ABERRATION LIMITS FOR ANNULAR GAUSSIAN BEAMS FOR OPTICAL STORAGE

Annularly apodized beams have been suggested for use in optical storag e because of their potential to go beyond the conventional spot size a nd depth-of-focus limits. One concern for such applications is the eff ects of small aberrations on beams in which the energy is concentrated in a small annular ring. We present calculations and experimental res ults that show that annular apodization of a Gaussian beam reduces the sensitivity to defocus as well as balanced spherical and coma aberrat ions. The sensitivity to astigmatism is increased by a small amount.