&lt;title&gt;Thermally induced distortion of a high-average-power laser system by an optical transport system&lt;/title&gt;

Chow, Robert H.; Ault, L; Taylor, John R.; Jedlovec, D. R.

doi:10.1117/12.369190

Cited by 3 publications

(5 citation statements)

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“…The TIA on the wedge-reflective surface was smaller than the detection threshold of our apparatus because the expansion coefficient was more than 20 times smaller than ∂n∕∂T. 55,72 In these conditions, the maximal TIA magnitudes were smaller than 10 −3 waves for the systems 11 and 12 made of Suprasil 3002 with a 21 mm total axial thickness at 400 W laser power. The systems 10, 15, 16, and 17 that yielded the combination of 14 mm N-BK7HT and 11 mm Suprasil 3002 demonstrated about 10 −2 waves total TIA strength.…”

Section: Experimental Setup and Methodologymentioning

confidence: 99%

“…In this case, the speed-power-pressure-FPP correlation is lost and process failure occurs. Contaminations of reflective surfaces yield considerably smaller beam deterioration 72 because ∂n∕∂T is irrelevant to thermal lensing.…”

Section: Paraxial Focus the Best Focal Spot And Focal Point Positiomentioning

confidence: 99%

“…However, knowing the actual LID shape in an interaction region is desired. None of the above parameters, including the aberration strength in the units of Seidel and Zernike 57,72 factors, provide this knowledge. It is clear that an LID shape distorted by aberration critically determines the laser cutting performance.…”

Section: Laser Beam Shape Position and Distortionmentioning

confidence: 99%

“…56,77,79 There is also the more delicate aspect of thermal lensing: although a thermal lens has relatively small optical power, it is strongly aberrated. [55][56][57]72 Chow et al 72 estimated the wavefront distortion as a few hundredths of the wavelength per kilowatt per 1 cm length for state-of-the-art fused silica plano-plano windows. The same measurements for a commercial fourlens transport system 57 yield a wavefront error up to several wavelengths per kilowatt per total thickness of anti-reflection coated glass.…”

Section: Paraxial Focus the Best Focal Spot And Focal Point Positiomentioning

confidence: 99%

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Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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Abstract. We analyzed the effects of the focal point aberrational offset in optical transport systems for highpower lasers. Transverse and near-axial laser intensity distribution transformations in the presence of both positive and negative spherical aberrations were numerically calculated and experimentally demonstrated for different strengths. We show that spherical aberration yields considerable asymmetry of the focused beam's caustic. Several optical transport systems with identical optical parameters (excluding the noncorrected axial beam spherical aberration) were designed. We examined the effects of the laser intensity profiles produced by these systems on the quality of oxygen-assisted laser cutting of medium-section mild steel. We show that high-quality cuts can be obtained for different shapes of laser intensity distribution. However, the greater the refocusing magnitude introduced by the spherical aberration correction, the more precisely the focal point position must be maintained during the laser cutting process. © The Authors. Published by SPIE under a Creative Commons 1 Introduction Laser cutting of metals and alloys is one of the most commercially valuable laser technology processes. Originating from basic research on laser-matter interaction, 1 the field has significantly developed, now offering a large arsenal of state-of-the-art techniques.2-5 Omitting the energy and resource efficiency issues, 6 the performance of laser cutting can be captured by only two output parameters. These are the cutting speed and kerf quality. Thus, laser cutting optimization reduces to achieving the maximal cutting speed with the best kerf quality. As far as the material separation is concerned, 7 the speed can be dramatically increased. On the other hand, the cutting quality depends on many parameters. The most important and frequently discussed are the kerf geometry (accuracy, width, and taper), the surface quality (cut-edge roughness, striations morphology, and dross and burr inclusions), and the mechanical and metallurgical properties (hardness and strength, heat-affected zone, and oxide layer). 8 The number of parameters dramatically affecting the cutting quality ranges from 25 9 to 75. 4,5 These are nearly evenly divided between the workpiece properties, assist gas parameters, laser machine, and laser beam characteristics. Input-output parameters relationships are mostly nonlinear and exhibit strong interdependence. In this regard, maximal precision is provided by the studies that focus on only one input-output parameter pair. Yet, this "one parameter at one time" approach does not provide complete information on the process as a whole.

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Section: Experimental Setup and Methodologymentioning

confidence: 99%

Section: Paraxial Focus the Best Focal Spot And Focal Point Positiomentioning

confidence: 99%

Section: Laser Beam Shape Position and Distortionmentioning

confidence: 99%

Section: Paraxial Focus the Best Focal Spot And Focal Point Positiomentioning

confidence: 99%

See 2 more Smart Citations

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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“…There are two established ways to get knowledge of thermal distortions; one employs a numerical model to calculate the thermal effect and the other uses a wavefront sensor to measure it directly. The most commonly adopted numerical method which is based on finite element analysis (FEA) simulates the working conditions of the amplifier slabs and calculates its thermal distortion [2]. However, for an accurate calculation we need to carefully consider factors such as the pumping uniformity, the geometric construction, the cooling gas characteristics, thermal characteristics of the laser medium, as well as the heat transfer coefficient.…”

Section: Introductionmentioning

confidence: 99%

Measurement of thermal distortion in high power laser glass elements using ptychography

et al. 2015

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The heat generated in the cavity of the high power slab laser amplifier makes it less stable and induces a thermal-lens effect which adds a spherical phase distribution to the wave-front of the laser beam. The commonly employed interferometry or Hartmann-Shack sensor based measurements are unable to provide an accurate measurement of the thermal distortion of the gain medium. It is demonstrated that this problem can be solved using a scheme based on ptychographical iterative engine. The complex transmittance of the outgoing laser is obtained by the proposed scheme while the amplifier is set at its turned off and turned on state and the thermal distortion caused by the pumping light is calculated from the obtained transmittance.

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计算光学成像在惯性约束聚变中的应用及技术进展

Chang Chengcheng,

Pan Liangze,

Xu Yingming

et al. 2023

光学学报

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<title>Thermally induced distortion of a high-average-power laser system by an optical transport system</title>

Cited by 3 publications

References 0 publications

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Measurement of thermal distortion in high power laser glass elements using ptychography

计算光学成像在惯性约束聚变中的应用及技术进展

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