Technology development of diffractive micromirror arrays for the deep ultraviolet to the near infrared spectral range

Abstract

A new generation of micromirror arrays (MMAs) with torsional actuators is being developed within the European research project MEMI in order to extend the usable spectral range of diffractive MMAs from deep ultraviolet into the visible and near infrared. The MMAs have 256 x 256 pixels reaching deflections above 350 nm at a frame rate of 1 kHz, which enables an operation in the target wavelength range between 240 nm and 800 nm. Customized driver electronics facilitates computer controlled operation and simple integration of the MMA into various optical setups. Tests in the visible wavelength range demonstrate the functionality and the high application potential of first MMA test samples

Calibration of diffractive micromirror arrays for microscopy applications

“…The MMA modulator consists of 65 536 torsion elements, monolithically integrated onto a CMOS backplane [6] (see Figure 2). The 256 x 256 actuator elements in the active area ensure a fill factor greater than 90 % with a pitch of 16 µm and 0.5 µm slit width.…”

“…The relative improvement certainly depends on the initial "non-calibrated" state, but the final state now is no more constrained by the spread of mirror deflections. The maximum MMA contrast becomes a function primarily of the single mirror deformation [8], which is guaranteed from the new MMA technology to locate in a very comfortable range well below λ/100 [6].…”

“…The main arguments are properties like real-time grayscale imaging at high-speed as well as high contrast operation within an extended wavelength range. Previously, some of these properties have been analyzed with focus on device technology and optical characterization [6], [7]. The present paper studies the steps, necessary to achieve the high contrast capabilities of a programmable, diffractive light modulator.…”

Spatially resolved contrast measurement of diffractive micromirror arrays

“…In order to meet this trend, from the developer's perspective two strategies are to be mentioned here: Firstly, the MEMS technology is continuously developed with process innovations, outlined in earlier publications [4]- [7]. Secondly, as complementary approach, the careful qualification and individual optimization of each single MEMS device may support highest optical performance.…”

Spatially resolved scatter measurement of diffractive micromirror arrays

“…From an SLM developer's perspective, two strategic directions are pursued to efficiently achieve a high phase accuracy. On the one hand, the technology is continuously improved by process innovations [17][18][19] and, on the other hand, precise characterization techniques are developed to better understand and optimize the individual device performance through calibration [20,21]. Because the surface topography is the most important factor for the optical performance of an MMA, optical profiling techniques such as white-light interferometric (WLI) microscopy are classical candidates for a variety of MMA inspection, characterization, and optimization tasks.…”