Ful high speed "camera" project - Page 1
Forum section: electronics / projects

author: BiOzZ
author_rank: Regular Contributor
timestamp: September 17, 2013, 05:02:44 am
content: i have been messing around for a fun little project idea for quite some time ... a simple .. simple ... in construction highspeed camera capable of MFPS speedthe idea is to get a whole fuckload (2.37 metric wankerloads for those not in the US) of SFH2701 photodiodeshttp://media.digikey.com/pdf/Data%20Sheets/Osram%20PDFs/SFH2701.pdf... 250 to be exact ... making a 250 pixel camera ... or about 10x25 pixthis is a mockup of the MASSIVE quality that 250 pix hasbut leave it open to expansion ... like adding another pixel arraywhat i want to do is sample directly from every photodiode by using some sort of analog multiplexing and a highspeed ADC like 2 AD9288 at 80MSPS than using an FPGA (still to be chosen) store it in high speed flash to be buffered untill it can be written in to an SD card in some sort of raw format that will be converted in to a video ... or a raw video format if i cana lens will be probably be a simple magnifying glassi have some basic experience in imaging and im a photographer but i have never made an image sensor beforeif its possible i know it would be a long, expensive, pain in my ass where all i will be left with is a peace of fun, fairly useless kit, a hole in my pocket but LOTS of knowledgeis this even a plausible thing to do?it would probably take over a year to makebecause im a broke college studentand need to save up as i go , it would be noisy and i am bad at FPGA stuff but i think it would be fun and we all can learn something even if it fails!thoughts?

author: tesla500
author_rank: Regular Contributor
timestamp: September 17, 2013, 08:16:57 am
content: You can buy high-speed image sensors off the shelf for somewhat reasonable prices. ON Semi makes the LUPA300, a 640x480 250fps sensor for about $150, capable of much higher speeds at reduced resolution, eg. 1000fps at 320x240. Basically it gives you 80 Mpix/s at whatever resolution you want. I built a camera based on this sensor (connected to an FPGA dev board with RAM to store the video) back in 2008. Some demo video from it:The photododes would be an interesting way of achieving ultra high frame rates. If you connected each to its own ADC, you could run millions of FPS, and the data rates would be "reasonable", 1GB/s for 4M fps.

author: poorchava
author_rank: Super Contributor
timestamp: September 17, 2013, 08:41:39 am
content: I think you may have a problem interfacing such a huge number of photodiodes. Photodiodes have high output impedance which means that even a small capacitance results in high time constants. Other thing is that every analog multiplexer has some leakage, and the leakage is a killer for photodiode designs.What I wrote is not based on an actual experimentation, but if that's true, then you'd most likely have to make a separate transimpedance amplifier for each diode, which would be both space- and money-consuming.

author: amyk
author_rank: Super Contributor
timestamp: September 17, 2013, 11:32:20 am
content: Givenhow cheap you can get a camera module these days, interleaving multiple image sensors might be a better way of getting huge framerates - although the optics might be somewhat more involved.These researchers several years agodecided to ignore that issue completely, and got rather good results.A resolution of 10x25 won't show anything interesting.

author: Marco
author_rank: Super Contributor
timestamp: September 17, 2013, 03:18:03 pm
content: You'd need onefront end/amplifierper photodiode ... in the numbers you're buying you're probably only talking a buck worth of components per pixel though.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 17, 2013, 03:23:51 pm
content: Before you get too excited, take some video and resize it to 10x25 and see if you can still make out anything in the image.And bear in mind you can get consumer cameras from Casio with pretty high framerates

author: mrflibble
author_rank: Super Contributor
timestamp: September 17, 2013, 04:28:02 pm
content: Quote from: amyk on September 17, 2013, 11:32:20 amHey, thanks for the link! That's a pretty neat approach. I like the approach of a screw it, forget about the optical distortions and lets just see what we get.With the low low loooow prices of simple cmos sensors these days you could make a seriously big array. And instead of time interleaving you could also play with the spatial side of it to try and get higher resolution. Again with optical issues, but in the spirit of these Stanford guys you could conveniently forget about those.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 17, 2013, 05:49:12 pm
content: Quote from: mrflibble on September 17, 2013, 04:28:02 pmEven with the cheapest camera modules, you still need to deal with the data. maybe a bunch of RasPi+cameras..I'm currently playing with an OV9655 module, which can be had for about £2. the problem with this sort of unit is it would be hard to get a low enough exposure time. You could probably deal with synchronisation, but by the time you've done mesing around it would still be cheaper to buy a high-speed sensor.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 17, 2013, 05:51:11 pm
content: Quote from: tesla500 on September 17, 2013, 08:16:57 amWhat happenned to that? - ISTR you got a fair way into doing a proper PCB (or am I thinking of someone else...?).If the chip is still obtainable, a PCB-only HS cam might make a nice kickstarter project, and rather cheaper than this one :http://www.kickstarter.com/projects/1521768569/edgertronictm-the-first-affordable-high-speed-vide?ref=live

author: tesla500
author_rank: Regular Contributor
timestamp: September 17, 2013, 06:57:10 pm
content: Quote from: mikeselectricstuff on September 17, 2013, 05:51:11 pmIt sat there for awhile while I was working on other projects, but I've been working on it again recently. I've simplified the system greatly, now it's just the image sensor and a Cypress FX3 streaming the data over USB3 to a PC, pretty much the cheapest it can possibly be done. Still working on some data issues with packets being committed in the wrong order, but it streams full speed.I have been working on the faster one too. I really need a software person. While embedded Linux is nice in theory with all the USB, ethernet etc taken care of for you, it has a very steep learning curve.

author: Dongulus
author_rank: Regular Contributor
timestamp: September 17, 2013, 08:53:32 pm
content: Nice silkscreen stamps.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: September 17, 2013, 09:53:46 pm
content: Interesting topic as there are some things we do at work where having about 20k FPS would be quite useful. Decent resolution is needed, and commercial cameras are stupidly expensive. I don't really understand why, since the sensors aren't that much, and the rest of the electronics and buffering should be far easier today than a couple decades ago. The good commercial cameras are in the $50k and up range. The Casio, at about 1k FPS is a heck of a bargain. I think a lot of golfers buy them to analyze swings. Not near fast enough for my needs though. Note that even at "moderate" frame rates of, say 20k FPS, you need a lot of light. For those mega FPS rates it helps to be filming on the surface of the sun, or at least an inner planet.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 18, 2013, 12:45:06 am
content: Quote from: Conrad Hoffman on September 17, 2013, 09:53:46 pmIt's simple supply & demand - limited market means all the dev costs get spread over fewer units. There's nothing inherently expensive about high speed sensors other than the low manufacturing volume.

author: MacAttak
author_rank: Unknown
timestamp: September 18, 2013, 04:36:34 am
content: Quote from: mikeselectricstuff on September 17, 2013, 05:51:11 pm$4,500 is classified as "affordable"?My wife would kick my arse if I ponied up that much for a KS pledge.

author: marshallh
author_rank: Unknown
timestamp: September 18, 2013, 04:37:42 am
content: Quote from: MacAttak on September 18, 2013, 04:36:34 am$4k is affordable compared to $50k... All about your perspective

author: peter.mitchell
author_rank: Super Contributor
timestamp: September 18, 2013, 08:35:24 am
content: Quote from: mikeselectricstuff on September 18, 2013, 12:45:06 amUnfortunately the supply-demand thing is probably a bit of a chicken-egg problem too, Eg, there'd be far more demand if they weren't 50k.As for $4k, I think thats very affordable for a lot of people, and probably a reasonable price for a commercial product, however, In the specialty quantity of these units, I think that their pricing is a lot more volatile.

author: amyk
author_rank: Super Contributor
timestamp: September 18, 2013, 10:09:11 am
content: Quote from: marshallh on September 18, 2013, 04:37:42 amI think they're still overdoing it with the "wank factor". Lose the fancy aluminium case, individualised laser engraving (note how the MAC address for most devices is usually on a sticker...), audio import (unless it does high speed audio too...!) and one of the USB ports, and you can probably get below $2k. Which is still more than enough to buy a hundred USB webcams...

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: September 18, 2013, 07:13:32 pm
content: People are always looking for something they can make a profit on, and this seems like an ideal candidate. The place I work would probably buy a 20 kFPS camera for $5k tomorrow, if such a thing existed. The same goes for thermal cameras, stupidly expensive for any decent resolution and the ability to focus closely on small targets. I'm not smart enough (or maybe motivated enough) to design either, but there are lots of people who are and could make a very nice business out of it. My guess is the minute they started eating the big guy's lunch, they'd be bought out for a handsome sum. Certainly the demand would be there if the price were reasonable, and I'm not talking web cam prices.

author: marshallh
author_rank: Unknown
timestamp: September 18, 2013, 07:50:39 pm
content: Quote from: amyk on September 18, 2013, 10:09:11 amIf you're offended they're making a profit, design your own and undercut them.They're not dumb, they know the image that is expected of kickstarter projects, and are appealing to that.

author: mrflibble
author_rank: Super Contributor
timestamp: September 18, 2013, 08:13:17 pm
content: Well, "image that is expected of kickstarter projects" seems to be coincide with "wank factor" fairly well in quite a few cases.Other than that, an affordable thermal imager as mentioned with usable resolution would be interesting. I'm sure there are quite a few on here that would love to check out thermal images of PCB + housing of their projects.

author: JoeyP
author_rank: Frequent Contributor
timestamp: September 18, 2013, 08:28:07 pm
content: Quote from: mikeselectricstuff on September 17, 2013, 03:23:51 pmThanks for pointing this out. I've been looking for an inexpensive high-speed camera for use in troubleshooting pick-n-place and other automation systems for a while. It's too bad they limit the resolution to 224x64 @1000 FPS, but I think it will still be useful, and the price is certainly right. Maybe the next gen will improve the resolution.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 18, 2013, 11:25:06 pm
content: Quote from: JoeyP on September 18, 2013, 08:28:07 pmI'd be surprised - they have been out for a while so maybe they don't see demand for anything faster - one problem as you head much above 1000fps is lighting becomes increaslingly hard

author: JoeyP
author_rank: Frequent Contributor
timestamp: September 19, 2013, 12:07:26 am
content: Quote from: mikeselectricstuff on September 18, 2013, 11:25:06 pmI'm content with 1000 fps. It's the resolution that I'd like to see increased. But, that would require more high-speed memory resident in the camera.I did look at some of the example videos on the net, and recognized that lighting is critical. But, for my apps I can use intense spot lighting if needed.I hope they are seeing demand. With some additional resolution those cameras might have some amazing applications in industrial control etc. The compact versions are quite cheap. I saw them new on ebay for as little as US$219.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 19, 2013, 12:30:41 am
content: Quote from: JoeyP on September 19, 2013, 12:07:26 amBandwidth is the limiting factor, which imposes cost barriers in terms of interfacing and either memory (both speed and capacity) or throughput for compressionA higher-res 1000fps would also be able to do even higher rates at lower res, but then you'd need silly lighting. Therefore the "headline" spec of the highest framerate wouldn't be very useable.Another factor is that the choice of media (SD card etc.) imposes a pretty finite limit on bandwidth, unless you have a ton of RAM.Also, as you go up in framerate, the number of everyday things that move quickly enough to be interesting at that rate reduces significantly, again reducing possible market.

author: mechknoll
author_rank: Contributor
timestamp: September 19, 2013, 06:42:16 am
content: If they used an EMCCD for the detector lighting becomes not a big issue.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 19, 2013, 11:47:01 am
content: Quote from: mechknoll on September 19, 2013, 06:42:16 amBut cost does - I don't know enough about EMCCDs (electron-multiplying, like a photomultiplier) to know if fast readout is possible, but combining two exotic image sensor technologies is not going to be cheap

author: Rasz
author_rank: Super Contributor
timestamp: September 19, 2013, 01:41:52 pm
content: About that Stanford experiment with webcams - you dont need to sync them in hardware, you dont even have to worry about clock drifts.All you need is a fast marker (lets say a 10K rpm motor with a colored plate) in the picture for use in post processing to sort frames.I could totally see an array of 10 Casios shooting 10K fps clip

author: JoeyP
author_rank: Frequent Contributor
timestamp: September 19, 2013, 05:27:59 pm
content: Quote from: mechknoll on September 19, 2013, 06:42:16 amThey use CMOS rather than CCD sensors. From what I read, CMOS sensors are supposed to be more sensitive than standard CCD sensors, but only marginally so.