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Making a Homemade Webcam?
Space-Bot asks: "I remember back in high-school photography the simple and very basic homemade cameras that we made that surprisingly worked fairly well. Amazing how something so great started so basic. These days we have all these high tech gadgets that do it all so quickly you never really think about any of the work behind it. Well I would like to start to understand the modern digital cameras more and I figure what better way then to make a homemade webcam of some sort. Might some of you Slashdot guru's have some ideas or experience for my project?"
That's about as home-made as you can get, given how cheap "real" (but crap quality) USB webcams are these days.
Got time? Spend some of it coding or testing
...like this guy. You can't get much closer to making your own webcam than this. It's not like you can print a CMOS Image Sensor from your bubblejet.
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Take the linear CCD array from it, add some mechanics, and with some luck you can get nice (in the range of megapixels) images.
These guys did it already: here and here
Better than a webcam, and pretty good for understanding how digital imaging works.
A home-made webcam is so far different from the type of pinhole camera that was likely made in school that it's not even funny.
It's one thing to make a cardboard box which uses some fairly standard physics to project an image on a chemical-coated piece of paper which can then be processed. Everything is big, can be made and handled by hand, etc.
With a webcam, it's not exactly like you can whip up a CCD, various other ICs, the code to run it, etc. Almost none of this can be done by hand, and it requires a extremely high level of knowledge to do it all. In fact, it's very unlikely that any one person has ever possessed all of the knowledge to make such a device.
This is like saying "well, since it's not hard to make a simple steam driven piston type engine in a metal shop, why doesn't anyone piece together an electronically controlled fuel injection engine?
Everyone keeps talking about how you can't make your own CCD chip. I don't know that that's what the poster intends. There's a lot more to creating a web cam than simply the CCD chip. First of all, you can buy CCD chips from a number of sources. You'd then need the associated logic.
Actually, a number of Astronomy hobbiests are into doing just this sort of thing because astronomy quality cams are quite expensive. A number of people have used regular web cams for astronomical work, usually with long-exposure modifications to the cams, with a great deal of success.
A team of French hobbiests created this Genesis cam from scratch. It's very impressive and better quality than most of the hobbiest level cameras you can buy since it's based on a very high-resolution and very light-sensitive CCD chip.
But if you want to create just a basic web cam, there are much cheaper CCD chips. The datasheets will probably give you enough of an idea for how to get started with a project.
It's worth pointing out that *any* silicon chip is light sensitive. The advantage of the memory chip is that it has a large array of identical components which are effectively your pixels.
When you are making light sensitive devices on a CMOS process (rather than a CCD) you will often use photodiodes. A diode is just a pn junction so, strictly speaking, a photodiode is a diode that is exposed to light.
I make camera chips on CMOS chips and we have to use the top metal layer to shield everything apart from the photodiodes from the light. Shame really, it doesn't look as nice under a microscope!
Cheers,
Roger
Do you have any better hostages?
Lots of people are saying you can't build the chip yourself. That's not exactly true.
Go through CMP and you can get say the AMS C35B4C3, a 0.35um 4 metal, 2 poly CMOS process, for 650 Euro/mm2. I'm sure lots of people will cringe at the 0.35um, saying that it is ancient. Well, maybe in digital terms, but it is quite nice for analogue/mixed chips imo. 0.8um is still around (290 euro/mm2)!
Alternatively, if you are part of an Educational Institution or Research Laboratory, how about the ST Microlelectronics 0.18um CMOS process for 990 euro/mm2?
Now get hold of a copy of Electric some spice or other and learn how to design design electronic circuits. geda may also be of interest.
That last step might take a while.
Design your chip, submit it to CMP, wait three or four months and you'll get it back. Now go on to do what the other comments are talking about with pin hole cameras etc.
Let's do a rough price breakdown. Suppose you want VGA (640x480) in grey scale. Let's also suppose you can get your pixel element down to 5um*5um (which would be quite small imho). This gives:
Width: 640*5um + 2*400um = 4mm
Height: 480*5um + 2*400um = 3.2mm
The 400um gaps are for the pads on each side. This doesn't include any other electronics, so let's just say it is 4mm*4mm = 16mm2.
You need packaging as well and are probably limited to JLCC packages because it needs to be exposed to the light. Let's assume a JLCC68 package. You get 20 chips back and each package costs 48 euro.
So, 16*650 + 20*48 = 11360 euro. Put another way, 568 euro per chip. Don't forget to add VAT if you pay it. For the UK, this means 9343 or 476/chip.
Now consider that 16mm2 is still a small chip (and colour would be at least 3 times larger). If you have access to a webcam and can get inside it to look at the light sensitive area, measure it and figure out how much it would cost!
Cheers,
Roger
Do you have any better hostages?