The application of yaw sensor for measuring carriage system
Laser interferometers have generally been used for the angular measurement of measuring tape calibration systems. Yaw error measurements using a yaw sensor have been carried out to determine the characteristics of yaw errors and analyze the behaviors of the structural guide. The yaw sensor technique is identical to the error compensation used in a measuring tape calibration, and also has some special parameters. However, the yaw error observation period is very short, but it is sufficiently accurate for a carriage yaw sensor. This paper presents the yaw sensor innovation for the measuring carriage application that would be compensated by using yaw error is approximately minimized to 65 arcsec and its repeatability is less than 30arcsec.
Optical sensor for measurement of roll + pitch + yaw angles over large distances with high accuracy
There are applications, where the relative orientation, i.e. the roll-, pitch-, yaw angles, between a reference system and a far distant object system must be known. If the systems are closed together, for example, the rotational encoder is a standard instrument to measure the roll angle. For large distances (up to intersatellite distances) this optical sensor is able to measure the roll angle between both systems with an accuracy of about 1 arcsec within a range of plus or minus 30 degrees. The measurement principle is based on the reception and evaluation of the transmitted polarization plane according to the law of Malus. Replacing one photodiode with a position- sensing detector (PSD), the other two degrees of freedom can be also measured with similar accuracy within a range of about plus or minus 5 degrees. The present sensor principle is characterized by the application of amplitude- and polarization modulation with two perpendicular linear polarized laser diodes in the transmitter and evaluation of the signals with a suitable algorithm. The advantage of the sensor is that it becomes insensitive to stray light, intensity fluctuations of the laser diodes, responsivity fluctuations of the photodiodes and the p-s transmission splitting due to non-perpendicular incident light.
5-m measurement system for traceable measurements of tapes and rules
Measurement uncertainty is an important topic for traceable measurements. Nevertheless not many literatures on the uncertainty of flatness measurements have been reported. In this paper, we report on this issue according to the Guide to the Expression fo Uncertainty in Measurements (GUM). First stability of the reference optical flat used in Fizeau interferometer is discussed analytically, numerically, and experimentally. Then other uncertainty sources in actual measurements are investigated. As a result the uncertainty of flatness measurement of a large aperture flatness interferometer made by National Metrology Institute of Japan is 1/77 wavelength.