EP0371781A2
Expired / Lapsed
EP
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High power laser with focusing mirror sets
Assignee: Coherent Inc
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Filing: 1989-11-29
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Granted: —
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Expires: 2009-11-29
Abstract
Abstract A laser system employs mirror sets (30, 31; 32, 33; 34, 35; 36, 37, 38, 39; 40, 41; 42, 43) having substantially astigmatism-free focusing power sufficient to maintain a desired laser beam diameter, to compensate for thermally-induced distributed lensing. The system is a high power gas laser system having a folded optical cavity with the mirror sets acting as 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. Each corner mirror set includes at least one curved mirror and at least one other mirror at each corner of the folded optical cavity. In one example, each corner mirror set is a spherical mirror (31) and cylindrical mirror (30). In another example, each corner mirror set comprises three nirrors (including three spherical mirrors, or two spherical mirrors and a planar mirror). In another preferred example, the 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 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.
Inventors
- 👤 James L. Hobart
- 👤 Michael W. Sasnett
- 👤 Wayne Sherman Mefferd
- 👤 Peter N. Allen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 08:20
CPC Classifications
B; B23; B23K; B23K26/00; B23K26/02; B23K26/06; B23K26/064; B23K26/0643; B23K26/0665; G; G02; G02B; G02B27/00; G02B27/09; H; H01; H01S; H01S3/00; H01S3/05; H01S3/06; H01S3/07; H01S3/073; H01S3/076; H01S3/08; H01S3/081; H01S3/08072
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
97 words
A laser system, including: an optical resonator cavity enclosing a lasing medium for producing a high power laser beam which propagates along a path, wherein the laser beam propagates along a first portion of the path within the optical resonator cavity, emerges from the cavity, and propagates along a second portion of the path outside the cavity; and a first mirror set positioned along the path, said first set having effective focal length providing sufficient distributed thermal negative lensing compensation to maintain substantially constant laser beam diameter along a region of the path adjacent said first set.
Claim 2
Dependent Claim
97 words
A laser system, including: an optical resonator cavity enclosing a lasing medium for producing a high power laser beam which propagates along a path, wherein the laser beam propagates along a first portion of the path within the optical resonator cavity, emerges from the cavity, and propagates along a second portion of the path outside the cavity; and a first mirror set positioned along the path, said first set having effective focal length providing sufficient distributed thermal negative lensing compensation to maintain substantially constant laser beam diameter along a region of the path adjacent said first set.
Claim 3
Dependent Claim
24 words
The system of Claim 1, wherein each mirror in the first set is shaped and oriented so that the first set is substantially astigmatism-free.
Claim 4
Dependent Claim
17 words
The system of Claim 2, wherein the first set includes a spherical mirror and a cylindrical mirror.
Claim 5
Dependent Claim
46 words
The system of Claim 3, wherein the spherical mirror and the cylindrical mirror have substantially equal radii of curvature, and the effective focal length of the first set is substantially equal to f = √2R/4, where R is the common radius of curvature of the mirrors.
Claim 6
Dependent Claim
59 words
The system of Claim 3, wherein the radius of curvature of the spherical mirror is substantially half in magnitude, and opposite in sign, to the radius of curvature of the cylindrical mirror, and the effective focal length of the first set is substantially equal to f = √2R/2, where R is the radius of curvature of the spherical mirror.
Claim 7
Dependent Claim
12 words
The system of Claim 2, wherein the first set includes three mirrors.
Claim 8
Dependent Claim
45 words
The system of Claim 6, wherein the three mirrors are spherical mirrors having radii of curvature substantially equal to R₁, R₂, and R₃, respectively, where (R₁)⁻¹ + (R₃)⁻¹ = (R₂)⁻¹, and wherein the mirrors have inverse focal length P₁, P₂, and P₂ - P₁, respectively.
Claim 9
Dependent Claim
26 words
The system of Claim 6, wherein two of the three mirrors are spherical mirrors, and the remaining one of the three mirrors is a planar mirror.
Claim 10
Dependent Claim
33 words
The system of Claim 1, wherein the lasing medium is gaseous, and wherein the first mirror set is positioned within the optical resonator cavity and provides compensation for intracavity distributed thermal negative lensing.
Claim 11
Dependent Claim
49 words
The system of Claim 9, also including a second mirror set positioned within the optical resonator cavity at a location spaced from the first set, so that the first and second sets provide periodic intracavity refocusing sufficient to maintain a substantially constant beam diameter throughout the optical resonator cavity.
Claim 12
Dependent Claim
97 words
A laser system, including: an optical resonator cavity enclosing a lasing medium for producing a high power laser beam which propagates along a path, wherein the laser beam propagates along a first portion of the path within the optical resonator cavity, emerges from the cavity, and propagates along a second portion of the path outside the cavity; and a first mirror set positioned along the path, said first set having an effective focal length providing substantially astigmatism-free focusing power sufficient to maintain substantially constant laser beam diameter along a region of the path adjacent said first set.
Claim 13
Dependent Claim
97 words
A laser system, including: an optical resonator cavity enclosing a lasing medium for producing a high power laser beam which propagates along a path, wherein the laser beam propagates along a first portion of the path within the optical resonator cavity, emerges from the cavity, and propagates along a second portion of the path outside the cavity; and a first mirror set positioned along the path, said first set having an effective focal length providing substantially astigmatism-free focusing power sufficient to maintain substantially constant laser beam diameter along a region of the path adjacent said first set.
Claim 14
Dependent Claim
23 words
The system of Claim 11, wherein the first set is positioned along the second portion of the path, and includes two spherical mirrors.
Claim 15
Dependent Claim
51 words
The system of Claim 12, also including a second mirror set positioned outside the optical resonator cavity at a location spaced from the first set, so that the first and second sets provide periodic refocusing sufficient to maintain a substantially constant beam diameter along the second portion of the beam path.
Claim 16
Dependent Claim
101 words
A laser system for producing a high power laser beam, including: an optical resonator cavity including a set of tubes for enclosing a gaseous lasing medium; and a first set of mirrors positioned between a first and a second of the optical resonator cavity tubes, for directing the laser beam to propagate from the first tube to the second tube, said first set of mirrors having a first effective focal length providing sufficient focal power to compensate for distributed thermally-induced lensing in the lasing medium and to maintain substantially constant laser beam diameter within the first tube and the second tube.
Claim 17
Dependent Claim
101 words
A laser system for producing a high power laser beam, including: an optical resonator cavity including a set of tubes for enclosing a gaseous lasing medium; and a first set of mirrors positioned between a first and a second of the optical resonator cavity tubes, for directing the laser beam to propagate from the first tube to the second tube, said first set of mirrors having a first effective focal length providing sufficient focal power to compensate for distributed thermally-induced lensing in the lasing medium and to maintain substantially constant laser beam diameter within the first tube and the second tube.
Claim 18
Dependent Claim
29 words
The system of Claim 14, also including a mirror housing connecting the first tube to the second tube, wherein the first set of mirrors is mounted within the housing.
Claim 19
Dependent Claim
17 words
The system of Claim 14, wherein the first tube and the second tube have substantially equal diameters.
Claim 20
Dependent Claim
13 words
The system of Claim 14, wherein the lasing medium includes carbon dioxide gas.
Claim 21
Dependent Claim
29 words
The system of Claim 14, wherein the mirrors in the first set are shaped and oriented so as to induce substantially no astigmatism in the beam reflected from them.
Claim 22
Dependent Claim
88 words
The system of Claim 14, wherein the optical resonator cavity also includes a third tube, and also including: a second set of mirrors positioned between the second tube and the third tube, for directing the laser beam to propagate from the second tube to the third tube, said second set of mirrors having a second effective focal length equal to or different from the first effective focal length and providing sufficient focal power to maintain substantially constant laser beam diameter within the second tube and the third tube.
Claim 23
Dependent Claim
33 words
The system of Claim 19, wherein the mirrors in the first set and the second set are shaped and oriented so as to induce substantially no astigmatism in the beam reflected from them.
Claim 24
Dependent Claim
76 words
A laser system for producing a high power laser beam, including: an optical resonator cavity enclosing a lasing medium for producing a high power laser beam which emerges from the cavity and propagates along an external beam path outside the cavity; and a first mirror set positioned along the external beam path, said first set having effective focal length selected to provide a desired beam diameter at one or more critical locations along the beam path.
Claim 25
Dependent Claim
76 words
A laser system for producing a high power laser beam, including: an optical resonator cavity enclosing a lasing medium for producing a high power laser beam which emerges from the cavity and propagates along an external beam path outside the cavity; and a first mirror set positioned along the external beam path, said first set having effective focal length selected to provide a desired beam diameter at one or more critical locations along the beam path.
Claim 26
Dependent Claim
28 words
The system of Claim 21, wherein each mirror in the first set is shaped and oriented so that the first set induces substantially no astigmatism in the beam.
Claim 27
Dependent Claim
18 words
The system of Claim 21, wherein only reflective optical elements direct the beam along the external beam path.
Claim 28
Dependent Claim
23 words
The system of Claim 21, also including a set of substantially equal diameter tubes which enclose the beam along the external beam path.
References Cited (Backward Citations)
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