# US 2013/0155827 A1 · Method and system for determining the quality of a storage system

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- Number: US 2013/0155827 A1
- Document ID: US20130155827A1
- Status: Published application
- Kind: A1
- Application number: 13/820,543
- Filed: 2011-09-06
- Published: 2013-06-20
- Earliest claimed: 2010-09-08
- Assignees: Thomson Licensing
- Inventors: Dietmar Hepper; Oliver Theis; Xiaoming Chen; Herbert Hoelzemann; Gael Pilard
- Web page: https://patentgrep.com/patent/US20130155827A1

## CPC

- G11B 20/1816: {Testing}
- G11B 7/1267: Power calibration
- G11B 7/24: Record carriers characterised by shape, structure or physical properties, or by the selection of the material (characterised by the arrangement of information on the carrier G11B7/007)
- G11B 20/182: {using test patterns}
- G11B 20/20: for correction of skew for multitrack recording
- G11B 20/10481: {optimisation methods}
- G11B 2220/2537: Optical discs
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

In accordance with an exemplary embodiment of the present invention, a method for measuring a quality parameter of an optical storage system comprising a non-diffraction-limited optical storage medium and a readout device, the method comprising the process of deriving an impulse response of the optical storage system, and the process of analyzing the impulse response to determine at least one of a width of the impulse response and a skewness of the impulse response as the quality parameter.

## Claims

### Claim 1

A method for measuring a quality parameter of an optical storage system, the storage system comprising a readout device and a non-diffraction-limited optical storage medium carrying predefined data, the method comprising:
deriving, based on a readout of the predefined data, an impulse response of the optical storage system, as a sequence of impulse response samples; and
analyzing the impulse response to determine as the quality parameter at least one of a width of the impulse response and a skewness of the impulse response.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the optical storage medium contains one of predefined sync data, predefined test data, and predefined user data, and the impulse response is derived at least in part by evaluating a readout signal of the predefined data from the storage medium.

### Claim 3 (depends on 1)

A method according to claim 1, wherein the width of the impulse response is determined by evaluating one of
the spatial distance of those locations where the impulse response has decreased to a predefined fraction of its maximum value, and
a second-order central moment of squares of the impulse response samples.

### Claim 4 (depends on 1)

A method according to claim 1, wherein the skewness of the impulse response is determined by evaluating a third-order central moment of squares of the impulse response samples.

### Claim 5 (depends on 1)

A system for measuring a quality parameter of an optical storage channel, comprising means configured to carry out a method according to claim 1.

### Claim 6 (depends on 3)

A method for determining an optimum readout laser power for a non-diffraction-limited optical storage medium, the method comprising:
setting the laser power to a start laser power;
determining the width of the impulse response at the set laser power according to a method according to claim 3;
modifying the laser power until the width of the impulse response has reached its minimum.

### Claim 7 (depends on 6)

A system for determining an optimum readout laser power for a non-diffraction-limited optical storage medium, the system comprising means configured to carry out the method of claim 6.