Coherent, Inc.

Peter N Allen

William Blake

Michael W Sasnett

James L Hobart

Wayne S Mefferd

Donald Bowes

A laser system employing one or more mirror sets having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, for example, to compensate for thermally-induced distributed lensing. In one class of preferred embodiments, the invention is a high power gas laser system having a folded optical cavity with a periodic intracavity refocusing means to compensate for distributed negative thermal lensing in the hot plasma that comprises the active medium, and thus maintain a substantially constant beam diameter throughout the optical cavity. The periodic intracavity refocusing means preferably includes a corner mirror set (including at least one curved mirror and at least one other mirror) at each corner of the folded optical cavity. In one preferred embodiment, each corner mirror set is a mirror pair including a spherical mirror and cylindrical mirror. In another preferred embodiment, each corner mirror set comprises three mirrors (including three spherical mirrors, or two spherical mirrors and a planar mirror). In another class of preferred embodiments, the inventive focusing mirror sets are not included within the optical cavity of a high power laser, but instead, one or more such focusing mirror sets are included within the output beam delivery optical components of a high power laser. For example, one of the inventive focusing mirror sets may replace a conventional lens to direct the output beam of a high power laser system along a desired path and maintain a desired beam diameter.

High power laser with focusing mirror sets

A laser system employing one or more mirror sets having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, for example, to compensate for thermally-induced distributed lensing. In one class of preferred embodiments, the invention is a high power gas laser system having a folded optical cavity with a periodic intracavity refocusing means to compensate for distributed negative thermal lensing in the hot plasma that comprises the active medium, and thus maintain a substantially constant beam diameter throughout the optical cavity. The periodic intracavity refocusing means preferably includes a corner mirror set (including at least one curved mirror and at least one other mirror) at each corner of the folded optical cavity. In one preferred embodiment, each corner mirror set is a mirror pair including a spherical mirror and cylindrical mirror. In another preferred embodiment, each corner mirror set comprises three mirrors (including three spherical mirrors, or two sperical mirrors and a planar mirror). In another class of preferred embodiments, the inventive focusing mirror sets are not included within the optical cavity of a high power laser, but instead, one or more such focusing mirror sets are included within the output beam delivery optical components of a high-power laser. For example, one of the inventive focusing mirror sets may replace a conventional lens to direct the output beam of a high power laser system along a desired path and maintain a desired beam diameter.

An improved gas laser is disclosed. The laser has a support tube to support and to maintain the alignment of the optical resonator structure. The gas lasing medium is used within the support tube to maintain the tube at a substantially constant temperature above the ambient. Furthermore, an active temperature controller is disclosed. The temperature controller maintains the gas lasing medium in the support tube at a substantially constant temperature. An active pressure controller is also disclosed. The active pressure controller uses a pressure sensor, an electronic processor, and a motor-driven needle valve to maintain the pressure of the gas lasing medium in the laser within the desired operating pressure range. The laser can also be switched in operation from a continuous mode to a pulsing mode. An active power control system is disclosed wherein the power output of the laser, through an active feedback loop is maintained at the desired level. Because the optical resonator structure is light weight, it can be mounted on a mechanical assembly. The beam is delivered to a desired location by the mechanical assembly. Finally, a distributive lasing system comprising a centralized pump delivering the lasing medium to a plurality of remotely located optical resonator structures is disclosed.

Laser

An improved gas laser is disclosed. The laser has a support tube to support and to maintain the alignment of the optical resonator structure. The gas lasing medium is used within the support tube to maintain the tube at a substantially constant temperature above the ambient. Furthermore, an active temperature controller is disclosed. The temperature controller maintains the gas lasing medium in the support tube at a substantially constant temperature. An active pressure controller is also disclosed. The active pressure controller uses a pressure sensor, an electronic processor, and a motor-driven needle valve to maintain the pressure of the gas lasing medium in the laser within the desired operating pressure range. The laser can also be switched in operation from a continuous mode to a pulsing mode. An active power control system is disclosed wherein the power output of the laser, through an active feedback loop is maintained at the desired level. Because the optical resonator structure is light weight, it can be mounted on a mechanical assembly. The beam is delivered to a desired location by the mechanical assembly. Finally, a distributive lasing system comprising a centralized pump delivering the lasing medium to a plurality of remotely located optical resonator structure is disclosed.

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Los Altos Hills, CA, United States of America

Peter N Allen