Focusing On Disorder

Ian S. Osborne The ability of high-end optical microscopes to image the smallest of features is very much dependent on the quality of the lenses. However, the preparation and milling of the best-quality lenses add a hefty premium to the cost. In a somewhat counterintuitive approach to improving resolving capability, van Putten et al. explore the use of lenses that are completely disordered. Laser light hitting such a disordered lens creates a random pattern, or speckle, of intense, highly focused spots. By manipulating the wavefront of the laser beam with a spatial light modulator before it hits the lens, the authors show that the multiple spots can be made coincident, thereby forming a spot smaller than that from a conventional lens. They then go on to demonstrate imaging of gold particles with sub–100-nm resolution. Such an adaptive optics approach might prove a useful and ultimately cheaper method of high-resolution microscopy.
Phys. Rev. Lett. 106, 193905 (2011).