Ultrafast movies get longer

Print edition : June 21, 2019

Images of the letter A written in dye, acquired at eight distinct wavelengths and at four different time delays: 0, 4, 8, and 12 picoseconds (ps). The technique captures both spatial and spectral information on the picosecond timescale.

Today’s fastest cameras can capture images at faster than a trillion per second rate. Despite this rate, they can only produce a handful of images in a single sequence when observing non-luminous objects. Engineers have now demonstrated a rate of nearly four trillion frames per second, capturing as many as 60 consecutive images. The technique should allow video analysis of ultrafast processes such as the interaction of light with eye tissue in laser surgery.

High-quality, fast cameras use semiconductor structures called CCD arrays to rapidly store image data before moving them off to longer-term storage. At the highest speeds, these cameras can only produce a handful of consecutive frames, mainly because of the limited CCD space. The images must be stored in non-overlapping sub-regions of the CCD, so increasing the number of images leads to a reduction in image resolution. To overcome this limitation, a research team led by Feng Chen of the Xi’an Jiaotong University, China, has exploited a technique called compressive sampling, which allows the storage of images in overlapping CCD regions. The research has been published in the latest issue of “Physical Review Letters”.