Coherent, Inc.

Ralph Saunders

Kevin P Connors

Greg J Spooner

Robert J Rorden

Gregory Dumond

An Er:YAG laser system has a resonant cavity including an Er:YAG rod pulse-pumped by a pulsed flashlamp. The pump-pulse repetition rate and average power is selected to provide a known essentially constant thermal-lensing power in the Er:YAG rod. Design parameters of the Er:YAG rod and the resonant cavity are selected to compensate for this thermal-lensing power. A shutter in the resonant cavity, when closed or open, respectively prevents or allows a laser output-pulse to be generated in response to a pump-pulse. Laser output-pulse duration is continuously variable and is controlled by controlling the duration of flashlamp-pulses. A sequence of laser output-pulses is controlled by opening and closing the shutter. This arrangement has the advantage that the laser output-pulse repetition rate can be selected to be the flashlamp-pulse repetition rate or some sub-multiple thereof while maintaining thermal-lensing power in the rod essentially constant and compensated for.

Rapid pulsed Er:YAG laser

A laser power supply including circuitry for converting standard, 115-120 volt, AC power from a wall outlet to current pulses for powering a laser, to generate a pulsed laser output beam having laser pulse amplitude and duration matching pre-selected parameters. In a preferred embodiment, the invention powers an argon laser tube and generates output laser beam pulses having power in the range from about 50 milliwatts to 2 watts, and duration in the range from about 0.01 second to 2 seconds. The invention converts standard AC power to current pulses having controlled duration, average amplitude, and ripple amplitude for powering a laser, and can produce laser output beam pulses with a turn-on time of less than 1 millisecond, with a switching frequency in the range from about 10 to 20 KHz without significant overshoot. A preferred embodiment of the invention powers a gas laser tube, and includes a magnet control circuit which enables the laser tube magnet in the absence of a special magnet control signal received at the magnet control circuit from a fiber optic link. The invention is particularly suitable for powering gas laser systems for use in ophthalmic and surgical applications, but is also useful for powering other types of laser systems. An important advantage of the invention is that its ability to accept standard, AC power from a wall outlet enables the inventive apparatus to be moved conveniently between treatment rooms (for use in any of the rooms), without the expense and inconvenience of installing special wiring.

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San Ramon, CA, United States of America

Ralph Saunders