A continuous fl ow microwave system based on a transmission line short-circuited waveguide reactor concept is described. The continuous fl ow reactor is capable of operating in a genuine high-temperature/high-pressure process window (310 ° C/60 bar), applying a microwave transparent and chemical resistant cylindrical γ -Al 2 O 3 tube as reaction zone. The system can be operated in an extremely energy effi cient manner, utilizing 0.6 -6 kW microwave power (2.45 GHz). The application of the reactor for processing four chemical transformations in a high-temperature/high-pressure regime with a throughout of 3.5 -6.0 l/h is demonstrated.
Communications cyclopentadiene by singlet oxygen has been chosen as a model reaction. The explosive endoperoxide, which is formed as an intermediate, was reduced to give 2-cyclopenten-1,4-diol (see Scheme 1), which is of pharmaceutical importance [8] and is produced as batch product where the explosive intermediate is formed in greater amounts [9,10].
Polymer replication technique enables for low cost devices even in the case of aspheric or irregular shaped surfaces, submicron or other challenging structures. The use of UV-reaction moulding on semiconductors, glass or other inorganic substrates as the replication technique leads to a high degree of stability and allows for the simultaneous integration of optoelectronics or ion exchanged GRIN elements. Thin polymer layers on inorganic substrates show high flatness and lower wavefront deviations with respect to all?polymer elements. They show low lateral shrinkage during the UV-polymerisation, and the lateral thermal expansion is determined by the substrate. Furthermore, sensitive substrates can be used because the process does not involve high mechanical stress or elevated temperatures. Original structures for the replication masters are fabricated by different resist technologies. Subsequently, they are proportionally transferred by dry etching (RIE) into glass or silicon, or, the resist structure is transformed into a metal master by electroplating. The utilisation of UV-transparent replication tools allows for the use of opaque substrates (i.e. detectors). Locally UV-transparent replication tools enable a combination of replication and resist technology (leading to elements with new features) or can protect sensitive areas like bond pads from being coated with optical layers. The fabrication of isolated polymer elements on arbitrary substrates is an advantage of UV?reaction moulding against injection moulding or hot embossing
A replication technique allowing for the wafer scale integration ofmicrooptical elements is presented and illustrated by various examples. The technique is based on polymer UV reaction moulding using a modified contact mask aligner where mask and wafer are replaced by the replication tool and an arbitrary substrate (on top ofwhich the microstructures are to be replicated), respectively. The technology takes advantage ofthe high precision and adjustment accuracy of photolithography equipment. The replication masters are nickel shims, etched Silicon wafers or uv-transparent fused silica tools. The latter ones allow for replication on opaque substrates. Additionally, polymer elements with unique properties can be obtained by the combination ofreplication and resist technology using partially transparent replication tools. Wafer scale hybrid integration of micro-optical subsystems is accomplished by replication of polymer elements like lenses, lens arrays, micro prisms etc. onto semiconductor wafers containing detectors or VCSELs, or, by combining micro-optical elements on both sides of a glass wafer. The use ofthin layers ofuv cured (crosslinked) polymers on inorganic substrates results in good thermal and mechanical stability compared to all-polymer devices.
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