Infineon Technologies North America Corp.

Infineon Technologies Ag

Imation Corporation

O. R. Technology, Inc.

Stephen W Farnsworth

Kirk Cook

Robert C Martin

Daniel P Stubbs

Robert S Jackson

John J Simbal

David M Perry

Mark P Lubratt

Lewis S Damer

Werner Spaeth

Curtis A Shuman

A lensless optical servo system () has an unfocused light source () and patterned photodetectors (). The unfocused light is reflected by the markings on an LS-120 disk () and the reflected light carries the pattern of the markings the considerable distance in its far-field to the photodetectors (). The convolution of this light pattern and a mating geometric pattern () on the photodetectors () causes the photodetectors to generate signals representing the position of the track on the disk. According to a presently preferred embodiment, a laser diode () and three detectors () are formed on the same silicon substrate (). Sinusoidal metalization () is applied to the detectors () in the radial direction. The period of the sinusoidal metalization is two times the tracking pitch of the disk radially and tangentially. The metalization on the first detector is approximately ninety degrees behind the metalization on the second detector and the metalization on the third detector is approximately ninety degrees ahead of the metalization on the second detector. Preferably, each detector () is provided with two sinusoidal patterns (), approximately one hundred eighty degrees out of phase with each other, and spaced apart in the tangential direction.

Lensless optical servo system for an optically assisted disk drive

A test system for positioning and measuring the far-field pattern of a laser diode under test (LDUT) using a single objective lens and two relay lenses. Positioning is achieved by passing light from the LDUT through a video microscope formed by the objective lens and a first relay lens, which focuses the light onto an image plane for capture by a first camera. Far-field pattern measurement is performed by reflecting a portion of the focused light through a second relay lens, which collimates the light and directs the unfocused light onto an infinity image plane, where it is captured by a second video camera. Angular orientation is achieved using a laser collimator that reflects beam energy from a datum plane of the LDUT. The reflected beam energy forms a point image at the infinity image plane that is used to determine and/or adjust the angular orientation of the LDUT.

Test system for laser diode far-field pattern measurement

A lensless optical servo system has an unfocused light source and patterned photodetectors. The unfocused light is reflected by markings on a rotating disk and the reflected light carriers the pattern of the markings to the photodetectors. The convolution of this light pattern and a mating geometric pattern on the photodetectors causes the photodetectors to generate signals representing the position of the track on the disk. In one embodiment, a laser diode and three detectors are formed on the same silicon substrate. Sinusoidal metalization is applied to the detectors in the radial direction. The period of the sinusoidal metalization is two times the tracking pitch of the disk. The metalization on the first detector is approximately ninety degrees behind the metalization on the second detector and the metalization on the third detector is approximately ninety degrees ahead of the metalization on the second detector.

Methods and systems for laser etching of optical servo patterns on magnetic data storage media using two or more beams of laser energy produced from a single source of laser energy to produce a servo pattern on the magnetic data storage media. By using two or more etching beams, the time required to produce a servo pattern on the magnetic data storage media can be significantly reduced. Alternatively, each servo track in the servo pattern can be written more than once. The servo patterns thus formed can be read optically or they may be read magnetically using magnetic overwriting (if the servo pattern is formed in a magnetic coating on the media). In either case, the servo patterns are either permanently formed in the media when read optically, or they can be recreated after bulk erasing if they are provided using magnetic overwriting. In yet another alternative, the servo patterns may be read both magnetically and optically, with the magnetic and optical reading occurring simultaneously or sequentially.

Multibeam laser servowriting of magnetic data storage media

A monolithic optical pickup has all passive optical elements aligned during fabrication, thereby requiring no alignment during the assembly of a system utilizing it. Its supporting structure is the monolithic passive device itself. A single surface incorporates all the functions of an optical pickup system including a focusing element, image creation apertures and stops, scattering/reflection reduction, and return path apertures and optics. The elements are formed from a metalized layer which is applied lithographically. Placing the apertures and stops on the principal plane of the focussing element allows for the image size to be precisely controlled by the image distance. The monolithic optical pickup is well suited for use with multiple detector elements. Alternate embodiments of the invention may omit some of the optical system elements.

Monolithic optical pickup and an assembly including the pickup with laser source(s) and optical detector(s)

An optical position detector system has a light emitting diode source, two detectors, and a diffraction grating which is frequency mismatched with the frequency of a reference grating. According to one embodiment for use in a reflective system, the source and two detectors are mounted on a single body and a single diffraction grating is placed over the source and detectors. There is no need to control the locations or phase differences between the source grating and the detector gratings because a single grating us used for all three. The spatial frequency of the single grating is chosen such that it is different from the frequency of the reference grating but still produces a signal having a maximized amplitude with the desired phase shift. Two alignments which formerly required tight tolerance are no longer necessary with the system of the invention. In addition, a fabrication feature of introducing a discrete phase step between the gratings covering both detectors is not necessary. In a second embodiment, for a transmissive system, a source with a source grating is mounted on one body and the two detectors are mounted on another body with the reference grating located therebetween. A single grating is applied over the two detectors and only the detector grating is mismatched with the reference grating.

Mismatching of gratings to achieve phase shift in an optical position detector

In an optical positioning system, a holographic optical element having a plurality of rectangular apertures has predetermined ones of its aperture edges castellated or notched in order to null out undesired light energy in target areas. The apertures may be fitted with diffraction grating patterns that may also be castellated for the same purpose. A method of using the aperture and grating pattern castellated holographic optical element is also provided.

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Loveland, CO, United States of America

Stephen W Farnsworth