July 3, 2008 -- According to a new research report issued by Specialised Imaging Ltd. (Hertfordshire, U.K.), researchers at the University of Michigan (Ann Arbor, MI, USA) achieved unprecedented performance levels using a dual-camera setup -- involving a simultaneous framing and streak camera in a single package -- to visualize nanoscale biomedical events.
The researchers, in the University's Department of Radiology, have long had a need to record the cycles of contraction and expansion of micro droplets and bubbles in a liquid medium when hit with an acoustic shock wave. The size and speeds at which these events take place make imaging such events a challenge: The acoustic wave in liquid travels at ~1500 m/s, and transition time through micro droplets is in the order of tens of nanoseconds. Cyclical events in the droplet occur in the sub microseconds and longer, thus the need for framing speeds of 1 million frames per second and faster and exposure time resolution less than 1 microsecond are required to stop and record the motion.
The report describes use of a SIM8-02 Ultra Fast Framing Camera (Specialised Imaging Ltd) and an Optoscope SC-10 Streak Camera (Optronis Gmbh) in a single package. Using this set-up, the researchers were able to achieve "performance levels never before achieved with a dual camera system," according to Specialised.
Framing data images in the report show extremely detailed two dimensional information of the full field of view. By comparison, the recorded streak images give a continuous record of time looking at a slit image of the diameter of the droplets. Both cameras together give a unique insight into the visualisation of biomedical micro and nanoscale events.
Recording simultaneous ultra fast two-dimensional and time-resolved images is of significant interest to scientists in a growing number of fields. Traditionally such measurements have been accomplished by the use of two independent imaging systems looking at the event at slightly different angles of view or through external imaging beam splitting optical configurations that can limit light collecting efficiency, says the company. More recently cameras with built in imaging beam splitters allowed for streak tubes and their electronics to be fitted into the same camera body as the framing electronics. These systems limited the versatility, primarily of the streak functions, as the designs necessitated that they used small streak tubes with small photocathodes and output screens and had closed fixed relay optics between the objective lens and the slit input to the streak tube.
Incorporating a supplementary optical port, that uses a beamsplitter to deliver 50% of the primary image to an image plane, the SIM8-02 framing camera allows secondary instruments such as streak cameras, high speed video or time resolved spectrometers to share the same optical axis as the framing channels. Using this supplementary optical port facility the SIM8-02 was integrated with an Optronis SC-10 Optoscope streak camera to give a true no-compromise simultaneous framing and streak camera system.
Benefiting from the SIM8-02 f2.8 imaging beamsplitting optics, the simultaneous framing and streak imaging system was able to deliver a distortion-free image of the primary image to 8 separate output ports where ICCDs are used to capture 8 individual frames of the event at framing rates up to 2 Billion fps and exposures as short as 500 picoseconds. Using the SC Optoscope streak camera fitted with the Slow Streak electronics unit the new simultaneous framing and streak imaging system is able to give streak speeds from 330 ps/mm to 5 ms/mm.
Specialised Imaging Ltd. is a knowledgeable, dynamic company focused upon design, manufacture, service and supply of ultra high-speed imaging systems and components for industrial, military and scientific applications.