This paper describes a successful technological transfer, from a state laboratory to an industrial company, for writing long and large submicron period gratings (potentially square-meter sized), implemented in an industrial direct laser beam writing equipment at 355 nm wavelength (Dilase 750 from KLOE SA company). The writing head, which has been inserted in the machine, consists of a phase mask which enables it to project a set of fringes pattern of small area onto a photoresist-coated substrate. As the substrate is continuously moving, one-dimensional or two-dimensional gratings can be fabricated over large areas limited only by the machine’s stage displacement range. The optical scheme is described from the beam shaping to the printing processes and the phase mask optimization. In order to demonstrate the technology, 600 nm period gratings of over 20 cm in length have been fabricated. Such submicron structures can be used in solar cell modules for photon trapping and as antireflection coatings.
Unique industrial transfer of write on the fly technique, to produce long and large sub-micron period
gratings on an industrial and commercial laser beam generator (Dilase 750 from KLOE company) has been
successfully achieved. The write on the fly technique, enabling to produce stitchingless long gratings, is based on
a continuous interferogram, generated by a high efficiency phase mask, illuminated with a laser beam and
projected onto a photosensitive film. As the substrate is continuously moving, the technique is able to write large
size gratings, limited by the displacement range of the machine. Demonstration is made on photopatternable solgel
thin films (TiO2 xerogel film) on which 600 nm period gratings, several cm long and a few mm wide were
written. This demonstration opens the way to cost-effective and rapid demonstrators and extends the possibilities
towards high volume products.
TiO2 based sol-gel microstructuring layer is applied to increase efficiency of solar cells modules or the
so-called PV planar concentrators, by reducing the amount of solar cells (silicon based solar cells)
while increasing the amount of solar energy trapped into the modules. The proposed solution is based
on linear grating whose role is to trap and diffract the incident beam to solar cells.
The design of the module and the optimized gratings, to be angularly and spectrally tolerant, are
presented. The paper also deals with the fabrication of large and long gratings (m2 area), using the
unique direct photopatterning sol-gel solution, based on the dynamic and continuous gratings writing
using phase mask lithograghy.