Surveying Instrument Collection
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Maker |
Kern & Co., Aarau (Switzerland) |
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Model |
DKM2-AEM |
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Serial Number |
271314 |
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Dimensions |
Telescope length 175 mm, Height 225 mm |
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Image |
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Description |
This Kern DKM2-AEM is a one-second (1") optical micrometer theodolite of high precision suitable for triangulation, traversing, deformation measurements, precise layout work in building construction and sub-surface work, astronomical observations, optical tooling and photogrammetric control. It incorporates a trunnion axis micrometer which serves the same purposes as a striding level (also included in the collection), and is used to increase the accuracy and reliability of the horizontal directions for steep sights. The trunnion axis micrometer permits to measure the inclination of the vertical axis in the direction of the trunnion axis. From these measurements the inclination of the vertical axis in trunnion axis direction and the correction of the horizontal direction can be computed. The practical measuring range of the trunnion axis micrometer is approximately ±30" and the inclination of the trunnion axis component of the vertical axis can be determined to ±1". The trunnion axis micrometer uses the same (dual-axes) liquid compensator as the vertical circle. The magnification of the telescope is 32x, the diameter of the objective lens of the telescope is 45 mm, and the shortest pointing distance is approximately 1.7 metres. Other features include a maintenance-free vertical circle liquid compensator (working accuracy of 0.3" and range of 2'), upright telescope image, digitised circle reading, optical plummet with adjustable focus, two-speed (course and fine) azimuth and elevation tangent screws, cam controlled short-stroke levelling system and course-fine circle orienting drive. The accuracy of the instrument is excellent since the scale interval of the micrometer is 1" and estimation can be made to 0.2". The diameters of the horizontal and vertical circles are 75 mm and 69 mm respectively. One mirror caters for the illumination of both circles. The sensitivity of the plate level is 22" per 2 mm. The instrument requires special 'Kern' centring tripods and is not compatible with any other brands. Centring with the KERN centring tripod produces an accuracy of 0.5-1mm. The theodolite is provided with a metal carrying case, and the tool compartment in the base of the carrying case contains a hexagonal wrench with screwdriver, one adjusting pin and two Allen wrenches (1.5 mm) for the adjustment of the collimation error. |
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History & comments |
This is most likely the best theodolite of its class. The instrument was first shown at the ISP congress 1968 in Lausanne, Switzerland. It is a constructive masterpiece by Hans Koch who has been employed with Kern since 1960. The basic design of the DKM2-AEM dual-axis liquid level sensor is now being used by most dual-axis level sensors in electronic theodolites. |
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Conservation |
Metal carrying case (L 210 mm, W 160 mm, H 300 mm) |
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Condition |
Excellent condition |
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Remarks |
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Dates |
Catalogued in 2000. |
