New Scientific Applications

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Figure 3. Using a 45 x 60 mm field of view and two RF500 flashlamps, a 16-channel SIM camera records the impact of a 25 mg projectile.
An application study demonstrates how technological advances in ultra-high-speed imaging technology are opening the door to scientific breakthroughs in a growing number of fields.

For space impact studies, like the analysis of hypervelocity impact into regolith simulant material, a 16-channel version of the SIM camera was used with variable inter-frame time (from 10μs to 25μs) and 20 ns exposures (see Figure 3). Two RF500 flashlamps created the backlighting, and the field of view was approximately 45 (H) x 60 (W) mm.

Under vacuum conditions, a 25 mg projectile impacted regolith simulant at 2.8 km/s. An electrothermal gun accelerated the particle, and the camera was triggered by the shot with a preset time delay. The total imaging sequence was 400 μs. Details of the ejecta cloud and the rebound of the projectile can be seen clearly in Figure 2. The multiple exposure capability of the camera, used in the first two images of the sequence, allowed an accurate measurement of velocity to be taken.

Studies of microscopic phenomena have also traditionally been a problem with earlier generations of high speed cameras, due to the often small working apertures and limitations of the optical systems when used with collimated light. The SIM camera optical design has made it possible to fit high magnification lenses or interfaces to microscopes without the need for additional optics. Therefore, studies of micro-phenomena, such as cavitation in micro bubbles, material studies on nano-materials, or micro exploding bridge wires can be hassle free.

Conclusion

Ultra-high-speed cameras have come a long way since the analog devices such as the Hadland IMACON700 and Cordin rotating mirror camera. With advances in electronics, and especially in FPGA technology, the cameras are getting smaller, faster, and much more reliable. It is important for the camera manufacturers to make these systems easier to set up and provide a robust triggering system so that cost of the experiment is controlled and data is captured each and every time. The next generation of cameras must give even more images at the very highest rates and even better sensitivity.

This article was written by Wai Chan, managing director at Specialised Imaging Ltd. (Tring, UK), and Keith Taylor, Technical Director of Specialised Imaging Ltd. For more information, visit http://info.hotims.com/34452-155.