Analytical Technologies Singapore

high speed camera

How to Capture an Event when the Whole Experiment Destroys itself?

Ariane group has kindly permitted Specialised Imaging to share a sequence taken of a shockwave travelling through an energetic material. The sequence was captured by the Specialised Imaging KIRANA ultra high-speed camera running at 5 million frames/second.

Capturing shock waves travelling though solids is an application often captured by the KIRANA camera. Another example can be seen via the link below, where shock transmission through concrete is visualized using Digital Image Correlation analysis of the images:

Kirana05 – Digital Image Correlation: Split Hopkinson Pressure Bar impact on concrete 2M FPS (youtube.com)

However, there are two significant differences between the two applications. One is the hazardous nature of energetic materials, and the other is that energetic material shocks are generated by a primary (donor) charge that detonates adjacent to the acceptor material. This presents two issues, firstly the whole test set up is destroyed. Secondly, the self-illuminating nature of the donor can saturate and obscure the acceptor with light.

So how can the over brightness (saturation) generated by one area of the set up be mitigated to clearly capture the area of interest which is not self-illuminating and significantly darker? There is rarely enough camera sensor dynamic range to allow one exposure time setting to reduce the saturation affect, while also allowing a bright enough image of the darker area of interest.

One step to achieving a usable exposure time is to add supplementary lighting to raise the brightness of the darker region to a level closer to the self-illuminating region. For this application the light generated by the donor charge is significant and too hazardous for expensive lasers, LED’s or flash lamps, so for these tests a sacrificial argon “flash-bomb” was used to deliver the supplementary illumination required. It was placed very close to the event and generated significant light for tens of microseconds. Whilst this illuminates the area of interest sufficiently to allow a short enough shutter to freeze motion blur – it does not “balance” the lighting enough to stop the over saturation of light from the donor charge.

For the sequence below the answer was very simple and made possible by the microsecond timescale of shock transmission: A piece of cardboard was placed between the donor charge and camera field of view to obscure the flash and hold back the products of the detonating donor charge for long enough to see the shock transition. Since everything in the test area is destroyed, using cheap and easily available materials is paramount – and sometimes the solution can also be very simple.

KIRANA Detonic shock 5Mfps Ariane (youtube.com)

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Supersonic Electrical Discharge in Water

Researchers at Loughborough University have been using a SIMX framing camera at frame rates up to 100 million frames / second to capture the initial stages of supersonic electrical discharges driven by nanosecond rise time, high-voltage ( 100 kV) impulses applied across a pair of electrodes mounted in water.

This research in high voltage breakdown in water, has progressed our understanding of how high-power ultrasound waves generated in a liquid by a high-voltage pulsed source can be used for industrial applications such as rock fracturing or in the medical or food industry domains to kill bacteria in a sterilisation process. The SIM camera was contained within a Faraday cage and viewed the electrodes mounted in a water tank. Pressure variation with different voltage rise times and interelectrode gaps were measured using a set of hydrophones placed 0.5m from the source.

This sequence shows results for an electrode gap of 3 mm and voltage rise time of 30 ns which corresponded to a streamer propagation speed of 63 Km/s and a peak pressure of 0.25 MPa.

Consistent peak pressures between 0.1 MPa and 1.1 MPa were found for inter-electrode gaps between 1 mm and 12 mm. The research concluded that the inter-electrode gap had a significantly greater effect on peak pressure than rise time for the same input energy.

The SIM camera’s nanosecond timing accuracy provided the flexible delays and exposure times required to capture and freeze the motion of these extremely fast events. To accommodate the different illumination conditions required to see both the source electrodes and the event, the camera control software “image merge” feature was used to overlay a static sequence, which used longer exposure times, with the dynamic sequence which used much shorter exposure times.

These merged images provide context and the relative positions of the event and electrode for all the tests.

Congratulations to Jessica Stobbs for receiving the EAPPC (Euro-Asian Pulsed Power Conference, Seoul, S. Korea, 2022) outstanding Young Researcher Award with this research.

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Advancing forensic interpretation of ballistic wounds

Ultra high-speed photography has been used by scientists at the Massachusetts Institute of Technology to study high-velocity micro-particle impact on gelatine and synthetic hydrogel. Potential advancements are, guiding the design of drug delivery methods using accelerated microparticles and the assessment of explosive–related injuries for better forensic interpretation in cases where fragments originating from explosions can cause severe tissue damage injuries. Micro debris, which typically travels at supersonic velocities, can cause serious injury by penetrating deep into tissue where it is hard to detect using standard medical imaging methods.

Multi–frame sequence showing a high-velocity impact on 10 wt% gelatine at 1290 m/s.

The research investigates the high-velocity impact response of gelatine and synthetic hydrogel samples using a laser-induced microparticle impact test platform for launching and imaging supersonic micro-particles travelling up to 1,500m/s. The micro-particles, typically less than 10um in diameter are captured prior and during impact penetration into translucent gels using a Specialised Imaging SIMX16 ultra high-speed multi-frame camera, capable of recording up to 16 images with nanosecond interframe time and short exposure times (down to 3ns) to stop motion blur. Illumination was provided by the Cavilux 640nm wavelength laser.

The impact response was quantified using the images by measuring pre-impact velocity, particle penetration depth and charted against time. These results were compared against a Poncelet predictive model for different gelatine samples. Further tests and measurements were conducted using an engineered protein hydrogel to investigate whether the Poncelet model could be applied to other soft materials which might be expensive to manufacture or otherwise in short supply.

The results indicate the Poncelet model provided a reasonable prediction of micro particle penetration and could offer an initial estimation of deformation of soft materials at high strain rates in more complex models.

See the Research Article here >> https://www.specialised-imaging.com/application/fi…

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Triggering for microsecond accuracy

Accurate triggering of framing cameras to capture fast events is one of the crucial aspects of high-speed imaging. Adding more instrumentation such as streak cameras and flash illumination can lead to a complex array of instrumentation, particularly when it comes to synchronising all aspects of data capture for one single microsecond timescale event.

Specialised Imaging’s SIM framing cameras can greatly simplify this trigger synchronisation process, with a built-in timing generator and control software to set up trigger outputs to these external devices.

If a streak camera is used to capture the same event it can be connected to the SIM’s (optical) auxiliary port and connected to the SIM’s trigger output to allow the streak camera trigger delay adjustment via the SIM camera control software. Any flash illumination can be connected to the SIM’s dedicated flash trigger (output) connection for timing adjustment also using the camera control software.

This application note describes how a SIM camera was used to capture energetic events, where microsecond accuracy was required. The SIM camera was used to trigger synchronise a streak camera and flash unit to capture images for detonator case expansion and tip velocity measurement.

Read the application note

Camera: SIMX-8 Resolution: 1280×960 px Exposure time: 100nS Interframe time: 4.27uS Frame Rate: 234K FPS Event: Detonator Illumination: Back illumination – AD500mage: New and old SIM (8 channel) camera design

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SIM Cameras now optimised for Ultra High-Speed Multispectral Imaging

Specialised Imaging’s latest version of the SIM ultra high-speed framing camera is making multispectral imaging simpler with the option of user interchangeable filters.

Specialised Imaging is continually evolving its products to meet new and challenging requirements. In response to increased requests, the latest evolution in the SIM cameras makes it simple to interchange standard size filters for multispectral imaging – capturing different wavelengths on each channel. Multispectral imaging was possible on previous SIM models, but the new SIM design simplifies the user exchange of filters for all channels.

This evolutionary step in the SIM camera design was driven by requests in the field of energetic materials research. Using filters in a camera allows researchers to obtain spectral, spatial and temporal information for comparing different energetic materials by focussing on the different spectral signatures. The nature of energetic materials mean you need an ultra-fast, light sensitive camera that can respond to a broad range of wavelength to provide a flexible solution for this and other applications.

Users can now easily interchange filters on all eight channels. The SIMX camera captures one high resolution image per channel, offering the potential to capture 8 mono/filtered images and potentially two monochrome and two full colour images using red, green & blue filters. Similarly, the SIMD camera captures two images on each of its eight channels, offering the capacity to capture 16 mono/filtered images, or four mono and four full colour images. By responding to our customer input and requests, this capability expansion of the SIM cameras continues to support new and novel applications for the advancement of research.

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Streak / Framing Camera Provides Unique Insight into Nano Events

Researchers on several projects have successfully used Specialised Imaging Simultaneous Multichannel Framing Camera and Streak Camera Systems to provide unique insights into an ultra-fast events.

Specialised Imaging ultra-fast camera systems offer scientists involved in electrical discharge, biomedical and energetic events research the potential to simultaneously record framing images and streak images.

Ultra-fast imaging and simultaneous streak image capture offers a unique insight into transient events that cannot be achieved with single-point measurements. Ultra-fast framing images show extremely detailed two-dimensional spatial information about the event, whereas the streak image is a continuous one-dimensional record with picosecond temporal resolution. When combined these images provide a unique visualisation of transient nanosecond timescale events.

Specialised Imaging’s system enables researchers to couple a streak camera directly into the same optical path used in their SIM ultra-fast framing cameras. This innovation allows for the capture of framing and streak data on the same event using the same optical path for direct correlation of 2D and streak image data. The combination streak and framing camera has allowed researchers to attain higher performance levels using dual camera systems with different optical inputs. Benefiting from using a common optical input and dedicated output window, the Specialised Imaging Simultaneous Multichannel Framing Camera and Streak Camera system drastically simplifies optical set up and eliminates perspective distortion (parallax errors). Beneficially, the set-up also allows use of an existing streak camera which can still be used independently.

Capable of capturing data at 1 billion frames per second, the SIM range of ultra-fast framing cameras offer the ultimate in ultra-high-speed imaging performance to scientists and engineers across all disciplines. The proprietary optical design of SIM cameras offers up to 32 images without compromising shading, or parallax. High resolution intensified CCD sensors controlled by state-of-the-art electronics provide almost infinite control over gain and exposure to allow researchers the flexibility to capture even the most difficult phenomena. In addition to enabling simultaneous streak and framing experiments, the optical port on the SIM camera can be used to couple high-speed video cameras for longer record durations, or to integrate a mass spectrometer for hyperspectral

Case Study

Researchers at the University of Michigan used a Specialised Imaging Simultaneous Multichannel Framing Camera and Streak Camera System to capture images of bursting microscopic droplets releasing the fluid within by focused ultrasound, and ultimately understand how this process can safely and effectively be applied to the delivery of drugs within the body.

Read the case study

Application Note

Ultra-high Speed Framing and Streak Camera Imaging of C4 Explosive

The University of Rhode Island used a Specialised Imaging Simultaneous Multichannel Framing Camera and Streak Camera System in research to quantify the shock speed and qualify the axisymmetric detonation development of a C4 booster test piece.

Read the Application Note

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