Abstract: A magnetic recording medium which is capable of improving durability and reliability while satisfactory electromagnetic conversion characteristics are being maintained, the magnetic recording medium incorporating a non-magnetic support member; and a magnetic layer formed on the non-magnetic support member and mainly composed of magnetic powder and a binder and having a two-layer structure composed of a first magnetic layer and a second magnetic layer, wherein Young's modulus of the first magnetic layer is 140×105 N/m2 to 160×105 N/m2 and Young's modulus of the second magnetic layer is 45×105 N/m2 to 50×105 N/m2. The specific surface area of the magnetic powder for use in the first magnetic layer is 42 m2/g to 46 m2/g and the specific surface area of the magnetic powder for use in the second magnetic layer is 32 m2/g to 35 m2/g.

Abstract: A light exposure device for a master optical disc capable of exposing to light a desired area of the master optical disc to high precision for forming crests and recesses of broad widths therein to high precision. Specifically, the light exposure device for the master optical disc exposes to light the portions of a photoresist coated on a substrate of the optical disc adapted to form a pre-set pattern corresponding to recorded information signals. The light exposure device for the master optical disc includes a light-condensing optical element 15 for condensing the laser light radiated from a light source, a deflecting optical element 16 for wobbling the laser light condensed by the light-condensing optical element 15 and an optical system 17 arranged downstream of the focal point position of the light-condensing optical element 15 for re-imaging the laser light wobbled by the deflecting optical element 16 at a location upstream of the objective lens.

Abstract: A resist having a three-dimensional shape of a microlens array and a material layer of the microlens array are simultaneously etched under a condition by which planar patterns transferred from the resist to the material layer are larger than planar patterns of the resist. The spacing between microlenses can be made narrower than the spacing between the planar patterns of the resist. Even when the planar shape of the microlens is an ellipse, the curvatures can be optimized in both the row and column directions by making the heights in these directions different from each other. It is possible to provide a microlens array having a small non-focusing region and a solid-state image pickup device having a high sensitivity and little smear.