13 March 2007 Compensator optics to improve the stability of laser beam delivery systems that utilize beam shaping technology
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Abstract
Focused and directed laser beams are commonly used for a variety of processes, such as drilling of blind, through and microvias, cutting, laser imaging, dicing of substrates and modification or customization of integrated circuits. Such processes have become very complex, often involving the concurrent or sequential use of single or multiple lasers, such as UV DPSS and IR CO2 lasers. The general object of such processes is to reliably direct, focus and concentrate the energy of the laser at a desired spot or image plane on the surface of object being processed. Several recurring problems of conventional laser systems directly effect how the laser process will perform. These problems are often referred to as, beam wobble or pointing instability which is a radial deviation from an optimum centerline and is often related to variations in pulse energy of the laser beam, which is also termed as pumping jitter. Another problem is referred to as thermal drift, which again causes the axis of the laser beam to drift from an optimum centerline. Thermal drift is generally due to changes in the parameters of the laser, such as duty cycle, heating during operation and changes in power level. Thermal drift tends to remain parallel to the optimum center line, but drifts laterally. These two issues greatly effect how well beam shaping optics, such as aspheric flat top generators or diffractive beams shaping optics perform. When illuminated poorly the beam shaping optics will produce undesirable effects such as hotspots. This paper will describe how pointing instability and thermal beam drift can be compensated to ensure that downstream beam shapers are illuminated optimally to produce the required beam profile.
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Todd Lizotte, Todd Lizotte, } "Compensator optics to improve the stability of laser beam delivery systems that utilize beam shaping technology", Proc. SPIE 6458, Photon Processing in Microelectronics and Photonics VI, 64580Y (13 March 2007); doi: 10.1117/12.702295; https://doi.org/10.1117/12.702295
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