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Sometimes it is necessary to fine determine the position of the optical axes of the convex-concave lenses, such as eyeglass lenses. If the lens has not yet been processed, and its boundary has the shape of a perfect circle — it's not hard to do. The problem occurs when the lens has already given shape to be installed in the frame. Currently, a mechanical method for determining the thickness of the lens has not a high accuracy. The proposed method for determining the position of the optical axis of the lens uses a double reflection of the laser beam. The reflected beams from the front and rear sides of the lenses create two point light source. These sources create a remote screen system of equal inclination rings. Observe the center of these rings on the screen is possible, if the laser beam falls into the thinnest position diverging lens or in the thickest collecting one. This method is applicable both for scattering as well as for collecting lenses. Lenses can be rotated to the laser beam, both convex and concave side. This method is also applicable to the adjustment lenses located on an optical bench. Since the angular dimensions of the rings are determined radii of curvature of the lens, its thickness and refractive index, the method can be used to determine the curvature of the lens surface. |
