Heat accumulation temperature measurement in ultrashort pulse laser micromachining

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F49777513%3A23640%2F21%3A43962081" target="_blank" >RIV/49777513:23640/21:43962081 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1016/j.ijheatmasstransfer.2020.120866" target="_blank" >https://doi.org/10.1016/j.ijheatmasstransfer.2020.120866</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.ijheatmasstransfer.2020.120866" target="_blank" >10.1016/j.ijheatmasstransfer.2020.120866</a>

Result language

angličtina

Original language name

Heat accumulation temperature measurement in ultrashort pulse laser micromachining

Original language description

Ultrashort pulse laser micromachining is affected by the heat accumulation resulting from the residual heat from previous laser pulses on the sample surface. Up to now, most of the works analysed the accumulation by numerical modelling. The present work focussed on development and application for the first time of a measurement system of heat accumulation temperature directly during the processes in nanosecond and microsecond time ranges. The measurement system was based on the infrared radiometry and contained liquid nitrogen cooled fast HgCdTe photodetector and paraboloid mirrors. Micromachining of grooves was done using a 14 W picosecond laser with different pulse energies, repetition frequencies and scanning speeds. Calibration of the measurement system was done in order to obtain temperatures from the measured signal. The calibration was not straightforward due to very small laser spot (25 μm), small signal and changing of the size of the heated area for low scanning speeds. Obtained heat accumulation temperature ranged from 300°C to 2600°C for scanning speeds from 8 m/s to 0.07 m/s and pulse energies from 0.1 µJ to 100 µJ. According to the scanning electron microscope (SEM) images, the material was already partially melted (small droplets on boarders) for low scanning speeds. Surface roughness and ablation rate were determined by 3D confocal laser microscope. Good correlation was found between the roughness and the heat accumulation temperature, thus confirming the validity of calibration. Measured heat accumulation temperature was surprisingly the highest for the most efficient ablation parameters and at the same time low surface roughness was achieved.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

20506 - Coating and films

Project

<a href="/en/project/EF18_069%2F0010018" target="_blank" >EF18_069/0010018: LABIR-PAV / Pre-application research of infrared technologies</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

ISSN

0017-9310

e-ISSN

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Volume of the periodical

168

Issue of the periodical within the volume

APR 2021

Country of publishing house

GB - UNITED KINGDOM

Number of pages

9

Pages from-to

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UT code for WoS article

000640991800025

EID of the result in the Scopus database

2-s2.0-85099169592