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Theodolites
Published in Leonid Nadolinets, Eugene Levin, Daulet Akhmedov, Surveying Instruments and Technology, 2017
Leonid Nadolinets, Eugene Levin, Daulet Akhmedov
The collimation axis of the telescope should be horizontal when the vertical circle read out is equal to zero. In order to meet this requirement, we should measure the vertical angle at two positions of the theodolite. The total sum of these readings must be 360° if the theodolite has an ordinary full scale (from 0° to 360°) of the vertical circle. Some low-precision theodolites have an inclination scale of ±90° instead of the full scale. In this case, sightings of the same target should have angles of inclination at both positions of the theodolites and must be equal but have opposite signs. The difference of the sum from 360° (0° for the instruments with the inclination scale) divided in two is called the vertical circle index error. In order to correct it we should correct the vertical circle read out by means of the vertical tangent screw. Then we superpose the horizontal line of the reticle to the target with the help of the vertical adjusting screws (see Figure 3.13). We suggest correcting only slight vertical index errors with the help of these screws. If the vertical index value is several minutes, the reticle's horizontal removal or inclination could appear. The horizontal removal of the reticle changes the collimation error value that must be corrected. The vertical index adjustment of low-precision theodolites can be fulfilled only adjusting the reticle screws.
Optical Instrument Structural Design
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
The eyepiece subassemblies are threaded into aluminum cover plates (see Figure 5.38 of Volume 1) that are screwed fast to the rear openings in the body housings. Gaskets are used to seal these joints. Adjustment of eyepiece focus for the user’s visual accommodation is achieved by rotating each eyepiece as a unit to translate the lenses axially. Since the military binocular is intended to view distant targets, it is focused at infinity. A calibrated reticle is placed at the left eyepiece focal plane for making angular measurements related to directing weapon fire.
A user-centred assessment of a less-lethal launcher: the case of the FN 303® in a high-pressure setting
Published in Ergonomics, 2019
The FN 303 uses compressed air to launch 18.0 mm fin-stabilised, plastic projectiles weighing 8.5 g. Impact-only rounds containing a clear, non-marking, non-irritant liquid payload were used for the study. The FN 303 weighs 2.9 kg, is 74.5 cm long, and is equipped with a rotary 15-round magazine. An electronic holographic sight (EOTech Model 552™, www.eotechinc.com) was affixed for the experiment. The sight superimposes a red aiming reticle on the target, enabling the operator to keep both eyes open in tactical situations (see Figure 1).