Wide field nanometric materials analysis by diffraction limited far field optical nanoscopy

In the development of nanomaterials and biomaterials, new characterization techniques are required that overcome the challenges presented by the increasing dimensional ratio between the different entities to be studied and the growing complexity introduced by the use of heterogeneous materials and technologies. Diffraction limited far field optical nanoscopy techniques are receiving growing interest because of their capacity to detect nm structures over very large fields and at high speed. In this paper we present a classification scheme of optical nanoscopy techniques and in particular highlight four categories of far field diffraction limited techniques based on increasing the contrast, measuring the phase, using deconvolution or using nano-markers. We thus demonstrate that by increasing the power of detectability, observability or measurability, a wealth of information concerning nanometric structures becomes available even though all the lateral details may not be resolved. These techniques conserve all the advantages of classical imaging such as real time or high speed measurement, large quantities of useful data, non-invasiveness, non-destructiveness and ease of use. Such a summary will be useful in stimulating the search for new solutions to certain difficult problems in nano-characterization of nanomaterials and biomaterials over wide fields.