The manufacture of precise optical prisms is time-consuming and requires appropriate manufacturing and metrological expertise. During fine grinding, an appropriate basic angular accuracy of the prism must be achieved, as the material removal during polishing is much lower than during grinding. During the polishing process only the fine correction of the prism angles is carried out. If the required basic angle accuracy is not achieved during fine grinding, this is usually only visible after polishing the measuring surfaces. Either adequate material reserves are still available to correct the prism according to the drawing with a further fine grinding and to finish it during the subsequent polishing, or the prism must be written off as production scrap. Until now, there was no easy and quick method to use a precise measuring device to measure the angular accuracy of ground prisms before polishing. The use of an appropriate measuring device holds a high potential for saving time and costs in the production process. In addition, the system can contribute to the optimization of the fine grinding process and thus to quality improvement.
Measuring Ground Prisms

The patent pending extension for ground prisms for the GONIOMAT M5/M10 Goniometers allows the measurement of prism angles with a fine grinding / roughness of up to R = 1.0 µm and a measurement uncertainty of less than 10 arcsec. The achievable accuracy and measurability of the test specimen depends on its surface size, and its roughness.

For technical data, see HERE.