Patent ID: 7209414

Claim:
An optical data read/write system comprising: a laser diode capable of emitting a beam having a measured wavelength; a beam splitter operably disposed to reflect the beam; a collimator operably disposed to allow the beam to pass there through; an objective lens operably disposed to focus the beam on a surface containing optical data; and, a detector operably disposed to receive portions of the beam reflected off of the surface; wherein: said objective lens has an actual thickness that differs from a designed thickness, thereby creating spherical aberration of a measurable magnitude and either a positive or negative sign when used with an ideal laser diode emitting a beam having an optimal wavelength; said laser diode operates at a measured wavelength which may differ from said optimal wavelength, the laser diode is characterized by creating a spherical aberration of a measurable magnitude and a sign when used with an ideal objective lens having said designed thickness, said magnitude and said sign being caused by the difference between the measured wavelength and the designed wavelength; and, said magnitude of the spherical aberration caused by the objective lens approximates the magnitude of the spherical aberration caused by the laser diode; said spherical aberration caused by the objective lens and said spherical aberration caused by said laser diode having opposite signs.