Editing Optical disc (section)

===Blu-ray===
''HTL'' ([[Blu-ray Disc recordable#HTL (high to low)|high-to-low type]]) Blu-ray discs are made differently. First, a [[silicon wafer]] is used instead of a glass master.<ref>{{Cite web |title=Post-mastering: galvanics and stamper preparation |url=http://www.media-tech.net/fileadmin/templates/BD_News/OTO222forMTA.pdf |url-status=dead |archive-url=https://web.archive.org/web/20090919181009/http://www.media-tech.net/fileadmin/templates/BD_News/OTO222forMTA.pdf |archive-date=September 19, 2009}}</ref> The wafer is processed in the same way a glass master would.

The wafer is then electroplated to form a 300-micron thick nickel stamper, which is peeled off from the wafer. The stamper is mounted onto a mold inside a press or embosser.

The polycarbonate discs are molded in a similar fashion to DVD and CD discs. If the discs being produced are BD-Rs or BD-REs, the mold is fitted with a stamper that stamps a groove pattern onto the discs, in lieu of the pits and lands found on BD-ROM discs.

After cooling, a 35 nanometre-thick layer of silver alloy is applied to the disc using [[sputtering]].<ref name="auto">{{Cite web |title=BLULINE II |url=https://www.singulus.de/fileadmin/user_upload/202003/BLULINE_II_2_2020.pdf |url-status=dead |archive-url=https://web.archive.org/web/20200411062738/https://www.singulus.de/fileadmin/user_upload/202003/BLULINE_II_2_2020.pdf |archive-date=April 11, 2020 |website=Singulus}}</ref><ref>{{Cite web |title=How to produce a Blu-ray? |url=https://hofa-shop.com/erp/owweb/spezi/en_14061.pdf |website=HOFA |access-date=2020-04-11 |archive-date=2020-04-11 |archive-url=https://web.archive.org/web/20200411062739/https://hofa-shop.com/erp/owweb/spezi/en_14061.pdf |url-status=live }}</ref><ref>{{Cite web |url=https://www.digital-scrapbooking-storage.com/blu-ray-technology.html |title=Blu Ray Technology and Disc Structure |access-date=2020-04-21 |archive-url=https://web.archive.org/web/20120305192336/http://www.digital-scrapbooking-storage.com/blu-ray-technology.html |archive-date=2012-03-05 |url-status=live }}</ref> Then the second layer is made by applying base and pit transfer resins to the disc, and are pre-cured in its center.

After application and pre-curing, the disc is pressed or embossed using a stamper and the resins are immediately cured using intense UV light, before the disc is separated from the stamper. The stamper contains the data that will be transferred to the disc. This process is known as embossing and is the step that engraves the data onto the disc, replacing the pressing process used in the first layer, and it is also used for multi layer DVD discs.

Then, a 30 nanometre-thick layer of silver alloy is then sputtered onto the disc and the process is repeated as many times as required. Each repetition creates a new data layer. (The resins are applied again, pre-cured, stamped (with data or grooves) and cured, silver alloy is sputtered and so on)

BD-R and BD-RE discs receive (through sputtering) a metal (recording layer) alloy (that is sandwiched between two dielectric layers, also sputtered, in BD-RE), before receiving the 30 nanometre metallization (silver alloy, aluminum or gold) layer, which is sputtered. Alternatively, the silver alloy may be applied before the recording layer is applied. Silver alloys are usually used in Blu-rays, and aluminum is usually used on CDs and DVDs. Gold is used in some "Archival" CDs and DVDs, since it is more chemically inert and resistant to corrosion than aluminum, which corrodes into [[aluminum oxide]], which can be seen in [[disc rot]] as transparent patches or dots in the disc, that prevent the disc from being read, since the laser light passes through the disc instead of being reflected back into the laser pickup assembly to be read. Normally, aluminum does not corrode since it has a thin oxide layer that forms on contact with oxygen. In this case, it can corrode due to its thinness.

Then, the 98 micron-thick cover layer is applied using UV-curable [[liquid optically clear adhesive]], and a 2 micron-thick hard coat (such as [[Durabis]]) is also applied and cured using UV light. In the last step, a 10 nanometre-thick [[silicon nitride]] barrier layer is applied to the label side of the disc to protect against humidity.<ref name="auto2"/><ref name="auto"/><ref>{{Cite web |title=BLULINE II: Enabling Fascination 3D |url=https://www.singulus.com/uploads/tx_pspublications/BLULINE_II_2012.pdf |url-status=dead |archive-url=https://web.archive.org/web/20200411062743/https://www.singulus.com/uploads/tx_pspublications/BLULINE_II_2012.pdf |archive-date=April 11, 2020}}</ref><ref>{{Cite web |title=BLULINE III |url=https://www.singulus.com/fileadmin/user_upload/202003/BLULINE_III_2_2020.pdf |url-status=dead |archive-url=https://web.archive.org/web/20200411062738/https://www.singulus.com/fileadmin/user_upload/202003/BLULINE_III_2_2020.pdf |archive-date=April 11, 2020 |website=Singulus}}</ref> Blu-rays have their data very close to the read surface of the disc, which is necessary for Blu-rays to achieve their capacity.

Discs in large quantities can either be replicated or duplicated. In replication, the process explained above is used to make the discs, while in duplication, CD-R, DVD-R or BD-R discs are recorded and finalized to prevent further recording and allow for wider compatibility.<ref>{{Cite web|url=https://www.replicat.com.au/content/replication-and-duplication|title=The Difference Between Replication & Duplication |website=Replicat |access-date=2020-04-09|archive-url=https://web.archive.org/web/20200311170517/https://www.replicat.com.au/content/replication-and-duplication|archive-date=2020-03-11}}</ref> (See [[Optical disc authoring]]). The equipment is also different: replication is carried out by fully automated purpose-built machinery whose cost is in the hundreds of thousands of US dollars in the used market,<ref>{{Cite web|url=https://www.cdvdpacking.com/A_Cinram/index.html |title=Cinram Machines|website=www.cdvdpacking.com|access-date=2020-04-11|archive-url=https://web.archive.org/web/20190930070519/http://www.cdvdpacking.com/A_Cinram/index.html|archive-date=2019-09-30|url-status=live}}</ref> while duplication can be automated (using what's known as an autoloader<ref>{{Cite web |url=https://www.vinpowerdigital.com/products/aero220-s0t-bd-bk |title=Aero Blu-ray/DVD/CD Autoloader - CD Copier, DVD Duplicator, Blu-Ray Duplicator |website=Vinpower Digital |access-date=2020-04-11 |archive-date=2020-04-11 |archive-url=https://web.archive.org/web/20200411101902/https://www.vinpowerdigital.com/products/aero220-s0t-bd-bk |url-status=live }}</ref>) or be done by hand, and only requires a small tabletop duplicator.<ref>{{Cite web |url=https://www.vinpowerdigital.com/products/slimmicro_bd_s0 |title=Slim Micro Blu-ray DVD CD Duplicator - CD Copier, DVD Duplicator, Blu-Ray Duplicator |website=Vinpower Digital |access-date=2020-04-11 |archive-date=2020-04-11 |archive-url=https://web.archive.org/web/20200411101859/https://www.vinpowerdigital.com/products/slimmicro_bd_s0 |url-status=live }}</ref>