Field line geometric effects on curvature emission and absorption are explored in detail. In particular, we consider field line distortion near the star's surface due to a quadrupolar component, with the field line geometry approximated by a local helix. The spectral power for a particle moving along the field line is derived from the familiar synchrotron formula, and the absorption coefficient is derived by appealing to the Einstein coefficients. Field line torsion can result in wave amplification, with the maser emission occurring very nearly along the field lines. The maser emission can be saturated by quasi-linear diffusion. The application of such maser emission to pulsar radio emission is discussed.