Abstract: An image of a scanning position on a faceplate on a light receiving region defined by an arrangement of n light receiving elements such that an amount of light received by the light receiving region becomes a peak at a center of the light receiving region in an arranging direction of the light receiving elements and is gradually reduced substantially symmetrically toward both ends thereof in the same direction. Therefore, if there is no defect in the surface of the faceplate, levels of light receiving signals of the light receiving elements arranged substantially symmetrically in position on both sides of the light receiving region with respect to the center thereof as a reference are substantially equal and there is no substantial difference therebetween.

Abstract: A defect detection optical system includes a light receiving system including n light receiving elements arranged in a direction perpendicular to a main scan direction, for focusing an image thereon such that the image becomes in the arranging direction of the light receiving elements, in which, when a width of the image focused thereon in the main scan direction is equal to or smaller than the width of the light receiving elements, light reflected from a recessed or protruded defect is swung in the width direction of the light receiving elements and a light receiving area of the light receiving elements is reduced. When the reflection light from the recessed or protruded defect is swung in sloped portions of the defect, an amount of light received by the light receiving elements is at least reduced, so that two detection signals having levels lower than those when there is no defect are obtained.

Abstract: Annular rays of light are received by a hollow optical member and focused as light beams on the surface of a disk to be tested and as the scattered light from the disk surface travels toward the hollow portion of the optical member, it is received by an objective lens and then received by a light receiver via the objective lens.

Abstract: The surface defect test method and tester according to the invention comprises a sensitivity calibration disk formed with n (n is an integer equal to or larger than 2) false defect rows each including 3 or more false defects each formed in a radial or peripheral direction provided in the peripheral direction of the calibration disk at a predetermined angle pitch.

Abstract: The tester and the test method for testing an eccentricity of a head turnout zone of a magnetic disk determine a turnout zone as acceptable or unacceptable by spirally scanning a turnout zone of a magnetic disk with a laser spot by rotating the magnetic disk and continuously moving either the laser spot radially of the magnetic disk or the magnetic disk radially thereof, obtaining a detection signal having amplitude corresponding to an intensity of a scattering light from the magnetic disk irradiated with the laser spot, extracting a first waveform of the detection signal corresponding to an intermediate region between an inside variation region in which an inside boarder line of the turnout zone radially of the magnetic disk by radial movement of the turnout zone caused by an ecentricity of the turnout zone and an outside variation region in which an outside boarder line of the turnout zone radially of the magnetic disk by the radial movement of the turnout zone caused by the eccentricity of the magnetic dis

Abstract: A calibration disk for calibrating a sensitivity of a surface defect tester, according to the present invention, comprises n (n is an integer equal to or larger than 2) false defect rows each including 3 or more false defects each formed in a radial or peripheral direction provided in the peripheral direction of the calibration disk at a predetermined angle pitch. The false defects of each false defect row take in the form of protrusions or recesses having substantially the same size, adjacent ones of the false defects are physically separated by a predetermined distance larger than a width of a laser spot and the false defects of a certain one of the false defect rows are different in size from the false defects of other false defect rows.