BENDING-IMPARTING DEVICE FOR MEASURING BENDING LOSS, AND BENDING TEST DEVICE

A bending applying device includes three mandrels and applies bending to an optical fiber by winding the optical fiber onto the mandrels. The mandrels are alternately arranged at predetermined intervals such that outer circumferences of adjacent mandrels in a longitudinal direction of the optical fiber face each other in a non-contact manner. A diameter of the optical fiber is D, a radius of the mandrel is r, an interval between the adjacent mandrels in the first direction is 2r + d, a direction orthogonal to the first direction is a second direction, an interval between the adjacent mandrels in the second direction is s, and an angle θ between the second direction and a common internal tangent of the adjacent mandrels is 0 degrees or more and 45 degrees or less, and the formed angle θ satisfies following formula.d+D+4rd−D+s2 = 2r+D2tanθ+scosθ