GB374429A - Improvements in or relating to means for the correlation of rotational and longitudinal movements in monochromators and other instruments - Google Patents

Abstract

374,429. Spectroscopic monochromators &c. HILGER, Ltd., A., TWYMAN, F., and PERRY, J. W., 24, Rochester Place, Camden Road, London. March 7, 1931, Nos. 7158 and 26906. [Class 97 (i).] In a monochromator or other instrument having a pivoted member or equivalent, the distance of the end of which from the pivot is required to bear a predetermined relation to the angular displacement of the member about the pivot, the said member is so dimensioned and pivoted that the locus of its end passes through three selected points lying on a straight line or deviating therefrom by specified small amounts. Preferably the said locus passes through the collinear points near the middle and ends of the desired range of movement. The Figures show the application of the invention to a double monochromator of the kind described in Specification 314,781, [Class 97 (i), Optical systems &c.]. Considering one half of this instrument, the pivoted member is here the light beam deviated by the prism 18 and passing through the rotating lens 2 and the end of this member is the focal point of the beam lying substantially on the axis of symmetry of the instrument, on which axis the mirror 15 is situated. By suitable selection of the angle of the prisms 18, 19, the axes of the first collimating lens 1 and the final imaging lens 4 can be arranged to remain parallel to each other and to the axis of symmetry over a wide range of wave-lengths. These lenses can then be mounted on a common carriage 7 movable along guides 8 and having a nut 9 engaging a rotatable adjusting-screw 10, the axis of which is in the plane of symmetry. An extension 12 of the screw 10 is also screw-threaded and is adapted to displace a carriage 13 on which is the mirror 15. The rotating lenses 2, 3 are carried by arms 16, 17 which are mounted on the carriage 13 in such a way as to be free to vary their inclination, these arms being rotatable about axes containing the second principal points of the lenses. The prisms 18, 19 are connected by gearing 20 to the lenses so as to turn at half the speed of the latter to ensure that rays reaching the mirror 15 have passed through the prism 18 under minimum deviation. Slight focusing errors may be corrected by a small adjustment of the carriage 7. A bell-crank lever 21, Fig. 3, pivoted to the nut 9 has at the end of its longer arm a roller 23 engaging a cam 24, and the short arm of the lever is connected by a link 25 to the carriage 7. Specification 363,264 is referred to.