Oblique-incidence optical reflectivity difference

Oblique-Incidence Optical Reflectivity Difference Microscopy... 

Landry IP, Zhu XD, Gregg IP. Label-free detection of microarrays of biomolecules by oblique-incidence reflectivity difference microscopy. Optics Lett. 2004 29 581-583. 

Zhu X Landry JP, Sun YS, Gregg JP, Lam KS, Guo X. Oblique-incidence reflectivity difference microscope for label-free high-throughput detection of biochemical reactions in a microarray format. Appl. Optics. 2007 46 1890-1895. 

Since the substrate may influence the anisotropic optical properties of the overlying film [595], the method of Buffeteau et al. [247, 566-568, 593] is conceptually more reliable when the MO is studied on solid transparent substrates, whereas the initial anisotropic optical constants are extracted from normal- and oblique-incidence transmission or polarized reflection of the same film on the same substrate. In the case when different substrates participate into the measurements (e.g., when MO in monolayers at the AW interface is studied), the comparison of the simulated and experimental spectra can be used for distinguishing chemical effects generated by specific film-substrate interactions [568b]. In particular, the kmm values derived from spectra of monolayers at the AW interface obtained by IRRAS are usually larger than those obtained by eUipsometric measurements of thin films on solid supports [247]. This difference has been attributed to a gradient in the optical properties of the interfacial water [71]. 

Ellipsometry was in fact the earliest optical technique to be applied to the study of electrode processes. It involves the determination of the change in polarisation state of an obliquely incident light beam upon specular reflection at a surface. In order to fully define a monochromatic light beam it is necessary, in addition to knowing the frequency, amplitude, and direction of propagation, to include information about the electric and magnetic vectors which describe the polarisation state. Since these vectors are orthogonal and related in amplitude it is, in fact, only necessary to consider one of them, and it is the electric vector that is usually chosen. If this vector lies in a plane then the beam is said to be plane polarized, and further if this plane lies parallel to the plane of incidence at a surface the beam is said to be p-polarised, whereas a beam polarised in a plane perpendicular to the plane of incidence is referred to as s-polarised. For any beam it is possible to resolve the electric vector into its s and p components, and when these components are of the same frequency but different phase and amplitude the beam is said to be elliptically polarised. This name arises from the... 

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