Microfabricated Fresnel Zone Plate Optical Tweezer (image) Harvard University Share Print E-Mail Caption (a). Photograph of microfabricated Fresnel Zone Plate optical tweezer, consisting of concentric gold rings (50 nm thick) on a microscope slide. The Zone Plate outer diameter is 100¼m, and the focal length is 8¼m. (b). CCD camera image of fluorescent bead (2¼m diameter) trapped in Zone Plate focus. Credit Ken Crozier, Harvard School of Engineering and Applied Sciences Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.