An integrated exposure and measurement tool for 5-DOF direct laser writing based on chromatic differential confocal sensing

Accurate and uniform fabrication of microstructures on highly curved substrates requires exposure with the waist of a focused laser beam at every point. In order to realize this, the exposure beam must be held perpendicular and focused onto the local substrate. Here we present an optical tool for our developed 5-axis nano-positioning and nano-measurement machine based on the chromatic differential confocal microscope. Thereby, we introduce the optical design methodology to realize high axial sensitivity from differential optical feedback via axial chromatic aberration. Additionally, the deflection angle is measured via a camera sensor to provide angular feedback. Overall, our probe attains a nanometer axial sensitivity and arc-minute angular sensitivity in a confined space of 50 × 80 × 36 mm3.