Abstract: An optical pickup device for focusing an irradiating ray from a light emitting element on a recording medium and letting a reflected ray reflected from this recording medium focus on a light receiving element is characterized in comprising a diffracting element disposed before the light emitting element and the light receiving element, at least a first diffraction region included in the diffracting element for separating the irradiating ray from the light emitting element into a main beam and sub-beams shifted from the main beam in a direction perpendicular to a track direction of the track where the main beam is focused, a second diffraction region included in the diffracting element for directing a reflected ray of the main beam reflected from the recording medium onto a main light receiving element and directing reflected rays of the sub-beams onto sub-light receiving elements, and an arithmetic circuit for detecting a tilt error signal showing the sub-beam's focusing condition according to the output of t

Abstract: A photo detecting device has a photoelectric converting element formed on a semiconductor chip with the photoelectric converting element being divided into first and second light receiving regions. The photo detecting device further has a signal processing circuit formed on the same semiconductor chip. The signal processing circuit includes a subtracting element for subtracting an output signal from the second light receiving region from an output signal from the first light receiving region.

Abstract: The present invention presents a beam converting apparatus which comprises a semiconductor laser element,means for converting the laser beam from the semiconductor laser element into a parallel beam, anda prism possessing a first plane for receiving the parallel beam and a second plane for fully reflecting so that the beam entering from the first plane may be emitted from the first plane, wherein the apex angle of the first plane and second plane is defined so that the sum of the incidence angle (.theta.1) to the normal of the first plane and the exit angle (.theta.2) to the normal of the first plane of the beam fully reflected from the second plane emitted from the first plane, (.theta.1+.theta.2), may be about 90 degrees.

Abstract: This image reading apparatus includes a light source for illuminating an object, a lens array for focusing reflected light from the object into a predetermined position, and an image sensor for reading an image formed by the focused light. The lens array includes a transparent base and a diffraction element provided on at least an incident plane and an emission plane of the base. The lens array includes an array having a plurality of lens areas. The employment of the diffraction element renders a shorter imaging distance of light from the object and thus a reduction in the size of the apparatus.

Abstract: An optical head device for reading information stored in a recording medium wherein a light beam from a light source converges onto an optical disk and a beam reflected from the optical disk is received by a light receiving element to read information stored on the optical disk. This device includes a diffraction element having first diffraction gratings for dividing the light beam from the light source into a zero order diffracted beam utilized for reading the information stored on the optical disk and a pair of first order diffracted beams utilized for reading tracking errors. The diffraction element also has second diffraction gratings for guiding the beam reflected from the optical disk to a light receiving element.