Specialised Imaging has achieved ground breaking results using its SIM High-Speed Framing Camera, specially optimized to capture ultra-fast events in the ultraviolet (UV) spectrum. Featuring a UV optical module and a UV-intensified CCD, this advanced camera system operates across the 200–600nm wavelength range, delivering crisp, detailed images at rates of up to one billion frames per second (1 Gfps).
Keith Taylor, Technical Director at Specialised Imaging, explained, “We’re excited to see the extraordinary research being carried out with our UV-optimized SIM cameras. Capturing the spark discharge behaviour inside high-voltage transformers events that last only a few tens of nanoseconds is one of the toughest challenges in imaging. Working closely with our client, we showed how the SIMX-16 UV camera could trigger with minimal delay and had the light sensitivity needed to capture these extremely brief, self-illuminating events.”
Capturing One of the Fastest Events: High-Voltage Spark Discharge
In the featured project, the team set out to capture a high-voltage spark jumping between a brass disc anode and a metal plate cathode. These sparks are incredibly brief, visible for just 10–20 nanoseconds. It is one of the fastest naturally occurring events that can be imaged, rivalled only by laser pulses.
Capturing such a fast event involved two major technical challenges:
- Accurately triggering the camera at exactly the right moment.
- Protecting the camera from high-voltage electromagnetic pulses (EMPs) that could damage sensitive equipment.
Smart Triggering: Pinpointing a 10-Nanosecond Spark
As the event happens so quickly, traditional triggering methods (which often involve signal conditioning) would cause too much delay. Instead, Specialised Imaging used a simple induction loop, a wire coiled around the experiment’s high-voltage trigger line. This produced an instant, safe trigger signal (up to 50V) with virtually no delay.
Even with the right trigger setup, finding the spark in time required a careful strategy. The SIMX-16 camera is equipped with 16 independently programmable channels. Here’s how they approached it:
- Channel 1 was set to a longer exposure time (10 microseconds) to increase the chances of catching the initial spark.
- Channels 2–16 were configured to take shorter, staggered exposures immediately following Channel 1’s trigger, effectively slicing the longer window into finer snapshots.
- By reviewing which channel captured the spark, the team could then narrowdown the correct timing and progressively refine exposure settings.
- With each successful refinement, exposure times were reduced, and the trigger delay was adjusted until the spark was captured precisely and clearly.
Careful gain adjustment for each channel ensured that the intensifiers weren’t damaged by the brightness of the spark.
Protecting the Camera: Beating High-Voltage Hazards
High voltages don’t just threaten to damage equipment through direct sparks—they also produce powerful electromagnetic pulses (EMPs) that can harm sensitive electronics.
To protect the SIMX-16 during the experiments:
- The camera was housed inside a Faraday cage, which shields against electromagnetic fields.
- Fibre optic communication replaced traditional metal Ethernet cables, avoiding EMP vulnerabilities.
- The power cable was run inside copper mesh trunking, extending from the cage to a distant mains socket, keeping the system isolated from electrical surges.
Beyond Sparks: Other Cutting-Edge Applications
Specialised Imaging’s UV-optimized SIM cameras aren’t just for spark studies. They’re also being used to:
- Capture short-duration flashes from sonoluminescence experiments (where tiny bubbles emit light under ultrasound).
- Study plasma behaviour used to modify the electrical properties of polymer films.
Thanks to continuous innovation, the SIM camera range is now recognized globally as a leader in ultra-high-speed imaging. With gating times down to 3 nanoseconds and the ability to capture events at up to one billion frames per second, these cameras allow researchers to explore and analyse phenomena that were once too fast to see.
