Optical recording system utilizing proportional real-time feedback control of recording beam intensity
OwnerDavid P. Gregg, Stephen K. Shu +1inventors
InventorsDavid P. Gregg, Stephen K. Shu, Kitchener C. Wilson
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Abstract
A system for optically recording information on a recording medium, such as a video disk, by pulse-code modulation (PCM). The medium includes a reflective and radiation-sensitive recordable stratum which changes optically in accordance with the signal being recorded. The signal is recorded on the medium by a slaved coherent light light beam whose intensity is controlled by the recording medium itself. The recording medium controls the recording beam power in a manner to reduce dropouts to a minimum and to assure fidelity in the recorded signal throughout a predetermined range of surface speeds of the medium despite irregularities in the recording stratum.
Claims15
An optical recording system for recording data on a radiation-sensitive stratum in an optical recording medium including;
- (a) a radiation source,
- (b) control means for electrically controlling the power output of said radiation source,
- (c) means for directing energy emitted by said radiation source onto said radiation-sensitive stratum,
- (d) means for sensing a change in an optical property of said stratum during irradiation of said stratum by said radiation source, said sensing means providing a feedback signal simultaneous with said irradiation,
- (e) means for comparing said feedback signal with an input command signal to produce an error signal, and
- (f) means operatively connected to said comparison means and said control means for continuously varying the power output of said radiation source in response to said error signal in real time.
An optical recording system for recording data on a radiation-sensitive stratum in an optical recording medium including;
- (a) means for directing onto said stratum an incident radiant beam modulated to contain data in accordance with a command input signal to be recorded on said recording medium, said radiant beam causing said recording medium to emit a secondary radiant beam inversely representing the power required by said stratum to record the data of said incident beam, and
- (b) means for comparing substantially in real time the amplitudes of said command input signal and said secondary beam to control the power level of said incident beam and to maintain said incident beam at the power level required by said stratum to properly record said data.
An optical recording system comprising:
- (a) a recording medium having both reflective and radiation-sensitive reactive characteristics,
- (b) radiation source beam means configured to irradiate said recording medium with a radiant energy beam,
- (c) beam splitting means disposed between said radiation source beam means and said recording medium for for transmitting an incident beam onto said recording medium, for reflecting a portion of said source beam to a first location, and for reflecting a portion of the incident beam which is reflected from said recorded medium to a second location,
- (d) means for causing said recording medium to move with respect to said transmitted incident beam,
- (e) first detecting means at said first location for monitoring the power level of said incident beam,
- (f) second, reflection detection means at said second location for monitoring the power level of said signal reflected from said recording medium,
- (g) normalizing means coupled to said first, incident power detecting means and to said second, reflection detection means for obtaining an absolute value feedback signal proportional to the instantaneous reflectivity of said recording medium,
- (h) differencing means coupled to said normalizing means and to an input command signal to be recorded for producing a error drive signal for said radiation source means inversely proportional to the instantaneous reflectivity of said recording medium,
- (i) read level comparator and reference level means, coupled to said second, reflection detecting means, for adjusting a read level in excess of a fixed reference level in response to average reflectivity of said recording medium, and
- (j) threshold driver means coupling said differencing means, and said first and second beam reflection detecting means to said radiation source means for powering said radiation source means at a real-time feedback controlled, continuous read level output and for powering said radiation source means at an intermittent write level output dependent upon the output level of said differencing means.
Dependencies are inferred from the claim text.