Entwicklung eines hochintegrierten digitalen Hochleistungsbelichters für die Belichtung von Lötstopplacken (DAHLIA): Schlussbericht im Projekt; Laufzeit des Vorhabens: 01.12.2015 - 30.11.2018
As part of the subproject, the metrological prerequisite was initially created to be able to measure the filter to be produced at all. For this purpose, a spectrometer was designed and contructed with which the s- or p-polarized transmission con be measured at angles of incidence to be set. The coating process has been improved in terms of scattering and absorption losses. A significant improvement of the scattering losses was achieved by modified process parameters. Relevant in this context is also the roughness of the substrates, which goes directly into the optical losses. Best results were obtained with superpolished substrates (P4) with a roughness (5 x 5 µm) better than 0.2 nm. Through a suitable layer design and an adapted monitoring strategy, filters with a very steep edge could be produced successfully. The width is below the resolution of the spectrometer and the angular divergence of the measuring beam of the insitu spectrometer. Edge filters with different wavelengths within a batch could be realized by shifting the carriers. The change in the distance between the target and the substrate resulted in a rate change that could be used very precisely to adjust the central wavelength
