Patent ID: 9726908
Date: 2017-08-08
CPC Classifications: A61H,G02C

Claim:
1. An optical device for restoring eyesight, comprising: a first tube configured such that a first convex lens having a first focal length is installed to an inner peripheral surface of a fore-end thereof; a second tube inserted into the first tube so as to move forward and backward within the first tube while a first concave lens having a second focal length and a second concave lens having a third focal length are installed to an inner peripheral surface of a fore-end thereof; a third tube configured such that a third concave lens having a fourth focal length and a fourth concave lens having a fifth focal length are installed to an inner peripheral surface of a fore-end thereof; a fixing unit for fixing the second tube to the third tube; and a fourth tube fixed to the fixing unit to cover the second tube, wherein the fourth focal length of the third concave lens installed to the third tube is equal to the fifth focal length of the fourth concave lens, and the third and fourth concave lenses are fixedly installed at a regular interval.