Thermal compensation for laser diodes using active feedback

An optical information recording/reproducing apparatus having a laser diode for radiating a laser beam capable of being modulated by digital video data and writing on a photostatic receiver material controlling the laser power level during a test period, said apparatus comprising:

• means for generating a sample signal to establish a test period;
• means for indicating the power level of the laser diode operating at a maximum level to produce a threshold current level in the form of a first signal;
• means for generating a second signal corresponding to the ambient temperature of said laser diode;
• means for generating a third threshold current reference signal that is proportional to said first and second signals;
• means for sampling said third signal at periodic intervals;
• means for measuring the current level of said laser diode when fully modulated during said test period to produce a modulated current reference signal;
• means for combining the threshold current reference signal with the maximized modulated current to produce a drive signal;
• and
• means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.

A method of providing thermal compensation for a laser diode that is modulated in response to digital video data and writing on a photostatic receiver material, said laser diode operating at a maximum output during a test period, said method comprising the steps of:

• generating a sample signal to establish a test period;
• generating a first signal corresponding to the light output of said laser diode operating at a maximum level to produce a first signal;
• generating a second signal that corresponds to the ambient temperature of said laser;
• generate and amplify an error signal which is proportional to said first and second signals combined;
• measure the current level of said laser when modulated by said digital video data to obtain an analog modulated current reference signal;
• sum said error signal and said modulated current reference signal to produce a drive signal;
• and
• operate the laser diode in response to said drive signal and modulate the laser with the digital video data.

A method of thermal compensation for a laser diode that is modulated in response to a digital video data and writing on a photostatic receiver material while controlling said laser power during a test period, said method comprising the steps of:

• generating a sample signal to establish a test period;
• generating a first signal indicating the power level of the laser diode operating at a maximum power level;
• generating a second signal corresponding to the ambient temperature of said laser diode;
• generating a third threshold current reference signal that corresponds to said first and second signals;
• sampling said third signal at periodic intervals;
• measuring the current level of said laser diode when modulated by said digital video data to produce a modulated current reference signal;
• combine the threshold current reference signal with the modulated current reference signal to produce a drive signal;
• and
• drive the laser in response to said drive signal and modulate the laser in response to the digital video data.

A drive circuit for driving a semiconductor laser having a light output that is modulated in response to digital video data comprising:

• means for generating a sample signal to establish a sampling period;
• means for generating a first signal corresponding to said light output at a maximum level to produce a threshold current reference;
• amplifier means for generating an error signal which is proportional to said first and second signal;
• means for measuring the current level of said laser when modulated to produce a maximum analog modulated current reference signal;
• means for summing said error signal and said modulated current reference signal to produce a drive signal;
• and
• means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.

An optical information recording/reproducing apparatus having a laser diode for radiating a laser beam capable of being modulated by digital video data and writing on a photostatic receiver material controlling the laser power level during a test period, said apparatus comprising:

• means for generating a sample signal to establish a test period;
• means for indicating the power level of the laser diode operating at a maximum level to produce a threshold current level in the form of a first signal;
• means for generating a third threshold current reference signal that is proportional to said first signal;
• means for sampling said third signal at periodic intervals;
• means for measuring the current level of said laser diode when fully modulated during said test period to produce a modulated current reference signal;
• means for combining the threshold current reference signal with the maximized modulated current to produce a drive signal;
• and
• means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.

A method of providing thermal compensation for a laser diode that is modulated in response to digital video data and writing on a photostatic receiver material, said laser diode operating at a maximum output during a test period, said method comprising the steps of:

• generating a sample signal to establish a test period;
• generating a first signal corresponding to the light output of said laser diode operating at a maximum level to produce a first signal;
• generate and amplify an error signal which is proportional to said first signal;
• measure the current level of said laser when modulated by said digital video data to obtain an analog modulated current reference signal;
• sum said error signal and said modulated current reference signal to produce a drive signal;
• and
• operate the laser diode in response to said drive signal and modulate the laser with the digital video data.

A method of thermal compensation for a laser diode that is modulated in response to a digital video data and writing on a photostatic receiver material while controlling said laser power during a test period, said method comprising the steps of:

• generating a sample signal to establish a test period;
• generating a first signal indicating the power level of the laser diode operating at a maximum power level;
• generating a second threshold current reference signal that corresponds to said first signal;
• sampling said second signal at periodic intervals;
• measuring the current level of said laser diode when modulated by said digital video data to produce a modulated current reference signal;
• combine the threshold current reference signal with the modulated current reference signal to produce a drive signal;
• and
• drive the laser in response to said drive signal and modulate the laser in response to the digital video data.