Micromirror based light modulator
23 May 2011 - 26 May 2011
Austria
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.
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.