Tolerances in optical mixing

Abstract

Analytical expressions are derived for the power spectral density of the current in optical heterodyning when phase front curvature mismatch, tilt or axis displacement occurs between the beating light beams. The signal beam is the far field of an incoherent source of circular shape, and the local oscillator is the fundamental mode of a stabilized laser. The cases in which the signal beam either illuminates the detector coherently or has a coherence area small compared with the detector area are shown to have simple solutions. An analogous analysis is carried out for homodyning (self-beating). The dependence of the signal-to-noise ratio on the detector aperture and optimum and tolerance values for the latter are obtained for a given misalignment.

The foreign body reaction—an experimental protocol

“…The nature of the interactions which occur at the interface between implant materials and their living host are still largely unknown or misunderstood (see [26] for a review). Detailed studies of the tissue reaction to implant materials, assuming such materials are very well characterized, especially with respect to their surface properties, should provide the data base which will aid us in understanding the nature of the phenomena which take place when a "foreign" object is placed in contact with living tissues.…”

Dynamic aspects of contact angle measurements on adsorbed protein layers

“…For a three-phase system, paraffin oil/ water/solid, the relation between the contact angle of an oil drop on the solid surface which is immersed in the aqueous phase is given by the Young-equation: %,w cos 0 = %,w -Ys,o, [1] where ~/is the interfacial tension IroN m-l], 0 is the contact angle measured through the oil phase, and s,w, and o indicate the solid, water, and oil phase, respectively. The interfacial tension between two mutually nondissolving phases 1 and 2 equals the sum of the surface tensions of the phases in vacuum minus twice the free energy of interaction (3"1,2) between the two phases.…”

“…At the same time blood coagulation will be initiated by a contact activation mechanism. Andrade (1,2) postulates that this activation is a function of the interfacial free energy between blood and the exposed surface. This implies that it is important to investigate how the nature of the exposed surface and the balance of intermolecular forces will be altered upon adsorption of protein molecules.…”