The AA-20DD real-time autocorrelator ofers smooth and fast measurement of femtosecond and picosecond pulse duration. Diferent models of the autocorrelator cover several wavelength ranges, with the AA-20DDM model combining the ranges by using 3 interchangeable photodetectors and optics. Two separate ranges can also be covered upon request. Input pulse duration ranges from 20 fs to 30 ps for easy monitoring of diferent laser systems, especially femtosecond and picosecond oscillators (for ampliier monitoring please see our ASF-20 single-shot autocorrelator).