A German research institute active in metrology has developed a low cost system, which enables the easy measurements of the roll angle of high-precision linear adjusters in optical metrology or in industrial manufacturing. The research institute has applied for a patent for the method that requires only two optical fibers and an image sensor without any additional optics.
The two optical fibres, which are positioned close to each other, are located on a moving object, for example a sliding table. The laser radiation emitted from the fibres leads to an interference pattern that falls on a sensor surface that is fixed in place. When the moving object rolls around the axis of linear motion, the interference pattern also rotates. The interference pattern is evaluated by means of line-by-line Fast Fourier Transformation (FFT) and its angle of rotation is calculated from this. The measuring range of 360° degrees can be detected with a resolution of better than 0.001°. In addition, the method is largely insensitive to pitch and yaw movements.
The invention is intended to replace much more complex procedures based on polarisation measurement. Application areas are scanning systems in surface metrology. Manufacturers of optical components can use it for quality assurance in the production of linear actuators. The high-precision feeding of components in the production process can also be monitored and controlled.
The German research institute is searching for licensees interested in the commercial exploitation and integration in surface scanning systems, quality assurance in the production of linear actuators and the manufacturing of high-precision feeding systems for components in the production.