Uncertainties in the Calibration System for Invar Leveling Rods

Chien-Ting  Wu; Chun-Sung Chen; Ming-Wei  Chang

doi:10.6180/jase.2013.16.1.10

Uncertainties in the Calibration System for Invar Leveling Rods

Chien-Ting Wu This email address is being protected from spambots. You need JavaScript enabled to view it.¹, Chun-Sung Chen² and Ming-Wei Chang³

¹Department of Civil Engineering, National Chiao Tung University, Hsinchu 300, Taiwan, R.O.C.
²Department of Geomatics, Chien Hsin University of Science and Technology, Zhongli City, Taoyuan County 320, Taiwan, R.O.C.
³National Measurement Laboratory, Industrial Technology Research Institute, Taiwan, R.O.C

Received: August 20, 2012
Accepted: November 28, 2012
Publication Date: March 1, 2013

Download Citation: ||https://doi.org/10.6180/jase.2013.16.1.10

ABSTRACT

Bar code line and barcode invar leveling staffs must be calibrated for precise leveling. According to first-order leveling specifications instituted by the Ministry of Internal Affairs, the fixed standard for rod calibration uncertainties is ≤ 50 μm. At the National Measurement Laboratory (NML), no equipment meets this requirement. The purpose of this study of the existing calibration system at the National Measurement Laboratory is to reduce the calibration uncertainties to an allowable level. An automated calibration system for invar leveling staffs was established in this study, and the uncertainty of the calibration data was evaluated. The National Measurement Laboratory, supervised by the Development Center for Measuring Technology of the Industrial Technology Research Institute, employs a stabilized-frequency laser interferometer, a charge-coupled device (CCD) microscopic monitor and a precise movement mechanism for the calibration of invar leveling staffs. As part of the process, the error factors and the amount of uncertainty associated with line scale and barcode leveling staffs are assessed. At the 95% confidence level, the expanded uncertainties of the graduations were 22 μm and 21 μm for line scale and bar coded staffs, respectively, which meet user requirements.

Keywords: Invar Leveling Staffs, Calibration System, Estimate of Uncertainty, Measuring Technology

REFERENCES

[1] MOI, Standard Operational Regulations for Measurement of First-Rank Levelling, Department of Land Administration, Ministry of the Interior, R.O.C. (2001).
[2] CMS, Process for the Calibration of stripe Leveling Rod, Center for Measurement Standard, Industrial Technology Research Institute, Report No. 07-3-92- 0153, Hsinchu, R.O.C. (2003).
[3] CMS, Systematic Evaluation Report on the Calibration of Standard Reading Rod, 3rd ed., Center for Measurement Standard, Industrial Technology Research Institute, Report No. 07-3-86-0119, Hsinchu, R.O.C. (2003).
[4] Chen, C. S., Wu, C. T., Chang, M. W. and Chang, W. C., “Establishing an Invar Levelling Calibration System,” Journal of the Chinese Institute of Engineers, Vol. 31, No. 5, pp. 861866 (2008).
[5] ISO, Guide for the Measurement of Uncertainty, International Organization for Standardization, Geneva, Switzerland (1995).
[6] Edlen, B., “The Refractive Index of Air,” Metrologia, Vol. 2, No. 2, pp. 7180 (1966)
[7] Birch, K. P. and Downs, M. J., “An Updated Edlen Equation for the Refractive Index of Air,” Metrologia, Vol. 30, pp. 155162 (1993).
[8] Croarkin, C., Measurement Assurance Programs Part II: Development and Aimplementation, National Bureau of Standars, Report No. NBS Sp676-II, Gaithersburg, MD, U.S.A. (1985).