Optatec 2012

Dresden, /

Layout and working principle of the light modulator
Complex wire bonding of the light modulator

May 22 - 25, 2012 in Frankfurt

Fraunhofer Pavilion hall 3, booth no. D 50

Fraunhofer IPMS, Dresden carries out customer specific developments in the field of micro systems technology and wireless microsystems serving as a business partner that supports the transition of innovative ideas into new products. In addition to R&D services the Fraunhofer IPMS offers ramp-up within a pilot production. With modern equipment and about 200 scientists and engineers, the range of projects and expertise covers sensor and actuator systems, microscanner, spatial light modulators as well as wireless microsystems.

At Optatec 2012 Fraunhofer IPMS will present a large aperture MEMS scanner module for three-dimensional distance measurement as well as a quasi-static resonant MEMS scanner. Further more Optatec visitors will find a novel electro-optically induced waveguide switching based on electro-active polymers that allows for the switching, splitting and modulation of light within fiber optics especially suitable for telecommunication purposes. A three-dimensional fluorescence microscope is another highlight. It stands for Fraunhofer IPMS' capability to create complete system solutions including optical and electronic design as well as software development. The central exhibit of the presentation will be a micromirror based light modulator.

Micromirror based light modulator

Light modulators modify laserlight and can be used in a wide range of applications, such as in Computer to Plate Imaging (CTP), Laser Direct Imaging (LDI), Waferlevel Interconnect, Holography, marking and processing of materials and in the field of IP protection as well as for laser based sintering of 3D-shapes.

Because of the inavoidable loading time, two-dimensional light modulators as LCDs or micro mirror based SLMs in general can be used with pulsed light only. In contrast one-dimensional light modulators are controlled directly and do not have any CMOS-circuit underneath the single micro mirrors, they display the information continuously and hence can be used to modulate continuous light and short pulse laser sources.

In order to gain a throughput comparable to two dimensional light modulators a higher frame rate is required. In contrast to liquid crystal based concepts micro mirror based light modulators offer this advantage, additionally they are applicable in the ultraviolet wavelength range.

Layout and function

The light modulator consists of a large aspect ratio rectangle array of single micromirrors. The micro mirror design is optimized for high resonance frequency and damping. All micromirrors of one column deflect simultaneously to a similar deflection. This column is reacting accordingly as a single pixel (so called meta pixel) with a large aspect ratio. The uniform properties within one column allow for extension of the illuminated area on the SLM. This leads to a reduction of engery density on the surface of the light modulator, which opens up the way to high power laser applications.

Each meta pixel creates one point in the image plane those intensity can be varied by the tilt of the micro mirrors.

In the image plane those meta pixels are arranged in a line. Scanning this line and simultaneously changing the gray values by tilting the micromirrors allows for writing gray scale images with high speed.