In the production of pigment-coated paper or paperboard, the method and rate of drying of the coating will significantly influence the print quality of the finished product. Improper drying during initial st sages can cause binder migration that leads to its non-uniform concentration on the surface of the coating. Such effect causes print mottle, and is a primary reason for poor print quality. The location at which binder immobilization has occurred is called the Gel Point. An on-line fiber optic sensor system has been applied to continuously monitor the location of the Gel Point. Each sensor consists of a light source, an optical fiber for delivering the radiation, two optical fibers for diffuse and specular radiation monitoring and two detectors. The ratio R between diffuse and specular signals indicates coating conditions. A system description and experimental results are presented. The Gel Point measurement system has show that is provides a sensitive measurement of the gel point location, as it is affected by machine speed, coat weight, incoming substrate moisture levels and drying energy and can predict print mottle. This provides the paper maker with a completely independent method for monitoring the coating drying process.
Laser welding has been used for connecting various tissues in the body. In urology such welding has the advantage of forming an immediate water tight seal. We have developed a fiberoptic system that makes it possible to monitor and control the temperature of the tissue during welding. In previous work we demonstrated that this system could be successfully used to weld punctures in the urinary bladder of rats. It was found that optimal welding was obtained at a temperature of 55 degree(s)C. In this work we used the same system for welding of large openings (cystotomy) in the urinary bladder of rats. In early experiments we used stay sutures and decompressing catheters. It was later found that complete closure can be obtained with CO2-laser welding alone. This work demonstrates the feasibility of using temperature controlled laser welding as an efficient surgical tool.
The morphometrical analysis of the effect of a pulsed CO2 laser on in vitro fresh rabbit vessel tissue was performed. The laser energy was delivered through a silver-halide fiber and the real time temperature was monitored via a second silver-halide fiber positioned on the external side of the irradiated tissue sample. In addition, a mathematical model was identified and applied on the analysis of the samples to quantify the internal temperature distribution. The model takes into account the dimension (coagulation, vacuolization) and the speed of the receding boundary between the ablated and normal tissue in a pulsed beam mode. Superficial hystological lesions were observed with ranges of energies of 20 msec/pulse, 1 Hz, 2 Hz, at 100 mJ, corresponding to a measured maximal external temperature range between 50 degree(s) and 60 degree(s)C. The used mathematical model has shown good agreement with these experimentally collected temperature measurements. Higher repetition rates for both 33 and 100 mJ/p were found to produce crater formation, in all the samples. The correspondent measured external temperatures were between 55 degree(s) and 95 degree(s)C and the calculated internal temperature of the injured layers were 142 - 306 degree(s)C, corresponding to the carbonization zones and depending on the type of tissue. The morphometrical analysis have shown: the CO2 laser effect on the tissue is dependent on the angle of irradiation, the stereo metrical configuration and the water content of the irradiated tissue. A threshold value for injury generation is proposed.
The temperature of the reaction zone is one of the main parameters for the characterization of laser-tissue-interaction. IR-radiometry, a noncontact temperature measurement method, is used to determine the temperature of the reaction zone. To be able to measure the inside of cavities, especially of hollow organs, we used IR-fibers to guide the temperature radiation to the complex receiver device. During the laser-tissue interaction the IR-radiation field of the reaction zone is focused on an IR-optical fiber made of AgClxBr1-x. The temperature is measured for Nd:YAG laser application with different power densities and compared with standard thermographic equipment.
Temperature monitoring of tissue (in vitro) and human skin (in vivo) during Ar-laser irradiation with the help of a radiometric temperature sensor based on IR silver halide optical fibers is presented. Fiber optic radiometry makes possible accurate temperature measurement and does not require contact with the heated biological object. Using a IR silver halide fiberoptic radiometric thermometer we obtained accurate temperature rise-decay dependencies of the heated biological object and demonstrated the non-uniform temperature distributions in them.
Infrared (IR) fiber optic radiometry of thermal surfaces offers several advantages over refractive optics radiometry. It does not need a direct line of sight to the measured thermal surface and combines high capability of monitoring small areas with high efficiency. These advantages of IR fibers are important in the control of nonuniform temperature and emissivity distributions, in which the parameters of closely situated points differ considerably and a high spatial resolution is necessary. The theoretical and experimental aspects of such radiometry are discussed in this report. Theoretical and experimental radiometric output functions of the sensor during scanning of an area with a nonuniform temperature and emissivity distributions were obtained and their dependence on the spacial location of the fiber and type of distribution were analyzed. The results suggest that IR fiberoptic radiometry will be useful in industrial, medical and domestic applications.
The heating of tissue by microwave radiation has attained a place of importance in various medical fields such as the treatment of malignancies, urinary retention and hypothermia. Accurate temperature measurements in these treated tissues is important for treatment planning and for the control of the heating process. It is also important to be able to measure spacial temperature distribution in the tissues because they are heated in a non uniform way by the microwave radiation. Fiber optic radiometry makes possible accurate temperature measurement in the presence of microwave radiation and does not require contact with the tissue. Using a IR silver halide fiber optic radiometric temperature sensor we obtained accurate temperature measurements of tissues heated by microwave, enabling us to control the heating process in all regions of the tissue. We also performed temperature mapping of the heated tissues and demonstrated the non-uniform temperature distributions in them.
The heating of tissue by microwave radiation has attained a place of importance in various medical fields, such as the treatment of malignancies, urinary retention, and hypothermia. Accurate temperature measurements in these treated tissues is important for treatment planning and for the control of the heating process. It is also important to be able to measure spacial temperature distribution in the tissues because they are heated in a nonuniform way by the microwave radiation. Conventional temperature sensors used today are inaccurate in the presence of microwave radiation and require contact with the heated tissue. Fiber optic radiometry makes it possible to measure temperatures accurately in the presence of microwave radiation and does not require contact with the tissue. Accurate temperature measurements of tissues heated by microwave was obtained using a silver halide optic radiometer, enabling control of the heating process in other regions of the tissue samples. Temperature mappings of the heated tissues were performed and the nonuniform temperature distributions in these tissues was demonstrated.
Infrared (IR) fiber optic radiometry of thermal surfaces offers several advantages over refractive optics radiometry. It does not need a direct line of sight to the measured thermal surface and combines high capability of monitoring small areas with high efficiency. These advantages of IR fibers are important in the control of nonuniform temperature distributions, in which the temperature of closely situated points differs considerably and a high spatial resolution is necessary. The theoretical and experimental transforming functions of the sensor during scanning of an area with a nonuniform temperature distribution were obtained and their dependence on the spacial location of the fiber and type of temperature distribution were analyzed. Parameters such as accuracy and precision were determined. The results suggest that IR fiber radiometric thermometry may be useful in medical applications such as laser surgery, hyperthermia, and hypothermia.
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