ABSTRACT
A system was developed to determine the potential role of infrared imaging as a tool for localizing anatomic structures and assessing tissue viability during laparoscopic surgical procedures. A camera system sensitive to emitted energy in the midinfrared range (3-5 micron) was incorporated into a two-channel visible laparoscope. Laparoscopic cholecystectomy, dissection of the ureter, and assessment of bowel perfusion were performed in a porcine model with the aid of this infrared imaging system. Inexperienced laparoscopists were asked to localize and differentiate structures before dissection using the visible system and then using the infrared system. Assessment of bowel perfusion was also conducted using each system. Infrared imaging proved to be useful in differentiating between blood vessels and other anatomic structures. Differentiation of the cystic duct and arteries and transperitoneal localization of the ureter were successful in all instances using the infrared system when use of the visible system had failed. This system also permitted assessment of bowel perfusion during laparoscopic occlusion of mesenteric vessels. These initial studies demonstrate that infrared imaging may improve the differentiation and localization of anatomic structures and allow assessment of physiologic parameters such as perfusion not previously attainable with visible laparoscopic techniques. It may thus potentially be a powerful adjunct to laparoscopic surgery.
Subject(s)
Laparoscopy/methods , Thermography/methods , Animals , Arteries/anatomy & histology , Cholecystectomy, Laparoscopic/methods , Cystic Duct/anatomy & histology , Disease Models, Animal , Dissection , Equipment Design , Gallbladder/blood supply , Infrared Rays , Intestines/blood supply , Laparoscopes , Light , Mesenteric Arteries/anatomy & histology , Mesenteric Vascular Occlusion/physiopathology , Mesenteric Veins/anatomy & histology , Monitoring, Intraoperative , Peritoneum/anatomy & histology , Splanchnic Circulation , Swine , Thermography/instrumentation , Tissue Survival , Ureter/surgeryABSTRACT
A porous plastic optical fiber has been developed for use in chemical gas sensing. This porous plastic waveguide, which was made with copolymer materials, has an interconnective porous structure as well as uniformity of pore size. These sensors are based on in-line optical absorption within the porous plastic fiber core and have much greater sensitivities than sensors based on evanescent coupling to a surrounding medium. Furthermore, this fiber simultaneously exhibits very high gas permeability and liquid impermeability. This combination makes the fiber particularly suitable for gas concentration measurements in aqueous samples. An ammonia gas sensor has been tested to demonstrate the effectiveness of this porous plastic waveguide.
ABSTRACT
The side-mode suppression ratio (SMSR) and single-mode continuous tuning range were measured for planar short-external-cavity semiconductor diode lasers to examine the positional and angular alignment tolerances of the external cavity mirror relative to the laser facet. For inverted rib waveguide lasers, the SMSR was found to be
ABSTRACT
Detection of CO(2) and CO at 1.58 microm (6322 cm(-1)) using an InGaAsP diode laser and mode control is described.Mode control is a technique whereby a short cavity, external to the laser, is used to force the laser to operate in a single mode. By monitoring the voltage across the terminals of the laser and using electronic feedback it is possible to optimize continually the external cavity so that the laser operates reliably in the mode of choice for scans >3.5 cm(-1). This technique offers the possibility of high-sensitivity detection over a region of ~30 cm(-1) with continuous coverage in overlapping sections of ~3 cm(-1) with conventional (and hence inexpensive) multimode diode lasers.
