Laser power control with stretched initial pulses

A laser power control system comprising:

• circuitry for generating laser power parameters in response to a desired laser power signal;
• PWM circuitry for generating a series of pulses to be applied to a laser responsive to the laser power parameters from the generating circuitry;
• and
• initial pulse circuitry for generating a first laser pulse, of a selected duration, to be applied to the laser responsive to a gate signal indicating that the laser is to be turned on, the initial pulse circuitry comprising:
• a one-shot multivibrator, for generating the first laser pulse responsive to the gate signal;
• and
• a disjunctive logic function, having inputs coupled to the one-shot multivibrator and to the PWM circuitry, and having an output for presenting a pulse generated at either of its inputs.

A laser power control system comprising:

• circuitry for generating laser power parameters in response to a desired laser power signal;
• initial pulse circuitry for generating a first laser pulse, of a selected duration, to be applied to the laser responsive to a gate signal indicating that the laser is to be turned on, the initial pulse circuitry comprising:
• a first pulse stretch store, for storing a value corresponding to a selected time duration by which an initial pulse of the laser is to be lengthened from that indicated by the laser parameters;
• and
• PWM circuitry for generating a series of pulses to be applied to a laser responsive to the laser power parameters from the generating circuitry, the PWM circuitry comprising:
• a pulse width limit circuit, for determining the duration of each PWM pulse;
• and
• a pulse width adder, for adding the selected time duration from the first pulse stretch store to the duration determined by the pulse width limit circuit, responsive to the gate signal.

A rapid prototyping system, comprising:

• a container for a fusible substance, the container defining a target surface of the fusible substance;
• a laser, for emitting laser energy of a wavelength suitable for fusing irradiated locations of the fusible substance at the target surface;
• a laser directional control system, for directing the laser energy at selected locations of the target surface corresponding to cross-sections of an article to be produced;
• and
• a laser power control system, comprising:
• circuitry for generating laser power parameters in response to a desired laser power signal;
• PWM circuitry for generating a series of pulses to be applied to the laser responsive to the laser power parameters from the generating circuitry;
• and
• initial pulse circuitry for generating a first laser pulse, of a selected duration, to be applied to the laser responsive to a gate signal indicating that the laser is to be turned on.