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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 55 (1992), S. 269-273 
    ISSN: 1432-0630
    Keywords: 42.60 ; 82.65 ; 73.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Continuous wave laser radiation from an argonion laser in the wavelength range 275–330 nm can be used to etch polyethylene terephthalate (PET) films with as little thermal damage as from a pulsed, ultraviolet laser (248 nm or 308 nm) provided the beam is focussed to a spot of 10–100 kW/cm2 of power density and is moved over the surface at speeds at which the transit time over its own diameter (which can be looked upon as a “pulse width”) is on the order of 10–200 μs. In contrast to results which had been obtained previously on the photokinetic etching of polyimide and doped polymethyl methacrylate films under similar conditions, the sensitivity of PET to etching is 〉5-fold greater than either of these polymers and increases steadily with increasing pulse width. There is lateral thermal damage as the pulse widths increase to 〉200 μs. The material that is removed is vaporized in part. More than 20% is probably ejected in a molten state and resolidifies at the edge of the cut. There is no acoustic report similar to that seen in ablative photodecomposition. The process appears to be largely thermal in nature.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 45 (1988), S. 289-292 
    ISSN: 1432-0630
    Keywords: 42.60 ; 82.65 ; 73.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Although polymethyl methacrylate (PMMA) is essentially transparent to light of 308 or 351 nm, it can be made sensitive to photoablation and etching by excimer laser pulses (20 ns half-width) of those wavelengths by the introduction of an organic dopant. The dopant (trade name=Tinuvin*) is actually a quencher of the first electronic excited state of PMMA and is therefore used commercially to stabilize the polymer against photodegradation. Laser etching of Tinuvin-doped PMMA can be shown to be a photochemical process in which the Tinuvin decomposes by the absorption of two or more photons and causes the ablation of the surrounding polymer.*[2-(2′-hydroxy-3′,5′-diisopentyl-phenyl) benzotriazole].
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 56 (1993), S. 417-423 
    ISSN: 1432-0630
    Keywords: 42.60 ; 82.65 ; 73.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Ablation of the surface of a polyimide (Kapton™) film by single pulses of 248 nm or 308 nm radiation (∼20 ns) or 9.17 μm laser radiation (∼170 ns) was studied by photographing the emergence of the blast wave and the plume by a pulse (〈1 ns; 596 nm) of visible laser light. The dynamics of the blast wave was similar in the ultraviolet and in the infrared but the composition of the plume was obviously different. A mass of opaque solid material was ejected for as long as 2.6 μs following the IR pulse in contrast to the minute amount of solids that are seen in the ablation by UV laser pulses of ns duration. UV laser pulses of 50–400 μs duration interact with polyimide surfaces in a manner that is similar to IR laser pulses of ns duration or longer. Chemical analysis of the ablation products that are obtained under various conditions of ablation when compared to the known modes of thermal degradation of polyimide show that the reaction is a thermal process when IR laser pulses or UV laser pulses of long (〉10 μs) duration are employed. Ablation by ns UV laser pulses differs fundamentally in the chemistry of the products from all of the cases mentioned above.
    Type of Medium: Electronic Resource
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