We discuss the process integration to manufacture a spatial light modulator (SLM) device for application in mixed and augmented reality. The MEMS-part of the device is integrated on an external 180nm CMOS. The SLM consists of an 8MPixel micro mirror array with a pixel size of 4μm x 6μm. To provide the vertical strokes necessary for RGB color image generation, a comb-drive actuator concept was developed. Besides the yoke and the stator of the comb-drive, the actuator uses a double spring structure to reduce tilting of the mirror and other stress-induced effects. At the beginning of the product development we used iLine-lithography only, while later for the final device we switched to KrF-lithography to provide the necessary feature size down to 200nm as well as better CD-uniformity and overlay specification. We describe the process development, with focus on the lithography and etching processes for the actuator. Especially the different processes for patterning the Titanium-Aluminum structures of ultra-thin springs as well as the yoke and the stator with their high aspect ratios, which are specific for MEMS processing. Finally we achieved post-etch CD-uniformity <10nm per wafer for all metal structures as well on-product-overlay accuracy <15nm.
Market penetration of automotive head-up displays (HUD) is increasing and extending from higher-end models to midrange and even compact cars. New HUD use cases will be motivated by autonomous driving as well as improved HUD abilities. Holographic 3D (H3D) HUD will contribute to further improve the usability and attractiveness, specifically by presenting images with a full consistency of all depth cues. Based on results from H3D-HUD implementations, it is explained how H3D images are created and how viewers benefit from the unique 3D solution that eliminates ambiguity of the presented information and improves safety by properly overlaying virtual 3D objects with the real world. The difference between possible SLM options is explained, including references to ongoing development of high-resolution phase-modulating micro-mirror-based SLM (micro mirror arrays, MMA). It is compared how use of MMA vs. LCoS can improve selected features and the user experience. Ongoing development of MMA in a consortium of expert companies and institutions and results of already manufactured MMA are presented.
Nowadays, virtual, augmented and mixed reality applications are becoming more and more widespread. With this, the requirements for image quality are getting more demanding, leaving room for improvement of the user experience of the existing systems. While many research groups and companies try to improve on fixed-focus stereo image systems, we propose to make use of real holography as the best possible solution providing all depth cues automatically in a consistent way. Within such holographic display systems, a spatial light modulator (SLM) is re-shaping the incident light generating the desired images. As SLMs with the required properties are not commercially available today, a novel device is being developed within the Horizon 2020 ’REALHOLO’ project funded by the European Union: a MEMS micromirror Array (MMA) with 8 million phase-shifting pixels based on a novel comb drive micro actuator concept. Earlier theoretical work and simulations had showed clear perspectives for a superior performance in comparison to other SLM technologies allowing high frame rates and high precision wave front modulation. By now the first samples of proof-of-concept MMA chips have been fabricated and in this paper we present experimental characterization results: microscope and SEM images, quasi-static response curves measured by white light interferometry (WLI) as well as the dynamic properties like resonance frequency and damping measured by laser doppler vibrometry (LDV). In addition an addressing approach for a minimum mirror settling time is also investigated. We discuss the impact of fabrication tolerances on the overall precision together with the response curve dependency on design parameters and compare the experimental results to simulations.
Earth Observation (EO) systems are generating an ever-increasing amount of data to be handled on board yet with limited resources, which sometimes hinders a full exploitation of the information content. In this paper, we present a demonstrator of a super-resolved compressive imager operating in whiskbroom mode in the Visible-Near Infrared (VISNIR) and Medium Infrared (MIR) spectral ranges. The demonstrator, which is under development in the frame of the EU H2020 funded SURPRISE project, is based on the use of a Digital MicroMirror Device (DMD) as a core element of its architecture and it is inspired by a single-pixel camera in order to avoid the use of large focal plane arrays. The demonstrator has 10 channels in the VNIR and two channels in the MIR and it can reach a super-resolution factor from 4 x 4 to 32 x 32, that is the ratio between the number of pixels of the image reconstructed at the end of the process and the number of pixels of the detector. Besides, on the grounds of the results obtained by image reconstruction tests on simulated datasets by using Deep Learning based algorithms, data are expected to be natively compressed with a Compression Ratio up to 50%. The study is expected to provide valuable insight for the future development of a novel class of EO instruments with improved performances in terms of ground sampling distance, native compression and on-board processing capabilities. Additional presentation content can be accessed on the supplemental content page.
Spatial Light Modulator (SLM) technologies are well established in many application fields over the last decades. Addressing challenging operational conditions, a special class of high-speed SLMs has emerged over the past 20 years, namely Micromirror Array (MMA) devices. Fraunhofer IPMS MMA technology has enabled several ultraviolet photolithography applications at industrial scale. Given the fact that these devices are available for scientific testing, we proposed to explore for the first time their functionality and performance with respect to the space application requirements for the European framework cooperation. Previous studies strongly support this approach with the investigation of several SLM technologies for space instrumentation. In this study, the key parameters of an already available 256 x 256 pixel MMA device have been assessed and its performance has been evaluated under environmental constraints of a future space mission, in terms of temperature (from -40 °C to 80 °C), vacuum (< 10-5 mbar) and vibrations in X-, Y- and Z-axes, showing zero failure rate for the MMA device after all tests. These experimental findings, together with simulations results, confirm the robustness of the MMA technology, especially against temperature changes, and encourage further activities for the development of a space-customized spatial light modulator technology.
The package of a Micro-Opto-Electro-Mechanical System (MOEMS), a Micro Mirror Array (MMA) based Spatial Light Modulator (SLM), has to stay stable over the full operation temperature range and throughout SLM lifetime in spite of the inevitably different coefficients of thermal expansion (CTE) of the various materials involved. Additionally, in our case the window not only protects the MMA from mechanical damage and corrosion but also serves an optical function as part of a beam combiner. Within the European Union funded Project REALHOLO we are therefore developing a packaging concept that accomplishes the desired optical functionality while meeting the challenge of precise alignment of the window relative to the micro mirrors in lateral direction, which is the motivating factor behind the FEM simulations presented here. The objective of this research is to stabilize the package when subjected to temperature changes by simulating its thermomechanical behaviour with Ansys WorkbenchTM. A heatsink, a silicon crystal-based MEMS chip, and a window are glued together to form the package. Materials used for window and heatsink components, respectively, are chosen for a best possible CTE match. The significant parameters to be considered for package optimization are the misalignment between window and chip, the stress induced in the package, especially the glue, and the global deformation of the MMA surface. This paper discusses the challenges and possible solution based on a series of simulation findings.
MEMS (micro electro mechanical system) based piston mirror arrays are key elements for real time computer generated holograms (CGH) in visualisation technologies like virtual, augmented and mixed reality (VR/AR/MR). The EU funded Project REALHOLO is developing a spatial light modulator (SLM) that is based on comb drive MEMS actuators that can fulfil the tight requirements of the optical and mechanical performance and the high level of integration. A previous design already outlined perspectives for a superior performance in comparison to other approaches for high frequency and high precision wave front modulation, but has restrictions due to the resolution and feature size of the i-line lithography system used for manufacturing. This paper discusses the optimisation of the design applying an advanced manufacturing process using DUV lithography that allows smaller features and therefore offers additional design options. By introducing an improved comb drive geometry the electrostatic force was significantly increased, which allowed the optimisation of other geometries, like horizontal and vertical gaps and additional shielding structures, for an even more linear actuator response and reduced crosstalk. The electrostatic and structural FEM simulations will show the significant improvements in overall performance, compared to the previous iteration and other types of SLMs. The improved actuator can potentially extend the field of application from the desired automotive driver assistance holographic 3D display to head mounted displays for VR, AR and MR applications as well as other technologies like material processing.
The need of high-resolution Earth Observation (EO) images for scientific and commercial exploitation has led to the generation of an increasing amount of data with a material impact on the resources needed to handle data on board of satellites. In this respect, Compressive Sensing (CS) can offer interesting features in terms of native compression, onboard processing and instrumental architecture. In CS instruments the data are acquired natively compressed by leveraging on the concept of sparsity, while on-board processing is offered at low computational cost by information extraction directly from CS data. In addition, instrument’s architecture can enjoy super-resolution capabilities that ensure a higher number of pixels in the reconstructed image with respect to that natively provided by the detector. In this paper, we present the working principle and main features of a CS demonstrator of a super-resolved instrument for EO applications with ten channels in the visible and two channels in the medium infrared. Besides the feature of merging in a single step the acquisition and compression phases of the image generation, its architecture allows to reach a superresolution factor of at least 4x4 in the images reconstructed at the end of process. The outcome of the research can open the way to the development of a novel class of EO instruments with improved Ground Sampling Distance (GSD) - with respect to that one provided natively by the number of sensing elements of the detector - and impact EO applications thanks to native compression, on-board processing capabilities and increased GSD.
Computer generated holography (CGH) offers the best possible solution for very interesting applications like virtual, augmented and mixed reality. To get the images from the computer into the real world, spatial light modulators (SLMs) are required that fulfil very demanding specifications. Unfortunately, none of the currently available kinds of SLMs can meet this challenge fully. Within the European Union funded Project REALHOLO we are therefore developing a novel kind of MEMS (micro electro mechanical system) SLM especially for CGH applications. The challenge is to modulate the phase of incoming coherent light with millions of individually controllable pixels. The pixels have to be only a few micrometers in size for acceptable diffraction angles and still have a stroke range of half the wavelength of visible light, about 350nm. Within this range, each pixel needs to be set very precisely to one of many deflection levels at frame rates of more than one kHz. This paper discusses the challenge and our solution: an innovative MEMS comb drive actuator array, monolithically integrated on top of a CMOS backplane. The advantages of this design are compared to other types of SLMs and its superior performance is shown by FEM simulations. We also discuss the impact of effects like charging and fabrication imperfections on the deflection precision. Our newly developed MEMS technology and SLM will also enable many other applications that may benefit from the fast and precise phase modulation by a large number of pixels, like wave front shaping or quickly re-programmable diffractive optical elements (DOEs).
We developed a novel 512 x 320 tip-tilt micro mirror array (MMA) together with the entire related technology platform, including mirror fabrication process, integrated CMOS address circuitry and external drive electronics. The MMA itself consists of 2axis-tip-tilt actuators at 48μm pixel size, allowing a continuous pure tip-tilt motion up to 3.5° in arbitrary directions, fully calibratable at standard deviations of better than 0.025°. The mirrors are realized within a 2-level architecture defined by three structural layers, two for hinge and reinforcement suspension and one for the overlying mirror. They are fabricated by surface-micromachining within a fully CMOS compatible process. MMA programming is accomplished by an underlying CMOS backplane supporting drive voltages up to 27V and frame rates up to 3.6kHz.
Applications like computer generated holography or wavefront shaping call for spatial light modulators (SLMs) with millions of phase-shifting pixels of only a few micrometers size which are precisely addressable in an analogue way at frame rates of many kHz. While liquid crystal on silicon (LCoS) devices are commonly used, they can't offer very high frame rates and their polarization effect is often considered a drawback. On the other hand, MEMS devices with phaseshifting micro mirrors are not readily available but have a high potential to fulfill the requirements. It is quite challenging to reach the desired deflection range with the limited available addressing voltages. For symmetry usually at least two springs are squeezed into the tight space the small pixels offer. This paper presents an innovative way to get a good sensitivity by using a single hinge per pixel that therefore can be made especially weak. It might be astonishing but there actually are various ways to design electrostatic actuators that deliver pure piston movement with only one spring. We discuss the basic concepts of such force-balanced single spring actuators and give a variety of examples and guidelines to tune a basic pixel layout for pure piston motion. Simulations show the tilt-free response and the stability against tilting torques that might be the result of possible imperfections in manufacturing, like lithographical overlay errors or stress gradients. We also show the possibility to dynamically balance the pixel for a pure piston first eigenmode.
Fraunhofer IPMS has developed a one-dimensional high-speed spatial light modulator in cooperation with Micronic
Mydata AB. This SLM is the core element of the Swedish company’s new LDI 5sp series of Laser-Direct-Imaging
systems optimized for processing of advanced substrates for semiconductor packaging. This paper reports on design,
technology, characterization and application results of the new SLM. With a resolution of 8192 pixels that can be
modulated in the MHz range and the capability to generate intensity gray-levels instantly without time multiplexing, the
SLM is applicable also in many other fields, wherever modulation of ultraviolet light needs to be combined with high
throughput and high precision.
The Fraunhofer Institute for Photonic Microsystems (IPMS) develops and fabricates MOEMS micro-mirror arrays for a
variety of applications in image generation, wave-front correction and pulse shaping. In an effort to extent the
application range, mirrors are being developed that withstand higher light intensities.
The absorbed light generates heat. Being suspended on thin hinges, and isolated from the bulk by an air gap, the mirrors
heat up. Their temperature can be significantly higher than that of their substrate.
In this paper we describe an experiment carried out to verify simulations on the temperature within the mirror plates
during irradiation. We created a structure out of electrically connected mirror plates forming a four-point electrical
resistor, and calibrated the thermal coefficient of the resistor in a temperature chamber. We irradiated the resistor and
calculated the mirror temperature.
In the experiment, the temperature in the mirror plates increased by up to 180 °C. The mirrors did not show significant
damage despite the high temperatures. Also, the experiment confirms the choice of heat transport mechanisms used in
the simulations. The experiment was done on 48 μm x 48 μm mirrors suspended over a 5 μm air gap, using a 355 nm
solid-state laser (4 W, up to 500 W/cm2).
The Fraunhofer IPMS, in cooperation with Micronic Laser Systems, develops and fabricates micromirror arrays used as
spatial light modulators (SLM) for image generation in microlithography. The SLMs used consist of 2048×512
individually addressable micromirrors of 16×16μm2 and can be operated in an analog mode at a frame rate of up to
2 kHz. There are continued efforts to improve the performance of the mask writers with respect to stability and CD
uniformity, which include measures to improve the SLMs used, especially with respect to the optical quality and the
stability.
Therefore, a new technology has been introduced which allows to use different materials for the mechanical suspension
and the mirror, thus optimizing them separately. The hinges are made of a thin layer of a material with very good creep
resistance, while the mirrors consist of a thick aluminium alloy with high reflectivity in DUV. Furthermore, the same
inorganic material is used for the planarization of the electrodes (by means of chemical mechanical polishing) and as
sacrificial layer for the actuator fabrication. Thus, at the end of the process, all sacrificial material, including that
between the electrodes is removed. In this way, the charging effects caused by dielectrics between the electrodes (as seen
in the previous devices) are eliminated.
The first devices using the technology described above have been fabricated and tested. The first tests in a lithography
machine show that considerable improvements in machine performance can be expected. The next steps are to stabilize
and optimize the process.
We describe charging effects on spatial light modulators
SLM. These light modulators consist of up to one million mirrors that
can be addressed individually and are operated at a frame rate of up to
2 kHz. They are used for deep ultraviolet DUV mask writing where they
have to meet very high requirements with respect to accuracy. To be
usable in a mask-writing tool, the chips have to be able to work under
DUV light and maintain their performance with high accuracy over a long
period of time. Charging effects are a problem frequently encountered
with MEMS, especially when they are operated in an analog mode. In
this work, the issue of charging effects in SLMs used for microlithography,
their causes and methods of their reduction or elimination, by
means of addressing methods as well as technological changes, is
discussed. The first method deals with the way charges can accumulate
within the actuator. It is a simple method that requires no technological
changes but cannot always be implemented. The second involves
the removal of the materials within the actuator where charges
can accumulate.
The present article discusses steps for the realistic description of optical properties of micro-mirror arrays (MMA),
which are utilized as programmable masks for microlithography. The article focuses on global contrast as an
elementary example for the understanding of MMA's diffractive operation principle. Central point will be a
discussion of those MEMS properties that influence the global MMA contrast, and how to introduce them into
simulation. Surface corrugations of single mirrors and slit properties will be taken into account. Comparison is
made with experimental contrast data to validate the theoretical assumptions.
This paper describes charging effects on spatial light modulators (SLM). These light modulators consist of up to one
million mirrors that can be addressed individually and are operated at a frame rate of up to 2 kHz. They are used for
DUV mask writing where they have to meet very high requirements with respect to accuracy.
In order to be usable in a mask-writing tool, the chips have to be able to work under DUV light and maintain their
performance with high accuracy over a long time. Charging effects are a problem frequently encountered with MEMS,
especially when they are operated in an analog mode.
In this paper, the issue of charging effects in SLMs used for microlithography, their causes and methods of their
reduction or elimination, by means of addressing methods as well as technological changes, will be discussed. The first
method deals with the way charges can accumulate within the actuator, it is a simple method that requires no
technological changes but cannot always be implemented. The second involves the removal of the materials within the
actuator where charges can accumulate.
KEYWORDS: Actuators, Electrodes, Mirrors, Capacitors, Analog electronics, Electronics, Finite element methods, Chemical elements, Safety, Electromagnetism
Electrostatic Micro-actuators are being increasingly used for a wide variety of applications such as spatial light modulators, scanning mirrors, optical cross connects, micro-valves, and others. Usually the electrical forces operate in one direction and are balanced by a mechanical spring. The resulting deflection is then either defined by a mechanical stop, or it is only a meta-stable equilibrium position: at an additional external force or deflection it will snap to a different position, frequently again defined by a mechanical stop. This issue is well known and is often called 'pull-in'. In the often used parallel-plate capacitor actuator, the instability already begins at a deflection of only on third of the original capacitor plate separation. For safety reasons and due to the steep response-curve one can only use an even smaller fraction of the mechanically possible movement. This means, that the gap below the actuator has to be designed very much larger than the required maximum deflection. To get the pre-described force and deflection, a much higher voltage is needed than for potential smaller gap widths. The useable range of deflection for many types of micro-actuators can be extended without the penalty of large drive voltage or low shock resistivity, by employing springs with steeper-than-linear restoring force. Alternatively, the voltage needed for a given range of deflection may be reduced. This paper shows the benefits and how to design and dimension these types of springs.
The Fraunhofer IPMS and Micronic Laser Systems AB have developed a technology for microlithography using spatial light modulation (SLM). This technology uses an array of micromirrors as a programmable mask, which allows parallel writing of 1 million pixels with a frame rate of up to 2 kHz. The SLM is fabricated at the IPMS using its high-voltage CMOS process. The mirrors are fabricated by surface micromachining using a polymer as sacrificial layer. The mirrors are operated in an analog mode to allow sub-pixel placement of pattern features. This paper describes the function of the SLM with an emphasis on the stability of the mirror deflection and a method to improve it which has been implemented.
The Fraunhofer IPMS and Micronic Laser Systems AB have developed a technology for the maskless DUV microlithography using spatial light modulation (SLM). This technology uses an array of micromirrors as a pro-programable mask, which allows writing up to 1 million pixels with a framerate of up to 2 kHz. The SLM is fabricated at the IPMS using its high-voltage CMOS process. The mirrors are fabricated by surface micromachining using a polymer as sacrificial layer. The mirrors are operated in an analog mode to allow sub-pixel placement of the features.
The Fraunhofer Institute for Microelectronic Circuits and Systems (FhG-IMS) has developed spatial light modulators (SLM), which are used in a pattern generator for DUV laser mask writing developed by Micronic Laser Systems. They consist of micromirror arrays and allow massive parallel writing in UV mask writers. The chip discussed here consists of 2048 × 512 individually addressable mirrors and can be run at a frame rate of 1 to 2 kHz. For this application it is necessary that the SLMs can be operated under DUV light without changing their performance. This paper discusses a failure mechanism of the SLMs when operated in DUV light and countermeasures to eliminate this effect.
The Fraunhofer IMS in Dresden is developing and fabricating spatial light modulators (SLMs) for micro lithography with DUV radiation. The accuracy of analog modulation is very important for the resulting accuracy of the generated features. On the other hand, fabrication tolerances create variations for example in spring constant, zero voltage deflection, and reflectivity. The slightly different response curves of the individual pixels therefore require an individual calibration. The parameters of these are stored in a look-up table so that the proper addressing voltage for the required optical response can be selected. As the deflection angle as well as the size of the SLM pixels are quite small, a direct measurement of the pixel response is not straightforward. An optical system similar to the one in the lithography machine has been set up, where the SLM is operating as a phase grating and the image is generated by a spatial filter. The pixel deflection can be calculated from the aerial image for isolated deflected pixels. The background pixels, that are not calibrated yet, contribute some error to this calculation. However, this error is not very large. Simulations regarding the accuracy of this measurement are discussed, and experimental results are shown.
Modern UV-lithography is searching for new highly parallel writing concepts. Spatial light modulation (SLM) offers such possibilities but special emphasis must be put on the ability of SLM devices to handle ultraviolet light (UV). We designed and fabricated micromirror arrays which fulfill these requirements. Possible applications for such UV-SLMs are direct writing systems for semiconductor and printing, and UV-stimulated biochemistry. For deep UV laser pattern generation (248 nm) e.g. we designed and fabricated a 2048x512 pixel UV-SLM with individually addressable aluminum micromirrors. They are illuminated by an excimer laser pulse and imaged onto a photomask substrate. A complete pattern is stitched together at a rate of 1 kHz. The minimum feature size is 320 nm and analog modulation of the pixels allows to realize an address grid of only 1.6 nm. The design of the array is modular so that other array sizes can be tailor made to customers needs. Design and fabrication aspects for a CMOS compatible realization of these micromirror arrays are addressed as well as their performance in lithography applications.
A new breed of pattern generators for photomasks using a new DUV spatial light modulator (SLM) technology is under development in a collaborative effort between Micronic Laser Systems AB, Taby, Sweden and the Fraunhofer Institute for Microelectronic Circuits and Systems (FhG-IMS), Dresden, Germany. Current pattern generator architectures using a limited number of scanning beams will not be able to support future production requirements with ever-increasing data complexity and resolution. The new SLM technology provides a means for high resolution and massive parallel exposure to alleviate these difficulties. There are many architectural similarities to that of a modern stepper and the technology can provide the resolution to rival that of e-beam pattern generators, yet with the productivity of laser patterning. In this paper we describe the architecture of an SLM exposure system, the SLM technology, and will consider key aspects for the intended application.
Over the last few years, high resolution spatial light modulators (SLMs) have been developed at the IMS Dresden. These are fabricated using one of two different technological processes. In one version a flexible, highly reflecting aluminum coating of about 50nm is evaporated onto a elastic layer, while the other version has quite rigid aluminum mirrors that are suspended by flexible hinges above the substrate. Both versions are fabricated on top of a CMOS DRAM matrix, which allows the addressing of individual pixels. So far SLMs with over 2 million pixels have been produced. In order to ensure a high quality of these SLMs a map of the SLM under test is needed showing the exact position of defective pixels together with the type of defect e.g. not responding, always deflected, wrong spring constant, poorly reflecting surface. Additionally information on the local and global flatness is required. This task can only be handled by an automated test stitching together many single measurements. A test system has bene set up using a white light interferometer. This allows to measure the response of each and every SLM pixel to applied voltages.
Design and modeling aspects of torsional 1D and 2D Micro Scanning Mirrors are presented. During the oscillation of the mirror plate the inertial moment gives rise to a deformation of the plate. This dynamic deformation results in a defocusing of the reflected laser beam. Therefore, the scan frequency of a device with a given size of the mirror plate and deflection angle is limited. Further restrictions arise from the demanded mechanical robustness like resistivity against shock and torsional stress. This leads to a minimum eignefrequency of the device which in the case of a rectangular shaped is proportional to the width of the spring. To enable a single mode operation it is advantageous that the torsion around the springs is the lowest mode sufficiently separated from all others. A FEM-analysis has been carried out to determine the mode sequence of a 1D and a 2D Micro Scanner respectively. The analytical calculated eigenfrequencies agree well with the numerical determined. Taken into account the result of the analytical and numerical investigations 1D and 2D Micro Scanning Mirrors have been designed and fabricated. The mirror and the springs are defined in a 20 to 30 micrometers thick single crystal silicon layer. The results of the experimental investigations with respect to the shock resistivity and the long run behavior probe the suitability of the modeling.
Three different types of deformable mirror Spatial Light Modulators (SLMs) based on device concepts like Viscoelastic Control Layer (VCL), Cantilever Beam Mirror (CBM), and Moving Liquid Mirror (MLM) have been developed. All of them allow to create deformation profiles which act as phase gratings whose period is defined by the pitch of the pixel electrodes. The diffraction of the incident light is used to achieve spatial light modulation. The operation principles of the different types of SLMs are outlined in detail. All the mentioned SLMs can be manufactured on top of a high voltage CMOS circuitry. SLMs with up to 2 million pixels in analog operation mode have been realized up to now. The benefits of the different approaches with respect to fabrication aspects and respect to different applications will be addressed. For the angular deflection of light a new type of resonant microscanner mirror was developed. The device is based on a silicon micromechanical torsional actuator. The new approach for the configuration of the electrodes and the resulting driving principle allows to achieve large scanning angles (plus or minus 30 degree optically at atmospheric pressure) at low driving voltages (20 V max.) and low power consumption (less than 1 (mu) W). The operation principle of the new device enables the realization of 2D scanners as well.
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