Laser Beam Shaping for Pitchfork Profile

Apparatus, systems, methods and devices of an optical system for producing a laser beam having pitchfork profile. The system includes a laser source providing an input Gaussian beam, refractive optical lenses for converting the input Gaussian bean into a super Gaussian beam. A focusing lens focuses the super Gaussian beam, where by diffraction effect after the focusing lens, the beam profile near a focal spot is a pitchfork shaped beam. In an embodiment, the refractive optical lenses are plano-aspheric lenses. Tne pitchfork shaped beam is produced by passing the input Gaussian beam through plano-aspheric lenses to produce the super Gaussian, output beam, and passing the super Gaussian output beam through a focusing lens to produce the output beam having a pitchfork profile. In an embodiment, the pitchfork shaped beam is applied to laser microvias drilling in, electronic packaging to produce residue free holes at reduced production cost with simplified procedures

Laser beam shaping

Práce krátce popisuje typy vln a svazků. Podrobněji jsou popsány parametry a vlastnosti Gaussova svazku, který je asi nejvíce využíván v atmosférických optických spojích. Hlavním cílem práce je prostudování možností tvarování laserového svazku a to hlavně na svazek Top hat. Jsou zde popsány důvody, proč je vhodné laserový svazek pro optické komunikace tvarovat, a nejčastěji využívané metody pro tvarování laserového svazku. Navržené postupy tvarování svazků jsou experimentálně ověřeny a vlastnosti svazků tvarovaných jednotlivými metodami jsou mezi sebou porovnány.Thesis describes shortly types of waves and beams. Gaussian beam properties and parameters are described in more details, Gaussian beam is the most used in atmospheric optical links. The main goal of work is studying of possibilities of laser beam shaping, mainly the beam Top hat. In this project reasons why is suitable to shape laser beam for optical communications and the most used methods for shaping of laser beam are described. The suggested processes of beams shaping are experimentally verified and properties of beams shaped of single methods are compared with each other.

Laser beam shaping for enhanced Zero-Group Velocity Lamb modes generation

Optimization of Lamb modes induced by laser can be achieved by adjusting the spatial source distribution to the mode wavelength ($\lambda$). The excitability of Zero-Group Velocity (ZGV) resonances in isotropic plates is investigated both theoretically and experimentally for axially symmetric sources. Optimal parameters and amplitude gains are derived analytically for spot and annular sources of either Gaussian or rectangular energy profiles. For a Gaussian spot source, the optimal radius is found to be $\lambda_{ZGV}/\pi$. Annular sources increase the amplitude by at least a factor of 3 compared to the optimal Gaussian source. Rectangular energy profiles provide higher gain than Gaussian ones. These predictions are confirmed by semi-analytical simulation of the thermoelastic generation of Lamb waves, including the effect of material attenuation. Experimentally, Gaussian ring sources of controlled width and radius are produced with an axicon-lens system. Measured optimal geometric parameters obtained for Gaussian and annular beams are in good agreement with theoretical predictions. A ZGV resonance amplification factor of 2.1 is obtained with the Gaussian ring. Such source should facilitate the inspection of highly attenuating plates made of low ablation threshold materials like composites.Comment: 11 pages, 12 figure

Refractive femtosecond laser beam shaping for two-photon polymerization

Three dimensional microstructure fabrication by two-photon polymerization is an established technique that normally uses single beam serial writing. Recently the use of a micro-optical element, to give multipoint beam delivery, was reported to give a degree of parallel processing. The authors describe an alternative approach to parallel processing using an axicon lens. This is a refractive element that, in combination with a high power microscope objective, efficiently transforms the laser beam from a Gaussian spot to an annulus. The authors demonstrate that the beam can polymerize a three dimensional shape, with nanoscale resolution. The use of more sophisticated refractive beam shaping is also discussed. (c) 2007 American Institute of Physics. (DOI:10.1063/1.2713787

Diffractive optical elements for pitchfork beam shaping

A set of laser beam shaping optics is designed by an iterative method using an adaptive additive algorithm to transform a Gaussian beam into a pitchfork beam. Two diffractive optical elements are designed based on Fresnel diffraction to reduce the amount of energy in the first-order diffraction ring and to increase the depth of focus for the optical system. These two beam properties are found to depend on the diameter of the desired beam and the Airy disk diameter. If the diameter of the desired beam is large, then the optical system yields better results in achieving the above-mentioned two beam properties. The performance of the diffractive optical elements is compared to a previous laser beam shaping system designed by the ray-tracing technique. A pinhole scanning power meter is used to measure the laser irradiance profile at the focal plane to verify the existence of the pitchfork beam. The irradiance profile measurement shows that diffractive optical elements allow better control for reducing the amount of energy in the diffraction side lobes

Imaging-based amplitude laser beam shaping for material processing by 2D reflectivity tuning of a spatial light modulator

We have demonstrated an imaging-based amplitude laser-beam-shaping technique for material processing by 2D reflectivity tuning of a spatial light modulator. Intensity masks with 256 gray levels were designed to shape the input laser beam in the outline profile and inside intensity distribution. Squared and circular flattop beam shapes were obtained at the diffractive near-field and then reconstructed at an image plane of a