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Measuring roll angles based on fiber optics

PTBnews 3.2020
25.09.2020
Especially interesting for

motion systems

manufacturers of optical components

surface metrology

The two point light sources (fiber optics) are located on the object in motion. The image sensor registers the interference pattern whose orientation indicates the roll angle.

PTB has developed a cost-efficient and very simple procedure to measure roll angles in high-precision translation stages in optical metrology and industrial production. This procedure is based on two single-mode fiber optics and a conventional image sensor and requires no further optics. The two ends of the fiber optics whose ends have a fixed position to each other are located on the object in motion. The emitted laser radiation generates an interference pattern consisting of parallel interference fringes on the sensor surface. This surface is space-bound. In the event of a rolling motion of the object, the interference pattern also rolls. The rotation angle is calculated from the interference pattern by means of Fourier analysis. The measuring range of 360° can be covered with a resolution of a few arc seconds (i.e. approx. 0.001°). In addition, the procedure is insensitive to small changes in pitch or yaw angle and to vertical or horizontal displacements along the optical axis. (Technology Offer 513)

Advantages

resolution of a few arc seconds

easy integration

insensitive to pitch or yaw motions

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