Focal point images of phase-shifted laser beam using femtosecond optical polarigraphy

2002 ◽  
Author(s):  
Aritsune Nagamura ◽  
Hiroki Shibata ◽  
Koichi Toyoda
Keyword(s):  
Laser Beam ◽  
Focal Point

Experimental Determination of the Focal Length of a Laser Beam from the Output Nozzle of a Laser Cutting Head

2017 ◽  
Vol 756 ◽  
pp. 71-79
Author(s):  
Martin Lachman ◽  
Jiří Šafka
Keyword(s):  
Laser Beam ◽  
Laser Cutting ◽  
Focal Point ◽  
Focal Length ◽  
Cutting Speed ◽  
Vital Role ◽  
Fibre Laser ◽  
Cutting Head ◽  
Industrial Operations

Laser technologies are considered to be unconventional technologies. Laser cutting is one of the most popular industrial operations that use a laser beam. Fibre lasers are most commonly used for cutting metallic materials. The aim of this paper is to experimentally demonstrate a procedure for determining the focal length of a laser beam from the output of the cutting head of a JK400FL fibre laser. Along with other factors, the correct position of the focal point of a laser beam cutting materials, plays a vital role in the quality of the cut and also in determining the cutting speed. It is possible to use a higher cutting speed of the laser machine, without compromising the quality of the cut.

scholarly journals Multi-objective optimization and analysis for laser beam cutting of stainless steel (SS304) using hybrid statistical tools GA-RSM

2021 ◽  
Vol 1201 (1) ◽  
pp. 012030
Author(s):  
A D Tura ◽  
H B Mamo ◽  
D G Desisa
Keyword(s):  
Genetic Algorithm ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Laser Beam ◽  
Response Surface ◽  
Focal Point ◽  
Cutting Speed ◽  
Machining Parameters ◽  
Multi Objective ◽  
The Impact

Abstract A laser beam machine is a non-traditional manufacturing technique that uses thermal energy to cut nearly all types of materials. The quality of laser cutting is significantly affected by process parameters. The purpose of this study is to use a genetic algorithm (GA) in conjunction with response surface approaches to improve surface roughness in laser beam cutting CO2 with a continuous wave of SS 304 stainless steel. The effects of the machining parameters, such as cutting speed, nitrogen gas pressure, and focal point location, were investigated quantitatively and optimized. The tests were carried out using the Taguchi L9 orthogonal mesh approach. Analysis of variance, main effect plots, and 3D surface plots were used to evaluate the impact of cutting settings on surface roughness. A multi-objective genetic algorithm in MATLAB was used to achieve a minimum surface roughness of 0.93746 μm, with the input parameters being 2028.712 mm/m cutting speed, 11.389 bar nitrogen pressure, and a focal point position of - 2.499 mm. The optimum results of each method were compared, as the results the response surface approach is less promising than the genetic algorithm method.

scholarly journals Two-photon controlled sol–gel condensation for the microfabrication of silica based microstructures. The role of photoacids and photobases

RSC Advances ◽  
2017 ◽  
Vol 7 (74) ◽  
pp. 46615-46620 ◽  
Author(s):  
J. Kustra ◽  
E. Martin ◽  
D. Chateau ◽  
F. Lerouge ◽  
C. Monnereau ◽  
...  
Keyword(s):  
Laser Beam ◽  
Focal Point ◽  
Sol Gel ◽  
Ph Changes ◽  
Two Photon ◽  
Photon Excitation ◽  
Sol Gel Process ◽  
And Control ◽  
Two Photon Excitation

Two-photon excitation of photobases is used to induce pH changes and control the condensation step of the sol–gel process at the focal point of a laser beam in a confocal configuration.

scholarly journals A semi-automated procedure for the emitter-receiver geometry characterization of motor-controlled lidars

2021 ◽  
Author(s):  
Marco Di Paolantonio ◽  
Davide Dionisi ◽  
Gian Luigi Liberti
Keyword(s):  
Laser Beam ◽  
Focal Point ◽  
Geometric Model ◽  
Quality Data ◽  
Signal Acquisition ◽  
Mapping Procedure ◽  
Alignment Procedure ◽  
Multi Wavelength ◽  
Design Characteristics

Abstract. To correctly understand and interpret lidar acquired signals and to provide high quality data, the characterization of the lidar transmitter-receiver geometry is required. For example, being fundamental to correctly align lidar systems, this characterization is useful to improve the efficiency of the alignment procedure. In addition, some applications (e.g. air quality monitoring) need to quantitatively interpret the observations even in the range where the overlap between the telescope field of view and the laser beam is incomplete. This is generally accomplished by correcting for the overlap function. Within the frame of Lidar based networks (e.g. ACTRIS/EARLINET) there is a need to define standardized approaches to deal with lidar geometry issues. The multi-wavelength multi-telescope Rayleigh-Mie-Raman “9-eyes” system in Rome Tor Vergata, part of ACTRIS/EARLINET, has the capability to change through computer-controlled servomotors, the orientation of the laser beams and the 3D position of the diaphragm of the receiving optical system around the focal point of the telescopes. Taking advantage of these instrumental design characteristics an original approach to characterize the dependency of the acquired signal from the system relative transmitter-receiver geometry (the mapping procedure) was developed. The procedure consists in a set of programs controlling both the signal acquisition as well as the motor movements. The approach includes solutions to account for atmospheric and laser power variability likely to occur during the mapping sessions. The paper describes in detail the developed procedure and applications such as the optimization of the telescope/beam alignment and the estimation of the overlap function. The results of the mapping applied to a single combination of telescope-laser beam are shown and discussed. The effectiveness of the mapping-based alignment was successfully verified by comparing the whole signal profile and the outcome of the telecover test, adopted in EARLINET, for a manual and a mapping-based alignment. A significant signal increase and lowering of the full overlap height (from 1500 m to less than 1000 m) was found. The overlap function was estimated down to 200 m and compared against the one obtained from a geometric model. The developed procedure allowed also estimating the absolute and relative tilt of the laser beam. The mapping approach, even in simplified versions, can be adapted to other lidars to characterize and align systems with non-motorized receiving geometry.

Double closed-loop control of the focal point position in laser beam welding

2003 ◽  
Vol 14 (11) ◽  
pp. 1938-1943 ◽  
Author(s):  
Zhang Xudong ◽  
Chen Wuzhu ◽  
Jiang Ping ◽  
Liu Chun ◽  
Guo Jing
Keyword(s):  
Laser Beam ◽  
Closed Loop ◽  
Focal Point ◽  
Laser Beam Welding ◽  
Closed Loop Control ◽  
Loop Control ◽  
Point Position

scholarly journals Mechanical and Metallurgical Characterisation of CO2 Laser Beam Welding AISI 4130 and AISI 310 Sheets of Steel

2021 ◽  
Vol 71 (2) ◽  
pp. 19-30
Author(s):  
Bijivemula Narayana Reddy ◽  
Pothur Hema ◽  
Chevireddy Eswara Reddy
Keyword(s):  
Laser Beam ◽  
Focal Point ◽  
Focal Length ◽  
Weld Zone ◽  
Laser Beam Welding ◽  
Processing Parameters ◽  
Fusion Welding ◽  
Work Piece ◽  
Steel Aisi ◽  
Aisi 4130

Abstract Laser Beam Welding (LBW) is the fusion welding technique in which coalescence is produced by heating the work piece by impingement of concentrated beam of laser light. In this paper a full depth butt welding of alloy steel AISI 4130 and stainless steel AISI 310 of 2 mm thickness by using CO2 Laser Beam Welding machine has been performed. Design of experiment is done by using Taguchi method L25 i.e. level 5 by considering process parameters i.e. power, welding speed, beam angle, focal point position and focal length. The experimental output results that are measured for the mechanical properties of welds (Ultimate Tensile Strength and Hardness). The analysis was carried out to explain the influence of the LBW processing parameters values on the mechanical and microstructural aspects. The weld Joint is analysed by Optical Microstructure and Scanning Electron Microscopy (SEM). The Energy Dispersive X-Ray Analysis (EDAX) was carried out to determinate the chemical composition of the weld zone.

scholarly journals An Analysis of the Mechanical and Metallurgical Behavior of AISI 4130 Steel After Co2 Laser Beam Welding Process

2020 ◽  
Vol 9 (4) ◽  
pp. 2230-2234
Keyword(s):  
Laser Beam ◽  
Weld Joint ◽  
Focal Point ◽  
Focal Length ◽  
Research Work ◽  
Weld Zone ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Bead Width ◽  
Aisi 4130

Alloy metal has received special attention in the aerospace and defense areas. The AISI 4130 alloy steel had been also considered, since it is applied in landing gears, small aircrafts engine cradles, and besides general industries. The Laser Beam Welding of high strength metals obtained small Weld Zone and better quality with good appearance. In this research work, a Laser Beam Welding (LBW) is used to weld AISI 4130. The experiments are conducted accordingly combination of Taguchi L25 based 5 levels of Laser Power, Speed, Angle, Focal Length and Focal Point Position. The AISI 4130 weld joint Bead Width and tensile strength are measured and analysed by ANOVA. Microstructure and SEM with EDAX are using to analysis the AISI 4130 weld joint.

A semi-automated procedure for the alignment and the overlap function estimation of stepper motor controlled lidars

2021 ◽  
Author(s):  
Marco Di Paolantonio ◽  
Gian Luigi Liberti ◽  
Davide Dionisi
Keyword(s):  
Laser Beam ◽  
Optical System ◽  
Atmospheric Aerosols ◽  
Focal Point ◽  
Geometric Model ◽  
Function Estimation ◽  
Before And After ◽  
Multi Wavelength ◽  
Stepper Motors ◽  
Automated Tools

<p><span>Lidar observations are fundamental to quantitatively study the vertical distribution of atmospheric aerosols. In particular, some applications (e.g. air quality monitoring) need the description of the particulate from the ground up to the top of the atmospheric boundary layer. To correctly interpret the received lidar signal in the lowermost range, where the overlap between the telescope field of view and the laser beam is incomplete, an optimized alignment and the knowledge of the overlap function are required. </span></p><p><span>The multi-wavelength multi-telescope RMR “9-eyes” system in Rome Tor Vergata </span>[1]<span> has the capability to move, through electronically controlled stepper motors, the orientation of the laser beams and the 3D position of the diaphragm of the receiving optical system around the focal point of the telescopes. Taking advantage of these instrumental characteristics, a set of semi-automated tools (the </span><span><em>mapping </em></span><span>procedure</span><span>) was developed for the optimization of the telescope/beam alignment and the estimation of the overlap function.</span></p><p><span>In this study the results of the </span><span><em>mapping</em></span><span> applied to a single combination of telescope-laser beam are reported. To demonstrate the effectiveness of the procedure the results were verified by comparing the whole profile of the signal and the outcome of the </span><span><em>telecover</em></span><span> test </span>[2]<span> before and after the alignment. The overlap function was estimated and the height of full overlap compared against the one obtained from a geometric model.</span></p><p><span>The proposed method gives the possibility to characterize the signal profile as a function of the position of the receiving optical system in the 3D space around the focal point. This characterization improved the accuracy of the system alignment protocol. The </span><span><em>mapping</em></span><span> applied to the laser beam can be used to align systems with fixed receiving geometry and, as presented, to estimate the overlap function. </span></p><p> </p><p>[1] F. Congeduti, F. Marenco, P. Baldetti, and E. Vincenti, ‘The multiple-mirror lidar “9-eyes”’, <em>J. Opt. Pure Appl. Opt.</em>, vol. 1, no. 2, pp. 185–191, Jan. 1999, doi: 10.1088/1464-4258/1/2/012.</p><p>[2] V. Freudenthaler, H. Linné, A. Chaikovski, D. Rabus, and S. Groß, ‘EARLINET lidar quality assurance tools’, <em>Atmospheric Meas. Tech. Discuss.</em>, pp. 1–35, Jan. 2018, doi: https://doi.org/10.5194/amt-2017-395.</p>

Sign in / Sign up

Export Citation Format

Share Document