Development of an Air Gap Servo System for High Data Transfer Rate Near Field Optical Recording

Lee, Ju−Il; Aa, M. van der; Verschuren, Coen A.; Zijp, Ferry; Mark, M.

doi:10.1143/jjap.44.3423

Cited by 68 publications

(34 citation statements)

References 8 publications

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“…The gap servo system provides an open-loop control signal to the head actuator to make the head approach the disk [184]- [187], possibly along a specific profile to reduce the pull-in time and avoid overshoot that may cause collisions. Because of the delay of the air-gap error signal, the introduction of an appropriate open-loop control signal is desirable to reduce the pull-in time and to prevent overshoot [188]. Use of a DOB to reduce the overshoot at the switching point between open-loop and closed-loop modes was demonstrated in [189].…”

Section: Near-field Recording Systemsmentioning

confidence: 99%

Control Methods in Data-Storage Systems

Cherubini

Chung

Messner

et al. 2012

IEEE Trans. Contr. Syst. Technol.

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Abstract-The recording performance of data-storage devices, in which write/read elements move relative to a storage medium to reliably store and retrieve information, depends on the capability of servo mechanisms to provide the necessary positioning accuracy. The desired characteristics of servo mechanisms for datastorage systems include robustness against variations of environmental parameters, high resolution, accuracy, stability, and fast response. This paper presents a comprehensive overview of advanced servo-control methods for data storage. The applications are to well-established recording technologies, including magnetic tape and magnetic disk systems as well as CD/DVD/Blue-Ray optical data-storage systems. Moreover, newer holographic and nearfield optical systems and the emerging probe-storage technology are also addressed. Emphasis is given to the potential exhibited by the technologies considered for achieving ultra-high storage capacity, as required by the exploding demand in data-storage capacity for archival systems and massive multimedia data storage.Index Terms-Control systems, hard-disk drive, holographic data storage, optical-disk drive, scanning-probe data storage, servomechanism, tape drive.

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Section: Near-field Recording Systemsmentioning

confidence: 99%

Control Methods in Data-Storage Systems

Cherubini

Chung

Messner

et al. 2012

IEEE Trans. Contr. Syst. Technol.

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“…The ramp-approach mode, which is used for the conventional-approach mode, is not affected much by this problem [6]. However, the exponential-approach mode has the remarkable advantages of fast settling time and small overshoot because the initial velocity for the hand-over mode can be very small, while the approaching velocity is high.…”

Section: B Exponential-approach Modementioning

confidence: 99%

Improved Air-Gap Control for SIL-Based Near-Field Recording System

et al. 2007

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We propose a gap servo method to reduce the overshoot in the near-field (NF) region. In general, we use a mode-switching servo which consists of approach, hand-over, and gap-control modes. However, there is a critical problem, such as an overshoot at the turning point from the approach mode to the hand-over mode, which may cause a collision between the SIL and the disk. In this paper, we propose an improved NF gap servo system using an exponential input in the approach mode which can reduce the overshoot and settling time of the mode-switching servo.Index Terms-Gap error signal (GES), mode-switching servo, near-field recording (NFR), overshoot.

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“…Generally, the near-field air gap, which is the sensing region in air-gap control, is extremely small, less than a quarter of a wavelength, due to the exponential evanescent decay of reflected light as a function of the air gap. Therefore, the SIL-based NFR servo system cannot directly apply the conventional pull-in process (Ishimoto et al 2003b;Lee et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Improved gap servo system using a brake pulse for a SIL-based near-field recording system

et al. 2009

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A mode-switching servo is widely used in solid immersion lens (SIL)-based near-field recording (NFR) systems to control the air gap between the bottom surface of the SIL and the top surface of the rotating media. In the mode-switching servo, it is very important to reduce the initial overshoot in the near field region, as this overshoot can cause collisions between the SIL and the media, and increase the settling time required for the SIL to be initially moved to the final air gap. In this paper, the modeswitching servo with a brake pulse is proposed to reduce the initial overshoot and settling time. The effectiveness of the proposed method is proved by experiments of which results show that the minimum air gap due to the initial overshoot is improved from 6.86 to 18.73 nm and the settling time is reduced from 30 to 4.5 ms.

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Development of an Air Gap Servo System for High Data Transfer Rate Near Field Optical Recording

Cited by 68 publications

References 8 publications

Control Methods in Data-Storage Systems

Control Methods in Data-Storage Systems

Improved Air-Gap Control for SIL-Based Near-Field Recording System

Improved gap servo system using a brake pulse for a SIL-based near-field recording system

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