Abstract: A super wide angle lens is a super wide angle lens which is of high-resolution and whose size, weight and cost can be reduced. It employs a four-group five-element constitution in which in the order from an object side, a meniscus single lens having a negative power, a single lens having a negative power, a single lens having a positive power, and a cemented lens having a positive power are included. The lenses excluding the meniscus single lens are plastic lenses and seven lens surfaces, that are a third surface, a fourth surface, a fifth surface, a sixth surface, a eighth surface, a ninth surface and a tenth surface, are aspheric.

Abstract: A super wide angle lens is a super wide angle lens which is of high-resolution and whose size, weight and cost can be reduced. It employs a four-group five-element constitution in which in the order from an object side, a meniscus single lens having a negative power, a single lens having a negative power, a single lens having a positive power, and a cemented lens having a positive power are included. The lenses excluding the meniscus single lens are plastic lenses and seven lens surfaces, that are a third surface, a fourth surface, a fifth surface, a sixth surface, a eighth surface, a ninth surface and a tenth surface, are aspheric.

Abstract: A zone phase correcting lens wherein a change in the third-order spherical aberration or the like is small in the case of a change in temperature and an optical head device having the zone phase correcting lens used as an objective lens. A minus sign is appended to the height measurement of a step formed so as to make the lens thickness in the optical axis thinner toward the outer region and a plus sign is appended to a step formed so as to make the lens thickness thicker toward the outer region. Supposing that D is an absolute value of the sum of the height measurements of the steps having the minus sign on the first surface and the second surface and E is an absolute value of the sum of the height measurements of the steps having the plus sign on the first surface and the second surface, a wavelength ?1 and a refractive index N1 of the lens for a first laser beam satisfy the following conditions: 10×?1<{D×(N1?1)}<30×?1 2×E<D.

Abstract: A ring zonal phase correction lens made of resin is provided with a refraction face structurally formed on at least one of a first lens face and a second lens face. The refraction face includes three or more ring zonal shaped refraction curved surfaces which are formed to be adjacent to each other through step portions formed in an optical axis direction for correcting a phase of a laser beam emitted from a laser by respective ring zonal shaped refraction curved surfaces. The step portion is formed such that a lens thickness of an outer ring zonal shaped refraction curved surface becomes thicker than that of an inner ring zonal shaped refraction curved surface and the step portion is formed at a half or more outer area of an effective radius of the refraction face.

Abstract: An optical element includes a diffraction grating by which both a first laser beam and a second laser beam are diffracted. A diffraction performance of the diffraction grating is expressed by an optical path difference function, a third spherical aberration SA31 of the first laser beam and a third spherical aberration SA32 of the second laser beam in a wave front aberration calculated by the optical path difference function satisfy the following conditional expressions: 0.005<|SA31?SA32|<0.015[?rms] SA31×SA32<0.