Roundness measurement by software datum method (2nd report)

An experimental optical sensor is developed to realize the mixed method in the measurements of roundness and rotational errors. The sensor has two probes, which can detect the displacement and angle at two points on the measured surface simultaneously. The angular distance between the probes is set to 45° according to the result of simulations. The displacement meter utilizes an imaging-formation system and the angle meter utilizes the principle of autocollimation. According to the calibration results, the resolution of the displacement meter and angle meter is 0.1 μm and 0.6s, respectively. To improve the performance of the optical sensor, an optical fiber system for power transmission is used to divide the light from a LD into two beams, which are utilized as the light sources of the two probes. The effectiveness of the fiber system is investigated by measuring the intensity distribution and its stability at the fiber output. The experimental results confirm that the output beams of the fiber system demonstrates fairly good performance. A measurement system is also constructed to realize the measurements of roundness and rotational errors by using the optical sensor. The stability of the profile measurements of the system is confirmed to be 0.05μm. The measurement results show that the mixed method can separate the roundness and the rotational errors clearly. The effectiveness of the mix method that can accurately measure high frequency components is also verified.