Photonics Circle of Excellence Award for AFM/NSOM 2002

This collaborative product brings together for the first time, in one commercial system, the chemical sensitivity of Raman spectroscopy and the ultra-high spatial resolution of scanning probe and near-field optical microscopy.

The spatial resolution of Raman systems employing normal optical microscopes is limited to approximately the wavelength of the light (about 0.5 µm), because both the illuminating laser light and the Raman scattered light are collected in the optical far-field (i.e. many wavelengths of light away from the scattering material).

This resolution is sufficient for many users, but some need the higher resolutions attainable with scanning probe microscopies (SPM), such as atomic force microscopy (AFM) and near-field scanning optical microscopy (NSOM). This need is fulfilled with the new combined Nanonics NSOM/AFM-100 Confocal™/Renishaw RM Series Raman microscope.

The Renishaw/Nanonics combined instrument can operate in two modes:

AFM/NSOM with far-field Raman - Offers users high spatial resolution scanning probe data, combined with far-field resolution Raman data (typically 0.5 µm spatial resolution). Now Raman data can be recorded and correlated with high spatial resolution topographic, electrical, thermal and near-field optical data.

AFM/NSOM with near-field Raman - Offers users high spatial resolution data for both scanning probe and Raman.

The hardware and the software of the Nanonics NSOM/AFM-100 Confocal™ system are integrated with the Renishaw RM Series microscope. Previously, investigating a sample with both scanning probe microscopy and Raman microscopy required moving the sample from instrument to instrument. The exact region being analysed by the Raman microscope could not generally be found again for imaging with the chosen scanning probe microscopic technique. The Nanonics/Renishaw microscope system makes simultaneous Raman spectroscopy and scanning probe microscopy possible.

The Nanonics system uses a patented optical fibre probe design. The cantilevered optical fibre is held between the objective lens and the sample without obstructing any aspect of the far-field conventional microscope. The tip of the fibre is exposed, allowing direct viewing of the scanned region in the microscope eyepieces or on the video viewer. This is not possible in a standard AFM that uses a silicon micromachined tip, which obscures the scanned region in the standard upright microscope. It is also not possible with straight near-field optical fibre probes.

When mounted on a Renishaw Raman microscope, the novel design of the Nanonics system means that the user can record a wide variety of scanning probe imaging modes in parallel with Raman spectroscopy. For example, while the silicon Raman peak of a microcircuit is being monitored to detect stress in the silicon, the Raman spectroscopist can simultaneously measure the micro topography with AFM, and the micro reflectivity with NSOM.