Abstract: The invention discloses novel dicyanostilbene derivatives bound to a methacrylic moiety that can serve as an active chromophore in a 3-dimensional optical memory, processes for its synthesis and its intermediates.

Abstract: An optical data carrier is presented. The data carrier comprises at least one recording layer, at least one non-recording layer, and at least one reflective interface. The recording layer is made of a material having a fluorescent property variable on occurrence of multi-photon absorption resulted from an optical beam, and has a thickness for recording therein data in the form of a three-dimensional pattern of spaced-apart recording regions arranged in a plurality of recording planes. The at least one non-recording layer interfaces with the recording layer on, respectively, at least one of upper and lower surfaces of the recording layer The non-recording layer has a fluorescent property different from that of the recording layer, and has a predetermined thickness selected to be equal or larger than a focal depth of an optical system producing the optical beam incidence onto the data carrier. The at least one reflective interface comprises at least one reference layer having a reflecting property.

Abstract: Cooperativity between groups within a polymeric photochromic medium provides the basis for enhanced writing effect. The cooperatively may be among photochromic groups being present in a high concentration.

Abstract: An optical data carrier is presented. The data carrier comprises: at least one recording layer composed of a material having a fluorescent property variable on occurrence of multi-photon absorption resulting from an optical beam, said recording layer having a thickness for forming a plurality of recording planes therein; at least one non-recording layer formed on at least one of upper and lower surfaces of said recording layer and differing in fluorescent property from said recording layer; and at least one reference layer having a reflecting surface being an interface between the recording layer and the non-recording layer.

Abstract: The invention discloses novel dicyanostilbene derivatives bound to a methacrylic moiety that can serve as an active chromophore in a 3-dimensional optical memory, processes for its synthesis and its intermediates.

Abstract: A non-linear optical data carrier is presented. The non-linear optical data carrier is configured for recording therein information defined by a pattern of spaced-apart marks arranged in virtual data layers. The data carrier medium comprises a sub-stance capable of being excited by a first multi-photon interaction to be switched from its first state into a second state, where the first and second states of the substance provide different response signals to a second multi-photon interaction. The substance when in the first and second states have substantially overlapping linear absorption wavelength peaks, and first and second wavelengths involved in the first and second multi-photon processes as well as the response signals wavelengths are outside the linear absorption spectrum peaks of the substance in its first and second states. The basic size of the marks and spaces is larger in the first than in the second layer.

Abstract: A formatter for inscription of marks on to a 3D translucent optical medium to enable recording and retrieval of information from the medium, includes a clamping mechanism to hold the media, and at least one optical unit calibrated to focus at least one diffraction limited spot within the medium at a respective depth therein. At least one light source is optimized for the inscription of marks, and at least one actuator moves the spot relative to the medium.

Abstract: A method for data inscription in an acrylic polymer-based photochromic medium is provided in which the photochromic groups are bound to the polymeric matrix. The data is inscribed by irradiating small volume portion with an electromagnetic irradiation that causes a change in state of the photochromic groups from a first to a second state. Said volume portion is heated so as to cause an increase in temperature of said portion at the time of data inscription. The heating may be external or internal. Internal heating makes use of additives that dissipate heat, following their irradiation, to their immediate vicinity. Provided is also a novel acrylic polymer-based photochromic medium comprising said additives.

Abstract: A method and apparatus for retrieving information from a three dimensional storage medium uses a three dimensional storage medium having an active medium capable of exhibiting first and second states, a data unit being represented by the ratio between the concentration of the first and second states in a given volume portion of the medium and a data sequence is represented by a sequence of data units. The active medium is irradiated with light as to concentrate light flux through a volume portion of the storage medium so as to generate in the volume portion a detectable non-linear optical response characteristic of the concentration ratio, which is detected and used for tracking.

Abstract: Disclosed is a swing type optical disc drive. The drive includes a disc rotating on a disc support and a swing arm pivoted at one of its ends and having a distal end communicating with an encoder. The pivot point and a point on distal end define a swing axis of the arm. The disc further includes an optical system mounted on the arm such that optical axis of the system is parallel with the swing axis and both axes lie in the same plane. A cam actuator imparts a swinging motion to the arm. The swinging motion of the arm positions the plane with the optical axis and the arm axes such that the plane is always tangent to a reading/recording track of the disc.

Abstract: The present invention is directed to a three-dimensional memory apparatus for storing information in a volume comprising of an active medium. The active medium is capable of changing from a first to a second isomeric form as a response to radiation of a light beam having an energy substantially equal to a first threshold energy. The concentration ratio between a first and a second isomeric form in any given volume portion represents a data unit. The active medium in the memory apparatus comprises of diarylalkene derivatives, triene derivatives, polyene derivatives or a mixture thereof. The invention is further directed to means for reading the data units from the isomeric states of the active medium in different portions of said active medium where the two isomeric forms have a substantially different absorption coefficient for absorbing energy of a second threshold energy. Reading may also be carried out by measuring the scattering pattern of the two isomeric forms.

Abstract: A method and apparatus for retrieving information from a three dimensional storage medium uses a three dimensional storage medium having an active medium capable of exhibiting first and second states, a data unit being represented by the ratio between the concentration of the first and second states in a given volume portion of the medium and a data sequence is represented by a sequence of data units. The active medium is irradiated with light as to concentrate light flux through a volume portion of the storage medium so as to generate in the volume portion a detectable non-linear optical response characteristic of the concentration ratio, which is detected and used for tracking.

Abstract: A three dimensional optical information carrier is presented. The information carrier comprises formatting marks disposed on the nodes of a three dimensional lattice formed by the intersection of equiangular spaced radial planes, equidistantly spaced cylindrical spiral tracks and virtual recording planes.

Abstract: A method and system are presented for use in recording/reading data from an array of data units within a three-dimensional storage medium. Exciting radiation is provided in the form of first and second light beams of first and second different wavelengths, respectively. The first and second light beams are concurrently directed and focusing onto desirably distanced from each other sites in the medium and excited light of a third wavelength coming from the excited site is collected to form and excited light beam to be directed towards a detector assembly, while correcting for chromatic and spherical aberrations of the light focusing and collection.

Abstract: The present invention is directed to a three-dimensional memory apparatus for storing information in a volume comprising of an active medium. The active medium is capable of changing from a first to a second isomeric form as a response to radiation of a light beam having an energy substantially equal to a first threshold energy. The concentration ratio between a first and a second isomeric form in any given volume portion represents a data unit. The active medium in the memory apparatus comprises of diarylalkene derivatives, triene derivatives, polyene derivatives or a mixture thereof. The invention is further directed to means for reading the data units from the isomeric states of the active medium in different portions of said active medium where the two isomeric forms have a substantially different absorption coefficient for absorbing energy of a second threshold energy. Reading may also be carried out by measuring the scattering pattern of the two isomeric forms.

Abstract: A method and apparatus for retrieving information from a three dimensional storage medium uses a three dimensional storage medium having an active medium capable of exhibiting first and second states, a data unit being represented by the ratio between the concentration of the first and second states in a given volume portion of the medium and a data sequence is represented by a sequence of data units. The active medium is irradiated with light as to concentrate light flux through a volume portion of the storage medium so as to generate in the volume portion a detectable non-linear optical response characteristic of the concentration ratio, which is detected and used for tracking.

Abstract: A method and system for correcting tracking errors in an optical storage medium having multiple tracks arranged in different layers of the optical storage medium, directs a reading spot that is nominally focused on to a track in the optical storage medium, and continually moves the reading spot in axial and radial directions so as to receive a signal having an amplitude which varies according to respective offsets from the track in radial and axial directions. The received signal is used to determine a direction of a respective offset from the track in radial and axial directions, and a location of the reading spot is adjusted accordingly.