A light emission adjustment processing unit of a laser diode sequentially instructs a D/A converter for light emission of a light emission by test powers at predetermined two points, allows the laser diode to emit the light, instructs a D/A converter for subtraction of subtraction currents corresponding to the test powers at two points, and measures each power by an A/D converter for monitoring. From the measurement results, a relation of the instruction values to an arbitrary power in each D/A converter is obtained by a linear approximation and registered into a power table. When deciding an optimum writing power by a test write, a limit power on the lower limit side is detected while gradually decreasing the writing power from a starting power and a predetermined offset is added to the detected limit power, thereby obtaining the optimum writing power.

Optical storage apparatus

A monitoring system for a communications network includes a set of components for transmitting and receiving data signals over the communications network. Each component includes a built-in self-test system for performing tests within the component and outputting corresponding test results. Each self-test system is configured to non-invasively determine waveform characteristics of the data signals. The system includes a set of processors. Each processor is coupled to a subset of the set of components, and is configured to evaluate the test results output by the components coupled to the processor. Each processor is configured to detect and predict faults in the communications network based on the evaluation of the test results.

Monitoring system for a communications network

A laser treatment apparatus for performing treatment on a treatment part of a skin by irradiating the part with a laser beam for treatment is disclosed. The apparatus includes a laser output device which outputs the treatment beam; a hand-piece provided with at least a part of an irradiation optical system for irradiating the treatment beam of a predetermined spot size, the hand-piece being held in contact with the skin; a detector which detects a moved position of the hand-piece on the skin; and a controller which controls an ON/OFF state of laser irradiation based on the moved position detected by the detector and information on the spot size.

Laser treatment apparatus

A method for fabricating read-only copy protected optical medium comprising a light-sensitive material at positions capable of altering the data read during copying of the optical medium but permitting read of the underlying data in the reading of the optical medium.

Copy-protected optical media and method of manufacture thereof

A control method and controller for an optical storage drive including: an optical head having a laser light source for applying light to an optical disk and a detector for receiving reflected light from the optical disk; and a seek mechanism for positioning the optical head on the optical disk. The control method includes: measuring a drive current value with which the laser light source provides a predetermined light power value by an emission adjustment; writing the measured drive current value into a non-volatile memory as an initial value; adjusting the emission of the laser light source so that it provides the predetermined light power value; and comparing the drive current value with which the emission adjustment has been made with the initial value stored in the non-volatile memory. Also disclosed is a control method which measures and stores a write power value providing optimum write performance in a non volatile memory for controlling the power of the laser light source with the measured value.

Optical storage drive controller with predetermined light source drive values stored in non-volatile memory

Calibration of the write signal power level applied to a transducer for marking a moving media to optimize a later recovered read-back signal is provided. An optimized read-back signal is one where the peak-to-peak amplitude of the read-back signal is maximized. The method provides marking test patterns on the recording media at a plurality of discrete, selected write signal power levels of the marking source, developing a read-back signal from the test pattern marks, correlating portions of the read-back signal with the write signal power levels and solving a relationship of the form W.sub.c =W.sub.o -KB.sub.2 /2B.sub.3 where W c is the calibrated write signal power level W o is an offset write signal power level. K is a minimum differential between write signal power levels B 2 and B 3 are parameters derived from a least squares fit of a second order polynomial equation to data provided by correlating read-back signals with write signal power levels.

Write power calibration utilizing least squares fit of read-back signals for moving media memory

Apparatus and method for calibrating the drive current circuit of a semiconductor laser diode subject to reflected optical feedback from a target surface such an an optical recording disk. The method makes use of two power output vs. drive current characteristic curves for the laser, one curve for in focus condition and one for out of focus condition, wherein the curves exhibit an asymptotic region at high power levels (P2). Measurement of drive current (I2) power level P2 is taken under an out of focus condition. Measurements of drive current at a predetermined low power level P1 are taken for both (I1) and in focus condition (I3). The linear slope of the in focus curve can thus be calculated to set desired power levels.

Laser power calibration by measuring laser drive current at out of focus and in focus conditions

A drive circuit for a laser which has the capability of eliminating transient conditions when switching a high frequency modulator on or off, and including elements for maintaining desired depth of modulation. These capabilities are included in a circuit that automatically compensates for changing conditions due to temperature, laser characteristics and fluctuations in media reflectivity.

Compensated laser drive circuit

An optical disk recorder employs laser drive signals having diverse current or power levels. A scaling digital-analog-converter (DAC) supplies a scaled reference signal to a plurality of scaled DACs. The scaled DACs supply the diverse laser drive signals. Calibrating the scaling DAC calibrates the scaled DACs. A base array of DACs include not only the scaling DAC but a plurality of base array DACs. Such base array DACs control reading operations as well as supplying a threshold current. The threshold current is that laser drive signal current level below which laser 25 does not emit a laser beam. During writing, the CUT current is added to the laser drive currents supplied by the scaled DACs. A desired CUT current is determined by calculating a slope of the laser drive current to emission of radiation. Then the slope is extrapolated to a zero emission point below which no coherent emission of radiation occurs.

Laser power-drive circuit having a scaling DAC supplying a scaled reference signal to a plurality of scaled DAC's that supply a plurality of scaled output signals

A write-once optical disk data recorder automatically calibrates a laser during a write data operation and using write pulses focussed to a disk. First, the laser is calibrated using a non-focussed laser beam. Each sector of the disk has a laser checking or test area, such as an automatic laser power correction field (ALPC) of two byte lineal extent. During a first write operation after a power up or disk load, a pulse width modulated (PWM) laser test signal is recorded using a laser power level set using the non-focussed laser beam and an indicated desired recording power level on the disk. The recorded laser test signal is read back. The length of the read back laser test signal is measured. The measured length is then compared with a desired length of the PWM laser test signal that indicates a desired laser power level. That is, as laser recording power levels increase, a resultant recorded signal grows in size. This property is used to measure laser power for calibrating laser operation.

Monitoring and adjusting laser write power in an optical disk recorder using pulse-width modulated power level checking signals

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