Propagation of a monochromatic light through a multimode fiber is considered in connection with the problem of image transmission. We discuss the variations of throughput scrambling, i.e., of the pixel-to-pixel Greens' function for transmission under the bends of the fiber axis. Two main statements are elaborated theoretically, which in principle allow the stabilization of the throughput scrambling. First, if the deformations are smooth enough, the modes are adiabatically modified without intermixing. Second, the variation δψ↓(m,n) of the phase of a mode M↓(m,n) can be expressed as a power series in a small parameter (ρ/R)↑（2）, where p is the core radius and R↑(-1) is the curvature of bending. A scheme for the compensation of those phase shifts is suggested based on prebending of the fiber with subsequent controllable adjustment of that prebending. # 1997 Optical Society of America
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