Continues efforts to develop low loss flexible waveguides, to transmit mid IR laser energy for minimal invasive surgical and diagnostic procedures, have been carried out by us and other groups in this area. We have introduced sulfide dielectric films coated over an Ag reflecting layer as another potential solution. The metal sulfides used, have high transparency in the infra red spectrum and their thickness can be tailored to minimize the attenuation over a selected wavelength range. The high refractive index contrast of the two metal sulfide materials enable to produce multi layer hollow waveguides. These waveguide will have low attenuation in both straight and bent conditions, low sensitivity to coupling and to surface roughness and a broad wavelength range. The straight lowest loss measured at 1.55μm for a 1,000-μm bore Ag/CdS/PbS/CdS HGW was 0.06 dB/m. This loss is three times less than that measured for a single layer Ag/CdS coated HGW at 1.55μm. A theoretical simulation applying the same conditions showed the same pattern with a good potential for improvement.
Two fiberoptic infrared multi-spectral radiometers were constructed for measurements of the temperature and the emissivity of gray bodies whose temperatures were close to room temperature (40-70°C). In one radiometer, the different spectral regions were obtained by using standard bulk interference filters, and in a second radiometer, the different spectral regions were obtained by using hollow glass waveguides (HGWs) as filters. Using these two radiometers, we carried out temperature and emissivity measurements of three gray bodies which had high emissivity (ε=0.97), medium emissivity (ε=0.71) and low emissivity (ε=0.025). We present the results obtained for these gray bodies and discuss the advantages and disadvantages using each of the radiometers.
Trans-endoscopic Infrared Imaging (IRI) relates the possibility to conduct IRI diagnosis of internal body surfaces under minimal invasiveness. It may also be utilized to control and to optimize the thermal interactions and the potential side effects during Minimally Invasive Surgeries (MIS). However, transferring the thermal images transendoscopically requires the usage of IR imaging bundles, which are neither yet mature nor commercially available. In our setup we have used two basic types of recently-developed imaging bundles: Ag/AgI-coated Hollow Glass Waveguide (HGW) bundles and Silver Halide (AgClBr) core-clad fiber bundles. The optical setup system was consisted of IR optics (e.g. ZnSe lenses, reflective objectives) and a thermal IR camera. We have succeeded to image objects through the bundles, such as various shapes of electrically heated wires, ex-vivo biological phantoms (samples of porcine stomach) and in-vivo phantom models (mice) irradiated by CO2 laser. Measurements were conducted for both - static and dynamic object states.
Coherent IR fiber optic bundles for use in IR imaging from 2 to 12 µm are fabricated from rigid hollow-glass waveguide arrays. The bore of each hollow glass tube in the bundle is coated with thin films of metallic Ag followed by AgI for enhanced reflectivity. The coating of the rigid bundle is done using liquid phase chemistry techniques applied to all tubes simultaneously. The hollow-glass arrays are composed of up to 900 individual tubes with bore sizes as small as 50 µm. Several rigid hollow-core arrays are used to transmit an IR image of a small loop of hot wire and a sample of tissue heated by a CO2 laser.
Metal sulfide dielectric thin films have been deposited using dynamic wet chemistry processing on silver coated hollow glass waveguides (HGWs). Metal sulfides like cadmium sulfide (CdS) and lead sulfide (PbS) possess excellent optical properties in the IR and have high refractive index contrast. A linear growth regime with deposition time has been observed for CdS and PbS thin films on Ag inside silica hollow glass waveguides. The thickness of these thin films can be tailored to minimize the attenuation of the HGW at the operating wavelength. We have made single dielectric metal coated HGWs using CdS and PbS. This paper discusses the processing and characterization of the thin films and the resulting dielectric metal coated hollow glass waveguides.
Different dielectric thin films are being studied in order to facilitate the processing of low loss multiple metallic dielectric hollow glass waveguides (HGWs). In this paper, we present our results for high index lead sulfide (PbS) and low index optical polymers, especially, polystyrene (PS) and cyclic olefin polymer (COP). We have observed that the morphology of the thin film is dependent on the processing conditions. The morphology of the metal and dielectric thin film affects the attenuation of the hollow glass waveguides. We have been successful in depositing and controlling the morphology of high n PbS thin films and low n polymer films. In order to aid in thin film characterization we have also deposited on planar substrates.
Low loss coherent bundles can be used in the area of broadband infrared and thermal imaging. We have been able to extend the present hollow glass waveguide (HGW) technology to very small bore sizes, from 250 down to 50 ?m. HGWs with bore sizes from 50 to 320 ?m have been used to make flexible bundles. These bundles are then coated with Ag/AgI thin films using liquid phase chemistry techniques. The optical properties of these bundles were studied by FTIR spectroscopy. These bundles have relatively low loss in the wavelength range of 8 to 12 ?m.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.