| In an effort to reduce the error characterization time of linear axes, a six degree of freedom optical sensor has been developed. The sensor consists of a fixed source and a small moving target. The sensor uses a 5 kHz sample rate to allow dynamic, simultaneous measurement of all six degrees of freedom. The moving element is purely optical, scales with beam size and can easily be reduced in size to a 25 mm cube that weighs approximately 50 grams.; Using a stabilized helium-neon laser source, the current system has a linear displacement resolution of 153 nm. The straightness resolution, with 0.4 meters between the source and the lateral effect photodiode, is 250 nm. This corresponds to a resolution for pitch and yaw of 1.25 μradians. With the current available laser input power, the theoretical resolution of the roll measurement is 2 μradians.; The majority of machine tools and coordinate measuring machines used today consist of stacked linear axes. In order to obtain three dimensional controlled motion, machines typically have three nominally linear axes. To increase the accuracy of these machines, high accuracy characterization tools, such as the one developed in this research, are used to measure errors along the axes of motion. These measured errors are then used to compensate the motion of the machine. |
