Schematic: The excitation laser light is focused through an aperture with a diameter smaller than the excitation wavelength, resulting in a near field on the far side of the aperture.

Instrument Calendar:

• WITEC alpha300 S

SNOM features:

• Micro-fabricated cantilever SNOM sensors
• Aperture size typically 100 nm, other optional
• Standard AFM cantilever probes
• Beam-deflection distance control for SNOM and AFM
• Low noise, highly focused optics for beam deflection laser
• No interference with excitation laser
• Ultra-low laser noise
• Near-field Mode 100 nm, depending on aperture size; Confocal Mode typically 200 nm diffraction-limited

Typical Applications:

• As scanning near-field microscopy requires only minimal sample preparation if any, it is ideally suited to quickly and effortlessly image the optical properties of a sample with resolution below the diffraction limit.
• Typical applications are found in nanotechnology research and particularly in the highly relevant fields of Nano-Photonics and Nano-Optics.
• In Life Science and materials research, SNOM allows the optical detection of the most miniscule surface structures of transparent as well as opaque samples.
• Using fluorescence techniques, even single molecule detection is easily achievable.

Switching from confocal to near-field allows portions of a sample to be measured with high resolution, like this 12 μm x 12 μm scan of a single human leukocyte in transmission.

Confocal fluorescence image of DNA strands solved in liquid, marked with ethidium bromide, then excited with an argon ion laser.