| 摘要 |
1,124,786. Electroscope dosimeters. R.A. STEPHEN & CO. Ltd. Dec. 1 1965 [Dec. 1, 1964], No. 48867/64. Heading G1Q. A radiation dosimeter, of the kind comprising a moving fibre electroscope 3 charged by the radiation to be measured, is enclosed in a housing in which a lens 5 focuses an image of the moving element on to a graticule 6, and a viewing lens 12 for reading the instrument is detachably mounted on or in the housing. For this purpose the housing has two fiducial surfaces, one defining an axis perpendicular to the graticule and one defining a plane to which this axis is perpendicular. In the assembled dosimeter, these surfaces are directly or indirectly engaged by corresponding surfaces of the viewing lens mount and such engagement ensures that the viewing lens will occupy the appropriate position in relation to the graticule. In Fig. the fiducial surfaces of the dosimeter housing are (a) the cylindrical inner surface of the cup-shaped insert 9 secured to the tubular outer shell 1 of the housing and (b) a surface of a groove 14 in this cylindrical surface. The corresponding surfaces of the lens mount 13 are (a) its cylindrical outer surface below the flange 11 and (b) a surface of a groove in this cylindrical surface. Surfaces (a) are in direct engagement, the lens mount being a sliding fit in the insert 9; surfaces (b) are in indirect contact, both grooves engaging a spring clip 15 whose presence ensures that corresponding surfaces of the two grooves are in alignment, with the viewing lens at the correct distance from the graticule. The clip may either be a loose fit in the grooves, serving merely as a location guide :for a temporarily attached viewing lens; or a tighter fit so that the lens will not be inadvertently disturbed if left attached to the instrument. In Figs. 2 and 3 (not shown) the spring and groove. locating system is dispensed with. In Fig. 2, the equivalent pair of fiducial surfaces are the plane end of the housing and the adjacent plane face of a flange, corresponding to flange 11 of Fig. 1, on the lens mount. These surfaces both engage a washer of appropriate thickness which is located between them. In Fig. 3, the lens mount is a cupshaped member which fits over the end of the housing and in this case the fiducial surfaces defining the distance between the viewing lens and the graticule are the adjacent end surfaces of the rim of this cup-shaped member and a collar on the outside of the instrument housing. In the Fig. 2 form, the telescopic engagement between the lens mount and the housing of Fig. 1 is replaced by a screw-threaded engagement. |
