Hacking CD/DVD/Blu-ray for Biosensing (2018) | Hacker News Reader

Blu-ray for Biosensing (2018)

ncbi.nlm.nih.gov

112 pointsgaraetjjte14 comments

From the paper it looks like most of the interesting work with the laser and optical train use an external board to recreate the feedback and control circuitry already present and required for normal operation in a DVD/BluRay drive. It would be great if you could have more control over the existing hardware in these drives.

I found a project that started the reverse engineering process on a popular bluray drive [1] but it really looks like an uphill slog against undocumented CPUs and motor control chips among other obstacles. Anyone know of any other resources for reusing the existing hardware but modifying the control software?

1. https://github.com/scanlime/coastermelt/

https://loetlabor-jena.de/doku.php?id=projekte:dvdlsm:start

https://www.gaudi.ch/GaudiLabs/?page_id=652

From memory the most applicable prior art is the "region free" firmwares for various DVD drives and, the drive hacks used to play "backup" (and some homebrew) games on the Xbox 360 while bypassing some of the attestation protections for online.

> It would be great if you could have more control over the existing hardware in these drives

You can blame the DRM lobby basically forcing manufactures into a veil of "security by obscurity"

Hackaday has featured a couple of projects featuring the ps3 optical pickup unit. The author of one of the projects breaks out the 40-pin ribbon cable and is able to drive it with some simple circuitry

https://hackaday.io/project/9205-blubeam-a-scanning-laser-mi...

https://hackaday.com/2019/11/12/tearing-down-a-ps3-blu-ray-d...

Cool. Made me remember when I was shown a presentation of a russian DIY project back in 2010s. It was a CD-ROM drive used as a real microscope, without hardware modifications (they put sample glass right in the CD tray). Presented by midschool student and his teacher (who did most of the reverse jobs, I presume). So, if that was possible, then THIS may also be possible using BR drive hardware. Anyway, proprietary documentation and code is always a blocker for progress.

This was insanely interesting. And I must say that paper must have taken a lot of effort by some very brilliant people.

The goal here is not reverse engineering these components, asics, chips and firmwares. Rather making it work with off the shelf blu-ray players, making it a completely turnkey solution for Biosensing.

>"The optical pickup unit (OPU) within a CD/DVD/Blu-ray drive integrates 780, 650, and 405 nm wavelength lasers, diffraction-limited optics, a high-bandwidth optoelectronic transducer up to 400 MHz, and a nanoresolution x-, z-axis, and tilt actuator in a compact size. In addition, the OPU is a remarkable piece of engineering and could enable different scientific applications such as sub-angstrom displacement sensing, micro- and nanoimaging, and nanolithography."

I've always wondered if CD/DVD/Blu-ray drives -- could one day (with a special-made disc, made with the right materials) be used to create Transistors, IC's and Chips...

The economic forces that led to cheap laser stages which can be used for science never fail to amuse me.

The equivalent, if you were clever and building things from components, would cost many thousands of dollars and engineering time and never be as reliable.

I'm still looking for a replacement for conventional motorized microscope stages (like https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=30... but for $150 instead of $1500).

https://journals.plos.org/plosone/article?id=10.1371/journal...

Heres a decent open source? stage that i adapted for one of my projects in the past. Resolution is 1 micron laterally. If i remember correctly they address several issues including stepper motor backlash and micro-stepping. Cost can be well below the $1000 they quote depending on the parts you choose, or e.g. if you do only two axis (xy) stage instead of three (xyz)

I built this stage already (XY with a separate stepper-based Z-stage). I agree, the cost is low, but I found endless problems with the motor to micrometer coupling. Specifically, the torque on the shaft changes quickly during rotation and that led to non-equal spaced steps. My guess is that the shafts I'm using are inferior to the ones they use, but honestly I can't tell (it's hard for me to justify spending $100+ for a cable if I don't know if it;'s going to work). Or, they have a different geometry for the cables.

Since then I've also tried another approach, using a GT2 belt, but the belt deflects significantly at the extent of stage range (50mm). My next attempt is going to be to fix the steppers to the stage itself so that they move witth the stage.

I'd like to see the stepper motor and linear actuator that's in the OPU but couldn't find anything. Any links?

After a bit of searching I found http://www.diyouware.com/node/161 which led me to https://www.aliexpress.com/item/32373422606.html

Thanks. I found this nice view: http://repairfaq.cis.upenn.edu/Misc/Blu-ray/site1/ps3diode-i...

I don't understand half the words in there, but I love the idea. Imagine how much more crazy stuff they'd be able to accomplish if the manufacturers just provided the datasheets like any reasonable engineer would...

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