News Column

Patent Issued for Optical Storage Device with Direct Read after Write

August 13, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- Oracle International Corporation (Redwood City, CA) has been issued patent number 8792317, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventor is Wilson, Scott D (Thorton, CO).

This patent was filed on March 9, 2012 and was published online on July 29, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "Optical recording devices, such as optical disk and optical tape drives, commonly use an Optical Pickup Unit (OPU) or read/write head to store and retrieve data from associated optical media. Conventional OPUs may utilize different wavelength semiconductor laser diodes with complex beam path optics and electromechanical elements to focus and track the optical beam within one or more preformatted tracks on the optical storage medium to write or store the data and subsequently read the data. Data written to the medium with a laser at higher power may be verified in a separate verification operation or process after writing using a lower laser power, or may be verified during the write operation by another laser or laser beam. The ability to read and verify the data during the write operation may be referred to as Direct Read After Write (DRAW). One strategy for providing DRAW functionality is to use multiple independent OPUs with one OPU writing the data as a second OPU reads the data for write verification, such as disclosed in U.S. Pat. No. 6,141,312, for example, where two separate OPUs are placed side-by-side to achieve DRAW functionality. While this approach may be suitable for some applications, it increases the cost and complexity of the storage device.

"Present OPUs may use a diffraction grating or similar optics in the laser path to generate two or more beams from a single laser element including a higher power beam used for reading/writing data and for focusing, and one or more lower power satellite beams used for tracking. The beams are focused to corresponding spots on the surface of the optical storage medium by the various optical and electromechanical elements of the OPU(s). In addition to writing data and focus control, the center spot may also be used for tracking operations in some applications. The lower power satellite spot(s) generated from one or more lower-power side-beams may be used for another type of tracking operation for specific types of media."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventor's summary information for this patent: "In one embodiment of the present disclosure, an optical storage system that receives an optical medium having a plurality of tracks for storing data includes an optical head having a first coherent light source modulated at higher power during writing of data to the optical medium and a second coherent light source operating in a continuous wave mode at lower power while the first coherent light source is writing data, optics that combine light from the first and second light sources and focus light from the first coherent light source to a first spot of a selected track on the optical medium and focus light from the second coherent light source to a second spot on the selected track downstream from the first spot relative to movement direction of the optical medium, the optics directing reflected light from the optical medium to a photodetector. A controller coupled to the optical head selectively positions the optical head for writing data along the selected track using the first coherent light source while reading data directly after writing from the selected track using reflected light from the second coherent light source detected by the photodetector.

"In one embodiment, an optical data storage system includes an optical pickup unit, a first laser disposed within the optical pickup unit, a second laser disposed within the optical pickup unit, and an amplitude beam splitter disposed within the optical pickup unit and positioned to combine light from the first and second lasers and direct combined light toward an optical storage medium. A collimating lens positioned downstream of the amplitude beam splitter collimates the combined light. The system also includes a polarizing beam splitter positioned downstream of the collimating lens, a quarter-wave plate positioned downstream of the polarizing beam splitter, an objective lens positioned downstream of the quarter wave plate and configured to focus light from the first laser to a first spot on a selected track of the optical storage medium, and to focus light from the second laser to a second spot on the selected track downstream of the first spot, a photodetector and associated optics configured to receive light reflected from the optical medium through the objective lens and polarizing beam splitter, and a controller in communication with the first and second lasers and the photodetector to modulate light from the first laser to write data to the selected track of the optical storage medium and read data from the selected track of the optical storage medium using the second laser to provide a direct read after write capability.

"Embodiments of the present disclosure include a method for providing direct read after write functionality for an optical storage device that reads and writes data to an optical storage medium includes combining light from a first laser modulated at higher power during writing of data to the optical storage medium and light from a second laser operated in a continuous wave mode at lower power, focusing light from the first laser to a first spot within a selected track on the optical storage medium, focusing light from the second laser to a second spot within the selected track on the optical storage medium downstream relative to the first spot in the direction of travel of the optical storage medium, and directing light reflected from the second spot to a photodetector to provide direct read after write functionality.

"Embodiments according to the present disclosure may provide various advantages. For example, an optical storage device according to one embodiment of the present disclosure provides direct read after right functionality for data verification using a single OPU or optical head, which reduces complexity and associated costs.

"The above advantages and other advantages and features associated with various embodiments of the present disclosure will be readily apparent from the following detailed description when taken in connection with the accompanying drawings."

For the URL and additional information on this patent, see: Wilson, Scott D. Optical Storage Device with Direct Read after Write. U.S. Patent Number 8792317, filed March 9, 2012, and published online on July 29, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8792317.PN.&OS=PN/8792317RS=PN/8792317

Keywords for this news article include: Oracle International Corporation.

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Source: Journal of Engineering


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