Researchers at ARCNL and the Vrije Universiteit Amsterdam have developed a fiber-based microscopy system that beats the theoretical limits of resolution and speed. The method was developed with minimally invasive bioimaging in mind, but it’s also promising for sensing applications in nanolithography.
In conventional microscopy at the nanoscale, samples are often illuminated point by point to create a picture of the entire sample. This takes a lot of time, as high-resolution images require many data points. The approach developed by Lyuba Amitonova and Johannes de Boer uses a fiber that produces a speckled laser beam, which allows for simultaneous illumination of many areas in the sample in a random way. The multifaceted light reflected by the sample is then collected as a single data point, from which relevant information is extracted.
Key to Amitonova’s approach is the fact that not all of the information in a data sample is needed to create a meaningful image. “Think of digital photography, which uses the JPEG compression format to limit the amount of data in a picture. The compression removes up to ninety percent of the image, but we can hardly see the difference,” she says. “This works because all conventional images of real-life objects are ‘sparse’, which means that most image points do not contain any information. In our measurements, we use this sparsity of information in an inverse way, by acquiring only ten percent of the available data and reconstructing the entire image via a mathematical computation method.”
“With point-by-point illumination, taking 256 data points would result in a 256 pixel image. With our method, the same number of measurements creates an image of about twenty times as many pixels,” says Amitonova. “Thus, compressive imaging is much faster, but we also demonstrate that it’s capable of resolving details that are more than two times smaller than can be resolved by conventional diffraction-limited imaging.”