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Optical coherence tomography (OCT) is a unique technique of noncontact and nondestructive examination of wide range of highly scattering materials. Introduce a polarization state analysis in OCT gives new possibilities in technical materials investigation and characterization. Polarization sensitive optical coherence tomography (PS-OCT) is capable to investigate not only a material's inner structure, but also determining its local properties of optical anisotropy. In this paper, the principles of OCT and its basic modifications focused on polarization-sensitive OCT have been presented. The experimental setup of PS-OCT has been shown, as well as an application of this technique for investigation of internal structure of materials. The experimental results of investigation of transparent and high scattering materials have been presented.

Low-coherence interferometric sensors are an important group of optical fibre sensors. Combining high measurement resolution with broad measurement range, these sensors can measure accurately several physical quantities e.g. temperature. In this article we present the fiber-optic temperature sensor using low-coherent interferometry, which has been designed and elaborated.

Optical Coherent Tomography is a measurement technique, which enables us to visualize the internal structure of the investigated object with very high resolution. In OCT systems on order to detect the measured signal the measurement techniques such as: optical frequency domain reflectometry to detect and optical low-coherent reflectometry (OLCR), are employed. In both methods it is necessary to use at Still, one most popular is configuration with Michelson Optical Coherent Tomography have been employed. Still, the most popular is configuration with Michelson interferometer, but also Fizuea is performed as well. Furthermore, it is known that using balanced configuration interferometer topologies is possible to effectively reduce noise-to-signal ratio. Hence, the use of the second interferometer is necessary. In this situtation a few of interferometer topologies for can be used. In this article the theoretical and experimental investigation of interferometer topologies for Optical Coherent Tomography will be analyzed. The optimal configuration of the designed system has been presented. By the use of a special configuration, our OCT system is sensitive to change of polarization of measured signals.

In low-coherent measurement techniques two kinds of optical signal processing can be used -spectral and temporal. When the temporal signal processing is used, the most critical problem is to identify the position of the central fringe in the interference fringe pattern. It is so important because this position corresponds to the zero of optical path difference and gives information about a measurand. Therefore, it is necessary to use the low-noise optical signal detection set-up in the low-coherent measurement systems. One of the most effective methods of noise-reduction in low-coherent system is using detection system in balanced configuration. In this article, authors present the designed low-coherent optical signal detection system. This system enables us to perform balanced and un-balanced detection, which allows to compare parameters of both configurations. The authors describe theoretical and experimental investigation of balanced and un-balanced low-coherent optical signal detection system.

Fiber-optic low-coherence tomography system with low-coherent reflectometry has been used to non-destructive characterization of ceramics. We presents experimental results showing that the measurements of ceramics internal structure can be done with suitable resolution.

An Optical Low-Coherence Tomography (OCT) is a novel optical measurement technique, which enables non-destructive and non-contact investigation of multilayer structures. Nowadays, this method is highly applied in medical diagnostics. Despite of great progress in optoelectronics and optical measurement methods there is lack of studies on the OCT for non-medical application. In this paper authors present a laboratory OCT system for surface and subsurface investigation of scattering technical objects such as polymer layers. Preliminary test results on subsurface technical objects investigation using OCT system have been presented and discussed.

The influence of low-coherence source parameters on the optical coherence tomography imaging has been studied. Experimentally and theoretically it is demonstrated, that by summing autocorrelation function of two superluminescent diodes with different wavelength, the effective coherent length of the source and signal-to-noise ratio required to identify the central fringe position can be greatly reduced.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The spectral shape of a light source in optical coherence tomography imaging is of prime importance because it determines resolution and quality of the image. Spectra and axial point spread function of photonic crystal fiber light source TB-1550 from Menlosystems GmbH before and after optical spectral shaping are presented. Low-pass and high-pass filters are simulated to shape the irregularities in light spectra of the source. Full-spectrum shaping results with use of spectral processor are calculated. Results show that shaping of a light source improves meaningly axial resolution and inhibits sidelobes of the point spread function.

Optical Coherence Tomography (OCT) is a new type of an imaging technique of the internal microstructure of the material. Among several detection techniques which can be used to implement OCT, Optical Low-Coherence Reflectometry (OLCR) is the most common and the most promising one. OLCR uses a broadband source, which parameters: the spectral characteristics and the noise property, determine metrological abilities of the designed OCT system. Authors measured the power spectral density of the intensity noise, as well as the spectral characteristic of various broadband sources. Obtained results has been used to determine metrological properties of the design OCT system.

Optical Coherent Tomography (OCT) is an imaging techniqu that enables a range of clinical applications where imaging can be carried out in situ and in real time. In OCT, cross-section images are generated by transverse scanning light beam across investigated tissue and by measuring the delay and magnitude of the back-scattered light. Among several detection techniques which can be used to implement OCT, Optical Low-Coherent Reflectometry (OLCR) or Optical Frequency Domain Reflectometry (OFDR) are the most promising. The paper presents merits of both techniques.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A monomode and multimode fiber white-light interferometric temperature sensor for biomedical applications is presented. The sensor uses a low-finesse Fabry-Perot interferometer working in reflective mode. Dependence of material parameters on fringe visibility is discussed and both construction of the sensor has been optimized with respect to fringe visibility. This new sensor system is expected to be a practical approach for many medical applications.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

White-light interfermetry, also referred to as low-coherence interferometry, is an interferometric technique employing broadband light sources in order to make absolute, high-resolution measurements of several physical quantities, such as position, displacement, temperature and pressure. In the paper a model of a low-coherence interferometric temperature sensor using a Fabry-Perot sensing interferometer is presented and optimization of the sensor is discussed. The sensor uses an inexpensive source such as LED or VCSEL, standard telecommunication fibers and components, which makes it a potentially low-cost solution.

In the paper, the analysis of the application of a tunable semiconductor laser working in 1550 nm band in a C-OFDR construction is presented. The laser was tuned in narrow 0.24 nm range by a PZT element and in wide 70 nm range by a stepping motor. The narrow range was used for signal separation from measurement points laying along optical fiber. The wide range can be used in to separate signals from branches of a fiber optic sensor network. The reflectometer was used for signal detection from quasi-distributed sensors network. Measurements were carried out for different distances of point fiber optic sensors from the reflectometer. As the models of point sensors air cavities were used. The influence of tuning range of the laser on measurement errors is discussed.

In this paper we describe an idea of a multiband system for non-contact temperature measurement and analytic techniques which allow calculate temperature and emissivity of the examined body from the measured data. Influence of some factors on measurement accuracy is discussed. Described technique gives a possibility to optimize construction of the whole system.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In the paper a setup for the measurement of instant velocity of samples subjected to breaking test is described. It was estimated that the maximum speed of deformation is 50 m/s and maximum strain is 5 mm. An optical method has been selected and a measurement setup was built. We discuss the setup performance and the measurement results.

The subject of this paper is a system for measuring thickness of opaque dielectric layers using the change of the coefficient of the magnetic coupling of two coils. This circuit was designed for measurements of thickness of elements in boats made from epoxy-glass laminates. It can, however, be used everywhere, where the need occurs to make non-destructive thickness measurements of dielectric layers in the range from 5 to 30 mm with an accuracy of 0,5 mm.

The fiber optic technique for relative humidity (RH) sensors based on the absorption spectrum of the optical fiber coated with colorimetric reagent cobalt chloride layer is discussed. Probe preparation, optical layout used in the experiment and the responses of the RH probes for different concentrations of cobalt chloride (PVA) solutions are presented.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The subject of this paper is an optical fiber temperature sensor using the techniques of optical time domain reflectometry. The sensor uses the dependence between the refractive index of epoxy resins and temperature and allows us to develop sensors working in transmission as well as in reflective mode.

The subject of this paper is the modelling of optical fiber temperature sensors that use blackbody radiation. The aim of modelling is in the optimum selection of optical fibers--in order to obtain the highest possible sensitivity in the assumed range of temperature measurements. Modelling takes into account the influence of the transmittance of optical fibers, the spectral sensitivity of photodetectors and the filters characteristics on the photodetector signal level.

The physical phenomenon and construction of optic fiber sensors are discussed in this paper. The description is limited to those sensors that are potentially applicable. Extrinsic sensors based on absorption, luminescence, thermal radiation and Fabry-Perot etalon are discussed. Intrinsic sensors based on absorption and backscattering are reviewed, too.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The subject of this paper is modelling and optimization of fiber optic refractometric sensors that based on the principle of attenuation caused by bends of the optical fiber. Sensors of this type are meant to measure the refractive index of fluids and, after some modifications, to measure temperature. The model designed allows us to optimize the construction of this type of sensors in order to obtain the highest possible sensitivity and linearity of characteristics in the assumed range of changes of the measured refractive index.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper the computer program CADFOS and its prerequisite were described. The program was designed for the purpose of modelling transmission of light in an arbitrary shaped optic fiber path. The program enables us to calculate the attenuation caused by bends of the fiber, the power distribution in any of its cross sections, the power distribution in the near field and far field at the far end of the fiber. Examples of the achieved results have been given.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The construction and principle of operation of optical fibre refractometer is given in the paper. The refractometer operates on attenuation changing measurement. The attenuation changing is a function of mode radiation from specially bent optical fibre. A quartz step index, optical fibre with polymer coat and 130 um core in diameter was used to develop the model of the sensor. At the place of bending the coat was removed. The sensors with a different diameter of bending were examined in liquids with known refractive indexes. In the transmitter was used LED while receiver was made with pin fotodiode.

The principle of operation of the fibre optical temperature sensor based on a blackbody radiation and its construction model is given in the paper. A quartz rod of 0.6 mm diameter and 20 cm length with a blackbody cavity at the one end was used to construct the sensor. The cavity was made by vacuum evaporation of a chromium layer and a silicone monooxide layer was used as a protection. Infrared radiation is transmitted by the fibre optic to the detection circuit. This sensor enables temperature measurement from 400 to 1200°C. The range of measurement is determined by the detection sensitivity and by rod softening. The resolution is of the order of 10-2°C. The sensor calibration was done by using PtRh1O-Pt thermocouple.

The principle of fibre optic pH sensor operation is given in this paper. PH measurement in 7.0-7.5 range is based on changing of optical property of a indicator. The indicator is sensitive to the hydrogen ion concentration in the water solution. Microspheres of the polymer XAD-2 (a styrene-divinylbenzene copolymer) containing bound phenol red were used as a indicator. Such prepared indicator was inserted in optrode. The optrode was connected with transmitter and receiver by a bundle of glass fibres (multicomponent glass). Transmitter was done by using green LED while receiver construction was based on pin photodiode.

On the basis of the analysis of PLZT ceramics, dispersion properties were determined: 1) G—the electrooptic coefficient; 2) β—the polarization potential coefficient for PLZT 12/40/60. In addition, domain distribution was determined and values of Ps and δns of this composition were calculated.

Methods of operating point stabilization of interferometric sensors using tunable lasers are presented. These methods employ circuits which control the wavelength of an external cavity tunable semiconductor laser. Modes of operation of the control circuits and problems related to their design are discussed. The limitations restricting the use of discussed control circuit types are analyzed. An interferometric force sensor was built and tested. Results of measurements carried out using the sensor are presented.