Abstract: A media library system capable of carrying out an access to each recording medium in very short time. A media exchange operation is controlled such that the storage cells of the storehouse are divided into at least two groups arranged in an order of average distances with respect to the media drive, including a first group with a shortest average distance with respect to the media drive, and when the previously used recording medium was mounted on the media drive from the first group, the previously used recording medium is stored in the first group, whereas when the previously used recording medium was mounted on the media drive from one group other than the first group, one recording medium with a lowest utilization frequency among an adjacent group of that one group having a shorter average distance with respect to the media drive than that one group is moved from that adjacent group to that one group and then the previously used recording medium is stored in that adjacent group.

Abstract: A micro optical head, for optically reading and/or writing digital data on a recording medium in which digital data 1 and 0, corresponding to a high reflection factor and a low reflection factor, is composed of a self-coupled semiconductor laser located close to the recording medium. A bias current of the laser is determined so that it is smaller than a first threshold current, in which the medium has a low reflection factor, and is higher than a second threshold current, in which the medium has a high reflection factor. Output light of the laser is either strong stimulated emission light, corresponding to the high reflection factor, or weak spontaneous emission light, corresponding to the low reflection factor. The present head is carried on a flying slider with a spacing length less than several .mu.m which provides a small beam spot of about 1 .mu.m, and has an excellent signal to noise ratio.