The topic of this paper is the accuracy verification of a 1D length measurement device up to 3 meters. Such devices are used for calibrating length standards like bar gauges, measuring rings, or long gauge blocks. The first part of the paper provides a detailed description of the interferometer's operation, the Renishaw ML10 laser interference system, and the method of displacement measurement using linear optics. In the experimental section, two different measurement setups were considered, meaning different arrangements of measurement optics on the 1D measuring device. Three types of measurements were conducted. The first preliminary measurement was carried out solely as a test measurement to assess the suitability of the initial laser system setup. However, due to the complexity of the measurement process and its duration, this approach proved unsatisfactory and was discarded for this purpose. In the second measurement configuration, a cycle of five unidirectional measurements with a spacing of 200 mm was performed. Using the obtained results, an accuracy analysis was conducted using the standard for determining accuracy and repeatability of positioning. Finally, in the same configuration, a cycle of three unidirectional measurements with a spacing of 100 mm was carried out to determine the reading error of the measuring device with a denser spacing. The results obtained indicate a certain linear shift attributed to the instability of environmental temperature conditions.