digital fluoroscope

Digital Fluoroscope

First prototype was arranged in an open top cardboard box. X-ray interference was bad. I arranged some steel shielding and experimented with mirror placement so I could get the camera out of the x-ray beam. I still had a lot of trouble with backscatter. Focus was difficult. Fixed-focus cameras had poor light sensitivity and were not sharp. Autofocus cameras could not work in the dark. Scintillating screen was old and poor quality.

I discovered a good camera that was intrinsically redistant to x-rays, Logitech c910. This camera also allows manual focus, so I could set focus in the light and keep it focused in the dark. I moved my equipment upstairs where it was easier to work on and shield.

Second prototype was made in a 9*9*9 cardboard box. Fully enclosed with c910 fixed behind screen. Camera was directly in the beam. X-ray noise was reduced with applying a median filter to multiple exposures. Focus was set with box open and lights on. With box closed I set previously established focus.

Third version is made with two 9*9*9 cardboard boxes. All surfaces were sprayed with matte black paint. Boxes were glued and tapped together with black gaffers tape -- $26 a roll! But this stuff is totally light tight. All seams and edges are tapped with black gaffers tape. I cut three inches off a 12 inch square mirror. This made an almost perfect 45 degree angle. Camera takes pictures to the side of the scintillating screen, outside of the direct x-ray beam. Camera is wrapped in lead foil. This also helps since the imaging chip surface now presents a less perpendicular target, so it has a smaller cross-section. External LED lights are used to illuminate a scale under the scintillating screen in order to allow focus calibration without opening the box.