Nano-spectroscopy in the visible and near-IR

Diffraction limits the resolution of standard optical microscopes. Breaking the diffraction limit is the motivation behind Scanning Probe Microscopy (SPM) that includes Atomic Force Microscopy (AFM) and Near-field Scanning Optical Microscopy (SNOM). SPMs create high-resolution maps of the sample’s surface by scanning the sample with nanometric probes. SNOM in particular, can simultaneously provide information on the morphology and on the optical properties of materials by illuminating the sample with a localized field provided by the microscope probe.

In SNOM microscopy, the amount of light to be detected is low, a million times weaker than the illuminating light. This forces to implement complex background suppression schemes based on interferometers and would be unrealistic to be adapted to Space Science.

Recently, a new optical scanning probe technique that provides nanometric resolution optical images without detecting any light. Such Dark microscopy is counterintuitive but possible. The technique is based on the detection of the weak optical forces established between the sample surface and the microscope probe when both are illuminated. Such scheme (photo-induced force microscopy (PiFM)) has intrinsic background suppression, avoiding complex interferometric schemes.

Scope of this Early Technology project is to develop broadband nano-spectroscopy in the visible and near-IR spectral range.

Project funding: European Space Agency (ESA)