Applied Science - 2012-11-27
I'll be presenting this work at EHSM: http://ehsm.eu/ I built an X-ray backscatter imaging system from parts found on eBay. This system works by scanning a very thin beam of X-rays across the target, and measuring the amount of backscatter for a given beam position. The beam is scanned mechanically by a rotating chopper (collimator) wheel, and by tilting the rotating wheel on an orthogonal axis. The output image is generated on an oscilloscope by matching the horizontal scan speed to the rotating wheel, and using a potentiometer to measure the vertical axis position. The scope's brightness (z axis) is controlled by the amount of backscatter signal received by a large-area detector. Thus, the image is constructed bit by bit. I used a long-exposure shutter on my camera to see the image formed by the moving oscilloscope trace. http://www.google.com/patents/US5181234
Impressive job.
My thoughts on the application of this as the name of the channel stated:
1. Exposure - compton scattering or backscatter means that you need high exposure or at least, large area of exposure (to the human body). That means, higher radiation doses.
2. Cost - The SIZE of the detector you'll gonna have for practical application means a lot of costs.
3. Shielding - Imagine this on an airport. Since your dealing with scattering, it is literally scattered all over the place. that's why an appropriate shielding is needed for airports. Cost too.
Most of these machines were removed on public airports (US and UK) due to some of these reasons.
Source: I'm a Linear Accelerator Tech.
Making this video and information public is going to have such far-reaching benefits for aspiring hardware enthusiasts all over the planet, especially as the internet spreads out. Way cool! Congratulations on being part of an awesome societal project to break down the barriers of what just a handful of humans can do when information is shared! Woot!
A big RC servo would be a quick & easy way to do the tilt. But I'm sure you're the sort of guy who would prefer to machine your own gears out of plate....
It just amazes me that someone is capable of building their own xray backscatter machine in their workshop. More impressive is the simple way in which you have been able to record the output
Very interesting project- very solid overlap of physics, mechanics, electronics, and a hefty dose of clever.
I am somewhat a recent subscriber of yours and was searching for xray optics or something that uses passive xray. You were years ahead XD
@Logician Writer because all you'd get each time you take a photo (assuming the camera is even sensitive enough) is a glowing area where x-rays are hitting the screen. There's no way to focus the x-rays being scattered back to the detector so you need the combination of scanning from the rotary aperture and the oscilloscope to do the same kind of "image processing" that an optical lens does. All the information you'd get without that processing is 'there's something in the way of the beam.'
Good idea! My original plan was to use an FPGA to fill a framebuffer, and output VGA or HDMI. I'd still like to do this, but the soundcard idea is probably more effective and easier in many ways. Hmm
Interesting. I worked with X-Ray imaging for Food Systems both Conveyor and Pumped food through a detection Window and to the detector array. That technology involved using a Collimator (?) for not focusing but only allowing the X-Ray beam into a thin line. That matched the detector width and the scan rate of the Detector Array and was dependent on the speed of the Conveyor or speed of the substance with a Pump system. It was not a backscatter setup but Emitter and Detector synchronized image. Airline Baggage scanners used this technology 30 years ago.
Materials with a low atomic number (water, plastics, etc) will scatter lots of X-rays, so there will be more signal from them. High-Z materials like metals will absorb more X-rays and backscatter fewer, so they will emit less signal. Density is also a factor. My oscilloscope has a z axis input such 0V = full bright, 1.8V = dark. The PMT outputs a 0 to -2 V signal with 100K load resistor, which is just brought above 0 by the opamp without inverting.
could post your blue prints that help you make this ( the link) i think it would be to cool to see
this gave me a couple of ideas: using x or gamma rays, make an imaging device using a: an old flatbed scanner with the lamp removed. should get very high res images if the carriage is slowed down enough for the rays to directly blast the linnear ccd pixels. b: make an image using an alpha emitter on the toner drum of a laser printer. alpha particles should nutralise the static and cause ink to fall off, producing a negative image of some kind
I have a very old version of SolidWorks at home. I use SolidWorks 2012 at work.
Ben, you are the Renaissance man. You use physics, mechanics, electronics as if each was just a simple tool on your shelf. Every new video of yours is more impressive than the previous one.
Way less sensitive as they are just photodiodes, and have a fairly small area - a photomultiplier is many orders of magnitude more sensitive, and Ben's detector has tens of thousands times more detection area - in all you're probably looking at maybe a million to a billion times more sensitivity.
I recommend watching mikeselectric tear down of an airport xray scanner if you haven't already. It uses many small sensors to create a vertical line and then the scan rate is determined by the conveyor speed
After adjusting to Ben Kr'asnow level of awesomeness, this is still awesome.
You're correct with your assumption. Most front-driven cars have two opposing tapered bearings on each drive shaft, and then one in the drum brakes/hub on the back wheels. Personally I've never replaced the wheel bearings of a rear-wheel driven car, so I don't know how it goes there, unfortunately.
Very nice!
Wow. That is an awesome project. I have thousands of thoughts going through my mind at the moment ranging from "Wish I had a cnc milling machine" to "does the tilt scan distort the actual imaging compared to a worm gear straight up and down scan?"
I remember reading in a physics book some years ago about using Iridium as a x-ray lens. I have a home made x-ray machine but I never been able to get a hold of Iridium to test it with. It would be neat to be able to build a x-ray camera because the traditional "shadow puppet" technique of X-ray imaging has it limits.
Two-part answer for both questions: The amount of back-scatter you get is dependent on A) the density of the thing being scanned and B) the energy level of the x-rays. The tendency of denser (metal, especially heavy dense metals like tungsten) materials to scatter WAY more than lower-density lighter things (bones, flesh, clothing, plastics, etc) allows the TSA to find guns, knives, etc. easier. Also, back-scatter scanners can be lower-powered and can use lower-energy x-rays to get a good image.
the long exposure on the oscilloscope was smart as fuck.. wow
Very nice!.. Is there any detailed tutorial?
Most of these projects are pretty high tech and outside my pocket but of real interest .
Wow amazing 😮. So simple and it would never have come to my mind that way. But you could do the same with an IR-Laserdiode instead and no money IR-Sensor to create a lowcost structure-scanner, even the runtime-sigal could be additionaly derived to get 3D info out of it..... so I guess at least 😅
Very impressive skills Ben.
One way to cook Christmas dinner :)
Wish i had the patience you do. Really lets you do some frick'n neat things.
Genius. I got Smarter Today.
Tapered bearing at the front supporting the wheel end of the axle and a tapered bearing at the rear in the differential supporting that end.
They are mirrored. Did you not see the shinyness at 2:07 ? The outside is black to prevent light from leaking INTO the detector.
Keep working on this! Hope you achieve more resolution and less noise!
A chikkin' in a jumper! The last thing i expected to see on applied science. i can't stop laughing 😂😂😂 Great intro :)
You use photo-multiplier tubes in several of your videos. Could you point me to some literature on these, or consider making a video on their operation and use?
This is very rad. I was wondering, I know that the light from your scintillator is very dim, but could you do some crystallography or tomography by utilizing the angle of the reflected X-ray?
That's up there in the upper echelon of amateur projects. Kudos.
But that was a transmissive scanner, you would need both the detector and and the x-ray source to move together or have the person get moved by on a conveyor :/ I wonder if the sensors in Mike's detector are any more or less sensitive though, being engineered for the job.
That is fantastic. Excellent work a lot of time went into this, I know because I've been watching you progress. Keep it up we all enjoy the videos. ~Russ
You could use an electric linear actuator from somebody like LINAK for a smooth controlled scan.
I agree, but that's what engineers do. This is a little snicker at all the artsy people out there who think engineers are somehow "limited".
No idea, I'm afraid.
Hey Ben, I'm a big fan of the channel. This video is a few years old but if you have any interest in discussing this technology further then let me know and we can prior art. I currently do mechanical design work on backscatter systems for Rapiscan/AS&E.
Yet another incredible DIY project! great job!
So well done I'm speechless!
Very impressed with your project.
Hey, thanks for telling me, you can learn something new everyday!
This guy is like a batman of real life!
Why the photomultiplier tube and oscilloscope? Couldn't you capture a comparable image with a camera directly from the phosphor screen>
Ben Krasnow you are one top guy
I miss-spoke, low-mass atoms scatter a lot, high-mass atoms absorb a lot. (water is a good reflector, lead is good at absorbing.)
@RimstarOrg - 2012-11-27
Fantastic work, and crystal clear explanation! Thanks! Your use of a potentiometer for detecting the Y position (3:03) reminded me of how I tracked the X and Y positions of a pen for input to a TRS-80 computer for a high school science project.