Abstract: A system for remote near infra red (NIR) spectral analysis of hydrocarbons using telecommunication optical fibers for real-time on-line transmission of NIR spectral information from an examined hydrocarbon sample to a remote analyzer comprising (a) a light source for generating near infra red radiation; (b) an optical probe head being at on-line contact with an analyzed hydrocarbon sample; (c) at least one telecommunication transmitting optical fiber for inputting the near infra red radiation into the optical probe head, such that the radiation passes at least once through the hydrocarbon sample, such that a spectrum of the sample is generated; (d) a detector for analyzing the spectrum, the detector and the light source being part of an analyzer; and (e) at least one telecommunication receiving optical fiber for receiving the radiation after the passing through the sample and inputting the radiation into the detector.

Abstract: An optical probe head for determining properties of the sample as a function of the depth of the sample, which is made up of a gradient index lens, at least one face of which is in contact with the sample, a number of transmitting optical fibers, preferably made up of a number of concentrically located sets, for inputting radiation into the gradient index lens in at least two optical locations, a mechanism for cycling the input radiation among the transmitting optical fibers, a receiving optical fiber, preferably centrally located, for receiving reflected radiation and a mechanism for processing the reflected radiation to obtain depth-related reflection information.

Abstract: An optical probe head for determining the index of refraction of a sample, which is made up of a gradient index lens in contact with the sample, a transmitting optical fiber for inputting radiation into said gradient index lens and a receiving optical fiber. The optical fibers and gradient index lens are aligned so that radiation from the transmitting optical fiber which is reflected from the interface of the gradient index lens and the sample is received by the receiving optical fiber. The probe can, with slight changes, also be used for determining the Raman or fluorescent spectra, for determining the absorption spectrum, and for determining the self-referencing transmission of a sample.