  Continuous-wave output at 229 nm for the application of laser cooling of Cd
atoms was generated by the 4th harmonic using two successive second harmonic
generation stages. Employing a single-frequency optically pumped semiconductor
laser as a fundamental source, 0.56 W of output at 229 nm was observed with a
10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458
nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By
applying a tapered amplifier as a fundamental source, we demonstrated
magneto-optical trapping of all stable Cd isotopes including isotopes
$^{111}$Cd and $^{113}$Cd, which are applicable to optical lattice clocks.
