The invention relates to an optical device for detecting and identifying damaged paper money by using a photosensitive element. The optical device comprises a luminous tube array, a receiving tube array, a
light transmission board and a bracket, wherein the
light transmission board is fixedly arranged above the bracket; a luminous
signal processing circuit board and a received
signal processing circuit board are fixedly arranged at the inner bottom of the bracket; the inner part of the bracket is partitioned into relatively independent
light detection cavities by partition walls; each
light detection cavity is opposite to the luminous
signal processing circuit board and the received
signal processing circuit board; and the luminous tube array and the receiving tube array which are matched with each other in the
light detection cavity are fixed on the luminous
signal processing circuit board and the received
signal processing circuit board respectively. By the optical device, the shortcomings of high error distinction rate and
leakage rate, high cost, high maintenance requirement and high installation difficulty in the prior art are overcome; due to the specific design, whether various damages exist on paper money or not can be judged accurately; and the optical device has the advantages of low cost, simple structure and low mechanical installation requirement; furthermore, the optical device is not contacted with the paper money, so the optical device is not required to be maintained frequently.