We describe the modified LPTF frequency synthesis chain, which starts from the cesium referenced CO2/OsO4 laboratory standard. This chain, with variations, is able to cover the whole visible spectrum. A particular scheme is given in order to measure the 385.3-THz frequency of the two-photon transitions in rubidium. To secure the phase lock, the diode lasers' linewidths have to be reduced. We report a 10-Hz beatnote linewidth obtained with two diode lasers stabilized on the same high-finesse cavity.