Marcin Roszko

Compact optical fiber refractive index differential sensor for salinity measurements

Design and initial tests of a compact differential refractometer of deviation type are described. The use of optical fiber instrumentation for detection of the beam deviation profited in a compact device for remote sensing. For the industrial application a reflection type of type differential refractometer was designed. The laser is launched into the refractometer cell through the single mode fiber and SELFOC to illuminate a detector in form of a gaussian beam. The detection system consists of the in-line arranged multimode fibers. The deviation of the beam due to salinity of water is evaluated from light intensifies detected by four sequentially arranged fibers. Analog digital conversion and numerical computation of the signal results in the accuracy in determination of salinity better than 0.5%. The salinity measurement range starts from the lowest concentrations through seawater up to coal mine salt water.

Investigation of organic materials by generalized m-line spectroscopy method

A generalized m-line spectroscopy method enables evaluation of the parameters (the refractive index, n and the thickness, W) of sub-guiding films deposited on a planar waveguide. A sub-guiding film (not reaching the guiding effect) when deposited on the existing planar waveguide influences the present guiding system and affects its guiding properties. In the method a laser beam is coupling via a prism to the sample and a light distribution decoupled by the same prism is studied. Complementary to the beam spot reflected geometrically from the prism base the light distribution takes a form of discrete lines, m-modes. This image is observed but only for some discrete values of the coupling angles. The refractive index, n and thickness, W of the waveguide are then calculated by numerical evaluation of the dispersion equation with a set of the coupling angles. From the previous and actual coupling angles the thin film parameters can be evaluated. In the paper an application of the generalized m-line spectroscopy method to biological samples is presented. Some initial measurements reveal an effect of the presence of the films on the coupling angles of the structure. The presence of glucose has been revealed in secretions of patients suffering from diabetes. Testing of glucose presence with the proposed method is performed with a trace amount of the patient secretion alike in medical preliminary tests.

Fiber optic salinity sensor: temperature influence on salinity measurement

The temperature influence on salinity measurement by optical fiber salinity sensor has been investigated. Study of the sensor sensitivity with temperature change in range of temperatures 20 - 80 degree(s)C is presented. The construction of the sensor has followed the example of differential refractometer. As a result of this construction and high sensitivity of sensor on salinity, temperature changes have not deformed salinity measurements with the use of this sensor.

Nonlinear Optical Experiments on Liquid Crystal Chiral Structures

Abstract Up to now there are only few reports in the literature on experimental examination of nonlinear effects in chiral liquid crystals. The presented data are sometimes confusing. We proposed a simple experiment in a probe+pump laser technics for studying periodic liquid crystalline structures. The paper presents initial results of examination of a cholesteric material in the region of selective light reflection. We have been interested if any nonlinear effect of the collective nature appeared by usually accessible light intensities, i.e. non-thermal but of optical reorientation origin. The investigation was oriented toward potential application in all-optical light modulators.

Growth control of polymer films deposited on the planar waveguide

Propagation of the light in a waveguide structure may be easily disturbed by the change of a cover. In this study multilayers of 7-octenylotrichlorosilane have been investigated as cover films. The multilayer films were deposited on the planar waveguide by self-assembly, followed by a UV illumination and repeated self-assembly processes. A growth control of the deposited films was performed by the generalized method of an m-line spectroscopy. M-line spectroscopy is one of the most sensitive methods of investigations of the cover materials parameters.

Investigation of multilayer planar waveguide parameters using m-line spectroscopy method for biological liquid sensing

A generalized m-line spectroscopy enables an evaluation of the parameters (the refractive index, n and the thickness, W) of sub-guiding films deposited on a planar waveguide. The method is based on a coupling of a laser beam with a prism coupler and studying of light distribution of the beam decoupled by the same prism. Additionally to the beam spot reflected geometrically from the prism base the light distribution takes a form of discrete lines - m-modes. This image can be observed but only for some discrete values of the coupling angles. The refractive index, n and thickness, W of the waveguide are evaluated by the numerical solution of the dispersion equation with a set of the coupling angles. A sub-guiding film (not reaching the guiding effect) when deposited on the existing planar waveguide influences the present guiding system and effects its guiding properties. From the previous and actual coupling angles the thin film parameters can be evaluated. In the paper an application of the generalized m-line spectroscopy to biological samples is presented. Some initial measurements reveal an effect of the presence of the films on the coupling angles of the structures. The presence of glucose has been revealed in secretions of patients suffering diabetes. Testing of its presence with proposed method can be performed with a trace amount of the patient secretion.

Fiber optic salinity sensor alarm

The modification of salinity sensor was achieved in such a way that it is possible to perform salinity measurement and directly to send the data about an exceeding of salinity level for the purpose of quick intervention permitted by National Environmental Standards. The designed system of a network of central controllable sensors may be useful to automatic monitoring of an environment.

Vortex flowmeter with polarimetric sensing

The paper presents initial studies of the fiber flowmeter realized by polarimetric sensing with highly birefringent polarization-maintaining optical fibers. In the studied system one fiber is applied as the both bluff body and sensing element. The flow velocity is evaluated from the amplitude modulated signal of the frequency of vortex shedding. The polarimetric sensing based on polarization interference presents the advantage of sensitivity compared to the interferometry measurement but without the expense of its complex arrangement.

Birefringence of some liquid crystals films in NIR

The refractive indices ne, and no, of thin films of some liquid crystalline substances in the region of the third telecommunication window, at 1.5 micrometer were determined. The thin LC films were applied as optical waveguides and with the m-line spectroscopy the refractive indices for three wavelengths in visible area were measured and then with the Cauchy formula the refractive indices ne, and no, within the field of interest were evaluated.

Dynamic response of stressed high birefringent fibers

Optical response on periodic stress on the high birefringent fibers was studied. The stress frequency was varied in the range from few hundreds Hz to few kHz. Sensitivity of the response dependence on the azimuth of an exerted force was examined. A phase change of the optical response with the azimuth variation was observed. As a result of the study detection of vibro-acoustic signals with a polarimetric sensor was proved.