Roll Angle Error Measurement of Linear Guideways Using Mini Autocollimators

Linear guideways are essential for precise linear motion in machinery, and load-bearing capacity for the purpose of providing rigidity. On other hands, linear guideways have critical applications in CNC machines, semiconductor manufacturing, and metrology instruments, ensuring precision and accuracy. However, guide rails in CNC machines are susceptible to six motion errors that significantly affects machining accuracy. Measuring roll angle errors, especially in the presence of mirror imperfections, poses a challenge. The main objective of this article is to measuring roll angle error with lens and without lens in order to reduce the mirror imperfection. In this paper mini collimator developed with and without lens developed and calibrated by using electro autocollimator instrument. Liner guideway was measured by using level meter and Mini autocollimator instrument with lens and without lens. Additionally, Mini autocollimator is fixed on the stable optical table which is perpendicular to the Liner guideway mirror and both the level meter and the mirror are fixed on the Liner guideway. From the measurement result it is observed that a sensitivity calibration value of $K=393.6^{\prime \prime}$ with the lens, compared to $K=-1432.8^{\prime \prime}$ without lens. Comparison residuals for roll angle errors are $\pm 0.9^{\prime \prime}$ and $\pm 2 "$ to $\pm 3^{\prime \prime}$ with lens and without lens respectively. The results highlight the crucial role of lens-equipped autocollimators in mitigating mirror imperfections and achieving precise angle measurements. In conclusion, this is evident in the substantial reduction of systematic error from $22.099^{\prime \prime}$ without the lens to $11.274^{\prime \prime}$ with it, indicating a significant improvement in measurement accuracy