No abstract

An unclad silver-halide fiber was coated with a 0.1-microm silver layer and immersed in ethyl alcohol, and the fiber transmission in the range 2-20 microm was measured. The loss, induced by the metallic layer, was used to calculate the extinction coefficient, kappa', and the index of refraction, n', of the layer by fitting the experimental data with the time-independent perturbation theory in the complex region. The dependence of the extinction coefficient on the wavelength was found to be logarithmic, kappa'(lambda) = kappa(0)' exp(a lambda), and not linear, as predicted by others. This simple technique may be used to study the optical constants of thin metallic films.

Suturing of corneal incisions requires significant skill. We demonstrate a noncontact method that will simplify the bonding process. 5-mm-long penetrating vertical and slanted incisions were made in corneas of eyes, extracted from dead piglets. A fiber-optic laser system was used for laser soldering of the incisions, under close temperature control, using albumin solder. The burst-pressure P B immediately after the soldering was found to be P B ≈ 92 and 875 mmHg, for vertical and slanted incisions, respectively. P B ¼ 875 mmHg is an exceptionally high figure, ≈10 times the clinically acceptable value for sutured incisions. Laser soldering was then performed on penetrating incisions made in the corneas of live healthy piglets, of weight ≈10 Kg. After a healing period, the eyes were extracted, and the corneas were examined by histopathology and by optical coherence tomography. Our method immediately generated watertight and strong bonding without noticeable corneal shape distortion. These results would be beneficial for cataract surgery and for corneal transplantations. The fiber-optic system makes it much easier to bond corneal incisions. In the future, laser soldering could be automated and efficiently used by less experienced surgeons, thereby reducing the workload on the experienced ones.

Internal biological tissue temperature measurements using zirconium fluoride fiber AIP Conf.

The infrared and ultraviolet emission spectra of hydrocarbons and toxicants was measured and analyzed as compared to theoretical data at room temperature. Based on this data we constructed an electro-optical gas detector for monitoring low concentration of flammable paraffins, aromatics and toxic hydrogen-sulfide.The optical method uses two wavelengths at several spectral bands: the signal and the reference which is sampled at a region where the hazardous gas does not absorb at all. Our apparatus is an innovative system that provides fast and reliable explosion detection at different LEL levels. As well, it can provide identification of low concentration of toxicants in the range of parts per million. The apparatus includes a fire detection option that can offer at the same time an automatic activation of fire suppression or neutralization system. It can detect paraffins in the range between 0.03 to 20 LEL per 1 meter by using the infrared spectral band and aromatics and hydrogen sulfide in the range between 100 to 2000 ppm per 1 meter by using the ultraviolet spectral band. At both regions the accuracy is about 20%. This open-path, line-of-sight gas detector can monitor and transmit an alarm signal prior to occurrence of fire or explosion.