Interferometric technique for controlling wedge angle and surface flatness of optical slabs

We report on a laboratory setup suitable for quality control and analysis of optical slabs in the sense of perfection of their geometry and optical bulk homogeneity. Our non-contact technique based on principles of interferometry permits high-speed, precise quantitative characterization of the wedge (apex) angle and/or face flatness imperfection, as well as bulk inhomogeneity of optical slabs. The setup has been subjected to test measurements on several samples manufactured from pure and MgO-doped LiNbO3 crystals for which the wedge angle and flatness deviation have been evaluated. The technique and the methodology developed by us can be offered for use in scientific research laboratories and industry.

► We offer an interferomeric setup for control of optical slabs.
► The technique is able to give precise quantitative characterization of the wedge angle.
► The technique evaluates face flatness and optical inhomogeneity of samples.
► The setup has been tested on several samples made of pure and MgO-doped LiNbO3.
► The proposed technique is applicable in research laboratories and industry.