SNOM more known as Near-field Scanning Optical Microscopy (NSOM), was developed because of the limitations posed by conventional optical microscopy, restricted only by the diffraction limit, and hence able to offer only a resolution of order half the wavelength of light used. SNOM has achieved resolutions as small as 20-100 nanometers by using evanescent waves created near the surface of a sample. It is the feature that makes it an invaluable tool for nanoscale structure observation and understanding of phenomena that traditional microscopy techniques cannot see. MaTestLab is one of the leading testing service providers in the USA and Canada. We have a large network of testing laboratories in the USA.
Principle and Methodology of SNOM
SNOM is a technique using a pointed probe to detect evanescent waves near a sample’s surface. The probe detects evanescent waves, exponentially decaying with distance from the surface, and involves the processes of fine tip preparation, near-field interaction, scanning, and signal detection. The data is then gathered, and image conversion is done by detectors and data processing software. This high-resolution imaging technique is basic to various areas of application.
Instrumentation
The instrumentation for SNOM includes a laser light source, a probe with a tapered optical fiber or a metal-coated tip, piezoelectric scanners to move it with high precision, photodetectors or spectrometers that capture the optical signals, and a feedback system intended to maintain the distance from the sample surface constant to provide the highest resolution and the strongest signal.
Applications of SNOM
SNOM applications in high-resolution optical imaging and spectroscopy span material science, biology, nanotechnology, the semiconductor industry, and chemical analysis. The technique investigates the optical properties of nanostructured materials, thin films, and composites and provides visualization of subcellular structures, investigation of protein interactions, and dynamics of biological membranes. Characterization by it of nanostructures, quantum dots, and nanowires ensures the quality and performance of semiconductor devices.
