Abstract: An apparatus and method for controlling the phase of a tunable laser is provided. Stabilization of the mode of a laser beam is provided as the laser is tuned to a target frequency. For one embodiment, a laser generates a reference beam and an output beam. The power of each of beam is measured by optical detectors, and a ratio thereof is utilized to detect when a mode hop occurs as the laser is coarsely tuned. The average of the pre and post mode hop ratios is utilized as a control setpoint while finely tuning the laser to the target frequency. Wavelength lockers, optical power dividers and optical detectors are utilized to determine power levels of the reference and output beams while also monitoring frequency characteristics thereof. A control unit utilizes the outputs from the wavelength locker to control the operation of the extended cavity laser during and after tuning.

Abstract: An apparatus and method for controlling the phase of a tunable laser is provided. Stabilization of the mode of a laser beam is provided as the laser is tuned to a target frequency. For one embodiment, a laser generates a reference beam and an output beam. The power of each of beam is measured by optical detectors, and a ratio thereof is utilized to detect when a mode hop occurs as the laser is coarsely tuned. The average of the pre and post mode hop ratios is utilized as a control setpoint while finely tuning the laser to the target frequency. Wavelength lockers, optical power dividers and optical detectors are utilized to determine power levels of the reference and output beams while also monitoring frequency characteristics thereof. A control unit utilizes the outputs from the wavelength locker to control the operation of the extended cavity laser during and after tuning.

Abstract: An apparatus and method for controlling the phase of a tunable laser is provided. Stabilization of the mode of a laser beam is provided as the laser is tuned to a target frequency. For one embodiment, a laser generates a reference beam and an output beam. The power of each of beam is measured by optical detectors, and a ratio thereof is utilized to detect when a mode hop occurs as the laser is coarsely tuned. The average of the pre and post mode hop ratios is utilized as a control setpoint while finely tuning the laser to the target frequency. Wavelength lockers, optical power dividers and optical detectors are utilized to determine power levels of the reference and output beams while also monitoring frequency characteristics thereof. A control unit utilizes the outputs from the wavelength locker to control the operation of the extended cavity laser during and after tuning.

Abstract: A method for improving servo seek settling performance by selectively activating a gain enhancement control signal during settling. As an actuator approaches a target location, absolute position and velocity of the read/write transducer head are monitored. If the absolute position changes absolute values (positive to negative or vice-versa) or the velocity approaches zero, the gain enhancement control signal is activated and combined with a nominal actuator control signal to further urge the actuator towards the target location. The gain enhancement control signal decays exponentially so as not to excite mechanical resonance of the actuator arms.

Abstract: A method for improving servo seek settling performance by selectively activating a gain enhancement control signal during settling. As an actuator approaches a target location, absolute position and velocity of the read/write transducer head are monitored. If the absolute position changes absolute values (positive to negative or vice-versa) or the velocity approaches zero, the gain enhancement control signal is activated and combined with a nominal actuator control signal to further urge the actuator towards the target location. The gain enhancement control signal decays exponentially so as not to excite mechanical resonance of the actuator arms.

Abstract: In a magnetic tape drive, a magnetic head simultaneously senses plural track lateral position indicators to generate a like plurality of independently generated sensed position error signals. The sensed position error signals are combined to provide an output position error signal that drives a positioning system to position the magnetic laterally of the length of the magnetic tape. The output position error signal represents an average of the position errors indicated by the sensed position error signals. The quality of the sensed position error signal is monitored, enabling eliminating poor quality signals from the output position error signal for maintaining a quality servo control. If less than a predetermined number of sensed position error signals have acceptable quality, then recording data is prohibited. Independently of sensing servo indicia on a record member to generate the sensed position error signals, a lateral position of the multi-track head is sensed.