  This thesis is devoted to asymptotic norm estimates for oscillatory integral
operators acting on the L^2 space of functions of one real variable. The
operators in question have compact support and an oscillatory kernel of the
form exp(i Lambda S(x,y)), where S(x,y) is a smooth real phase function, and
Lambda is a large real number.
  I study how the norm of the operator decays as Lambda goes to infinity, and
how the rate of this decay can be determined from the properties of the phase
function S(x,y).
  For C^infinity phase functions I prove results formulated in terms of the
Newton polygon of S(x,y), improving previously known estimates by Phong and
Stein, and Seeger. My estimates are best possible or differ from the best
possible ones by at most a power of log Lambda.
  Main results of the thesis are based on a geometric analysis of the zero set
of the Hessian S''_{xy} using Puiseux decompositions, and have appeared before
in [math.CA/9911153]. New results obtained by a different method based on a
stopping time argument are also included.
