New Developments in High Speed Imaging to Aid Aerospace Testing

By Doreen Clark, Senior Product Manager, Vision Research

Issue 79

Comprehensively testing designs in aerospace can be complex and difficult.  High speed imaging lends a helping hand to understand the dynamics of designs, providing valuable information that may be otherwise difficult or impossible to gather. However, high speed imaging has its own inherent issues – it can require incredible amounts of light, can generate large amounts of data, and can incorporate trade-offs in camera size or features, for example, to achieve core frame rate and image quality capabilities.   

Vision Research, designer and manufacturer of Phantom cameras, has introduced cameras and features to help address issues found in high speed imaging, making the technology more useful for the demanding testing needs found in aerospace. 

Ultra-High-Speed 1Mpx family for ultimate speeds

Vision Research introduced the Phantom Ultra High Speed (UHS) family of cameras in 2013 and has since revised the platform twice to offer increased capability. The latest version has throughputs of up to 25Gpx/sec, or 25,000 frames per second (fps) at full 1 Megapixel resolution of 1280 x 800.  At reduced resolutions, the cameras can achieve up to 663,250 fps, or up to 1 Million fps with the export-controlled FAST option. If an application requires a frame rate of 200,000 fps, for example, a UHS camera can provide resolution up to 360 x 200 pixels to capture more of the event. The family has four cameras offering four levels of throughput performance ranging from 12 Gpx/sec throughput to 25 Gpx/sec throughput. Researchers can buy the level of performance they need immediately, and upgrade to higher performance if the need arises in the future. 

A challenge many high-speed imaging applications face is that as frame rates increase, they require significantly more light to see the image, although in many cases it is difficult to add more light. Therefore a high speed camera’s light sensitivity is very important, and the Phantom Ultra-High-Speed cameras were designed with maximum light sensitivity, achieving ISO ratings of 32,000D (monochrome) and 6,400D (color).  

Supporting the NASA Hypervelocity Lab

Phantom Ultra High Speed (UHS) cameras support many important aerospace and defense applications, such as the testing conducted at NASA’s Remote Hypervelocity Test Laboratory.  The lab simulates the effect debris has on space equipment and space suits.  To closely simulate the speed debris travels in orbit, the lab fires projectiles constructed of aluminum, nylon, and stainless steel at speeds over 25,700 km/hour, more than six times faster than a rifle bullet. The speed of impact is significantly faster than the human eye can see, so to record and analyze the impact the team uses high speed cameras. They incorporated a Phantom V2512 from the Ultra High-Speed family not only to leverage the camera’s 25 Gpx/sec throughput, but also its high light sensitivity.  The camera was able to capture shock waves in an impact as well as other phenomena in a low light experiments, helping the team specifically determine the improvements that were needed in space craft and spacesuits, and their components. 

Introducing the V2040/v2640 4Mpx Cameras for Ultimate Image Quality

In the beginning of 2018, Vision Research is introducing the Phantom v2040/v2640, a 4Mpx Ultra High-Speed camera built on the same platform as its 1Mpx cameras, to support applications that require very high image quality and detail. The v2460 provides exceptional image quality for more accurate analysis and flexibility to accommodate multiple requirements.  It can achieve up to 26 Gpx/sec throughput, or 6,500 fps at full 4Mpx resolution of 2048 x 1952. 

Image quality: The v2640 offers very high image quality for a clearer image and better analysis.  It performs CDS directly on the sensor, providing a very high dynamic range of 63dB and very low noise of 7.4 e-.  A high dynamic range provides more levels of variation in an image’s tones, so that more detail can be distinguished especially in the very dark and very light regions of an image.  Low noise equates to a cleaner image, allowing the small details of an experiment to be more visible and not obscured by flecks or spots in the image.  While performing CDS, the camera achieves a throughput of up to 20 Gpx/sec. Additionally, it has an ISO rating of 16,000D (Monochrome), and 3,200D (Color), the highest ratings in the industry for a multi-megapixel high-speed camera. Combined, these attributes give researchers who need high resolution, high-speed imaging a cleaner, more detailed image for analysis. The low noise benefit is most evident in the dark regions of an image, which are often the most difficult to analyze.  

Flexibility: The v2640 sensor is also equipped with a non-CDS mode (HS mode), to provide up to 34% higher throughput to achieve 26 Gpx/sec.  It may also employ 2x2 Binning on Monochrome cameras in either CDS mode or HS mode.  Binning converts the camera into a 1 Mpx camera with increased light sensitivity and throughput. For applications that require extremely low exposure times, an Export-controlled Fast option can be applied to both the CDS and HS modes, reaching as low as 500 ns in CDS mode and 150 ns in HS mode. All modes are selectable in software, and may be purchased according to need. Combined, these modes provide significant flexibility to accomplish a wide range of applications.  No other sensor offers as many modes and thus, as much flexibility. 

Programmable I/O: To increase flexibility in testing and experiments, the v2640 incorporates an internal pulse processor which supports programmable I/O, giving the ability to assign and define signals to manage camera activity.  Signals that can be modified include F-Sync, Strobe, Event, Pre-trigger, Memgate, Timecode-out, Ready, Aux, and Auto-trigger. In most cases the signal polarity, delay, pulse width and edge (rising or falling) can be set according to the needs of the application and interfacing equipment.  The ability to assign and define signals allows the camera to accommodate an application workflow more readily, giving ultimate camera control and flexibility. 

Flex 4k -GS:  Often, the observation of fine details from a distance requires high resolution. For example, seeing detailed shockwave movement from afar is a phenomenon that aerospace researchers typically require. In response to this need, the Phantom Flex4K-GS camera has been developed.  This modification of the well-known and highly acclaimed 4K resolution media camera means that research and development now has access to image quality not previously available.  The key component is the switch from a rolling shutter (low noise, improved visual quality for cinema) to a global shutter.  A global shutter, allows researchers to observe quickly moving and rotating events without producing classic rolling shutter image artifacts (e.g. the bending of helicopter rotor blades). Like the media camera, the Flex4K-GS will deliver 1,000 fps at 4K resolution (4096 x 2304), 1900 at 2K resolution (2048 x 1152), and 2930 fps at 1280 x 720.

Miro N-series:  The Aerospace industry is heavily influenced by structural size requirements for a variety of projects.  For this reason, the tiny Phantom N-Series is the best option for recording hard-to-access events. At just over a 1-inch cube (32mm x 32mm x 29mm) this camera can fit in the smallest spaces and still deliver quality images to researchers.  At full resolution (768x600), this tiny, but powerful device can deliver 560 fps and can reach over 9,000 fps at lower resolutions. Another benefit of the N-Series setup is that the camera head is attached to a base at the end of a long cable.  Using CoaXPress (CXP) the protocol ensures that every image is safely stored away from the camera head.  In potentially destructive environments, this means that the all required data and images are safe if the head is destroyed.  The camera head is easily replaceable in the field and does not require lengthy downtime. 

Features for Ease-of-Use

Often scientists and researchers are experts in their field of study, but don’t have time to become experts in high speed imaging.  Incorporating high speed cameras as a tool in research has its own challenges, so Phantom cameras have features to help alleviate those challenges.   

Data Management: As a high speed generates a large amount of data, the UHS cameras can be equipped with up to 288GB of RAM and have 10G Ethernet as standard.  10Gb Ethernet provides up to 500 MB/second download speed to an optimized system, significantly reducing download time compares to 1Gb Ethernet.   They also have an option for up to 2TB removable CineMag media.  These features provide researchers quick data downloading options for easier data management and faster results.    

Exposure Index: High speed applications are light starved. The higher the frame rate, the more additional light is required, so a camera’s light sensitivity, typically reported as its ISO rating, is important.  The sensitivity is a derivative of the sensor design and processing. In addition to the native sensitivity, post image processing can be applied through software to lighten images.  However, post image processing can be time consuming, and too much processing can add noise and lose detail in the image, rendering it less useful. Exposure Index, available in almost all Phantom high speed cameras, helps alleviate that.  Following the same concept found in many DSLR cameras, Phantom cameras have eight preset options to lighten an image while adding minimal noise. The options are based on adjustments of an image’s tone curve, rather than gain or gamma, and applies to both monochrome and color images. The example below shows the Ultrahigh-speed v2512, operating at 99,000 frames per second, with the lowest Exposure Index of 8000 and the highest of 40,000. 

About Vision Research: 

Vision Research designs and produces a broad range of high speed cameras to fit scientific, academic, and cinematic applications. For more information, visit www.phantomhighspeed.com.