Smiths Group Plc

Specac Limited

Graham Poulter

Leslie L Day

Grant Thomson

Mark Julian Gunning

Anthony George Ernest Atkins

An infra-red liquid sampling cell has a sapphire base plate with a part-spherical concave recess. A sapphire upper plate is hinged relative to the base plate larger radius of curvature than the recess. When the upper plate is lowered into contact with the base plate its convex surface contacts the liquid sample thereby excluding air bubbles and, when in contact with the edge of the recess, produces a well-defined sample thickness. An infra-red source directs radiation down through both plates and the liquid sample to a detector.

Optical sampling arrangements

An imaging infrared spectrometer system includes an ATR unit () having a sample window () above an optical system () that directs radiation through the window onto the sample and directs radiation from the sample via corrective optics () to an imaging detector (). The corrective optics is in the form of a wedge-shape prism () with a reflective surface () and is located near a focus of the optical system (). The wedge prism () is effective to correct the focal plane orientation and anamorphic magnification at the sample.

Spectrometer apparatus

A thermal probe system has a Wollaston thermal sensor connected in one arm of a bridge. The other arms of the bridge are provided by resistors and a voltage is applied from a low-noise source via several op-amps. The output of the bridge is connected with a primary winding of a step-up transformer, the output of which connects with the input of an output amplifier, which, in turn, provides an output to a display.

Thermal probe systems

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

Orpington, United Kingdom

Graham Poulter