Back Side Illumination Gets Fast

With speeds of over 1 million frames per second, high-speed imaging is an invaluable research tool capable of capturing the most fleeting events in scientific and engineering applications. 

High-speed camera technology is able to achieve a maximum gigapixel/second (Gpx/sec) throughput. This limitation can be manipulated by adjusting the trade-off of frame rate to resolution. For example, a 25 Gpx/sec camera reaches 25,700 frames per second (fps) at a resolution of 1280 x 800 pixels and can achieve a higher frame rate of 28,500 at a smaller resolution of 1280 x 720. Both combinations have almost the same throughput. Very high frame rates, such as 1 million fps, are restricted to very small resolutions, making it more challenging to see the subject matter.

As frame rates increase, the exposure time a pixel has to light decreases. At 25,700 fps, each frame has a maximum exposure of 39 microseconds (μs), and at 1 million fps, the maximum exposure time is only 733 nanoseconds (ns). The short exposure times require high levels of illumination to compensate for the short time the pixel receives light. In fact, many high-speed applications are light starved — meaning that, given the very short exposure times at high frame rates, the available illumination won’t deliver enough light to the camera’s imaging sensor to produce an ideal image and may even be impractical in certain applications. 

High-speed camera operators have become adept at balancing their need for speed and resolution with their need for adequate illumination. While they can capture spectacular images that advance the frontiers of scientific understanding and engineering analysis, the trade-offs become more difficult to manage as users push the boundaries of high-speed imaging.

New Sensor Drives High-Speed Imaging Improvements

Vision Research has made a technical breakthrough and developed a new high-speed image sensor that employs back side illumination (BSI) to increase the pixel surface area that can capture photons. Because it’s more effective at capturing light, the BSI sensor is better suited for applications requiring high frame rates as it eases the speed-resolution-sensitivity constraint. 

This new sensor debuted March 2021 in our new Phantom TMX cameras, the fastest of which — the TMX 7510 — can shoot 76,000 fps at a full resolution of 1280 x 800 pixels. In this camera, we’ve increased throughput — or the maximum frame rate times maximum frame resolution — by a factor of three times compared to previous generations of high-speed CMOS imaging sensors.

Be on the lookout for upcoming posts that explain how BSI works, as well as the challenges and benefits of using BSI sensors for high-speed imaging. In the meantime, visit our TMX product page to learn more.