We have improved the correlator developed by J. -C. Diels. In the new type it is consisted of only four prsims; and henoe three pairs of glued optical surfaces become unnecessary. The angle tolerance of prisms is less than 5 second. Auto-ajustment method with prisms is presented in this papers We have designed a reasonable system fyr transmission in which the intensity and phase correlation curves are obtained by onlp changing the voltage applied on the motor. It is worth pointing out that the phase correlation curve carries information of pulsewidth, which can be measured more accurately from the phase correlation ourve.