We propose a new measurement technique to investigate the highly focused light used in optical data storage systems named immersion high resolution interference microscopy (HRIM). This system allows three-dimensional (3D) measurements of the amplitude and phase of light fields in a static scheme. In contrast to scanning techniques, HRIM allows the nondestructive investigation penetrating through the optical disc. We investigated the focusing of light in high-definition digital versatile disc (HD DVD) systems. The experimental spot sizes agree well with the theory in intensity measurements. The measured phase distributions resemble the wavefront propagation of aberration-free converging light beams. The observed phase singularity positions near the focal plane demonstrate the super-resolution capability of such measurements and give access to details of the Airy pattern. Our results prove the applicability of studying highly focused beams in advanced optical systems and its use to clarify storage mechanisms for future generations of optical memories. # 2010 The Japan Society of Applied Physics