This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Most conventional methods of ultrafast photography use evenly spaced intervals in which images are taken, but new developments have shown how much can be left out of the story, especially when multiple timescales are involved. Ultrafast events, such as a laser pulse or shock-wave emission, can be captured using ultrafast imaging.
Conventional methods of imaging operate on microsecond (millionths of a second) or millisecond (thousandths of a second) timescales and usually have a set, evenly spaced—or mostly evenly spaced—interval in which images are taken. While this can work to capture some characteristics of the ultrafast event, not every important and observable dynamic happens at neatly spaced intervals. To address this, a team led by associate professor Keiichi Nakagawa of the Department of Bioengineering at the University of Tokyo developed a method to capture these unseen instances by focusing their limited image captures on the times during which dynamic changes take place, using logarithmic ultrafast photography and band-resolved individual delay generation (BRIDGE).
The work is published in the journal Optica. Logarithmic ultrafast photography is a process that distributes a set number of single-shot frames across a period of time, timed to correspond to moments of characteristic importance in the target occurrence. The team developed this technique to better capture instances otherwise unseen due to their speed of reaction and the shortcomings of conventional techniques.
The concept of logarithmic ultrafast photography is implemented in sequentially timed all-optical mapping photography, or STAMP, which offers high image quality and ultrafast operation, using BRIDGE. BRIDGE extracts wavelength bands sequentially and allows for the independent adjustment of these bands while maintaining the ability to map them to specific instants during the dynamic process. Within this process, a finite number of frames can be placed across femtosecond (quadrillionths of a second) to nanosecond (billionths of a second) timescales.
With BRIDGE, timing control is accessible across timescales and can enhance observation of what normally occurs too quickly to be seen. "We wanted to find a way to connect these very different timescales in a single measurement. In other words, we wanted to see both the first instance and what follows, without having to choose one or the other," said Keitaro Shimada, a postdoctoral researcher in the Nakagawa Group and lead author of the study.
By customizing the intervals between frames when taking ultrafast images, researchers are able to slow down key moments that might otherwise be missed with regular intervals, allowing the beginning of an ultrafast event to be captured in addition to what follows immediately afterward, in one shot. This technique allows for 11 frames to capture the key instances across five orders of magnitude in time—from around 100 femtoseconds to 10 nanoseconds. Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly.
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