Patent GB-1356234-A (GB)
Title: Scanning apparatus
IPC: G01T1/29
Filed: 1972-01-26
Abstract: 1356234 Screw-and-nut mechanisms L' OREAL 26 Jan 1972 [29 Jan 1971 30 Nov 1971] 3775/72 Heading F2Q [Also in Divisions G1 and H1] In an arrangement in which a measuring device for detection of physical and/or chemical properties is to be traversed over a surface being studied, e.g. that of a thin layer chromatogram, the thin-layer medium is fixed in position on a support table, across which the measuring device moves, by at least one elongate magnetizable member, the table top being composed of magnetized material. Figs. 1-3 (not shown) illustrate an arrangement in which a geiger counter for sensing radio-activity from a chromatogram is manually adjustable in position across the transverse dimension of the table, but is motor-driven in the longitudinal direction. In a more sophisticated arrangement, Figs. 4, 5 and Fig. 6 (not shown), at the end of a longitudinal scan of the assembly 14 carrying the detector 29, microswitches 118 (electronic, hydraulic or pneumatic) are actuated, causing motor/gear unit 112 to be operated and drive carriage 23 through an incremental distance, before a return longitudinal scan is carried out. In this way the whole surface of the layer medium 27 can be scanned. The unit 14, comprising carriage 23 and guide bars 20a, 20b &c. can be tilted away about pivot 15 to allow introduction of the layer medium, which is laid on the table top 1 and are held by two thin steel strips 28, which are attracted strongly by the magnetic table top, and thus prevent waviness and rucking of the layer 27. In an alternative form, the holding arrangement is a thin plate with a window. The material of the table top 1 is suitably of an aluminium alloy which has a uniform distribution of cylindrical seals in which are held ferrite pellets 11 to provide the magnetic field. The arrangement of Figs. 4, 5 includes a manually operable device, including handle 103 which frees the unit 14 from the motor drive and allows rapid positioning of the unit in the longitudinal direction. Alternatively, an automatic form may be provided which disconnects the drive from the normal scanning drive motor to ahigh-speed drive. Scales 114, 115 are provided for transverse and longitudinal position indication. Two measuring devices may be carried by the carriage 23, one above and one below the table. Each detector is adjustable in position vertically with respect to the table. The counter outputs may be integrated and printed out. The carriage may carry a marker device recording on a fixed sheet the detector output as the longitudinal scan progresses. The speed of traversing the surface may be adjustable or variable. Applications. - Besides chromatography, transmitting of the thin layer medium may be measured, a source on one side of the medium and a detector in the other, being carried by the carriage 23. Transparent zones in the table top are provided. Alternatively, by having source and detector on the same side of the material, reflection measurements are possible. Typical measurements are of colour densities, gloss, fluorescence, transparency, particle size. Radiation in the form of visible input and invisible near light wavelengths, alpha, beta and gamma are suggested. Ultrasonic energy, e.g. using echo techniques to determine surface condition, may be used.