Multi-Stage Air-Gap Fiber Optic Probe

Multi-stage air-gap fiber optic probe (MAFOP) is used to measure detonation velocity for solid and liquid explosives. The MAFOP is made of plastic fiber with 0.8 mm in diameter, 10 meters in length and 0.25 in numerical aperture. There are four holes drilled on the input end of the fiber which are used as the air-gaps of the probe. The diameter of the holes is 0.25 mm and the distance between holes can be changed as needed. When the air-gaps of the MAFOP are inserted into the solid or liquid explosives and detonation wave propagates and reaches the probe, the air-gaps will light intensively. The output ends of the fibers are put on the slit of image converter streak camera. A transient analyzer consisted of photocamera and micro-processor stores and processes the image data on the image tube phosphor screen. The measured results used MAFOP for TNT/RDX (40/60, =1.70 g/cm3) and nitromethane are presented in the paper. The results also show that the MAFOP is very useful in studying of explosive detonation when combined with image converter camera.