Ultrafast imaging of ultraviolet laser ablation and etching of polymethylmethacrylate

Srinivasan, R.; Braren, Bodil; Casey, Kelly G.; Yeh, Mildred

doi:10.1063/1.101910

Cited by 98 publications

(39 citation statements)

References 8 publications

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“…33a. Such darkening upon laser ablation was reported for PMMA and poly(ethylene terephthalate) (PET) by other researchers and assigned to scattering by ejected materials or bubble formation in the irradiated surface upon laser ablation [194,195]. In this time region, the expansion dynamics measured with both internal and surface configurations were quite similar to each other, as shown in Figs.…”

Section: Darkening and Small Expansion At The Early Part Of The Excimsupporting

confidence: 62%

“…For example, it has been revealed that cyclic multiphoton absorption and mutual interactions between excited states were brought about, causing rapid temperature elevation of the polymer matrix [93,95,96] and thermal decomposition of the polymer [95,192]. On the other hand, morphological dynamics has been studied mainly with respect to ejection behavior of fragments or plume [94,172,[194][195][196][197]. Of course the ejection dynamics is a reflection of the molecular process, but direct information is not clearly contained in the ejection behavior, since the primary molecular processes are already completed when fragments or plume ejection are brought about.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Laser Application of Polymers

Lippert

2004

Polymers and Light

150

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Laser ablation of polymers has been studied with designed materials to evaluate the mechanism of ablation and the role of photochemically active groups on the ablation process, and to test possible applications of laser ablation and designed polymers. The incorporation of photochemically active groups lowers the threshold of ablation and allows high-quality structuring without contamination and modification of the remaining surface. The decomposition of the active chromophore takes place during the excitation pulse of the laser and gaseous products are ejected with supersonic velocity. Time-of-flight mass spectrometry reveals that a metastable species is among the products, suggesting that excited electronic states are involved in the ablation process. Experiments with a reference material, i.e., polyimide, for which a photothermal ablation mechanism has been suggested, exhibited pronounced differences. These results strongly suggest that, in case of designed polymers which contain photochemically active groups, a photochemical part in the ablation mechanism cannot be neglected. Various potential applications for laser ablation and the special photopolymers were evaluated and it became clear that the potential of laser ablation and specially designed material is in the field of microstructuring. Laser ablation can be used to fabricate three-dimensional elements, e.g., microoptical elements.Keywords Laser ablation · Ablation mechanism · Photopolymers · Polyimide · Spectroscopy This was not always true, of course. For many years, the laser was viewed as "an answer in search of a question". That is, it was seen as an elegant device, but one with no real useful application outside of fundamental scientific research. In the last two to three decades however, numerous laser applications have moved from the laboratory to the industrial workplace or the commercial market. Lasers are unique energy sources characterized by their spectral purity, spatial and temporal coherence, and high average peak intensity. Each of these characteristics has led to applications that take advantage of these qualities: -Spatial coherence: e.g., remote sensing, range finding and many holographic techniques. -Spectral purity: e.g., atmospheric monitoring based on high-resolution spectroscopies. -and of course the many other applications in communication and storage, e.g., CDs.All of these high-tech applications have come to define everyday life in the late twentieth century. One property of lasers, however, that of high intensity, did not immediately lead to "delicate" applications but rather to those requiring "brute force". That is, the laser was used in applications for removing material or heating. The first realistic applications involved cutting, drilling, and welding, and the laser was little more advanced than a saw, a drill, or a torch. In a humorous vein A.L. Schawlow proposed and demonstrated the first "laser eraser" in 1965 [4], using the different absorptivities of paper and ink to remove the ink without damaging the und...

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Section: Darkening and Small Expansion At The Early Part Of The Excimsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Laser Application of Polymers

Lippert

2004

Polymers and Light

150

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“…Similar nanosecond photography was applied to PMMA and polyimide films by Srinivasan et al, reporting that a shock wave was observed at 60 ns and followed by an explosion of fragmented debris. 17 The shock wave was not clearly confirmed in present work, which may be ascribed to differences in experimental conditions. increases.…”

Section: Resultsmentioning

confidence: 49%

Time-resolved spectroscopic and photographic studies on laser ablation of poly(methyl methacrylate) film doped with biphenyl

Fukumura¹,

Takahashi²,

Masuhara³

1995

J. Phys. Chem.

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Nanosecond time-resolved spectroscopic and photographic measurements have been conducted for studying the mechanism of laser ablation of polymer films doped with biphenyl. Comparisons between the two different measurements made it possible to assign transient species observed during the ablation. The triplet state of the dopant was detected prior to the polymer ejection, while the excited singlet state was confirmed with its fluorescence. Besides these, biradicals such as C2, CH, and CN were identified and plasma emission was observed, but only when the fluence was increased highly above the laser ablation threshold. The excited singlet and triplet states were concluded to be main transient species leading to ablation. Temporal behavior of the excited singlet state was simulated with a model involving the ground, excited singlet, and triplet states, and the ablation mechanism was discussed.

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“…The deeper structures, cluster of redeposited material that is formed close to the ablated holes, are then removed by ultrasonic cleaner. Laser ablation has primarily been used on PMMA [96]. A disadvantage of the ablation technique is that it can lead to polymer surface property change in comparison with a polymer's bulk properties [97].…”

Section: Direct Machiningmentioning

confidence: 99%