ray disc can store up to the 50 GB data. Double layer can store up to the 27 GB. So if you have the double layer then it can hold up to the 50 GB of the data which is more than the 20 hours of the standard video which is enough to hold about a 4.5 hours of the high definition video or more than a 20 hours of the standard video. Let us see the Blu-ray disc structure. The figure shows the cross section of the Blu-ray disc. So the first layer is a hard coat layer and this layer is about 0.002 mm in thickness. The hard coat layer is specially formulated material to prevent the scratches, dirt and the dust which is built up onto the disc and in order to avoid the fingerprints. The next after the hard coat layer is the cover layer. The cover layer is of the size of 0.098 mm. The cover layer will protect the data layer which is present underneath and provide the separation so that a laser can properly focus onto the data layer. Now after the cover layer there is a molded pits form which is nothing but the metal reflective layer in which the information is stored that is why it is called as a data layer. The data or the information is stored in the form of pits. These different sized pits represent the digital information which is stored onto the disc. A metal reflective layer is then deposited onto the pits in order to make a disc readable. Let us see the difference between CD, DVD and the blu-ray disc. Here the picture shows the microscopic view of the CD, DVD and the blu-ray disc. So you can see obviously the pit length in case of the CD is much larger as compared to DVD and blu-ray. Pit length in case of the DVD again larger as compared to the blu-ray. So the blu-ray has a very small pit length as compared to the CD and the DVD. That's why the blu-ray can hold a maximum information as compared to the DVD and the CD. You can see that the minimum pit length in case of the blu-ray disc is about 0.15 micrometer whereas in case of the DVD is about 0.4 micrometer. In case of the CD is about 0.8 micrometer. So the blu-ray uses the blu laser which have a shorter wavelength that is 405 nanometer. That's why the blu-ray can hold a more information as compared to the DVD and CD. The blu-ray has reduced the track pitch from 0.74 micron to 0.32 micron. The smaller pits, the smaller beam and the shorter track together enable the single layer blu-ray disc to hold a 25 GB of the information. Let us see the structure of the dual layer disc. A dual layer disc can hold the twice information as compared to the single layer disc. It has two recording layers that is a metal layer, a recording layer 0 and a recording layer 1. These two recording layer have, the recording layer 0 has a transmission stack of 0 and the recording layer 1 has a transmission stack of the 1 in order to pass the laser beam. Then there is a one cover layer after that we have one recording layer, there is spacer layer in between the two layer recording layer and finally, we have the substrate on the top of the blu-ray disc. Formation recording layer is above 100 micrometer away from the laser incident plane which is defined as a layer 0 and other in recording layer is above 75 micro mm away from the layer 1. Because of the dual layer disc, the rear layer is recorded through the frontal layer. Hence, it is important that the front layer should have a sufficiently large transmittance and to transmit a laser from recording one layer recording layer to the another recording layer. It is natural that the front layer itself should be recorded and read with a certain light power. Therefore, the target value of its transmittance will be 50 percent to share the light between the both layers. Let us see the block diagram of the blu-ray player. The block diagram consists of the optical pickup which is driven by the laser driver. Then the user data is modulated by 17 pp binary data modulator and given to the right pulse modulator which will create the multiple signal in order to drive the laser. The laser will guide the optical lens and as per that the information is recorded and then the reproducing unit consists of equalizer, phase lock loop, analog to digital converter and PRML. The recording, let us see how the recording is done. The user data is modulated or encoded into the 17 parity preserving non-return to zero inverted that is 17 pp NRZI signal by the 17 pp binary data modulator. This 17 pp NRZI signal is sent to the right pulse compensator where the signal is modulated into the multipulse signal. By adjusting the leading edge of the first pulse and the trailing edge of the cooling pulse of the multipulse signal, we can control the amount of thermal accumulation relative to the mark length which will enable the accurate placement of the mark edge. The pulse waveform is thus modulated and sent to the laser driver which will modulate the power of the laser beam to record the or mark the space data on the recordable blu-ray disc. Playback the to play back the recorded data the reproduced signal is fed through the equalizer to the phase lock to loop. Output signal of the equalizer is fed to the analog to digital converter that is a to d converter which is converted into the digital signal using the PLL clock timing. The output of analog to digital converter is then passed through the partially response maximum likelihood that is PRML channel to record any initial bit error. Output and the output as the NRZI signal to be demodulated from 17 pp code and any remaining errors are corrected using the EECC signal. These are the references for the session. Thank you.