Ultrahigh-speed scanning near-field optical microscopy capable of over 100 frames per second

Scanning near-field optical microscopy is a powerful technique offering subdiffraction-limit optical resolution. However, the range of applications is limited by slow image acquisition rates. In this letter we demonstrate an implementation of a near-field optical microscope capable of scan speeds of 150 mm/s producing images of an area $20 μm2$ in less than 10 ms, i.e., over 100 frames/s. To achieve this, a method of measuring the optical near-field intensity with a high bandwidth of greater than 1 MHz has been developed. A second original aspect is that the scan system uses a mechanical resonance of the probe to address the sample. The presented microscope is over 1000 times faster than a conventional scanning near-field optical microscope and $∼10$ times faster than any scanning probe microscope to date.