Abstract: A method is disclosed for coating the surface of an optical structure, such as a diffraction grating, useful for the detection of a ligand, which method comprises forming on the surface of the optical structure a thin, uniform layer of a polymerizable material, particularly one which polymerizes on exposure to light or heat, and subsequently exposing said material to polymerizing conditions. A specific binding partner is subsequently absorbed on or bound to the cured polymer layer, either directly or indirectly. Complex formation between the specific binding partner and ligand present in the sample to be analyzed alters the optical properties of the device and the change forms the basis of an assay.

Abstract: Apparatus for attenuating noise, particularly in an aircraft cabin, comprising a diaphragm (10) one side of which is subjected to the noise, sensing means (16) for sensing the displacement of the diaphragm in response to the noise, and deflecting means (20) responsive to the sensing means for deflecting the diaphragm in order to cancel the displacement, to attenuate noise transmitted from one side of the diaphragm to the other side of the diaphragm.

Abstract: An assay technique for the qualitative and/or quantitative detection of a chemical, biochemical or biological species in a sample comprising (a) coating at least a predetermined part of a pre-formed surface with a thin film of a material capable of binding the species to be assayed, said thin film incorporating a fluorescent compound whose fluorescent properties show a dependence upon it's molecular environment and said surface being optically active with respect to radiation over a predetermined band of wavelengths (b) contacting the coated surface with the sample and (c) measuring the change in fluorescent properties of said fluorescent compound before and after binding of said species. The preformed surface is preferably a diffraction grating.

Abstract: A method and apparatus for analysing the spectrum of light reflected by a reflecting structure (24) in which the effect upon the analysis results of variation in the angle between the reflecting structure and the incident beam (22) is minimised. The method and apparatus may utilise a dispersive element (26) constructed and arranged so as to minimise the effect of the variations. The method and apparatus may also utilise a calibration technique in which light with a known spectrum is reflected off the reflecting structure and analysed so that compensation may be made for the effect of the variation.