Successful development of an innovative evaluation platform for spatial light modulators

Fraunhofer IPMS presents its advanced, high-performance evaluation kits for spatial light modulators, which now feature tilting or piston mirrors as actuator types. The tiny micromirrors of the spatial light modulators can manipulate light on a pixel-by-pixel basis. They play a vital role in the generation of high-precision light patterns for applications in lithography, medical technology, astronomy, or quantum computing.

The institute develops spatial light modulators with several million individually analogue-controllable mirrors on a single semiconductor chip. The components form optical key elements for multiple applications and deliver high versatility. Depending on the application, the micromirrors can be tilted along one or two axes or lowered horizontally. This enables them to control and manipulate light in its direction, intensity or phase, creating precise light patterns.

Simplified application transfer with high precision

To enable the transfer of this highly integrated, fast and precise technology into new applications, the institute offers its customers evaluation kits with 64k (256 x 256) mirrors. Researchers in the Spatial Light Modulators business unit are excited to present a notable innovation: The systems, usually based on one-axis tilt mirrors, have now been expanded to include piston mirrors as a new type of actuator. The successful technology implementation into the first version of the evaluation kit enables customers to test a large part of the portfolio of micromirror arrays on a single, central platform. With this versatile solution, the institute offers a unique testing platform. Dr Michael Wagner from Fraunhofer IPMS explains: "Normally, different mirror technologies also require corresponding test systems because the individual mirror arrays are based on individual CMOS backplanes. Our kits allow users and developers to test the spatial light modulators on a central platform."

Depending on the mirror type and system setup, the evaluation kits can be used from the ultraviolet spectral range through the visible spectrum up to the near-infrared. The researchers are currently working on extending the application range of the evaluation kit to the deep ultraviolet range, as other SLM-platforms from the institute are already used within this range. In the ultraviolet range, smaller details can be resolved, allowing a detailed and high-precision imaging. The advanced control electronics of the evaluation kit further support very high modulation frequencies up to the kilohertz range. "Typically, the modulation frequency of a micromirror array is limited by the control setup, not by the properties of the chips themselves. A powerful setup can exploit the full capabilities of the micromirrors," adds scientist Mario Nitzsche. The evaluation kits achieve high performance through nanometer-accurate calibration of the micromirrors, ensuring precise and high-resolution analogue (quasi-continuous) lowering or tilting movement. The complete evaluation kit includes the control electronics, a 64k micromirror chip (256 x 256 pixels), and the appropriate software. Support for integration and for optimal operation is supplied.

High-precision light modulation for industry, medicine, and astronomy

The spatial light modulators are used in various applications. In microscopy, one-axis tilt mirror arrays are employed to selectively illuminate samples. The semiconductor industry, and specifically microlithography, benefits from the expertise of the institute in modulator development for the deep ultraviolet range: The analogue-controllable mirror arrays enable improved performance of mask writing tools. With two-axis tiltable mirror arrays, precise redistribution of incoming laser light with minimal intensity losses can be realised, which is, for example, beneficial for material processing. Piston mirror arrays, on the other hand, can implement precise phase modulations, which enable the generation of 3D holography images. They are considered a promising key component for real 3D head-up displays. So-called 'real' 3D displays generate an actual hologram within the three-dimensional space, unlike previous 2D modulations that create a depth effect through special visual effects. Precise phase modulation is also of great relevance for other application fields, such as adaptive optics in astronomy, medical technology, or the generation of optical traps for quantum computing.

At this year's Laser World of Photonics, the team of the Spatial Light Modulators business unit will showcase its new spatial light modulator evaluation kit and a comprehensive portfolio of high-end spatial light modulators. Interested parties are invited to visit Fraunhofer IPMS in Hall A2, Booth #415, from 24-27 June 2025.