Speckle-free laser marking of metals with liquid-crystal-based spatial light modulator

Krystian Wlodarczyk, Jarno Kaakkunen, Pasi Vahimaa, Duncan Hand

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

A liquid-crystal-based spatial light modulator (LC-SLM) is used for laser beam patterning and manipulation in order to produce very small, speckle-free 2D marks on metal surfaces. To avoid speckles within the laser marked area, which is a typical drawback of current SLM-based laser marking processes, an array of "non-interfering" beamlets is produced by the LC-SLM and used for generating micro-patterns. The micro-patterns (e.g. 20*20 pixel datamatrices with overall dimensions of less than 320?m by 320?m) are generated in a series of 16 steps, using a Fresnel zone lens (FZL) which is written into a computer-generated hologram (CGH) that produces an array of beamlets. By shifting off-axis the whole kinoform (FZL+CGH) for each step, the array of beamlets is spatially moved along the imaging plane, producing the required micro-pattern. In comparison to other SLM-based laser marking approaches already reported in the literature, our method not only eliminates (or at least significantly reduces) unwanted speckle interference but also reduces the laser power required for marking.
Original languageEnglish
Title of host publicationProceedings of LAMP2013
Publication statusPublished - 2013
MoE publication typeNot Eligible
Event6th International Congress on Laser Advanced Materials Processing, LAMP 2013 - Niigata, Japan
Duration: 23 Jul 201326 Jul 2013

Conference

Conference6th International Congress on Laser Advanced Materials Processing, LAMP 2013
Abbreviated titleLAMP 2013
CountryJapan
CityNiigata
Period23/07/1326/07/13

Fingerprint

light modulators
marking
liquid crystals
metals
lasers
lenses
kinoform
metal surfaces
manipulators
pixels
laser beams
interference

Keywords

  • laser marking
  • spatial light modulator
  • piosecond laser
  • laser material processing
  • laser ablation

Cite this

Wlodarczyk, K., Kaakkunen, J., Vahimaa, P., & Hand, D. (2013). Speckle-free laser marking of metals with liquid-crystal-based spatial light modulator. In Proceedings of LAMP2013
Wlodarczyk, Krystian ; Kaakkunen, Jarno ; Vahimaa, Pasi ; Hand, Duncan. / Speckle-free laser marking of metals with liquid-crystal-based spatial light modulator. Proceedings of LAMP2013. 2013.
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author = "Krystian Wlodarczyk and Jarno Kaakkunen and Pasi Vahimaa and Duncan Hand",
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Wlodarczyk, K, Kaakkunen, J, Vahimaa, P & Hand, D 2013, Speckle-free laser marking of metals with liquid-crystal-based spatial light modulator. in Proceedings of LAMP2013. 6th International Congress on Laser Advanced Materials Processing, LAMP 2013 , Niigata, Japan, 23/07/13.

Speckle-free laser marking of metals with liquid-crystal-based spatial light modulator. / Wlodarczyk, Krystian; Kaakkunen, Jarno; Vahimaa, Pasi; Hand, Duncan.

Proceedings of LAMP2013. 2013.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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N1 - The Proceedings of LAMP2013 has been published online. URL, LOGIN ID and PASSWORD for the proceedings have been provided to the participants by e-mail. Project code: 74520

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N2 - A liquid-crystal-based spatial light modulator (LC-SLM) is used for laser beam patterning and manipulation in order to produce very small, speckle-free 2D marks on metal surfaces. To avoid speckles within the laser marked area, which is a typical drawback of current SLM-based laser marking processes, an array of "non-interfering" beamlets is produced by the LC-SLM and used for generating micro-patterns. The micro-patterns (e.g. 20*20 pixel datamatrices with overall dimensions of less than 320?m by 320?m) are generated in a series of 16 steps, using a Fresnel zone lens (FZL) which is written into a computer-generated hologram (CGH) that produces an array of beamlets. By shifting off-axis the whole kinoform (FZL+CGH) for each step, the array of beamlets is spatially moved along the imaging plane, producing the required micro-pattern. In comparison to other SLM-based laser marking approaches already reported in the literature, our method not only eliminates (or at least significantly reduces) unwanted speckle interference but also reduces the laser power required for marking.

AB - A liquid-crystal-based spatial light modulator (LC-SLM) is used for laser beam patterning and manipulation in order to produce very small, speckle-free 2D marks on metal surfaces. To avoid speckles within the laser marked area, which is a typical drawback of current SLM-based laser marking processes, an array of "non-interfering" beamlets is produced by the LC-SLM and used for generating micro-patterns. The micro-patterns (e.g. 20*20 pixel datamatrices with overall dimensions of less than 320?m by 320?m) are generated in a series of 16 steps, using a Fresnel zone lens (FZL) which is written into a computer-generated hologram (CGH) that produces an array of beamlets. By shifting off-axis the whole kinoform (FZL+CGH) for each step, the array of beamlets is spatially moved along the imaging plane, producing the required micro-pattern. In comparison to other SLM-based laser marking approaches already reported in the literature, our method not only eliminates (or at least significantly reduces) unwanted speckle interference but also reduces the laser power required for marking.

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Wlodarczyk K, Kaakkunen J, Vahimaa P, Hand D. Speckle-free laser marking of metals with liquid-crystal-based spatial light modulator. In Proceedings of LAMP2013. 2013