Techniques for producing optical medium that can be read at substantially high speeds with greater stability and accuracy are disclosed. According to one aspect of the techniques, a molding station includes an optimized stampler which does not have an exact inverse image of a replica. To account for an inherent distortion in a substrate after being stamped, a stampler is pre-distorted so that the pit geometry in the stamped substrate becomes nearly perfect after the inherent distortion. In one embodiment, the injection of a molten material, the mold position and compression are respectively controlled to account for possible non-uniform density distribution of the material. To provide an effective bonding process, a bonding station is employed with what is referred to as index bonding technique and/or pulse bonding technique. The index bonding is provided to ensure that non-flatness of substrates is compensated when two substrates are bonded together so as to minimize possible dynamic imbalance of a disc. The pulse bonding is provided to eliminate bubbles from a type of glue used to bond two substrates, wherein a high voltage used to generate a pulse of electromagnetic field is programmable in accordance with the substrates and the characteristics of the glue.