Specac Limited

Leslie L Day

Graham Poulter

An optical fiber probe for attenuated total reflectance measurements comprises a tubular body within which pass input and output optical fibers. The optical fibers are mounted within the body so that radiation emitted from the end of one of the optical fibers can pass through the optical system of the probe and be reflected back and focused on to the end of the other optical fiber for transmission back to a spectrophotometer. The optical system includes an attenuated total reflectance element, preferably of zinc selenide, which has a cylindrical body having at one end two perpendicular cut-away surfaces to form a roof mirror and at the other end a convex surface which acts to focus the radiation on to the end of the output optical fiber. The material to be tested is allowed to come into contact with the surfaces of the roof mirror, and then radiation is sent through the element and is totally internally reflected within it. Sealing around the element is effected by means of an O ring seal which extends around the element's cylindrical surface. Since there are no internal reflections from this surface, the spectrum of the O ring is not picked up.

Optical fiber probe for attentuated total reflectance measurements

An optical fibre probe for use with a spectrophotometer, for remote analysis of samples, includes a probe assembly having an outer tubular body member, a sleeve member, and a further tubular inner body member within that. Input and output optical fibres pass into the assembly from one end, and the fibres are terminated in ferrules secured within a ferrule plate which is mounted by means of grub screws at the end of the inner body member. Radiation emerging from the end face of the input optical fibre is reflected back within the probe to be focused on the end of the other fibre, after total internal reflection in the case of an ATR probe or after passing through a transparent sample in the case of a transmission probe. Lateral positioning of the ferrule plate and thus the ends of the optical fibres, across the optical axis, is achieved by differential tightening of the grub screws. Focusing is achieved by sliding the inner body member longitudinally in the sleeve member, and also rotating the inner body member if necessary. The inner body member and the sleeve member are then locked together by fully tightening the grub screws.

Growing community of inventors

Caterham, United Kingdom

Leslie L Day