#video #toread about #Alpha-Phoenix’s #precision 2-billion-frame-per-second #cameras
on 02025-10-18#Alpha-Phoenix #video of a laser pointer at 2 billion frames per second. With a single pixel, so he then scans it over the setup with a gimbal-mounted mirror, and repeats the experiment, hundreds of thousands of times (3000 times per second). “Every one of these pixels was recorded separately, as a 1×1 pixel video!” Integrated encoder feedback in the motors was the key. He geared the pitch servo down with a timing belt to get better angular resolution because Katić, Domitran, Horvatek, and Lagator wrote a paper saying timing belt transfer accuracy was fine for angle metrology applications. “After figuring out which LLM code snippets were useful and which LLM code snippets were the reason I’d been frustrated for hours...” His optics train is one lens and one pinhole and, I assume, one photodiode. No, holy fuck, it’s a photomultiplier tube. His data acquisition rig is a benchtop 2Gsps oscilloscope, a Siglent SDS824X HD, 200MHz, 12 bits. He points out that the analog signal path amounts to a 58-frame delay line. To include the synchronization signal on the same line (because the scope can only do 2Gsps on one channel), he used a 500ns coax delay line from the laser. #precision #optics #cameras
on 02025-10-17#Alpha-Phoenix #video on #UHV #vacuum for molecular beam epitaxy (#MBE), explaining copper gaskets. Apparently MBEs are all equipped with quadrupole mass spectrometers to help in tracing UHV leaks, which give you a molecular mass spectrum calibrated in daltons, which is pretty cool since you can see spikes for individual isotopes, and you spray helium at your flanges. He also used a random bubble-wrap bag to raise the helium concentration around the suspected leak, and some masking tape to tape off a candidate joint. He mentions that there’s a kind of epoxy “leak seal” option when tightening the bolts isn’t good enough. An unfortunate amount of talking-head footage, but still informative.
on 02024-09-02#Alpha-Phoenix #video about how electrical impulses propagate through wires, reflecting a step off a short circuit and varius other impedances. Very nice four-dimensional plot of voltage against position, time, and impedance.
on 02024-05-20#Alpha-Phoenix first-surface mirrors. #optics #video he’s using the silvering process from the Tollens #materials test (silver nitrate, lye, ammonia, and a reducing sugar). Probably this process would be useful for #electroplating non-conductive objects as an alternative to graphite paint. He prints some things in an unspecified plastic with FDM #3D-printing, sands them, applies a two-part epoxy filler (“XTC-3D”) to smooth the surface, and silvers it by spraying precursors from a commercially-bought silvering kit onto it. To keep the resin from dripping off before it cures, he rotates a part slowly on a slanted axis so that it drips back to where it started. This introduced errors far too large for #optics. To try to silver the surface evenly he added a surfactant. In one batch, his epoxy reacted with one or more of the sprayed precursors, getting silver but with a terrible surface finish. In fact, that kept happening afterwards; he found that he had to cure the resin indoors (heat? humidity?) and needed to have the resin component ratio skewed toward component “A”.
on 02024-04-03