Optical coherent techniques, inteferometry and microscopy are applied for visualization of phenomena associated with laser-based lithotripsy. Shadowgraphy and ballistic imaging is used to visualize the phenomena generated around a stone during the action of a laser pulse. Results are confirmed using optical and electron microscopy.
An unconventional microscopy is applied to visualize and measure the phenomena during the laser-based destruction of a stone. By using the ultra-fast microscopic technique and shadowgraphy, some unknown phenomena akin to the laser lithotripsy are studied.
Fluorescent images of gallbladder stones, tissue and bile are obtained using a streak camera. A Match Spatial Filer (MSF) is made using a stone fluorescent image. The MSF is used to perform correlations with fluorescent tissue and bile image. A method for recognition of the stone and rejection of the tissue during the laser lithotripsy is proposed using the correlation outputs.
Shadowgraphy of gall bladder stone, which is held by a basket and immersed in a civete is performed. The exposure time is determined by the time of a N-Dye laser pulse used as a lightening source for photography. The shadowgram is projected in the objective of a camera which is connected to a microscope. The light coming from the laser, illuminates the civete collecting optical information of the stone and physical phenomena appearing above the stone. On top of the stone a tip of optical fiber is fixed, which is used for transmitting Ho:Yag laser power to the stone. Using a computer and time delay the laser pulses used for destruction and illumination are synchronized. Since the N-Dye laser pulse is pico-second range and the Ho:Yag laser pulse is in the range of micro-second, many image frames are obtained within the time of one pulse applied during the destruction. It is known that in the process of stone destruction several phenomena like plume, plasma, shock wave and bubble formation take place. However, the physical mechanism of the stone destruction is not yet completely understood. From the obtained results the above phenomena are studied which gives new information and clue for understanding some of the mentioned phenomena. The laser power which is guided by an optical fiber into the gall bladder or kidney of the human body can damage the living tissue and cause some serious health problems. For this reason the fiber needs to be oriented properly during the action of the laser power.
In this work, morphological processing is applied to study a bubble, which is crucial factor in laser-induced shock-wave lithotripsy. Erosion, dilation and subtraction are applied for edge detection of a bubble Hence the position and the shape is measured. The image of the bubble is extracted from the actual image of the stone (shadowgram). The image is obtained by fast photography using an N-Dye laser for illumination. A Ho:yag laser is used for fragmentation of the stone. Using a time delay, an oscilloscope and a computer, two laser pulses are synchronized. A microscope and a Kodak-camera are used to photograph the stone and the phenomena around.
For the design of optically realizable correlation filters, two apparently different methods, the minimum Euclidean distance optimal filters and the multicriteria optimal trade-off filters have been proposed. In this paper, the equivalence of these two approaches is established by considering the operating regions that include the origin and figures of merit that include the detector noise.
Using high speed imaging techniques, the gall bladder stone immersed in liquid is detected and identified. The detection of the shock waves induced by laser power is reached by using interferometry technique. Using gall bladder and tissue images obtained by ultra-fast photography and time resolved laser fluorescence the correlation of correlation is performed. The tissue image is used to perform the correlation filter. Hence lower correlation output is used for firing of the laser power.
Ultra fast imaging and destruction of the gall bladder stone is performed using Ho:YAG laser. A laser guided approach for lithotropsy is proposed. The correlation output peak is introduced as a feedback signal for firing the laser pulse for stone destruction and 'discrimination' of the tissue image so that the risk of damaging and perforation of the tissue is reduced. A system constituted by correlation of ballistic images and fluorescent signals is proposed.
Signal glow graph technique has been adopted to the task of calculating the transmission and reflection formula of light passing through a weakly absorbing three layer, or five phase system. It yields an exact closed form solution without neglecting higher order reflections between layer boundaries. Flow graphs have been solved by the analytical and topographical method leading to the same result.
The states of polarization of the light after reflection and transmission through the sandwich structure of the refractive layers are analyzed. Calculated by Wolter formula, the complex transmission coefficient of multilayer system indicates that the transmitted light, having linear polarization at incidence, is elliptically polarized. The ellipticity and the azimuth of the transmitted light is connected with K and L coefficients which represents the real and imaginary parts of the inverse transmission coefficients values. These coefficients can be calculated for the parallel and normal field components, from the found recursive formulas and for any sandwich consisting of m boundary planes between (m-l) layers. From the calculated expressions different number of layer plates, is shown that the transmitted light is elliptically polarized, except at normal incidence and when the incident light azimuth is 0 or 90 degree. Under these conditions the transmitted light preserves its linear polarization and the azimuth of the vector field vibrations. The reflection case is analyzed by using Wolter formula as well.
Optical morphological correlators are considered for shading and illumination problems that arise in robotics and product inspection and for contrast problems that arise in infrared (IR) imagery for automatic target recognition (ATR).