Abstract: In an optical scanner for reducing shading, a semiconductor laser or a semiconductor laser array is set to a light source and a laser beam from the light source is deflected by a light deflector having a deflecting reflecting face and is converged by a lens for scanning as a light spot on a scanned face to perform an optical scanning operation. The optical scanner has an antireflection coating film disposed on only a refractive face for providing a largest change in incident angle in the deflection of the laser beam with respect to faces of optical elements arranged on an optical path from the light deflector to the scanned face to transmit the laser beam through the optical elements. The optical scanner may have an antireflection coating film disposed on one or more lens faces of the scanning lens such that transmittance of the scanning lens is gradually increased from an optical axis thereof toward both end portions in a main scan-corresponding direction.

Abstract: In an optical scanner for reducing shading, a semiconductor laser or a semiconductor laser array is set to a light source and a laser beam from the light source is deflected by a light deflector having a deflecting reflecting face and is converged by a lens for scanning as a light spot on a scanned face to perform an optical scanning operation. The optical scanner comprises one or more bending mirrors for bending an optical path of the laser beam and arranged between the light deflector and the scanned face; and an increased reflecting coating film disposed on a mirror face of the one or more mirrors such that reflectivity is gradually increased from a central portion of the increased reflecting coating film in a main scan-corresponding direction toward both end portions of the film.

Abstract: An objective lens for an optical disk has a first lens group constructed by joining a negative meniscus lens, a biconvex lens, and a negative meniscus lens sequentially arranged from the side of a light source; and a second lens group constructed by a positive meniscus lens. The first and second lens groups are sequentially arranged from the side of the light source toward the side of the optical disk. A combined focal distance f of the entire lens system, a focal distance f.sub.1 of the first lens group, a radius r.sub.i (i=1 to 6) of curvature of an i-th lens face from the side of the light source, and a refractive index n.sub.j and an Abbe number .nu..sub.j (j=1 to 4) of a j-th lens from the side of the light source satisfy the following conditions,(I) 0.7.gtoreq.f.sup.2 /.vertline.r.sub.2 .multidot.r.sub.3 .vertline.<2.0,r.sub.2 >0,r.sub.3 <0(II) 2.0<[(n.sub.1 -1)+(n.sub.3 -1)]/(n.sub.2 -1)<3.0(III) 15<[(.nu..sub.2 -.nu..sub.1)+(.nu..sub.2 -.nu..sub.3)]<90and(IV) 2.0<(f.sub.

Abstract: A semiconductor laser source unit includes a semiconductor laser chip emitting a laser beam, a base member supporting the semiconductor laser chip, and a protection cover mounted on the base member so as to seal the semiconductor laser chip. The protection cover has a lid portion formed at an end thereof and an opening at an opposed end thereof facing the base member. The lid portion has a window. The semiconductor laser source unit also has a single aspherical lens fastened to the lid portion of the protection cover so as to cover the window formed in the lid portion. The single aspherical lens collimates the laser beam emitted from the semiconductor laser chip.