Active aberration- and point-spread-function control in direct laser writing

We control the point-spread-function of high numerical aperture objectives used for direct laser writing with a spatial light modulator. Combining aberration correction with different types of amplitude filters to reduce the aspect ratio of the point-spread-function enhances the structural and optical quality of woodpile photonic crystals. Here, aberration correction is crucial to ensure the functionality of the filters. Measured point-spread-functions compare well with numerical calculations and with structures generated by direct laser writing. The shaped point-spread-function not only influences the maximum achievable three-dimensional resolution but also proximity effect and optical performance of woodpile photonic crystals. (C) 2012 Optical Society of America