Abstract: There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference ? in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

Abstract: There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference ? in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

Abstract: There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A microlens array 20 of a screen 2 includes upper-level microlenses 21H and lower-level microlenses 21L which are formed on the incidence surface of the screen 2, which have the same effective diameter, and which have a structure that generates an optical path length difference ? in transmission light. By disposing the upper-level microlenses 21H and the lower-level microlenses 21L at an interval based on the effective diameter, the basic periodic structure of a lens period PL is formed. Further, the upper-level microlenses 21H and the lower-level microlenses 21L form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period PL.

Abstract: There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference ? in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

Abstract: There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A micro lens array of a screen includes upper-level microlenses and lower-level microlenses which are formed on the incidence surface of the screen, which have the same effective diameter, and which have a structure that generates an optical path length difference ? in transmission light. By disposing the upper-level microlenses and the lower-level microlenses at an interval based on the effective diameter, the basic periodic structure of a lens period is formed. Further, the upper-level microlenses and the lower-level microlenses form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period.

Abstract: There is provided a lens array and an lens array capable of suitably preventing irregular brightness without reducing resolution. A microlens array 20 of a screen 2 includes upper-level microlenses 21H and lower-level microlenses 21L which are formed on the incidence surface of the screen 2, which have the same effective diameter, and which have a structure that generates an optical path length difference ? in transmission light. By disposing the upper-level microlenses 21H and the lower-level microlenses 21L at an interval based on the effective diameter, the basic periodic structure of a lens period PL is formed. Further, the upper-level microlenses 21H and the lower-level microlenses 21L form a basic block comprising a combination of the lenses having a structure that generates the optical path length difference. A concave-and-convex period PC based on the basic block is an integer multiple of the lens period PL.

Abstract: An optical element includes a first microlens array unit and a second microlens array unit in each of which a plurality of microlenses are arranged. The first and second microlens array units are arranged opposite to each other with a distance which is longer than a focal length of the microlenses arranged in the first microlens array unit. The first microlens unit is arranged on a light-incident side with respect to the second microlens array unit. The interval between the microlenses arranged in the second microlens array unit is narrower than the interval between the microlenses arranged in the first microlens array unit. The optical element can appropriately suppress the occurrence of excessive pixel bright spot.

Abstract: An optical element includes a microlens array on which plural microlenses are arranged. The microlens array includes plural areas whose microlenses have different curvature radii per area. The plural areas are configured so that the farther the area exists from the center of the microlens array, the smaller the curvature radius of the microlenses arranged on the area is.

Abstract: An optical element includes a first microlens array unit and a second microlens array unit in each of which a plurality of microlenses are arranged. The first and second microlens array units are arranged opposite to each other with a distance which is longer than a focal length of the microlenses arranged in the first microlens array unit. The first microlens unit is arranged on a light-incident side with respect to the second microlens array unit. The interval between the microlenses arranged in the second microlens array unit is narrower than the interval between the microlenses arranged in the first microlens array unit. The optical element can appropriately suppress the occurrence of excessive pixel bright spot.

Abstract: An optical element includes first and second microlens array units on which microlenses are arranged. The microlenses are formed by lens contour having a polygonal shape in a plan view. The first and second microlens array units are arranged opposite to each other at a position where a distance between the first and second microlens array units is at least longer than a focal distance of the microlens, and are formed so that a direction of vertices of the lens contour of the microlens arranged on the first microlens array unit is different from a direction of vertices of the lens contour of the microlens arranged on the second microlens array unit. According to the above optical element, it is possible to appropriately suppress an influence of shift of the position between the first and second microlens array units, and it becomes possible to produce the optical element with ease.

Abstract: An optical element includes first and second microlens array units on which microlenses are arranged. The microlenses are formed by lens contour having a polygonal shape in a plan view. The first and second microlens array units are arranged opposite to each other at a position where a distance between the first and second microlens array units is at least longer than a focal distance of the microlens, and are formed so that a direction of vertices of the lens contour of the microlens arranged on the first microlens array unit is different from a direction of vertices of the lens contour of the microlens arranged on the second microlens array unit. According to the above optical element, it is possible to appropriately suppress an influence of shift of the position between the first and second microlens array units, and it becomes possible to produce the optical element with ease.

Abstract: There is provided a type judgment device capable of rapidly and safely identifying the type of an optical disc while preventing unexpected information recording or information erase. An optical beam as parallel light is applied in a circular polarized state to an optical disc having recording tracks and the polarization characteristic in the reflected light is detected. According to the detected polarization characteristic, the type of the disc is judged in accordance with the interval of the adjacent recording tracks.

Abstract: There is provided a type judgment device capable of rapidly and safely identifying the type of an optical disc while preventing unexpected information recording or information erase. An optical beam as parallel light is applied in a circular polarized state to an optical disc having recording tracks and the polarization characteristic in the reflected light is detected. According to the detected polarization characteristic, the type of the disc is judged in accordance with the interval of the adjacent recording tracks.

Abstract: A detection signal S1 outputted from a light reception unit (11A) of detection elements (11) formed by four-division light reception element is added to a detection signal S4 outputted from a light reception unit (11D) so as to obtain an addition signal S14 and a phase difference signal P1 indicating the phase difference between the addition signal S14 and the detection signal S1. Furthermore, a phase difference signal P4 indicating the phase difference between the addition signal S14 and the detection signal S4 is obtained. The phase difference signal P4 is subtracted from the phase difference signal P1 so as to generate a tracking error signal TE1.

Abstract: A detection signal S1 outputted from a light reception unit (11A) of detection elements (11) formed by four-division light reception element is added to a detection signal S4 outputted from a light reception unit (11D) so as to obtain an addition signal S14 and a phase difference signal P1 indicating the phase difference between the addition signal S14 and the detection signal S1. Furthermore, a phase difference signal P4 indicating the phase difference between the addition signal S14 and the detection signal S4 is obtained. The phase difference signal P4 is subtracted from the phase difference signal P1 so as to generate a tracking error signal TE1.

Abstract: An optical disc includes an information recording layer having a record of information as a pit train with a predetermined track pitch and a light-transmissive layer formed on the information recording layer so that the information can be reproduced by a beam of light illuminated through the light-transmissive layer to the information recording layer by an objective lens. The optical disc includes a feature in that a relationship of 0.194(?/NA)2?TP ×Tmin?0.264(?/NA)2 is satisfied, provided that the track pitch is TP, a pit shortest length is Tmin, a wavelength of the light beam is ? and a numerical aperture of the objective lens is NA. The optical disc also includes a feature in that a pit width is 120 nm or smaller in a range of a track pitch of 0.280 to 0.325 ?m.

Abstract: A tracking servo apparatus in which reflection light obtained when a laser beam is irradiated onto a recording surface of an optical disc is photoelectrically converted, thereby obtaining a photoelectric conversion signal, a tracking error signal showing a deviation amount of an irradiating position of said laser beam for a track in a disc radial direction on the recording surface is generated by the photoelectric conversion signal, a spherical aberration occurring in an optical system is detected, a level of the tracking error signal is corrected on the basis of the detection result, and the irradiating position of the laser beam is moved in the disc radial direction in accordance with the level-corrected tracking error signal.

Abstract: A system for detecting a tracking error comprises a two-divided type light detector (2), LPFs (4a, 4b), first and second waveform generator (5a, 5b), first and second delay circuits (6a, 6b), first and second adders (7a, 7b) and a phase comparator (8). The detector (2) has two photo detecting elements (2a, 2b) disposed separately in the radius direction of an optical disc. The LPFs (4a, 4b) remove high frequency components from the outputs of the elements (2a, 2b). The first waveform generator (5a) generates a sine wave (B1) with amplitude corresponding to the output level of a signal (A1), which passed the LPF (4a). The second waveform generator (5b) generates a sine wave (B2) having the identical frequency to the wave (B1), with amplitude corresponding to the output level of a signal (A2), which passed the LPF (4b). The first delay circuit (6a) delays the wave (B1) by the prescribed amount of delay to form a sine wave (C1).

Abstract: An information reproducing apparatus(100) is provided with: a focusing device(11a) which makes a signal-reading probe light converge onto an optical recording medium(10); a focus servo device(12) which maintains a focus on a recording layer of the optical recording medium(10) by controlling the focusing device(11a); an offset providing device(14) which provides a predetermined offset to a target value used by the focus servo device(12); and a spherical aberration detecting device(17) which detects a signal indicative of spherical aberration contained in the probe light on the basis of an intensity of a signal reproduced based on a plurality of target values obtained by the offset providing device(14) generated on at least one signal of at least one predetermined spatial frequency recorded on the optical recording medium(10).

Abstract: The present invention provides an optical information recording medium with favorable signal reproduction characteristics that comprises a substrate, a reflective layer and a protective layer, and performs playback by allowing a laser beam for signal playback to enter via the protective layer, wherein the substrate is provided with a phase pit array for holding information. Each phase pit of the phase pit array is formed as a cavity which is reentrant as viewed from the entrance side of the signal playback laser beam.