We report on our investigation to precisely actuate diffractive micromirror arrays (MMA) with an accuracy of lambda/100. The test samples consist of analog, torsional MEMS arrays with 65 536 ( 256x256) mirror elements. These light modulators were developed for structured illumination purposes to be applied as programmable mask for life science and semiconductor microscopy application. Main part of the work relies on the well known characterization of MEMS mirrors with profilometry to automatically measure and approximate the MMA actuation state with high resolution. Examples illustrate the potential of this strategy to control the tilt state of many thousand micromirrors within the accuracy range of the characterization tool. In a dynamic range between 0 and >250 nm the MMA deflection has been precisely adjusted for final MMA application in the deep-UV - VIS - NIR spectral range. The optical properties of calibrated MMAs are tested in a laser measurement setup. After MMA calibration an increased homogeneity and improved image contrast are demonstrated for various illumination patterns.

The present article discusses an optical concept for the characterization of diffractive micromirror arrays (MMAs) within an extended wavelength range from the deep ultra-violet up to near-infrared. The task derives from the development of a novel class of MMAs that will support programmable diffractive properties between 240 nm and 800 nm. The article illustrates aspects of the achromatic system design that comprises the reflective beam homogenization with divergence control and coherence management for an appropriate MMA illumination as well as the transfer of phase modulating MMA patterns into intensity profiles for contrast imaging. Contrast measurements and grey scale imaging demonstrate the operation of the characterization system and reflect the encouraging start of technology development for multispectral, diffractive MMAs.