Focusing of Multimode Laser Beams with Variable Beam Parameters

Iffländer, Reinhard; Weber, Horst

doi:10.1080/713822056

Cited by 23 publications

(3 citation statements)

References 6 publications

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“…Because the propagation path is very shot, the couple of mode can be neglected and kJ = 0 . Then I = (p,G,)2 + : (10) p1 R In experiment, high-power CO2 laser beam is measured by Laserscope UFF100 and its measuring method is illustrated in Fig.1. Laser beam is irradiating a hollow needle which is amounted in the rotator.…”

Section: The Propagation Ofblending Mode Laser Beammentioning

confidence: 99%

High-power CO 2 blending-mode laser beam propagation and focus due to phase shifts

et al. 1998

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In laser materials processing , the transverse intensity distribution of focus affects processing quality greatly. In this paper, phase shifts is used to analyze high-power CO2 laser beam propagation and focus, especially the change of transverse intensity distribution along beam propagation path. From theory, the phase shifts of high-power blending laser beam determines the transverse intensity distribution. It is also found that ifthere contains odd mode in blending laser beam, the asymmetry of laser beam is broken. Moreover the high-power laser beam focus and unfocused diagnosis system UFF100 is used to test the beam transverse intensity distribution. Theory is accord with measurement. According to the theory, two optical transformation system is designed to attain the minimum intensity changes.Keywords: blending mode laser beam, phase shift, high-power CO2 laser, laser materials processing Generally the mode ofthe low-power CO2 laser beam is fundamental Gaussian type. And its transverse intensity distribution is Gaussian type, and remains same along its propagation path. However, for high-power CO2 laser, its output mode is not Gaussian, but the superposition of some modes of beam, named after blending mode laser beam. And the characters of highpower laser beam propagation and focus are different from the low-power's. With the development of laser materials processing, the high-power laser is used widely in industries. So it is important to study the propagation and focus of highpower laser beam to promote it's use in industry.For a long time, people have been concentrated on the research of the single fundamental laser mode, and objectively neglect the function of laser phase shift. This is partly due to the fact that the phase shift of fundamental Gaussian laser beam doesn't affect the transverse intensity distribution. As concerns multimode beam, M2 (beam quality factor)"2 is usually adopted. Then the multimode beam can be treated as fundamental Gaussian beam. Although this treatment can result in many conveniences, the fact that the transverse intensity distribution of multimode beam varies along its propagation is usually neglected. In addition q parameter and ABCD laws can not be used to analyze the focus ofmultimode laser beams3.In this paper transverse intensity distribution and focus characters of blending mode laser beams are analyzed by phase shifts. The regularity of change of laser beam transverse intensity along its propagation path and the focus formule of blending mode laser beams are obtained. And the influence of the odd mode upon transverse intensity distribution is studied. The experiment is accord with theory . Atlast, in order to attain the minimum transverse intensity changes of focus, two optical transformation systems are designed according to phase shifts.

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Section: The Propagation Ofblending Mode Laser Beammentioning

confidence: 99%

High-power CO 2 blending-mode laser beam propagation and focus due to phase shifts

et al. 1998

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“…By this method, it is convenient to obtain a focal spot of constant size [14] (e .g . for injection in a fibre or cutting or welding thin materials) if the beam power has to vary during processing .…”

Section: 2 2 Confocal Symmetric Resonatormentioning

confidence: 99%

A Single Rod Stable Resonator of Constant Multimode Divergence over a Wide Power Range

Maillotte

Pieralli

Tribillon

1991

Journal of Modern Optics

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“…4 -Change in spot radius and shift in effective focal length at several power levels for a 127 mm plano convex lens.…”

Section: Distance From Lens (Mm)mentioning

confidence: 99%

Spot size and effective focal length measurements for a fast axial flow CO{sub 2} laser

Steele

Fuerschbach²,

MacCallum

1997

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Focusing of Multimode Laser Beams with Variable Beam Parameters

Cited by 23 publications

References 6 publications

High-power CO 2 blending-mode laser beam propagation and focus due to phase shifts

High-power CO 2 blending-mode laser beam propagation and focus due to phase shifts

A Single Rod Stable Resonator of Constant Multimode Divergence over a Wide Power Range

Spot size and effective focal length measurements for a fast axial flow CO{sub 2} laser

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