Abstract: According to the invention, a high power diode pumped solid state laser is provided. The laser includes a first and second reflective surfaces which form an optical resonator cavity. A laser medium, particularly a Nd doped laser medium for example: a Nd:YAG, a Nd:YLF, or a Nd:YVO4 crystal is provided within the laser cavity. A fundamental frequency laser beam propagates from the front and back ends of the laser medium. The first reflective surface is highly reflective for fundamental beam. The second reflective surface is at least partially reflective for fundamental beam. The laser medium is end pumped by at least one diode pumping apparatus for example, a laser diode, or diode array, or fiber coupled laser diodes, whose wavelength matches at least one laser medium absorption band. The diode pumping apparatus is located adjacent either the front end or the back end of the laser medium, or both. The optical resonator cavity is configured to provide a laser beam diameter in the laser medium from about 0.

Abstract: According to the invention, a variable power laser beam delivery apparatus is provided. The apparatus includes a generator for delivering a preselected wavelength beam preferably an ultraviolet (UV) beam along a beam path. A dichroic mirror, desirably two (2) or more preferably four (4) dichroic mirrors, for transmitting the preselected UV wavelength beam at P-polarization and for highly reflecting the preselected UV wavelength beam at S-polarization are located along the preselected wavelength beam path delivered from the laser beam generator. A beam polarization rotator is mounted along the beam path of the laser beam provided from the laser beam generator. The beam polarization rotator is located between the laser beam generator and the dichroic mirror along the laser beam path. A beam output is provided by directing the beam transmitted by the dichroic mirror or reflected by the dichroic mirror to a preselected location as the output of the device.

Abstract: According to the invention, a method and apparatus for generating an Nth harmonic frequency beam (N>2) is provided. A laser fundamental resonator cavity generates a preselected fundamental beam. The laser cavity comprises two fundamental beam reflective mirrors, which define the laser cavity, and a lasing medium. A 2nd or 3rd harmonic cavity is at least partially separate from and the fundamental cavity and at least partially overlaps the fundamental cavity. The harmonic cavity is formed between 2nd or 3rd harmonic beam reflective surfaces and contains a 2nd or 3rd harmonic generator, preferably a harmonic nonlinear crystal. The beam from the fundamental cavity is directed into the harmonic cavity to incident on the harmonic nonlinear crystal for converting at least a portion of the fundamental beam to a harmonic beam.

Abstract: A pulsed laser preferably a tunable laser having a narrow band width is provided which has a high conversion efficiency at a high repetition rate. The laser includes a diffraction grating located in the laser's optical cavity. The optical cavity is defined by a mirror and diffraction grating or two mirrors with a diffraction grating therebetween. A tunable laser material is located within the optical cavity between the mirror and the diffraction grating. Desirably the diffraction grating is movably mounted within the optical cavity so that a beam of a presected wave length diffracted by the grating can be directed across the laser material. Optionally where two mirrors define the optical cavity, one of the mirrors or the grating or both can be movably mounted within the optical cavity. Preferable the movable grating and the movable mirror are rotatably mounted.

Abstract: A fourth harmonic frequency generating method and apparatus is provided. The system includes within the optical cavity an active laser medium, a second harmonic generator for generating second harmonic frequency of the fundamental frequency emitted by the laser. The fundamental beam is directed to a second harmonic generation crystal where a portion of the fundamental beam is converted to a second harmonic beam. Both the second harmonic and unconverted fundamental beams are directed back across the second harmonic generator by reflective surfaces for a second pass prior to any conversion of second harmonic beam to a higher harmonic beam. Preferably the second harmonic and fundamental beams are reflected by one of the laser cavity reflective surfaces for the second pass. Optionally, there can be separate reflective surfaces to reflect each of the fundamental and second harmonic beams.

Abstract: According to the invention, a method and an apparatus for producing a laser beam having a preselected output frequency which has a longer wavelength than does the fundamental beam of the lasing medium is provided. In one aspect of the invention a laser resonator cavity is formed between two reflective surfaces such as mirrors. A lasing medium is located within the laser resonator cavity for generating a fundamental wavelength beam. An optical parametric oscillator cavity is also formed between one of the laser resonator cavity reflective surfaces and a third reflective surface for example a mirror. A nonlinear crystal cut for phase matching conditions for the fundamental beam wavelength and the output beam wavelength is located in optical communication with the first and the third reflective surfaces. The optical axis of the laser resonator and the optical parametric oscillator are at least partially separate and partially overlap.

Abstract: A fourth harmonic frequency generating method and apparatus is provided. The system includes within the optical cavity an active laser medium, a second harmonic generator for generating second harmonic frequency of the fundamental frequency emitted by the laser. The fundamental beam is directed to a second harmonic generation crystal where a portion of the fundamental beam is converted to a second harmonic beam. Both the second harmonic and unconverted fundamental beams are directed back across the second harmonic generator by reflective surfaces for a second pass prior to any conversion of second harmonic beam to a higher harmonic beam. Preferably the second harmonic and fundamental beams are reflected by one of the laser cavity reflective surfaces for the second pass. Optionally, there can be separate reflective surfaces to reflect each of the fundamental and second harmonic beams.

Abstract: A method and apparatus for forming machine readable code on an optical information storage disk is provided. The code is formed by periodically pulsing a laser along a path and directing the laser pulse to a preselected point. The laser pulse is adjusted to a preselected spot length and width. A prerecorded optical disk is placed in the path of said laser pulse at said preselected point. The disk is then selectively moved relative to the laser upon each pulse of the laser so that a machine readable mark is made at a different location in the program area of optical information storage disk upon each laser pulse to form a preselected machine readable code.

Abstract: Third harmonic generated from intra-cavity frequency tripled resonator is disclosed in which type II phase matching crystal is used as the tripler. Type I phase matching is used for second harmonic generation. The resonator efficiently converts the fundamental laser frequency to its third harmonic laser beam. The laser is highly efficient with high third harmonic output stability. Overall conversion efficiency exceeds 25% and preferably is 50% or higher.