Close

Search

Search Menu
Photonics Media Photonics Buyers' Guide Photonics EDU Photonics Spectra BioPhotonics EuroPhotonics Industrial Photonics Photonics Showcase Photonics ProdSpec Photonics Handbook
More News
share
Email Facebook Twitter Google+ LinkedIn Comments

Silver Fiber Transmits IR Images

Photonics Spectra
Nov 2000
Michael Moss

TEL AVIV, Israel -- Scientists at Tel Aviv University are developing an infrared endoscopy technique that employs bundles of silver-halide fibers. Infrared endoscopy could detect cancerous tumors or monitor laser surgery and may find a place in surveillance applications for monitoring activity outside a vehicle or building.

Today endoscopy is limited to the visible light range. The silica-based or polymer fibers in an endoscope that transmit images from inside the body to a CCD detector are opaque to mid-infrared wavelengths, which makes it impossible to carry out thermal imaging.


Researchers at Tel Aviv University are using silver halide fibers to transmit IR images. A cooled thermal camera directly images a tungsten wire heated to 40°C (left); the same image, transmitted to the camera through a 900-fiber bundle (right), lacks resolution but holds promise for endoscopy.

The team, whose method is detailed in the April 3 issue of Applied Physics Letters, decided to look to silver halide. Silver halide has many advantages over other IR-transmitting materials such as chalcogenide, including good room-temperature transmission between 3 and 30 µm. It is also nontoxic and nonhygroscopic.

The researchers produced the fiber bundles using multiple extrusion. They inserted an AgBr rod in AgCl, which has a lower index of refraction, and extruded the coated rod to form a 0.7- to 0.9-mm-diameter clad fiber. They cut the fiber into shorter lengths, and then ordered and again extruded these segments to form a 900-fiber bundle.

Several problems still remain. The silver-halide bundles are flexible only when their diameter is less than 1 mm, but the team estimates that approximately 10,000 fibers are needed in a bundle to achieve acceptable resolution. The group has produced bundles of 100 to 9000 elements, with outer diameters of 2 to 8 mm.

Work is under way to produce bundles with smaller diameters, higher density of fibers and lower transmission losses.

Research & TechnologySensors & DetectorsTech Pulse

Comments
Terms & Conditions Privacy Policy About Us Contact Us
back to top

Facebook Twitter Instagram LinkedIn YouTube RSS
©2018 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, info@photonics.com
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.