An optical information processing device writes and reads information on an information recording medium having recording layers. The optical information processing device includes: first and second light sources; a light condensing element that condenses light from the first and second light sources on the medium; a first photodetector that receives light reflected by the medium after being emitted from the first light source and generates a first focusing error signal; a second photodetector that receives light reflected by the medium after being emitted from the second light source and generates a second focusing error signal; and a focusing control circuit that controls the light condensing element by using the first focusing error signal in such a manner that the light from the second light source is condensed on each of the recording layers. The second focusing error signal is used to add a correction to the focusing control circuit.

An optical encoder is provided. The encoder includes an optical disc mounted on a shaft, the optical disc containing pit and land markings; an optical pickup unit for an optical disc that receives light from the optical disc and supplies as an output an electrical signal representative of the received light, comprising: a reading head objective lens, and dynamic steering actuators that control the focus and tracking of the reading head objective lens; a processor that receives as an input the electrical signal from the optical pickup unit and reports motion of the substrate based on the received at least one electrical signal.

An absolute position encoder includes a position location medium containing position identifier code words providing absolute position indications, and an optical source, an optical detector, an optics subsystem and a code word decoder. The optics subsystem focuses a source beam onto the position location medium and directs a return beam to the optical detector, detects a focus condition from the return beam, and automatically adjusts focus of the source beam to maintain a predetermined focus condition during operation. The code word decoder responds to the detector signal to detect a code word and generate a decoder output indicative of a corresponding code word value and corresponding detected position.

An absolute position encoder includes a position location medium containing position identifier code words providing absolute position indications, and an optical source, an optical detector, an optics subsystem and a code word decoder. The optics subsystem focuses a source beam onto the position location medium and directs a return beam to the optical detector, detects a focus condition from the return beam, and automatically adjusts focus of the source beam to maintain a predetermined focus condition during operation. The code word decoder responds to the detector signal to detect a code word and generate a decoder output indicative of a corresponding code word value and corresponding detected position.

An improved optical encoder uses an optical pick-up unit that provides for degrees of freedom in the tracking and focus axes that are unavailable in conventional optical encoders thereby improving the encoders' performance. In an embodiment the encoder employs an optical disc marked with pits and lands which may be arranged in a spiral pattern. The optical disc is mounted on the shaft whose motion is to be monitored by the optical encoder. The encoder may be arranged to read the markings on the optical disc using the three-beam pickup method.

Systems and methods for long-term non-volatile non-rotating optical storage of digital information rely on storage elements that include optical storage media, an access subsystem configured to access bits of information from one of the storage elements, and a support structure configured to support multiple storage elements. A laser used to retrieve and/or record bits of digital information may be moved along two orthogonal dimensions while the storage element is non-rotating.

Systems and methods for long-term non-volatile non-rotating optical storage of digital information rely on storage elements that include optical storage media, an access subsystem configured to access bits of information from one of the storage elements, and a support structure configured to support multiple storage elements. A laser used to retrieve and/or record bits of digital information may be moved along two orthogonal dimensions while the storage element is non-rotating.

Disclosed is a lens driving apparatus. The lens driving apparatus includes a base, a yoke coupled to the base, having an upper surface formed with a hole, a closed side surface, and an opened bottom surface, a bobbin movably installed in an inner portion of the yoke, a lens module coupled to the bobbin to go in and out the hole according to movement of the bobbin, a magnet fixed to an inner portion of the yoke, a coil fixed to an outer portion of the bobbin while facing the magnets, and springs coupled to the bobbin to provide restoration force to the bobbin.

A detection apparatus determines whether a recording layer of an optical disc is at a focal point of an objective lens. The detection apparatus includes an objective lens, a beam splitter, a reflector, a detector, and a servo controller. The reflector and the detector are disposed opposite to each other on two sides of an optical axis of the objective lens, and a normal line of the reflector is perpendicular to the optical axis. The beam splitter is disposed between the reflector and the detector and is located on the optical axis. The servo controller is connected to the detector.

An optical information processing device writes and reads information on an information recording medium having recording layers. The optical information processing device includes: first and second light sources; a light condensing element that condenses light from the first and second light sources on the medium; a first photodetector that receives light reflected by the medium after being emitted from the first light source and generates a first focusing error signal; a second photodetector that receives light reflected by the medium after being emitted from the second light source and generates a second focusing error signal; and a focusing control circuit that controls the light condensing element by using the first focusing error signal in such a manner that the light from the second light source is condensed on each of the recording layers. The second focusing error signal is used to add a correction to the focusing control circuit.