High-density optical data storage requires high-numerical-aperture
(NA) lenses and short wavelengths. But, with increasing NA and
decreasing wavelength, the depth of focus (DOF) decreases
rapidly. We propose to use pure-phase superresolution apodizers to
optimize the axial intensity distribution and extend the DOF of an
optical pickup. With this kind of apodizer, the expected DOF can be
2–4.88 times greater than that of the original system, and the spot
size will be smaller than that of the original system.
© 2001 Optical Society of America
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