DIY Backscatter X-Ray Machine

This is pretty badass. A guy built his own backscatter X-Ray machine using stuff off eBay (x-ray tube, scintillation screen, photomultipler tube) and some home-shop CNC machined parts.

He demos it as if it were an airport machine, but backscatter X-ray has rather more applications: it lets you do X-ray imaging without needing access to the other side of an object. I suspect a higher-power version for safecracking would be possible, and land-mine removal folks could probably just use this one.

Another cool part is the mechanical scanning. It uses a spinning horizontal disc with slots radiating out of it as apertures: as the slots pass across the x-ray exit aperture, the x-ray beam gets scanned across the target.

“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 measures 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.”


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