| 摘要 |
PURPOSE:To form an elastic arch lens by running a cord through a plate lens at four corners and curving the lens by drawing the cord. CONSTITUTION:In a thin elastic plate lens 1, small holes 2 are made at four corners. Cord 3 whose surface is easy to slide is passed through respective holes 2, and both ends 5 of cord 3 are further passd together through cord stopper 4 made of a tube, etc., of adequate length. Then, drawing both ends 5 of cord 3 to right and left tightens cord 3 via cord stopper 4 as a fulcrum, and consequently plate lens 1 curves, so that the plate lens in an arch shape, namely, arch lens 6 can be formed. Loosening cord 3 by moving cord stopper 4 decreases the curvature of arch lens 6 and it becomes flat eventually. Thus, the elastic arch lens can be formed. |
