Investigation of the focusing lens course in the spotting scopes of digital levels

To ensure the required accuracy of elevation and angle measurements, measures are taken at the station to rectification or significant reduce of the influence of the main instrumental errors. With regard to leveling, main errors are the violation of the main condition of the level (the influence of the constant component of the angle i), as well as the incorrect course (oscillations) of the spotting scope focusing lens when it is refocused (the variable component of the angle i). In this regard, in order to significantly reduce their influence, leveling at the station is carried out by the middle with an acceptable shoulder difference. The influence and magnitude of the focusing lens travel on the measurement, as well as methods for reducing the errors, are well covered for instruments with visual reading. With regard to the spotting scope of digital levels, which have different design and shorter focal length, the nature and magnitude of this influence is not covered enough. This circumstance is important when performing measurements with the instruments in terms of the possible expansion of technological tolerances for the inequality of the shoulders at the leveling station when performing geometric leveling.Therefore, the purpose of this research is to determine the nature and magnitude of stroke of the focusing lens of digital levels and, taking into account its influence, to make recommendations to existing measurement methods. To solve this problem, a verification technique was implemented by leveling the excesses from two stations. Studies have established that in high-precision digital levels, the amount of stroke of the focusing lens does not exceed 0.14 mm. This allows, when performing high-precision leveling, to increase the inequality of the shoulders at the station with virtually no loss of measurement accuracy.