Laboratory Testing of Leica At401 Laser Tracker

Abstract

Abstract. This paper describes laboratory tests on a Leica AT401laser tracker. As the newer Leica AT402 model also uses the same firmware package, most of the results should also be valid for this device. First, we present the instrument's firmware errors and the software used for testing. The ASME B89.4.19-2006 standard for testing laser trackers is briefly presented. The warm-up effect of the instrument is inspected with respect to both angle measurement and distance measurement. The absolute distance meter (ADM) is compared with a laboratory interferometer on a 30-meter long rail and also on a bench with automated movement of the carriage of the reflector. A time series of measurements for determining the additive constant is evaluated. A simple test of the stability of the distance measurement in field conditions is introduced. Most of the tests were carried out at the Research Institute of Geodesy, Topography and Cartography (RIGTC) and at the Faculty of Civil Engineering (FCE) of the Czech Technical University in Prague (CTU).

Results of development of a stand for evaluation of the accuracy characteristics of absolute trackers

“…Experimental studies have shown that the values of the absolute error in measuring the length and volumetric measurements, determined using the model of the stand, do not exceed the permissible values established when the type of the absolute tracker Leica AT401 was approved [7]. Thus, a model of a stand for metrological support of absolute trackers has been proposed and developed, a method for assessing the metrological characteristics of absolute trackers has been proposed and tested.…”

Warm-Up Effect and Warm-Up Time of a Laser Tracker

“…Thermal expansion caused by the process of internal heating has a significant impact on the measurement. There is also information from the Leica geosystem given in [4] that the inclination sensor in the oil bath suffers from heating as well and changes its zero position. According to the manufacturer, this is the major contributor to the warm-up effect.…”

“…It specifies a period after which LT reaches a stable internal temperature level. This value also depends on the model of LT, but research has shown that it takes around two hours to reach a stable temperature for different LT [4], [5], [6]. Manufacturers are providing more optimistic information.…”

Survey of Selected Procedures for the Indirect Determination of the Group Refractive Index of Air

“…The author of this paper has tested the Leica AT401 in laboratories of Research Institute of Geodesy, Topography and Cartography (RIGTC) and Czech Technical University in Prague, Faculty of Civil Engineering. The main purpose was to prepare the instrument and other equipment for high accurate field measurements at Czech national field length baselines [21].…”