Chosen Solution
My mid-2011 iMac came with a DVD drive. Is it possible to swap this for a Blu-Ray drive?
Yes you can, but there’s a limited range of Blu-Ray drives that fit the bay correctly. You’ll need a 9.5mm slot-load SATA drive, such as the Panasonic/Matsushita UJ-267 CD/DVD/BR burner. Most of the laptop-style bare drives available are both 12.7mm and tray-load, and won’t fit the iMac at all. Assuming that your internal SuperDrive still works acceptably, it might make more sense to buy (or assemble) an external Blu-Ray player, and connect to your iMac through USB. OWC carries several Blu-Ray players/burners, in both laptop and desktop sizes. This helps you avoid the risk of pulling the display out of the iMac case. Remember that Apple has never released a Blu-Ray player application; they have never modified DVD Player for Blu-Ray playback. There are a variety of commercial Blu-Ray player apps, most of which are around $30 (Leawo Blu-Ray Player, Aurora Mac Blu-ray Player and Macgo Mac Blu-ray Player are the ones I’ve paid for; they often come cheaper as part of software bundles, and Leawo does giveaways sometimes). For a lot of people, the freeware VLC is a perfectly adequate Blu-Ray player. Similarly for disk burning, you can burn Blu-Ray data disks using standard OS tools such as Finder and Disk Utility. But to burn Blu-Ray player compatible movie disks requires third party software, such as Roxio Toast. EDIT: I failed to note in the original answer that you can also use a ‘combo’ drive: CD, DVD recorder/Blu-Ray player. There are a wider variety of Blu-Ray combo drives available that will fit the iMac optical bay; apparently those drives are now a common option in Windows laptops. The same physical limitations still apply: 9.5mm thick, SATA, slot-load. The iMac case won’t accommodate the far more common tray-load drives or 12.7mm drives. ANOTHER EDIT, FIVE YEARS ON: On BR player software, I failed to mention in the original answer that all BR player software on Mac is just terrible. The commercial players don’t generate the clickable graphical interface you get with a standalone player, or with DVD player software. They don’t even list tracks by name; all you get is a list of numbered tracks with playing duration, and you have to guess what you want to see. On a disk with a lot of extras, you may see 100 tracks or more, without many obvious clues about what to choose. YUCK! However, Macgo has released an upgraded version of their player: Macgo Blu-Ray Player Pro. This application does use a GUI, so you can choose tracks as you would expect. One quirk is that mouse/trackpad movement/clicks do not work; apparently, standalone BR players use a Java applet for navigation between UI elements, and Java is no longer supported by macOS. You can navigate through the interface using the arrow and return keys. VLC also uses a GUI, but its drawback is that it will only play BR disks that are not copy-protected.
I believe the answer above is wrong. I am adding this in case someone else wonders. My 2010 iMac certainly required a 12.7mm drive which I have fitted. It’s the Macbook Pro that requires a 9.5mm drive. There are many more options for slot-ins here, both Blu Ray burners and players, UJ265 from Panasonic is what I went for.
