Laser 2009

Dresden, / April 30, 2009

June 15 - 18, 2009 in Munich/Germany

Joint Booth of the Fraunhofer Gesellschaft
Hall B2 Stand 421

The Fraunhofer IPMS carries out customer specific developments in fields of microelectronic and micro systems technology in Dresden, serving as a business partner that supports the transition of innovative ideas into new products. The Fraunhofer IPMS develops and fabricates modern CMOS technology products in its own clean room facilities, up to small pilot series production. With modern equipment and about 240 scientists, the range of projects and expertise covers sensor and actuator systems, microscanner, spatial light modulators, lifetronics and organic materials and systems.

At the LASER 2009 in Munich the Fraunhofer IPMS presents:

1. Laser projection systems in measurement and industrial applications

Ultra compact laser projection systems based lasers as light source and micro scanning mirrors for light deflection are considered as future products with enormous market potential for the infotainment sector, because it will be possible to integrate them into mobile devices rather soon. Image generation is achieved via the Flying Spot principle: the laser beam reflected by the two-dimensional micro scanning mirror describes a dense Lissajous pattern on the projection screen that hits every virtual pixel at least once during the time available for one image frame. By modulation of the intensity of the laser beam and the driving of the scanning mirror in a strictly synchronous manner, projection of arbitrary images can be achieved. However, also measurement and industrial applications may profit from the advantages of such systems. This is proven by the demonstrator of Fraunhofer IPMS shown at LASER 2009. The system detects the continuously changing distance to one object and projects the measured value on the surface of the object. Because of the quasi unlimited depth of field, the projected image is always in focus. Concrete applications include support of maintenance and assembly tasks, Augmented Reality and all other industrial systems, where the job will become easier for the worker if additional information is displayed.

2. MEMS Spatial Light Modulator Demonstrator

MEMS Spatial Light Modulators (SLMs) are used to arbitrarily modulate the entire cross section of an incident beam of light simultaneously. Usually, MEMS thin film technology is used to fabricate an array of micromirrors on top of a CMOS backplane. Each mirror can be addressed and moved individually to control either intensity or phase of one pixel. SLMs are used in a range of applications from video projectors to Adaptive Optics (astronomy, ophthalmology) and mask writers in the semiconductor industry. Contrary to the digitally addressed SLMs in projectors that use time multiplexing to generate grey levels, the SLMs developed by Fraunhofer IPMS are addressed with analogue voltages that enable the chip to directly generate analogue intensities. Micronic Laser Systems ABs mask writers exploit this feature to shift the generated patterns with accuracies far smaller than the system's pixel resolution. The mirrors of the Fraunhofer IPMS device are specified for monochromatic light between 248 nm up to 520 nm, enabling not only the use of the DUV excimer wavelengths, but also the less aggressive (and less costly) near UV light sources. One example where the mirrors could be used is pattern generation for High Definition Interconnect (HDI) for Laser Direct Imaging (LDI) of printed circuit boards, but also other areas that require a combination of both highest resolution and throughput. The SLM is capable of patterning 1 million pixels at a framerate of 2 kHz (that is, 2 Gpixel/s). The demonstrator setup visualizes the function of the SLM. A green LED generates a light beam, lenses and mirrors guide the light onto the SLM, where it is modulated. The reflected beam is then filtered and projected into a camera. The live image of this camera shows the pattern programmed in the SLM.

3. Miniaturized Laser Scanning Microscope

A very compact laser scanning microscope will be presented at the LASER 2009, which is based on a 2d micro scanner mirror developed by Fraunhofer IPMS. Many applications use laser microscopes for the evaluation of different kinds of samples. Always the object is scanned by a laser beam and light intensity strayed back from the samples is gathered by a suitable detector unit. A simple image of the object can directly be taken from the intensities measured and the position information of the laser spot. Some applications would require a small robust device which can be operated mobile. For this task Fraunhofer IPMS has invented a MEMS based miniaturized laser scanning microscope (LSM). The MEMS based LSM operates similar to the larger systems based on classical optics, but uses a miniaturized MEMS scanner mirror for light deviation as core component. The prototype is only 200 x 100 x 40 mm³ wide and 800 g light. The optical bench has been realized in a way, that leads the intensity of a semiconductor laser on the scanner mirror, than through a beam splitter and finally through a telecentric objective on the sample. After the interaction with the sample surface, the intensity strayed back is gathered through the objective in reverse direction by a detector behind the beam splitter. The image can have up to 1000 x 1000 pixels from an object up to 10 x 10 mm² wide. Selected light sources and detectors with suitable filters could feature fluorescence images. An aperture stop can be used to get dark field images instead of the normal bright field image. Besides the scanner mirror itself Fraunhofer IPMS invented the optical bench, the complete system electronics and the software for operation and image reconstruction.

4. Microscan – a 1D scanner module

Based on its competence in developing and fabrication of micro scanner devices the Fraunhofer IPMS presents a 1D micro scanner module. Its modular platform approach was developed to bridge the gap between the supply of bare micro scanner die and the final integration in the customer application. With the drastic enhancement of the short term availability of OEM-capable customized solutions the institute proofs its competence for packaging, electronics development and system design. The application specific scanner system can be composed referring a kit of compatible and as far as possible pre-developed components. Keeping the interface constraints even single components can be modified in a wide range according to the customers' request.

The complete modular platform consists of:

  • Micro scanner device (customized developed and fabricated at Fraunhofer IPMS),
  • Chip carrier with optional hermetic housing and front optics,
  • Optoelectronic sensor for mirror deflection measurement,
  • Electronics for driving the scanner and the deflection sensor with a standard communication interface (SPI) and I/O ports.