101–110 of 115 posts
Earlier quoted context omitted.
We already have a useful and established term with which to describe just one pixel from a video frame. That term is "pixel".
So what if he captured 2 pixels at a time, would that constitute enough to be a definition of a frame?
Tl:dw for how this works: He scans one line at a time with a mirror into a photomultiplier tube which can detect single photon events. This is captured continually at 2MSample/s (2 billion times per second: 2B FPS) with an oscilloscope and a clever hack. The laser is actually pulsing at 30KHz, and the oscilloscope capture is synchronized to the laser pulse. So we consider each 30KHz pulse a single event in a single p…
Yup, this technique also allows oscilloscope capture signal with frequency higher than their Nyquyst bandwidth. The downside is it only works with repeative signal.
Earlier quoted context omitted.
The author uses "real time sampling" to acquire evolution of light intensity for one pixel at 2 GSps rate. The signal is collected for approximately one microsecond at each firing of the laser, and corresponding digital data is sent from the oscilloscope to the computer. "Equivalent time sampling" is a different technique which involves sliding the sampling point across the signal to rebuild the complete picture over…
I think parent meant that the image construction technique is analogous to equivalent time sampling. You’re correct in the mode of the oscilloscope’s use. However, the mode of the larger system is using a repetitive signal and sliding sampling points across it.
Earlier quoted context omitted.
What this experiment does is very similar to how an ordinary LIDAR unit operates, except that during a LIDAR scan the laser and the receiver are always pointed in the same direction, while in this demonstration the detector is scanning the room while the laser is stationary and is firing across the room. But in principle, a LIDAR could be reconfigured for the purposes of such demonstration. If one wants to build the…
And "Flash LIDAR" captures every pixel all at once. (But the frame rate is limited by how quickly the buffer can be read out and the sensor readied for the next frame.)
I think some of the short range depth cameras (Kinect v2 was one) use time-of-flight technique, and could in principle be reconfigured to perform a similar demonstration, though it would not be as "homemade" and cool as the system built for the Youtube video.
Earlier quoted context omitted.
Good explanation. One detail though: it is one pixel at a time, not one line at a time. Basically does the whole sequence for one pixel, adjusts mirror to next one, and does it again. The explanation is around the 8 minutes mark. Just want to make it clear that in any one instant, only one pixel is being recorded. The mirror moves continuously across a horizontal sweep and a certain arc of the mirror's sweep is local…
One piece I'd like to see more clarification on is, is he doing multiple samples per pixel (like with ray tracing?). For his 1280x720 resolution video, that's around 900k pixels, so at 30Khz, it would take around 30s to record one of these videos if he were to doing one sample per pixel. But in theory he could run this for much longer and get a less noisy image. I find it interesting that a project like this would ea…
Tl:dw for how this works: He scans one line at a time with a mirror into a photomultiplier tube which can detect single photon events. This is captured continually at 2MSample/s (2 billion times per second: 2B FPS) with an oscilloscope and a clever hack. The laser is actually pulsing at 30KHz, and the oscilloscope capture is synchronized to the laser pulse. So we consider each 30KHz pulse a single event in a single p…
Good explanation. One detail though: it is one pixel at a time, not one line at a time. Basically does the whole sequence for one pixel, adjusts mirror to next one, and does it again. The explanation is around the 8 minutes mark. Just want to make it clear that in any one instant, only one pixel is being recorded. The mirror moves continuously across a horizontal sweep and a certain arc of the mirror's sweep is local…
Tl:dw for how this works: He scans one line at a time with a mirror into a photomultiplier tube which can detect single photon events. This is captured continually at 2MSample/s (2 billion times per second: 2B FPS) with an oscilloscope and a clever hack. The laser is actually pulsing at 30KHz, and the oscilloscope capture is synchronized to the laser pulse. So we consider each 30KHz pulse a single event in a single p…
Can we not find why the strange behavior of a double split experiment occurs using this setup?
But as sibling said, this is still a measurement and will collapse the quantum system. You can't use this to peek under the hood and look at the quantum mechanics.
Earlier quoted context omitted.
Yup, this technique also allows oscilloscope capture signal with frequency higher than their Nyquyst bandwidth. The downside is it only works with repeative signal.
Rare enough though that the Fs/2 is higher than the analogue bandwidth on an oscilloscope.
https://www.tek.com/en/products/oscilloscopes https://www.keysight.com/us/en/catalog/key-34771/infiniivisi...
"Sampling" oscilloscopes are a much less common product -- they are useful for analyzing signals that are too fast to digitize in the ordinary way. They typically sample at a very slow repetition rate -- some hundreds of kilohertz, but each sampling aperture can be exceptionally short, allowing to record signals to 100 GHz frequency.
Earlier quoted context omitted.
Does anyone have a $50,000 scope they could just give to this dude? He seems like he would make great use of it.
Honestly I think if we each wrote a nice personal letter to Keysight they’d probably gift him one in exchange for the YouTube publicity. Several other electrical engineers on YT get free $20-50k keysight scopes not just for themselves, but once a year or so to give away to their audience members. And yes, this person could make use of it. His videos are among the highest quality science explainers - he’s like the 3B1…
Earlier quoted context omitted.
Yup, this technique also allows oscilloscope capture signal with frequency higher than their Nyquyst bandwidth. The downside is it only works with repeative signal.
Rare enough though that the Fs/2 is higher than the analogue bandwidth on an oscilloscope.