Calibrating optical disk lasers using a minimal amount of write-once data storage space

A method of calibrating a write-once read-many (WORM) optical disk recorder, said recorder having a controllable laser means for emitting a laser beam to said optical disk for reading and writing data from and thereto, a detector in said recorder for receiving and detecting a laser beam reflected from said optical disk, said optical disk having a plurality of substantially concentric addressable tracks, a manufacturing area at one radial extremity of said optical disk having a plurality of said tracks, a data-storing area having a multiplicity of said tracks, each of said tracks having a plurality of addressable sectors, each one of said sectors having predetermined control data stored therein and a predetermined number of data byte storing locations for storing user data, a laser check area in each of said sectors, said laser check area being scanned by a laser beam from said controllable laser beam means before scanning said data byte storing locations are scanned;

• the method including steps:
• establishing a desired range of predetermined laser signal power levels for laser test signals;
• selecting one of said sectors for writing first ones of said user data into said selected sector;
• emitting from said controllable laser means an emitted laser test signal for writing a first laser test signal into said laser check area of said selected sector;
• while writing said first laser test signal into said laser check area of said selected one of said sectors, measuring and indicating a measured signal power level of said emitted laser test signal;
• comparing said measured and indicated signal power level with said desired range, if said comparing indicates that said measured power level is within said desired range, then writing said first ones of said user data into said data byte locations of said selected one of said sectors, otherwise indicating that said laser write power level is to be calibrated and delaying said data writing until after calibrating said laser write power level in a first predetermined laser beam calibration;
• in said first predetermined laser beam calibration;
• selecting a predetermined one of said addressable sectors in a predetermined one of said addressable tracks;
• generating a first calibration signal having a predetermined bit pattern of a given number of data bytes;
• writing said first calibration signal into said data byte storing location of said predetermined one of said addressable sectors as a written first calibration pattern;
• reading back said first calibration pattern;
• then, examining said read back first calibration pattern including measuring and indicating relative signal amplitudes in said first calibration;
• evaluating said measured relative amplitudes for indicating a laser power level that resulted in said first calibration pattern having a maximal read back amplitude, identifying said indicated laser power level as a different power level;
• then generating a desired control signal having said different power level for actuating said controllable laser means;
• selecting a second one of said addressable sectors to receive and store second user data;
• scanning said selected second one of said addressable sectors for emitting from said controllable laser means said emitted laser test signal for writing said first laser test signal into said laser check area of said second one of said addressable sectors;
• while writing said first laser test signal into said laser check area of said selected second one of said addressable sectors, measuring and indicating a measured signal power level of said emitted laser test signal as a second indicated power level;
• comparing said second indicated power level with said desired range, if said comparing indicates that said second indicated power level is within said desired range, then writing said second user data with an error correction redundancy into said data byte locations of said second one of said addressable sectors, otherwise indicating that said laser write power level is to be calibrated and delaying said data writing until alter calibrating said laser write power level in a second predetermined laser beam calibration;
• if said measured pulse power level is equal to said desired pulse power level, then continue writing in other ones of said sectors, otherwise initiating a second predetermined laser beam calibration;
• in said second predetermined laser beam calibration:
• selecting a second calibration one of said addressable sectors for performing multiple parameter calibrations therein;
• generating a second calibration pattern having more than ten bytes of data for calibrating said controllable laser means to emit a write laser beam signal having an intensity that produces a maximal read back signal amplitude;
• writing in said second calibration one of said addressable sectors a predetermined number of samples of said second calibration pattern at respective diverse laser power levels respectively as written samples of said second written calibration pattern;
• reading back said written samples of said second written calibration pattern, then measuring the relative amplitudes of said read back written samples;
• analyzing said measured relative amplitudes of said read back written samples for indicating a laser emitted write beam intensity for identifying a maximal readback amplitude;
• and
• writing additional data in said second ones of said addressable sectors using said indicated laser emitted write beam intensity generated in said second calibration phase.

Apparatus for calibrating a write-once read-many (WORM) optical disk recorder, said recorder having a controllable laser means for emitting a laser beam to a write-once optical disk in said recorder for reading and writing data from and thereto, a detector in said recorder for receiving and detecting a laser beam reflected from said optical disk, said optical disk having a plurality of substantially concentric addressable tracks, a manufacturing area at one radial extremity of said optical disk having a plurality of first ones of said tracks, a data-storing area having a multiplicity of data ones said tracks, each of said first and data ones of said tracks having a plurality of addressable sectors, each one of said sectors having predetermined control data stored therein and a data-storing portion for storing user data;

• in combination:
• calibrate start means for indicating that a laser write power level is to be calibrated:
• sector selection means connected to said calibrate start means for responding to said indication to select one of said addressable sectors in a predetermined one of said tracks as a selected sector;
• test signal means connected to the calibrate start means for generating a laser test signal having N spaced-apart predetermined bit patterns, each of said patterns having given number of bytes, N being a positive integer;
• said laser means connected to said test signal means for receiving and writing said laser test signal into said data-storing, portion of said selected sector;
• parameter means for indicating a desired power level for said laser test signal;
• data recording control means connected to said laser means for actuating the laser means to use said desired power level for writing said laser test signal to said selected sector;
• examining means connected to said laser means and to said parameter means for receiving and examining said laser test signal for comparing a power level of said laser test signal with said desired power level;
• evaluation means in said examining means for evaluating said comparison for generating a desired control signal for actuating said laser means to emit an enhanced emitted laser signal;
• said data recording control means selecting said desired control signal to be a laser drive signal amplitude for actuating said laser to emit a laser writing beam having a predetermined light intensity;
• data means for supplying data to be recorded in said selected sector;
• error means connected to said data means for receiving said data for generating an error correcting code redundancy having a capability of correcting N spaced-apart errors using N syndromes in said data after being recorded in said selected sector, said N errors being caused by said laser test signal and supplying said data and redundancy to said laser means;
• said laser means responding to said data and redundancy for writing said laser test signal and said redundancy in said selected sector;
• and
• reading means for reading said written data and redundancy from said selected sector as read signals and having error correction means for error correcting errors in said read signals caused by said laser test signal, pointing means in the reading means for pointing to said errors in the read signals.