A simple technique for screening near-field probes

In near-field microscopy, probe quality usually limits the microscopeʹs resolution and sensitivity. Although examining the probe in an electron microscope and imaging a test pattern with the probe in a near-field microscope provide detailed information about probe quality, both techniques are time consuming, often requiring that the probe be coated with metal. A qualitative technique is presented for rapidly screening fiber tapers for defects by examining their diffraction patterns.