Abstract: An arrangement for optical measuring concentration of substances has a measuring space which is composed of a material selectively permeable for particles to be measured, acting back on the particles and transparent for a measuring radiation, and a measuring space is arranged in working connection with the object to be measured and the measuring radiation passes through the measuring space. The measuring space has a layer that is a water-insoluble solvent or made of poly(ethylene terephthalate) or polytetrafluoroethylene. The layer excludes a reaction from the particles to be measured.

Abstract: An optode designed to prevent washing away of the indicator and reagent from a membrane is located within an optical device that measures substance concentrations. The reagent and indicator materials are covalently bound on the membrane. The membrane can be a polysaccharide, especially cellulose, an acid glycol ester, or it can contain silicon. The indicator and/or reagent can be covalently bound to the membrane by a bridge molecular, particularly a multifunctional aldehyde, glutaraldehyde or a silane.

Abstract: A sensing arrangement for measuring physical parameters or concentration of particles is assembled of a laminar source of luminescent radiation. Fluorescent indicating particles are arranged in an indicator layer adjoining one major side of the laminar light source. The indicator layer adjoins a measuring space containing the object of measurement whose particles enter the indicator layer by diffusion. Fluorescent indicating particles are arranged in the indicator layer to emit fluorescent light when illuminated by the laminar light source. Photoelectric receiver is adjacent the opposite side of the laminar light source to measure the intensity of the fluorescent radiation. In a modification, luminescent phosphors and fluorescent particles are arranged in a common matrix.

Abstract: To measure potential differences in second-class conductors without interference potentials, there are provided a potential generator cooperating with a potential-measuring structure. This structure includes a substrate of electrically highly insulating and chemically inert material embedding optical indicators whose optical properties change as a function of the applied electric potential difference. Both the potential generator and the potential-measuring structure have boundary surfaces which are in contact with the second-class conductor and opposite surfaces interconnected by an equalizing conductor. A light-measuring device is arranged for intercepting light changes in the indicators, thus measuring the potential difference.

Abstract: In order to increase measuring sensitivity of a fluorometer, a transmitter of monochromatic test light beam is arranged opposite a receiver of a measuring light beam. A measuring chamber including a fluorescent indicator space is arranged between the transmitter and the receiver. The distance between the transmitter and the receiver is adjustable to match to the thickness of the measuring chamber.

Abstract: An arrangement for measuring diffusing particles has at least one monochromatic radiation source and a light measuring device, as well as at least one material limited particle-permeable indicator chamber provided with an optical fluorescent indicator which is optically changeable by the particles to be measured, and a carrier body having a surface which is arranged to face an eyelid and has depressions in which the indicator chambers are arranged.

Abstract: Process and apparatus for directly measuring the ion strength of an electrolyte solution is disclosed. The pH value of the electrolyte is measured by means of a first measurement with a first indicator dependent on the ion strength and by means of a second measurement with a second indicator dependent on ion strength in a manner different from the first indicator whereby the ion strength is computed by means of the approximation ##EQU1## J=ion strength Jo=ion strength upon calibrationpH'(N)=pH value, measured with a first indicator N dependent on the ion strength (HPTS)pH'(X)=pH value, measured with a second indicator X dependent on the ion strength, the ion strength dependence of which is different from that of the first indicatorW(N)=valency of the first indicatorW(X)=valency of the second indicatorwith ##EQU2## The ion strengths of other ions and of unknown electrolyte may also be computed.

Abstract: An apparatus for an optical measurement of the concentration of substances ncluding at least one monochromator means, one photometer means and one optometric means. A further reference indicator means is added to the indicator means. This further indicator means changes the measuring light and will not be changed by the concentration of the substance to be measured.

Abstract: A method and an arrangement for measuring the concentration of gases in a mple includes the generation of a monochromatic light beam having predetermined color characteristic. An indicator generates light signals indicative of the concentration of the gases in a sample to be measured and includes a light-transmissive surface positioned to be impinged by the monochromatic light beam, a diffusion membrane adapted to be placed in the proximity of a sample and being permeable to a selected gas component thereof, and an indicating substance positioned to be impinged by the monochromatic light beam penetrating the light-transmissive surface and by the gas component penetrating the diffusion membrane. The indicating substance reacts when illuminated by the incident monochromatic light by emitting a resultant light beam having an emitted component which has a color characteristic different from the predetermined color characteristic of the monochromatic light beam.

Abstract: A method and an arrangement for measuring the concentration of gases in a sample includes the generation of a monochromatic light beam having predetermined color characteristic. An indicator generates light signals indicative of the concentration of the gases in a sample to be measured and includes a light-transmissive surface positioned to be impinged by the monochromatic light beam, a diffusion membrane adapted to be placed in the proximity of a sample and being permeable to a selected gas component thereof, and an indicating substance positioned to be impinged by the monochromatic light beam penetrating the light-transmissive surface and by the gas component penetrating the diffusion membrane. The indicating substance reacts when illuminated by the incident monochromatic light by emitting a resultant light beam having an emitted component which has a color characteristic different from the predetermined color characteristic of the monochromatic light beam.