Lumonics Inc.

Graham Burrows

David Gurwicz

James M Burch

A laser system comprises an optical head, a power supply and a computer for controlling the power supply. The optical head comprises a pair of mirrors and four pumping sections. Each pumping section comprises a pair of gas discharge lamps pumping an Nd:YAG laser element. The power supply provides the lamps with alternating current at 25 kHz so that the laser system produces a continuous, modulated or pulsed output light beam. The power supply comprises three boost converters connected in parallel for converting three phase mains supply to direct current and four DC-AC converters. Each DC-AC converter converts the DC output from the boost converters to an AC supply for the lamps of a respective one of the pumping sections. Each DC-AC converter comprises a resonant circuit having an inductor and capacitor connected in series, the lamps being connected across the capacitor, a pair of transistors for conducting current through the resonant circuit in alternating directions, and a control circuit for the transistors. The power supply is also arranged to supply alternating current at a relatively high voltage to the lamps for triggering a discharge. In a modification, the output of the power supply is rectified before it is supplied to the lamps.

Laser system

In order to compensate for the thermally induced lens in the active element of an optical stage of a laser, the optical stage is provided with a telescope. The telescope comprises first and second lens arrangements. The first lens arrangement is located so that thermally induced lens is located at one of its focal planes. The position of the second lens arrangement is adjusted so as to compensate for variations in the power of flashlamps which pump the active element. In one embodiment, the laser has an oscillator stage and an amplifier stage. The telescope is placed after the oscillator stage and comprises two convex lenses.

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Rugby, United Kingdom

Graham Burrows