A method for laser keyhole welding is disclosed to weld two pieces together made of a metal alloy. The method independently adjusts power in a focused center beam and power in a concentric focused annular beam. At the termination of a weld, the power of the annular beam (PA) is reduced, motion of the focused beams is stopped, the power of the center beam (Pc) is increased, and the power of both beams is initially ramped down rapidly and then ramped down slowly. Increasing the power of the center beam equalizes the temperature of both pieces prior to solidification and cooling at the termination of the weld. An additional pulse of power may be applied to prevent the formation of defects or to erase any defects.
A method for laser keyhole welding of metal alloys is disclosed. The method independently adjusts power in a focused center beam and power in a concentric focused annular beam. At the termination of a weld, the power in the center beam is initially ramped up and then ramped down, while the power in the annular beam is ramped down. Increasing the power in the center beam enables a controlled and prolonged contraction of the keyhole and melt pool, thereby preventing undesirable cracking.
Apparatus for distance gauging in laser material processing includes a source of laser-radiation, an electrically-conductive focusing assembly, a constant-current source, and a voltmeter. The focusing assembly focuses laser-radiation towards an electrically conductive workpiece being processed. The focusing assembly and the workpiece form a capacitive sensor. The constant current source provides a constant electrical current to the focusing assembly for a constant time. The focusing assembly and the workpiece are separated by a distance that is proportional to a change in voltage measured on the focusing assembly during the constant time.
In a flow cytometer, an objective lens (20) focuses in a common plane (P) an input laser-beam having four different wavelengths. The objective (20) consists of three single-lenses (CL1, CL2, FFL), the two first ones (CL1, CL2) being cylindrical for shaping and reducing the size of the input laser-beam, the third one (FFL) being spherical to focus the reduced-size laser-beam in the common plane (P).
A61B 18/20 - Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
G02B 9/16 - Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or – having three components only arranged + – + all the components being simple
G02B 13/00 - Optical objectives specially designed for the purposes specified below
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