Abstract: An optical disk recorder is capable of operating with diverse types of optical media. A device initialization procedure is repeated for each receipt of each optical medium. Such procedure includes moving an objective lens to an extreme radial position, defocussing the lens at a most remote position, then calibrating the laser circuits to ensure that the emission of radiation from the laser will not inadvertently destroy signals recorded on the just received medium. Then the medium type is read from the medium and based upon the type indication, various additional calibrating procedures are followed and different sources of laser control values are used for signal exchanging operations between the recorder and received optical medium.

Abstract: An optical head for an optical signal recorder includes a nonpolarizing beam combiner for combining the light beams from two like-frequency, sic wavelength, lasers along one light path. The combined beams travel slightly diverging paths so that a first one of the beams can record signals on a disk while a second beam follows the first beam on the disk for direct reading-after-recording. Intermediate the combiner and the disk are a polarization type beam splitter and a focuser. One or more detectors receive reflected light from the disk via the beam splitter for detecting focus, sensed recorded signals and for tracking the beams to tracks of the disk. The combiner and splitter are preferably secured together as a single unit. The combiner uses refraction and internal reflection properties to combine the two like-frequency beams without polarization changes of either beam.

Abstract: A multi-layer assembly includes a support block with a plurality of circular cylinder bores, each receiving optical elements. Juxtaposed along the length of each of the bores in a circumferentially spaced-apart relation is a pair of positioning rods having surfaces extending into the bore. The surfaces are precisely aligned with a desired optical axis to be established by the optical element. A plunger pushes the optical element against the rods to establish the optical axis. Lasers and adjustment apparatus are included in the assembly.

Abstract: An optical device, such as an optical digital data recorder, includes a variable optical wedge in the light path. The variable wedge facilitates assembly by a two-step adjustment process; the first step aligns a light receptor portion to receive an input light beam at an angle so as to remove ellipticity from the input beam while the second subsequent step adjusts the wedge assembly to align a transmit and reflected light path for optically coupling the wedge to a record medium. The receptor portion includes a semicircular cross-sectioned lens movable disposed in a mating cavity for adjusting the angle of reception independently of the reflected wave position.

Abstract: A transducer or optical head arrangement for an optical disk recorder includes an adjustably mounted dichroic beam combiner. The adjustments are in two degrees of freedom about a pivot point located near a light beam entry point. The write light source has its emitted beam reflected to the optical disk through a minimum of optical elements. The readback or sensing elements are optically coupled to the optical disk via a light path extending through the beam combiner entering at about the pivot point. The sensing elements include a second light source, an optical detector and a beam splitter. The two light sources are shown as semiconductive laser-emitting different frequency light beams. A four-screw, adjustably-mounted aperture plate retains a partial spherical dichroic beam combiner in a cavity of an optical support.

Abstract: A signal conditioning method and apparatus for preconditioning an FM code signal prior to its processing by a limited bandwidth medium such as an audio magnetic recording track. The FM code signal is preconditioned to limit its bandwidth and alter its phase equalization prior to processing by the medium. The phase equalization is altered in a way opposite to the alteration performed subsequently by the limited bandwidth medium, such that the conditioned signal after recovery from the medium has substantially no phase distortion relative to the input signal and no high energy distortion. The invention is particularly useful when an FM code signal is to be mixed with an analog signal and the composite signal is first processed by a limited bandwidth medium and is then processed by a further analog medium, such as an FM modulator.

Abstract: A method and apparatus for encoding a plurality of bytes of digital data into a further plurality of bits suitable for storage in a storage medium, and for recovery therefrom, and for decoding the stored bits retrieved from the storage medium, for the recovery of the encoded bytes. The digital data bytes are arranged into a plurality of code blocks, each having a first predetermined number of columns and a second predetermined number of rows of bytes. A parity block of bytes of data is generated having a number of columns and a number of rows of bytes corresponding to the first predetermined number of columns and to the second predetermined number of rows of bytes, respectively, of the code blocks, the bits of data in the parity block corresponding to the computed parity of the combined corresponding bits in each of the code blocks.

Abstract: A servo control apparatus for maintaining a scanning device, such as a beam of radiation, aligned with an information recording track on a moving recording medium, such as a record disc. The apparatus is especially adapted for use in correcting for tracking deviations brought about by temperature-induced expansion and contraction of the disc, which causes the recording track being scanned to move radially outwardly or inwardly relative to the beam of radiation. In the preferred embodiment, the apparatus includes a movable mirror for oscillating the beam in a radial direction, in accordance with a periodic dither signal. This causes a corresponding variation in the intensity of the beam reflected by the disc, with the amplitude and phase angle of this intensity variation, relative to that of the dither signal, indicating the direction and magnitude of the deviation of the beam from the track centerline.