# Evaluation of the Large-Length Indoor Standard Installation Based on Single Point Scanning
## 1 Introduction  
With the development of industrial measurement technology, large measurement devices such as laser interferometers, laser trackers, laser radars and scanners have become indispensable measurement tools of data measurement in the various fields of national defense, aerospace, shipbuilding, and manufacturing. Large measurement devices need to be tracked back to LLISI. Indematically, seven countries including Germany, the United States, Finland, Japan, and China have established a measurement system of their own for LLISI. In China, an 80-meter LLISI was established by the Chinese Academy of Metrology and Science [1], and several other 50-meter LLISIs were established by the Institute of Metrology in Shanghai, Guangzhou, and Guangxi. In addition, the Great Wall Institute of Metrology and Testing Technology in Beijing established a 35-meter LLISI [2]. The domestic LLISIS all adopt the air-floating guide operation mode. LLISI is widely used in the measuring field, particularly for the calibration of laser tracking three-dimensional (3D) coordinate measurement systems [3], ground-based laser scanners [4], laser interferometers [5], range finders, and ballbar-based measurement [6]. It can also be used for the calibration of linear displacement sensors, liquid level meters [7, 8], invar baseline wires and other non-standard length devices. A laser tracker system (LTS) is a large measurement device with high accuracy used in industrial measurement systems. It collects various advanced technologies such as laser interference ranging technology, photoelectric detection technology, fine mechanics technology, computer and control technology, modern numerical calculation theory, etc., to track the space motion target andmeasure the target's spatial 3D coordinate [9]. It is characterized by high accuracy, high efficiency, real-time tracking and measurement, quick installation, and easy operation, which is suitable for real-time measurement of geometric quantities in a large space [10,11]. Laser trackers can be used in combination with sphere targets to realize single-point measurement and single-point scanning, and can work with an intelligent probe system to realize single-point measurement, and with a linear scanning system to realize multi-point scanning. In a study by [PERSON] et al. a laser tracker was combined with a servo control system to greatly improve the performance and stability of the dynamic measurement of the laser tracker [12]. [PERSON] et al. proposed a laser tracker automatic guidance method based on the rotating laser scanning angle measurement technique, which proved that the laser tracker has better robustness for fast motion measurement of the target [13]. [PERSON] et al. proposed a closed iterative combination weighting method using laser trackers to calibrate and compensate the volumetric errors of machine tools, which provided a research direction for the use of laser trackers to measure high-accuracy linear guides [14]. [PERSON], [PERSON] et al. proposed a novel method for measuring the waviness of cylindrical surfaces, which proved that the measurement accuracy of the V-block method used to measure the waviness deviation of cylindrical parts depends on the measurement parameter [15]. [PERSON] et al. introduced a sampling strategy to avoid data gaps and obtain evenly distributed data points in the case of an over-fitting deformation analysis in the engineering measurement field [16]. Recently, several studies have investigated various indexes for evaluating LLISI, such as straightness and flatness, while no research has been carried out to evaluate its operation speed which can directly affect measurement accuracy. In this paper, to improve the speed performance of the linear guide of LLISI and analyze its common measurement intervals, we compared a laser tracker method based on single-point scanning and the laser interferometer method under three nominal measurement speeds, and evaluated the local speed of the linear guide using the laser tracker method.