The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives and analyses light reflected from the polymer-based single-mode fibre-optic sensor system.

An optical position-measuring device includes a scale and a scanning unit. The scale is connected to a first object, extends along a measurement direction and includes a first track having an incremental measuring graduation, and a second track having an absolute measuring graduation. The scanning unit is connected to a second object and includes a light source, a detector having an absolute detector arrangement configured to detect an aperiodic light pattern transmitted from the absolute measuring graduation onto a detection plane and an incremental detector arrangement configured to detect a periodic light pattern transmitted from the incremental measuring graduation onto a detection plane, and a fiber-optic plate arranged as a continuous component in front of the absolute detector arrangement and the incremental detector arrangement, wherein both absolute track information and incremental track information in the respective detection planes are transmitted via the fiber-optic plate in this manner.

An optical probe that measures the level of a liquid in a tank includes a transparent and refracting optical waveguide for receiving an injection of a collimated light beam. The optical waveguide internally reflects the collimated light beam according to a total reflection regime in any part of the optical waveguide located in a gaseous medium and refracts the collimated light beam according to a refraction regime in any part of the optical waveguide immersed in a liquid medium. The optical waveguide switches from the total reflection regime to the refraction regime at the interface between the gaseous medium and the liquid medium, and mirrors are arranged around said optical waveguide and reverse the path of a light beam collimated and refracted by the optical waveguide, the optical path covered by the collimated light beam representing the level of the liquid in the tank.

An optical fiber distributed acoustic sensor system makes use of a specially designed optical fiber to improve overall sensitivity of the system by a factor in excess of 10. This is achieved by inserting into the fiber weak broadband reflectors periodically along the fiber. The reflectors reflect a small proportion of the light from the DAS incident thereon back along the fiber, typically in the region of 0.001% to 0.1%. To allow for temperate compensation to ensure that the same reflectivity is obtained if the temperature changes, the reflection bandwidth is relatively broadband. The reflectors are formed from a series of fiber Bragg gratings, each with a different center reflecting frequency, the reflecting frequencies and bandwidths of the gratings being selected to provide the broadband reflection. The reflectors are spaced at the desired spatial resolution of the optical fiber DAS.

In a sensor device, a plurality of light guides having a respective first end and a respective second end are arranged on a common carrier, with the first end of each light guide of the plurality of light guides at a respective defined position on the carrier. At each of the second ends of the light guides there is provided at least one sensor element which exhibits an optical behavior dependent on an analyte. The second ends are at defined perpendicular distances to the carrier. At least two of the second ends differ with respect to the defined perpendicular distances.

The present invention provides a method for measuring an optical sensor system comprising an array of intrinsic fiber optic sensors at an interrogator comprising an optical source and an optical detector. The method comprises the steps of emitting an optical signal to an array of intrinsic fiber optic sensors; detecting optical responses to the emitted signal from the sensors; associating each detected optical response with an individual sensor by determining within which region among a plurality of detection regions assigned to the individual sensors the optical response is detected wherein each detection region corresponds to a wavelength range in the bandwidth of the optical sensor system; and performing signal processing on each optical response to measure the value of the physical parameter detected by its associated sensor. A calibration of the detection region assigned to each sensor is performed at predetermined intervals.

An optical fiber distributed acoustic sensor system makes use of a specially designed optical fiber to improve overall sensitivity of the system by a factor in excess of 10. This is achieved by inserting into the fiber weak broadband reflectors periodically along the fiber. The reflectors reflect a small proportion of the light from the DAS incident thereon back along the fiber, typically in the region of 0.001% to 0.1%. To allow for temperate compensation to ensure that the same reflectivity is obtained if the temperature changes, the reflection bandwidth is relatively broadband. The reflectors are formed from a series of fiber Bragg gratings, each with a different center reflecting frequency, the reflecting frequencies and bandwidths of the gratings being selected to provide the broadband reflection. The reflectors are spaced at the desired spatial resolution of the optical fiber DAS.

An optical position-measuring device includes a scale and a scanning unit. The scale is connected to a first object, extends along a measurement direction and includes a first track having an incremental measuring graduation, and a second track having an absolute measuring graduation. The scanning unit is connected to a second object and includes a light source, a detector having an absolute detector arrangement configured to detect an aperiodic light pattern transmitted from the absolute measuring graduation onto a detection plane and an incremental detector arrangement configured to detect a periodic light pattern transmitted from the incremental measuring graduation onto a detection plane, and a fiber-optic plate arranged as a continuous component in front of the absolute detector arrangement and the incremental detector arrangement, wherein both absolute track information and incremental track information in the respective detection planes are transmitted via the fiber-optic plate in this manner.

A distributed optical fibre sensor is discussed which is arranged to detect acoustic vibration and at least a first of two or more other measurands, which could be for example two or more of changes in temperature, changes in static pressure, and changes in static strain. At least first and second optical waveguides are arranged to have optical path length response characteristics to at least one of the other measurands which are different from each other, and an analyser is arranged to determine at least said first other measurand using differences between the interference signals from each of the optical waveguides.

Embodiments of the invention provide an improved optical fiber distributed acoustic sensor system that makes use of an optical fiber having reflector portions distributed along its length in at least a first portion. In particular, in order to increase the spatial resolution of the sensor system to the maximum, the reflector portions are positioned along the fiber separated by a distance that is equivalent to twice the distance an optical pulse travels along the fiber in a single sampling period of the data acquisition opto-electronics within the sensor system. As such, no oversampling of the reflections of the optical pulses from the reflector portions is undertaken, which means that it is important that the sampling points for data acquisition in the sensor system are aligned with the reflections that arrive at the sensor system from along the sensing fiber. In order to ensure such alignment, adaptive delay componentry may be used to adaptively align the reflected optical signals (or their electrical analogues) with the sampling points. Alternatively, control over the sampling points can also be undertaken to re-synchronise the sampling points with the returning reflections. In addition, in order to allow higher speed sampling to be undertaken, reflection equalisation componentry may also be used to reduce the dynamic range of the returning reflections.