This paper discusses the width increase of a chirped pulse compressed in an optical compressor when there are various types of mismatches of the components of its diffraction gratings, such as the deviation of the gratings from parallelness and relative rotations and shifts of the grating segments of a composite compressor. Formulas are presented for computing the increment of the dispersion of the group delay and the width increase of the reconstructed pulse, which is associated with the presence of residual angular dispersion, along with formulas for computing the angles of deviation of the diffraction waves for relative rotations of the grating segments and the width increase of the compressed pulse accompanying such rotations. Formulas are obtained for calculating the phase shifts accompanying relative shifts of the grating segments. The question of the diffraction efficiency and the absorption of light energy at the grating surface is considered. The range of groove depths of a sinusoidal grating that makes it possible to maximize the efficiency with the minimum losses of light energy is obtained.