  We present linear optical schemes to perform generalized measurements for
conclusive teleportation when the sender and the receiver share nonmaximal
entanglement resulting from amplitude errors during propagation or generation.
Three different cases are considered for which the states to be teleported are
unknown superpositions of (a) single-photon and vacuum states, (b)
vertically-polarized and horizontally-polarized photon states, and (c) two
coherent states of opposite phases. The generalized measurement scheme for each
case is analyzed, which indicates that the success probability is much more
resistant to amplitude errors for case (c) than for case (a) or (b).
