New camera offers ultrafast imaging at a fraction of the normal cost
phys.org
phys.org
> The team created a DRUM camera with a sequence depth of seven frames, meaning that it captures seven frames in each short movie.
Seems like their movies could possibly only be 7 frames in length so not really comparable to Phantom type cameras which can capture a lot more content.
Still, it’s great to see the mirror tech used in DLP projectors having other uses. Some 3D resin printers use it too but that’s still projection I guess. I think those dlp mirror chips are amazing and probably fascinating to hack around with.
My guess is the ‘sequence depth’ relates to the amount of diffraction gates. So perhaps all that’s needed is an ultrafast shutter to string together a long ‘movie’
I didn't mean to conflate the two, it's gating through a... 'grating'. Though the article and the paper do use the term 'diffraction gating'.
> "Luckily, it is possible to accomplish this type of swept diffraction gate by using a digital micromirror device (DMD)—a common optical component in projectors—in an unconventional way," said Liang. "DMDs are mass-produced and require no mechanical movement to produce the diffraction gate, making the system cost-efficient and stable."
"Diffraction-gated real-time ultrahigh-speed mapping photography"
https://opg.optica.org/optica/fulltext.cfm?uri=optica-10-9-1...
> 1,750,000 frames per second at a resolution of 1280 x 32
It’s just a slit! This is wild it’s even possible.
[1] https://www.nnss.gov/docs/fact_sheets/DOENV_1136.pdf
Is this saying that light through a lenticular lens sheet comes out slightly early/late depending on angles, and the sheet could be used as an array of delay lines with different time constants?
But I'm not familiar with your terminology, so maybe that's what you said :)
Edit: Ah, they're using a DMD. The paper is published here: https://opg.optica.org/optica/fulltext.cfm?uri=optica-10-9-1.... Iiuc when the DMD mirrors are switching between on and off you can get different diffraction patterns while they're shifting, and these different diffraction orders will move the image on the camera.
are you listening to the words you're saying? seriously? yes, we can make light go slower so that the sensor receives light at different times. i'm with you all the way to the point you make some ridiculous not thought out comment about making light go faster. No. Just stop. We cannot do that. We can only slow light down.
When light transitions from glass to air, it goes faster.
It's when electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium at a speed greater than the phase velocity (speed of propagation of a wavefront in a medium) of light in that medium.
If you want the light to arrive at different times you can either do something to make the paths different lengths, or to make the speed of light different on the two paths, or both. You can't make the speed faster than c on either of the paths but you can make it slower by making the light go through something with an index of refraction greater than 1.
Now suppose you've got some thing that you have built to process light, and you care about the differences in arrival time of the light to different parts of the thing. There's probably going to be some part of your thing that it makes the most sense to use as a reference, and then describe light arrival times elsewhere relative to that reference point.
There's usually no particular reason to pick as the reference the point on your thing that light first reaches. If you do indeed pick a reference that is not the earliest place of contact with the light, then you can have light arrive earlier at other parts of your thing.
There are different kinds of sensors sensing different aspects of the incoming light. You need to combine them, making sure that you are combining readings that come from the same plane of the wavefront.
But one of your sensors takes a little longer than the others to process and produce a reading. You either need to make that sensor start processing earlier than the other sensors, or make the other sensors start processing later, or add some sort of delay between the other sensor outputs and the thing that combines all the sensor outputs.
If you fix this by moving that one sensor a little out of your sensor plane, moving it toward the light source, most people, including most scientists, would say that your fix was to make the light arrive at that sensor earlier, because the light in fact arrives at that sensor now before it arrives at the other sensors.
Let's say that the sensors process different wavelengths of light. Then another adjustment you might do to get the outputs synced would be to fill the space between where light enters and the sensor plane with a gas that happens to have a low index of refraction for the wavelengths the slow sensor uses and a high index for the wavelengths the other sensors use.
That would make the light arrive later at all the sensors than it would have if the gas had not been added, but it will less later at the slow sensor. But again nearly everyone would say that what you fix did was make the light arrive earlier at the slow sensor, because before the fix light arrived at the slow sensor at the same time it arrived at the other sensors, and after the fix it arrives at the slow sensor before it arrives at the other sensors.
Fast and slow light. Read and be edified.
It has pictures of:
Fig. 3. Side-view observation of laser-induced breakdown in distilled water https://i.imgur.com/s4NeSmP.jpg
Fig. 4. Front-view imaging of cavitation dynamics https://i.imgur.com/GCyW6xY.jpg
Fig. 5. Imaging the laser ablation of single-layer onion cells https://i.imgur.com/K7H0uso.jpg
As well as setup and configuration