Laser scanning microscopes are useful for all kinds of tiny investigations. As it turns out, you can build one using parts salvaged from a Blu-ray player, as demonstrated by [Doctor Volt].
The trick is repurposing the optical pickup unit that is typically used to read optical discs. In particular, the build relies on the photodiodes that are usually used to compute focus error when tracking a disc. To turn this into a laser scanning microscope, the optical pickup is fitted to a 3D printed assembly that can slew it linearly for imaging purposes.
Meanwhile, the Blu-ray player’s hardware is repurposed to create a sample tray that slews on the orthogonal axis for full X-Y control. An ESP32 is then charged with running motion control and the laser. It also captures signals from the photodiodes and sends them to a computer for collation and display.
[Doctor Volt] demonstrates the microscope by imaging a small fabric fragment. The scanned area covers less than 1 mm x 1 mm, with a resolution of 127 x 127, though this could be improved with finer pitch on the slew mechanisms.
When you think of high-throughput ptychographic cytometry (wait, you do think about high throughput ptychographic cytometry, right?) does it bring to mind something you can hack together from an old Blu-ray player, an Arduino, and, er, some blood? Apparently so for [Shaowei Jiang] and some of his buddies in this ACS Sensors Article.
For those of you who haven’t had a paper accepted by the American Chemical Society, we should probably clarify things a bit. Ptychography is a computational method of microscopic imaging, and cytometry has to do with measuring the characteristics of cells. Obviously.
Anyway, if you shoot a laser through a sample, it diffracts. If you then move the sample slightly, the diffraction pattern shifts. If you capture the diffraction pattern in each position with a CCD sensor, you can reconstruct the shape of the sample using breathtaking amounts of math.
One hitch – the CCD sensor needs a bunch of tiny lenses, and by tiny we mean six to eight microns. Red blood cells are just that size, and they’re lens shaped. So the researcher puts a drop of their own blood on the surface of the CCD and covers it with a bit of polyvinyl film, leaving a bit of CCD bloodless for reference. There’s an absolutely wild video of it in action here.
This problem only applies to 4K Blu-ray discs with DRM. Presumably any 4K discs without DRM will still play, and of course you can still play the DRM discs on older Intel processors. Do you have a collection of DRM 4K Blu-ray discs, and if so, do you play them via your computer or a stand-alone player?
[Prof. Edwin Hwu] of the Technical University of Denmark wrote in with a call for contributions to special edition of the open-access scientific journal Biosensors. Along the way, he linked in videos from three talks that he’s given on hacking consumer electronics gear for biosensing and nano-scale printing. Many of them focus on clever uses of the read-write head from a Blu-ray disc unit (but that’s not all!) and there are many good hacks here.
For instance, this video on using the optical pickup for the optics in an atomic force microscope (AFM) is bonkers. An AFM resolves features on the sub-micrometer level by putting a very sharp, very tiny probe on the end of a vibrating arm and scanning it over the surface in question. Deflections in the arm are measured by reflecting light off of it and measuring their variation, and that’s exactly what these optical pickups are designed to do. In addition to phenomenal resolution, [Dr. Hwu’s] AFM can be made on a shoestring budget!
Speaking of AFMs, check out his version that’s based on simple piezo discs in this video, but don’t neglect the rest of the hacks either. This one is a talk aimed at introducing scientists to consumer electronics hacking, so you’ll absolutely find yourself nodding your heads during the first few minutes. But then he documents turning a DVD player into a micro-strobe for high speed microfluidics microscopy using a wireless “spy camera” pen. And finally, [Dr. Hwu’s] lab has also done some really interesting work into nano-scale 3D printing, documented in this video, again using the humble Blu-ray drive, both for exposing the photopolymer and for spin-coating the disc with medium. Very clever!
If you’re doing any biosensing science hacking, be sure to let [Dr. Hwu] know. Or just tear into that Blu-ray drive that’s collecting dust in your closet.
The problem stems from the logging system that stores user data and passes it back to Samsung over the Internet. Which data is logged and sent back is managed by an XML file which contains the policy settings that control this behaviour. According to a source known only as “Gary” “Gray”, the XML file posted on Samsung’s servers on June 18 featured a malformed list element. This caused a crash in the player’s main software routine, leading the player to reboot.
The failure was exacerbated by the fact that the XML file is parsed very early in the boot sequence, even before checking for firmware updates or a new XML file. This has prevented Samsung from rolling out an update or fix over the air, and is why the player gets stuck in a loop of continuous reboots.
Reportedly, the file can be found at this URL, though is now an updated version that shouldn’t brick players. Samsung have had to resort to a mail-in repair scheme, wherein technicians with service tools can manually remove the offending XML file from the player’s storage, allowing it to boot cleanly once again. While this shows our initial assumptions were off the mark, we’re glad to see a solution to the problem, albeit one that requires a lot of messing around.
Last Friday, thousands of owners of Samsung Blu Ray players found that their home entertainment devices would no longer boot up. While devices getting stuck in a power-cycling loop is not uncommon, this case stands out as it affected a huge range of devices all at the same time. Samsung’s support forum paints a bleak picture, with one thread on the issue stretching to 177 pages in just a week.
So what is going on, and what can be done to fix the problem? There’s a lot of conflicting information on that. Some people’s gear has started working again, others have not and there are reports of customers being told to seek in-person repair service. Let’s dive in with some wild speculation on the problem and circle back by commiserating about the woes of web-connected appliances.
Optical drives are somewhat passe in 2019, with most laptops and desktops no longer shipping with the hardware installed. The power of the cloud has begun to eliminate the need for physical media, but that doesn’t mean the technology is any less marvellous. [Leslie Wright] and [Samuel Goldwater] took a deep dive into what makes the PS3’s optical drive tick, back in the heyday of the Blu Ray era.
The teardown starts by examining the layout of the assembly, and the parts involved. This is followed by a deep dive into an exploration of the triple-laser diode itself, There are tips on how to safely extract the delicate parts, which are highly sensitive to electrostatic discharge, as well as exhaustive specifications and measurements of performance. There’s even a break down of the optical package, too, including a patent search to shed more light on the complicated inner workings of the hardware.
And if this lures you to dig deeper into Sam’s Laser FAQ, prepare to spend the rest of the week.
We’ve seen other optical teardowns before, too – like this look inside a stereo microscope. It’s quite technical stuff, and may fly over the heads over the optically inexperienced. However, for those in the know, it’s a great look at the technology used in a mass-produced console.