The ablation characteristics of various polymers were studied at low and high fluences. The polymers can be divided into three groups, polymers containing triazene groups, polyesters with cinnamylidenemalonyl groups, and polyimide (PI) as reference polymer. The polymers containing the photochemically most active group (triazene) are also the polymers with the lowest threshold of ablation and the highest etch rates, followed by the designed polyesters and then PI. The triazene-polymer (TP) was studied at low fluences with additional techniques. UV–Vis spectroscopy and TOF-MS reveal that the triazene-chromophore decomposes also upon irradiation with fluences below the threshold of ablation. At the threshold fluence, a pronounced change is detected, i.e., an approximately 10 times higher decomposition rate. Nanosecond surface interferometry was applied to detect changes of the surface morphology of the TP and PI after irradiation with fluences above the threshold of ablation. In the case of the TP, no swelling of the surface is observed and etching starts and ends with the laser pulse, while a very pronounced swelling is detected for PI. The clear difference between PI and the designed polymers can be explained by a pronounced thermal part in the ablation mechanism of PI, while photochemical activities are more important for the TP. The combination of phase masks and the TP allows an efficient fabrication of three-dimensional topographies using laser ablation. The TP also reveals superior properties for applications in the near-IR. The carbon-doped polymer shows properties that are useful for the application of polymers in laser plasma thrusters for microsatellites.

The ablation characteristics of various polymers were studied at low and high fluences. The polymers can be divided into three groups, i.e. polymers containing triazene and ester groups, the same polymers without the triazene group, and polyimide as reference polymer. At high fluences similar ablation parameters, i.e. etch rates and effective absorption coefficients, were obtained for all polymers. The main difference is the absence of carbon deposits for the designed polymers. At low fluences (at 308nm) very pronounced differences are detected. The polymers containing the photochemically most active group (triazene) exhibit the lowest threshold of ablation (as low as 25mJcm−2) and the highest etch rates (up to 3μm/pulse), followed by the designed polyesters and then polyimide. The laser-induced decomposition of the designed polymers was studied by nanosecond-interferometry. Only the triazene-polymer reveals etching without any sign of surface swelling, which is observed for all other polymers. The etching of the triazene-polymer starts and ends with the laser pulse, clearly indicating photochemical etching. The triazene-polymer was also studied by time-of-flight mass spectrometry (TOF-MS). The intensities of the ablation fragments show pronounced differences between irradiation at the absorption band of the triazene group (308nm) and irradiation at a shorter wavelength (248nm).

Photopolymers designed for UV laser ablation were tested in quite different applications at very different irradiation wavelengths, i.e. in the UV (308nm) and in the near-IR (935nm). Diffractive gray tone phase masks were optimized for laser ablation and used to fabricate micro-optical elements. The application of the photopolymers (triazene-polymers) allowed a faster processing due to the high sensitivity, and showed less contamination of the surface by ablation products. The designed polymers also revealed superior properties for applications in the near-IR. Near-IR irradiation is used to create a plasma which could be used as a thruster for microsatellites. The carbon-doped triazene-polymer shows higher values of the momentum coupling coefficient and specific impulse than a commercial polymer. The well-defined threshold for the momentum coupling coefficient was only observed for the designed polymer. This threshold is an important feature for the design of real laser plasma thrusters for microsatellites.

The ablation characteristics of various polymers were studied at low fluences, and structure property relations were obtained. The polymers containing the photochemically most active group (triazene) are also the polymers with the lowest threshold of ablation and the highest etch rates, followed by a designed polyester and then polyimide. No pronounced influences of the absorption coefficients, neither αlin nor αeff, on the ablation characteristics are detected. The thermal properties of the designed polymers are only of minor importance. Intensities of fragments obtained by time-of-flight mass spectrometry measurements show pronounced differences between irradiation at the absorption band of the triazene group (308nm) and irradiation at a shorter wavelength (248nm). The larger fragments reveal lower intensities for 248nm irradiation, due to the additional decomposition of these fragments by the higher energy of 248nm photons and the lower etch rates for 248nm irradiation. An excimer lamp emitting at 308nm is applied to decompose the triazene group without major decomposition of the aromatic system. Irradiation with shorter wavelengths, i.e. 222 and 172nm, causes in addition the decomposition of the aromatic system. Two novel applications for the special designed photopolymers are shown. These polymers can be applied in combination with phase masks for the fabrication of microoptical elements using laser ablation. Another quite different application utilizes near-IR irradiation. The plasma created by laser ablation acts as a micro thruster.