The manufacture of microlens arrays and fan-out gratings in photoresist

Photoresist is often regarded as a binary medium in that once it has been exposed to a suitable pattern of light and developed, it either remains or is totally removed to reveal a clear substrate. However, by using alternative processing techniques, it is also possible to generate a range of continuous profiles within the limits imposed by the thickness of the resist. This has been used in the manufacture of spectroscopic diffraction gratings and certain display holograms. The authors consider extending the techniques to the manufacture of some of the components required by developments in electro-optics and optical data handling. In particular, they consider microlens arrays and fan-out gratings