In view of the recent progress in visible lasers for next-generation optical disks, we describe the influence of source wavelength, aberration, and noise on eye-diagram jitter, which determines the ultimate disk density. The analysis indicates that the sources used in a readout of a 6× areal density, (4,22) run-length-limited code with a minimum mark length of 0.4 µm must have a wavelength that satisfies the Nyquist condition of relationship between the spot size and the minimum mark length, a wave-front aberration of less than 0.035 rms λ, and relative intensity noise of less than -125 dB/Hz.