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US 5,025,446 AGranted
Intra-cavity beam relay for optical harmonic generation
AssigneeLaserscope
InventorDirk J. Kuizenga
Life of this patent
Estimating the term…
Abstract
Intra-cavity generation of second and higher harmonic frequency laser radiation is improved by inclusion of a lens or multiple-lens arrangement that focuses electromagnetic radiation emitted by the active laser medium on a wavelength conversion means within the cavity or on removal means to remove the second or higher harmonic radiation from the cavity.
Claims24
A laser resonator system that comprises:
- a first and second mirror forming an optical resonator, where said first and second mirrors have radii of curvature R1 and R2 respectively;
- a laser medium positioned within said optical resonator wherein said laser medium provides gain to a beam of electromagnetic radiation at a certain wavelength, referred to as the fundamental wavelength, said beam at the fundamental wavelength having a diameter D.sub.2 after it passes through said laser medium;
- an optical element positioned within said optical resonator said optical element being substantially transparent to said beam of electromagnetic radiation at the fundamental wavelength;
- a means for imaging, positioned between said laser medium and said optical element within said optical resonator, that accepts said beam of radiation with diameter D.sub.2 from said laser medium and images said beam with diameter D.sub.2 to a beam of radiation with diameter d.sub.1 in said optical element such that the ratio of diameters d.sub.2 /D.sub.1 depends only on the properties of said means of imaging and said ratio of diameters D.sub.2 /D.sub.1 is independent of the position and radii of curvature of said first and second mirrors and is independent of any focusing properties of said laser medium or said optical element.
1 more element
A laser resonator system that comprises:
- a first resonator mirror and a second resonator mirror, said first resonator mirror and second resonator mirror being highly reflecting at a fundamental wavelength, said first resonator mirror and said second resonator mirror forming an optical resonator at said fundamental wavelength and said first resonator mirror and said second resonator mirror having radii of curvature R.sub.1 and R.sub.2 respectively;
- a solid state laser rod positioned within said optical resonator;
- an optical source for pumping said laser rod to excite said laser rod and provide gain to a beam of electromagnetic radiation at said fundamental wavelength, where said optical source for pumping heats said laser rod thereby inducing thermal focusing in said laser rod;
- a nonlinear optical crystal positioned within said optical resonator for generating a second harmonic wavelength;
- an optical relay consisting of a first and a second relay mirror with radii of curvature RR.sub.1 and RR.sub.2, respectively, said first and second relay mirrors being positioned between said laser rod and said nonlinear crystal such that the first relay mirror with radius RR.sub.1 is a distance d.sub.1 from said nonlinear crystal, the second relay mirror with radius RR.sub.2 is a distance RR.sub.1 /2+RR.sub.2 /2 from the first relay mirror, and where a face of said laser medium is a distance d.sub.2 from the second relay mirror and where said distances d.sub.1 and d.sub.2 are related by
- m d.sub.1 +d.sub.2 /m=RR.sub.1 /2+RR.sub.2 /2,
- where m=RR.sub.2 /RR.sub.1 and is the magnification of said optical relay;
- an electromagnetic beam of radiation with diameter D.sub.1 in said nonlinear crystal and with diameter D.sub.2 in said laser rod and where the ratio of the diameters D.sub.2 /D.sub.1 is completely determined by the properties of said optical relay such that D.sub.2 /D.sub.1 =m=RR.sub.2 /RR.sub.1 and where said ratio of diameters D.sub.2 /D.sub.1 is independent of the radii of curvature R.sub.1 and R.sub.2 of said first and second resonator mirrors, and is independent of said thermal focusing in said laser rod;
- means for output coupling the second harmonic wavelength comprising said first relay mirror, said first relay mirror being highly reflecting at said fundamental wavelength and highly transmitting at the second harmonic wavelength;
- wherein the maximum output power at the second harmonic wavelength is obtained by choosing values of the radii of curvature of said first and said second relay mirrors such that said ratio of beam diameters D.sub.2 /D.sub.1 will maximize the second harmonic output power for said laser rod and said nonlinear crystal.
7 more elements
A laser resonator system that comprises:
- a first resonator mirror and a second resonator mirror, said first resonator mirror and second resonator mirror being highly reflecting at a fundamental wavelength, said first resonator mirror and said second resonator mirror forming an optical resonator at said fundamental wavelength and said first resonator mirror and said second resonator mirror having radii of curvature R.sub.1 and R.sub.2 respectively;
- a solid state laser rod positioned within said optical resonator;
- an optical source for pumping said laser rod to excite said laser rod and provide gain to a beam of electromagnetic radiation at the fundamental wavelength, where said optical source of pumping heats said laser rod thereby inducing thermal focusing in said laser rod;
- a nonlinear optical crystal positioned within said optical resonator for generating a second harmonic wavelength;
- an optical relay consisting of a first and a second relay mirror with radii of curvature RR.sub.1 and RR.sub.2, respectively, said first and second relay mirrors being positioned between said laser rod and said nonlinear crystal such that the first relay mirror with radius RR.sub.1 is a distance d.sub.1 from said nonlinear crystal, the second relay mirror with radius Rr.sub.2 is a distance RR.sub.1 /2+RR.sub.2 /2 from the first relay mirror, and where a face of said laser medium is a distance d.sub.2 from the second relay mirror and where said distances d.sub.1 and d.sub.2 are related by
- m d.sub.1 +d.sub.2 /m=RR.sub.1 /2+RR.sub.2 /2,
- where m=RR.sub.2 and is the magnification of said optical relay;
- an electromagnetic beam of radiation with diameter D.sub.1 in said nonlinear crystal and with diameter D.sub.2 in said laser rod and where the ratio of the diameters D.sub.2 /D.sub.1 is completely determined by the properties of said optical relay such that D.sub.2 /D.sub.1 =m=RR.sub.2 /RR.sub.1 and where said ratio of diameters D.sub.2 /D.sub.1 is independent of the radii of curvature R.sub.1 and R.sub.2 of said first and second resonator mirrors, and is independent of said thermal focusing in said laser rod;
- and
- means for output coupling the second harmonic wavelength provided by said second relay mirror wherein said first relay mirror is highly reflecting at both the fundamental wavelength and the second harmonic wavelength, and said second relay mirror is highly reflecting at the fundamental wavelength and highly transmitting at the second harmonic wavelength;
- wherein maximum output power is obtained at the second harmonic wavelength by choosing values of the radii of curvature of said first and said second relay mirrors such that said ratio of beam diameters D.sub.2 /D.sub.1 will maximize the second harmonic output power for said laser rod and said nonlinear crystal.
8 more elements
Dependencies are inferred from the claim text.