Leslie Wright and Samuel Goldwasser of www.fineartradiography.com dissected the Blu-ray reader assembly of a PS3 and wrote the following description.
"The optical assembly contains some very strange and novel optics, unlike anything ever seen in an optical pickup before. Because of this the optical assembly now has its own page!
Sam Goldwasser and I have done a number of patent searches in order to determine exactly how this fascinating thing works! It would appear that the strange components are a result of Sony using its three diode laser, and a common beam-path for all the used wavelengths. This approach reduces the size of the pickup (as opposed to two objective designs), but does make the optical design somewhat complex!"