786 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. … · 786 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 4, AUGUST 2006 Two-Axis Electromagnetic Microscanner for High

786 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 4, AUGUST 2006

Two-Axis Electromagnetic Microscanner for HighResolution Displays

Arda D. Yalcinkaya, Hakan Urey, Dean Brown, Tom Montague, and Randy Sprague

Abstract—A novel microelectromechanical systems (MEMS)actuation technique is developed for retinal scanning displayand imaging applications allowing effective drive of a two-axesscanning mirror to wide angles at high frequency. Modeling ofthe device in mechanical and electrical domains, as well as the ex-perimental characterization is described. Full optical scan anglesof 65 and 53 are achieved for slow (60 Hz sawtooth) and fast(21.3 kHz sinusoid) scan directions, respectively. In combinationwith a mirror size of 1.5 mm, a resulting opt product of 79.5deg mm for fast axis is obtained. This two-dimensional (2-D)magnetic actuation technique delivers sufficient torque to allownon-resonant operation as low as dc in the slow-scan axis whileat the same time allowing one-atmosphere operation even atfast-scan axis frequencies large enough to support SXGA (12801024) resolution scanned beam displays. [1653]

I. INTRODUCTION

SCANNED light beams are used to produce display imagesfor a wide variety of applications, including such applica-

tions as automotive head-up displays and head-worn displays[1]–[4]. A mirror producing angular motion is used to deflecta modulated light beam on an image plane to create a display.In order to construct a two-dimensional (2-D) rasterlike rectan-gular image, the mirror is rotated about two orthogonal axes atdifferent frequencies.

High performance microelectromechanical systems(MEMS)-based display design is a very challenging work.The scanner represents the system’s limiting aperture, re-quiring a sufficient size. Besides, the mirror flatness of fractionsof a wavelength has to be realized so as not to distort the beam’swave front. The scan frequency has to be high enough to handlethe many millions of pixels per second. Two-axis scan oversignificant angles has to be performed in order to paint a wideangle, 2-D image. Using the presented new actuation method,MEMS scanner designs have been implemented satisfying therequirements of a variety of display and imaging applications.

This paper describes modelling and characterization of anovel high performance 2-D MEMS scanner for display ap-plications. The presented device uses mechanical coupling ofthe outer frame motion into the scan mirror. The outer frame isactuated in two axis using an electromagnetic torque, createdby a single coil interacting with an external magnet placedat 45 to the orthogonal axis. This novel actuation technique

Manuscript received July 9, 2005; revised November 14, 2005. Subject EditorN. C. Tien.

A. D. Yalcinkaya and H. Urey are with the College of Engineering, Koç Uni-versity, TR 34450 Istanbul, Turkey.

D. Brown, T. Montague, and R. Sprague are with Microvision, Inc., Bothell,WA 98011 USA.

Digital Object Identifier 10.1109/JMEMS.2006.879380

Fig. 1. Conceptual optics of the retinal scanning beam display (RSD). The finalimage on the retina is a 2-D raster pattern.

allows producing large scan angles at low actuation powers dueto high mechanical quality factors obtained in air. Since thereis no direct electrical or mechanical loading on the scan mirror,exceptionally high quality factors are obtained in air. Anotherstrength of the device is to use single coil, single magnetexcitation for 2-D scan profile, yielding a simple yet low-powerdrive. Scan angle, mirror size and operation frequency of thepresented device allows 30 Mpixel/s addressibility for a 2-Dretinal scanning display (RSD). The structural material of thedevice is single crystalline silicon (SCS) and implementation isdone through standard MEMS fabrication processes.

Important features of the retinal scanning displays are out-lined in Sections II. III describes the display operation and ben-efits of the actuation technique used in the proposed device.Section IV gives a brief information on device realization. InSection V, equations of motion will be obtained through energymethods. Finite element analysis and electrical equivalent mod-eling of the microscanner is supplied in this section as well. InSection VI, experimental results and compatibility of the FEAand analytical models with the measurements are discussed. Fi-nally, in Section VII concluding remarks are supplied.

II. SYSTEM DESCRIPTION

The basic concept of a scanned beam display is shown inFig. 1. The beam from the light source is sent to the MEMSscanner and focused onto an intermediate image plane with col-lection optics. The position of this focus point is determinedby the angle of the scanning mirror. During the operation, themirror is scanned biaxially, creating a 2-D pattern onto the in-termediate image plane [4]. A set of relay optics is used to relay

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YALCINKAYA et al.: TWO-AXIS ELECTROMAGNETIC MICROSCANNER FOR HIGH RESOLUTION DISPLAYS 787

this image pattern onto the viewer’s eye. The focused spot po-sition on the retina is a direct function of the biaxial angles ofthe mirror.

Assuming that the aberrations are controlled and the systemis only limited by diffraction, the beam spot size is given as [5],[9]

(1)

where , is the focal length, is the diameterof the exit pupil and is a shape factor which stands for var-ious aperture shapes and illumination conditions. If the scannerserves as the aperture stop of the system, number of resolvablespots is then found to be

(2)

where is mechanical zero-to-peak angle, and is op-tical full range scan angle. In addition to (2), other factors, suchas mirror overscan and incoming beam angle have to be takeninto account for a more precise resolution calculation for dis-plays. Along the horizontal scan frequency , the product of

is the most important performance measure of scannerbased displays, as it determines the display resolution along thehorizontal axis. The ratio of horizontal scan frequency to dis-play refresh rate determines the vertical display lines. Illustra-tive numbers of for two extreme cases QVGA (320240) and HDTV (1280 720) can be given as 16 at 8kHz and 100 at 36 kHz, respectively.

In order to form the rectangular image, the mirror is deflectedhorizontally at a high-frequency and vertically at the desired re-fresh rate. The horizontal scan is sinusoidal and bidirectional.The drive frequency is chosen to be at the horizontal resonantfrequency of the mirror. The vertical scan is a unidirectionalramp at 60 Hz, which is well below the vertical resonant fre-quency of the mirror.

III. OPERATION OF BIAXIAL MAGNETIC SCANNER

Operation of the biaxial scanner depends heavily on super-imposing the drive torques of the slow and fast scan directions.The superimposed torque is applied at 45 relative to the two or-thogonal scan axes. This approach uses Lorentz’s force excita-tion of the scanner, created by an external magnetic fieldand a current carrying coil [8], [10]. Fig. 2(a) shows the layoutof the scanner, where a suspended outer frame with a multi turnspiral coil and an inner mirror (scan mirror) attached to the outerframe through fast scan flexures can be identified. As shownin Fig. 2(a), slow (vertical) scan is performed about -axis andfast (horizontal) scan is realized about -axis. The externalfield is produced by an off-chip permanent magnet. The out ofplane force acting on a current carrying conductor is given as[12]

(3)

Fig. 2. (a) Schematic of the biaxial microscanner. The outer frame is connectedto the silicon substrate through the slow-scan flexures. In the figure only twoturns of the actuation coil are shown for simplicity. Direction of the forces atpoints a and b are into the paper plane, at points c and d are out of the paperplane. (b) Mechanical schematic of the outer frame-mirror coupled system. (c)Biaxial MEMS scanner die photo.

where is the current running through a closed path of andis the external magnetic field. Since the coil drive current formsa loop on the gimbal, the current direction is reversed acrossthe scan axes. This means the Lorentz forces also reverse signacross the scan axes, resulting in a torque normal to the externalmagnetic field. This combined torque produces responses in the


two scan directions depending on the frequency content of thetorque. The torque about axis can be approximated as

(4)

where is the number of coil turns, is the coil current,is the pitch between the coil turns, is the side length of

first coil turn on the short side of frame and is the side lengthof first coil turn on the long side of frame, respectively. Thefirst term in the summation component of (4) stems from theLorentz force, the second term stands for the torque arm. Ac-knowledging that the torque arm and coil side lengths inter-change between each other for different axes, magnitude of theactuation torques around and axes are the same. In order tocalculate the torque about axis, the first and the second termsof the summation are interchanged.

The mirror diameter and scan angles, along with the scan fre-quency, are chosen as design parameters for obtaining the de-sired resolution requirements of the display, as indicated by (1).A vertical refresh rate of 60 Hz with a 600 line (SVGA) display,the horizontal scan rate must exceed 18 kHz. Additionally, thespot size has to be small enough for the desired resolution, dic-tating a mirror flatness requirement. The mirror is designed tokeep the dynamic deformation within 1/10 of the wavelength ofthe scanned beam.

In order to eliminate undesirable image artifacts, the verticalmirror motion is required to be a linear ramp. This means thevertical drive must provide sufficient torque to allow non-reso-nant actuation. Since the maximum torque must be applied atthe extremes of angular deflection, pulse drive methods, suchas the electrostatic comb drive often used in MEMS devices,are not suitable. It is desirable to avoid the relatively high volt-ages required for electrostatic actuation, so this type of driveis not suitable for this application. Other commonly used drivemechanisms, such as parallel plate electrostatic, comb-drive, orelectromagnetic require small gaps, which interfere with theflow-field of the mirror, reducing the -factor. Another advan-tage to this structure is not having any electrical conductors run-ning through the fast scan flexures, which can create fatigue andstress problems. Additionally, the scanner assembly should besmall and inexpensive to produce, which means that reducingtorque requirements by vacuum packaging is undesirable. Suffi-ciently high factor can be obtained without requiring vacuumpackaging, yielding low cost products.

For the horizontal (fast) scan, operation at atmospheric pres-sure produces high damping. A high drive torque is requiredto overcome this damping. For the vertical drive, the nonreso-nant operation demands a high torque to overcome the torsionalflexure stiffness. This stiffness cannot be set very low due to re-quirements for shock and handling robustness. The suspendedmass cannot be reduced due to mirror size and dynamic flatnessrequirements. A magnetic drive produces the necessary hightorques over the large scan angles needed to achieve the desiredoperation of both scan axes.

The slow scan motion of the scanner is performed by the nettorque produced by the forces at points and . The fast scan

Fig. 3. Packaged die assembly of the scanner and integrated position sensor.

is performed by exciting the outer frame in rocking motion, byutilizing the out-of-plane, out-of-phase forces at points and .This motion is coupled to the inner mirror and amplified by thehigh mechanical quality factor of the mirror resonance. As canbe seen from (4), it is possible to properly excite both scan axeswith only one applied drive mechanism.

The frequency components of the applied torque are selectedto excite the horizontal mirror resonance (21.3 kHz) and to pro-vide a ramp drive for the vertical mirror motion. The frequencyresponse characteristics of the mirror and gimbal respectivelyact as a band-pass filter and a low-pass filter to separate thetorque components into their respective motions. Resonant re-sponse modes of the scanner are shown in Fig. 4. The verticalresonant (slow-scan) mode and the horizontal mirror (fast-scan)resonant mode are shown in Fig. 4(b) and (d). Note that fastscan mode includes a counter-rotation of the gimbal ring withrespect to the mirror. This counter-rotation that is excited by the21.3 kHz drive signal component. Detailed analytical and ex-perimental results about the frequency spectrum of the scannermodes will be given in Sections V and VI. It is worth noting thatsince the operation of this device relies on separation of torquesabout - and -axes, it would not work as a 2-D pointing mirrorfor arbitrary rotations.

IV. REALIZATION

A picture of the scanner, highlighting the single drive coil onthe outer gimbal, along with the vertical and horizontal torsionalflexures, is shown in Fig. 3. The scanner is produced using stan-dard bulk MEMS fabrication techniques. All silicon features areformed from the starting wafer’s single crystal structure. Thisresults in extremely robust structures and highly reliable opera-tion even at large scan angles.

The die incorporates two integrated piezoresistive positionsensors, one for each axis, and the full die assembly includesa bottom protective cover [6]. The resulting assembly is easyto handle and assemble with very few interconnects required.The drive itself only requires two connections to drive bothscan axes. The remaining interconnects provide bias for the in-tegrated position sensors for each axis. These sensors are very


Fig. 4. FEA simulations of the mechanical modes of the 2-D scanner. (a) Points1–3 shown on the layout. (b) Torsion mode of the outer frame (slow scan). (c)Rocking mode of the outer frame in-phase with the mirror. (d) Rocking modeof the outer frame out-of-phase with the mirror (fast scan).

precise, allowing for the accurate scan angle control required ofhigh-performance displays.

V. MECHANICAL ANALYSIS AND ELECTRICAL

EQUIVALENT CIRCUIT

In this section, for the magnetically actuated scanner system,equations of motion will be obtained via the Euler–Lagrange(E–L) method. An equivalent schematic describing the parts ofthe system to be modelled is given in Fig. 2(b). In this figure,a scan mirror is suspended with a torsional spring to a frame,which moves both about its own torsional axis and fast-scanaxis. A convenient way of obtaining equations of motion is touse E–L method, where potential and kinetic energies for eachcomponent in the system is inspected. Defining the Lagrangianas

(5)

where and are the kinetic and potential energies, respec-tively, one can write the equations of motion as follows:

(6)

For the system sketched in Fig. 2(b), three variables arechosen as , and . Assuming a linearsystem, total kinetic energy, stemming from the inertial forceson the mirror and the outer frame, is

(7)

where , and are rotational mass moment of inertias forthe mirror torsion mode, outer frame rocking mode and the outerframe torsion mode. includes moment of inertias of both theouter frame and the scan mirror about the slow scan axis. Ef-fective values of can be calculated using tabulated formulas[9]. Potential energy term comes from the energy stored in thesprings

(8)

where is the torsional spring constant of the mirror, is thespring constant of the outer frame rocking mode and is thespring constant of the outer frame torsion mode, as illustrated inFig. 4. Substituting (7) and (8) into (5) results in

(9)Introducing damping terms, that are linearly dependent on an-

gular velocity as , to the right-hand side of (6), and substi-tuting , , and , following equations canbe derived:

(10a)

(10b)

(10c)

where is the viscous damping factor. In this model, dampingfactors are used as a parameter to fit the simulation data withthe experimental results. Equations (10a)–(10c) include timederivatives of the variables , and . Defining intermediatevariables as , , and , we can representthe equations of motion in the frequency domain ,in order to construct a transfer matrix between effort variables(force and torque) and flow variables (velocity)

(11)

This notation resembles with the -parameter set definition of alinear time invariant three-port electrical network

(12a)

(12b)

(12c)

where the reciprocity of the system can be observed from thematrix (i.e. ). Solution of (11) is

(13)


Fig. 5. Electrical equivalent of the mechanical system. The loop on the left-hand side stands for the scanner mirror and the one on the right-hand side standsfor the outer frame actuator. Component values are obtained using the geometryof the device through tabulated calculations [9].

where is the column vector representing the angular ve-locities, is the -parameter matrix of the 3-port electro-mechanical system and is the torque vector.

An electrical equivalent circuit of the mechanical system canbe constructed through the analogy between the mechanical andelectrical domains. Starting point for this effort is the matrixnotation of the system given (11). Choosing the effort and theflow as the torque and the angular velocity, electrical voltage ismapped to the force and similarly electrical current is mappedto the velocity. If a T-type coupling network is chosen as shownin Fig. 5, then each loop can be used to represent the corre-sponding row of matrix. Each loop in the equivalent circuitwill have a series resonator circuit as an electrical equivalent tothe mechanical spring-mass-damper model. Coupling betweenthese loops is done through the compliance of the mirror tor-sional spring. Inductors are used to emulate mass or momentof inertia, capacitors for compliances and resistors for dampinglosses. The branch containing elements of , , and con-ducts the current of and models the slow-scan motion of thescanner. Since the torsional motion of the outer frame does nothave any effect on the fast-scan motion, no coupling is used be-tween the slow-scan and fast scan loops. The rocking mode ofthe outer frame is modelled with , , and and cou-pled to the torsion mode of the mirror ( , and ) by a T-shapedcapacitor network.

SPICE simulation of the described equivalent circuit is pre-sented in Fig. 6. This plot represents the frequency spectrum ofthe points 1–3, previously shown in Fig. 4(a). The slow scan res-onance, associated with the torsion of the outer frame, occurs at400 Hz. This mode of the outer frame is followed by the mirrorand used for vertical scan operation at the refresh rate of 60 Hz.Refresh rate is chosen to be around the skirt of the resonancepeak, yet the actuation toque is sufficient to create large angulardisplacements. The resonance at 4 kHz belongs to a mode wherethe outer frame and the mirror are moving in-phase. The outerframe is in the rocking mode which is translated into the tor-sion of the mirror. This mode is not used in the operation of thescanner for display applications. The fast scan resonance, mod-elled by the mirror torsion box in Fig. 5 appears at 21.3 kHz. Thelarge ratio between the angular rotations of point 1 and point 2at this resonance proves the concept of the mechanical coupling.Essentially, a small rocking displacement of the outer frame isband-pass filtered, phase shifted and -times amplified at the

Fig. 6. SPICE simulation of the equivalent circuit given in Fig. 5.

resonance frequency to give peak scan angle. This mode doesnot respond significantly to the low frequency components ofthe drive torque, so the resulting scan motion is pure sinusoidalmotion at the resonant 21.3 kHz frequency.

Spectrum of point 2 presents a zero around 21.2 kHz stem-ming from the coupling between the outer frame and the mirror.The origin of this mechanical zero can be understood from (11),which defines the transfer function between the angular rotationand the respective drive torque of point-2. The location of thezero is outlined by element of the matrix, which constitutesthe nominator of the transfer function of point-2.

The frequency response of vertical (slow) scan mode greatlyattenuates the 21.3 kHz component as can be seen by the fre-quency spectrum of point-3 in Fig. 6. However, the lower fre-quency drive components of the vertical ramp do effectivelydrive the slow-scan mode motion. Even frequency componentsas high as 2 kHz still have enough gain to affect the scanner’smotion. This is important for producing a high fidelity linearramp profile.

In summary, the scanner mechanism acts as a high- me-chanical filter, separating the superimposed drive torque into itscomponent parts. This allows for biaxial scan control with onlyone applied drive force mechanism.

VI. MEASUREMENTS

Scanner frequency response is characterized using the setupshown in Fig. 7. The setup consists of a laser Doppler vibrom-eter (LDV), a function generator and an oscilloscope. Commu-nication between the oscilloscope and the function generator isaccomplished by GPIB interface. LDV sends a laser beam tothe section of interest and measures the Doppler shift of thereturning beam to give an voltage at its output. In the experi-ments, both coil excitation voltage (current) and the LDV output


Fig. 7. Gain-phase analyzer setup used in extraction of the transfer function.Data collection PC controls the function generator and the oscilloscope, througha custom MATLAB program, to obtain magnitude and phase values simultane-ously as the frequency of the input signal is swept.

voltage are sinusoidal signals. For a given setting of the LDV,output voltage is converted to velocity by scaling it with a con-stant. Assuming a peak-to-peak displacement of , positionand velocity of an arbitrary spot on the scanner in time domainis given as

(14a)

(14b)

where corresponds to peak-to-peak velocity. Equation(14b) is the counterpart of the LDV output. Thus, for a givensinusoidal excitation, by finding the peak velocity and the phaseof the LDV output for each frequency step, one can obtain thetransfer function of the scanner in terms of gain-phase plots.

Characterization of the scanner is executed in the ambient air,at three locations on the device shown as points 1–3 in Fig. 4(a).Due to the high mechanical quality factors of the device, theinput excitation is kept small around the resonance peaks. Thisavoids the saturation of the LDV output and results in reliablemeasurements. The overall spectrum is a combination of rota-tion angles normalized to the input excitation. Fig. 8 shows thenormalized rotation angles as a function of frequency for points1–3 on the scanner.

Point 1 is a location on the mirror and therefore does not ex-hibit any motion around slow-scan resonance (400 Hz). Twomain peaks associated with this point are at 4 and 21.3 kHz.The latter one corresponds to the fast scan operation, where theouter frame moves in the rocking mode meanwhile the mirroris in the torsion mode with a relative phase difference of 180 .The angular motion of point 2 is essentially amplified by the

-factor of the mirror and translated into mirror torsion. Thespectrum of point 2 features a valley around 21.2 kHz, just be-fore the fast scan resonance. This mechanical zero is the signa-ture of the coupling between the outer frame and the mirror. Theouter frame displacement is under substantial attenuation, whichcan physically be explained as the outer frame transferring all ofits energy to the mirror. One important property of this coupledsystem is that there are no drive components or features near the

Fig. 8. Frequency spectrum of angles of the three locations on the device. (a)DC-to-22 kHz spectrum. (b) 20.8 kHz-to-21.5 kHz spectrum showing the polesand zeros associated with the fast scan operation.

mirror. This results in reduced gas damping a higher mechan-ical quality factor for the mirror. Any displacement of point 2 inthe rocking mode will be amplified by the mirror quality factorof and converted into torsion of the mirror. Low actuationforces, created by the low excitation signal (coil power) can ef-fectively drive the mirror to create large angular displacements,therefore high factors. The torsional resonance mode of theouter frame about slow-scan axes is designated to appear around400 Hz as can be seen from the curve of point 3 in Fig. 8. Asdiscussed before, the scanner is driven at the off-resonant fre-quency of 60 Hz to implement vertical display refresh.

The measurement setup depicted in Fig. 7 allows detectionof rotation angles with a high dynamic range ( 106 dB), in therange of 5 to 1 deg/mA with the proper excitationsignals.

Transient response of the vertical scan angle and superim-posed drive current are shown in Fig. 9. The plot in the lowerleft shows the composite drive current for both the vertical andhorizontal axes. Only the envelope of the 21.3 kHz componentis visible in this time scale. The plot in the upper left shows theresulting vertical scan angle amplitude response.

The two plots on the right show magnified views of the retracescan portion of these two left hand plots. The lower right plot


Fig. 9. Transient behavior of the vertical scan angle and superimposed drivecurrent.

Fig. 10. Slow and fast scan optical angles as a function of coil drive current.

clearly shows the superimposed 21.3 kHz horizontal drive com-ponent, while the upper right plot shows how the slow scan re-sponds to this composite drive current. Notice that there is verylittle 21.3 kHz component visible on the slow scan angular am-plitude response curve.

The fast scan angular response is a pure 21.3 kHz sinusoidalcurve (and is therefore not plotted). As mentioned above, itsfrequency response to the superimposed lower harmonics is solow that it is not visible in the scan amplitude response at all.

The plots of Fig. 9 show an optical scan angle of for thevertical axis. Scanners have been tested using bimagnetic actu-ation to much greater angles. Fig. 10 shows the optical angles offast-scan and slow-scan as a function of the drive current. Theslow-scan frequency response exhibits a linear dependency onthe coil current.

Fig. 10 shows the fast and slow scan optical scan angles asa function of drive current. Due to the off-resonance operation,the slow scan axis is relatively linear with drive current up to 65scan angle. The fast scan axis, with the benefit of -amplified

Fig. 11. Comparison of the scanners published in the literature.

operation on resonance, is able to achieve 58 optical scan anglewith decreasing drive efficiency.

These high scan angles are made possible by the high drivetorque capabilities of the new bimagnetic drive design, by thecareful design of stresses throughout the torsional flexures, andby careful control of the quality of the etched surface side walls.Based on our current MEMS scanner design and fabrication ca-pabilities, it is now possible to make a scanner meeting the re-quirements for SXGA (1280 1024) resolution retinal scan-ning displays.

VII. CONCLUSION

A new drive mechanism has been developed to meet the needsof high performance raster scanning mirrors. Using a simpleelectro-magnetic drive it is possible to achieve high frequencyscanning in one axis and a fully linear sawtooth ramp in the otheraxis all in ambient air operation. The one-atmosphere operationeliminates the need for a glass cover on the package, improvingsystem performance while lowering fabrication costs. As a re-sult of the simplification in packaging allowed by this design,the high performance of this scanner can be achieved at very lowcost. Fig. 11 compares the scanners published in the literature,according to product and scan frequency [9], [11], [13],[15]–[24]. As seen from Fig. 11, the scanner presented in thispaper is far superior in performance compared to others avail-able in the literature and incorporates two-axis operation and in-tegrated position sensors on both axis. This design encompassesthe desired goals.

• Two axes of the scanner are driven from one magnetic fieldand one current drive loop.

• Scanner mechanical dynamics separate the drive har-monics to create the desired mechanical response.

• Actuation mechanism results in high torque drive on bothaxes allows one-atmosphere fast scan operation as well asdc to 2 kHz actuation of slow scan axis over entire scanangle.


• Realized device is a high performance two-axis scannerdesign with an integrated on-chip position sensor.

• This novel drive concept makes it possible to develop scan-ners capable of supporting SXGA displays without vacuumpackaging and with linear-ramp slow-scan operation.

This new scanner actuation mechanism has already been in-troduced into Microvision’s production NOMAD Expert Tech-nician System Head-Worn Display.

ACKNOWLEDGMENT

The authors would like to thank W. Davis of MicrovisionCorp. for helping in the mechanical analysis of the device. Ç.Ataman of Koç University is also thanked for his assistance inautomation of the characterization setup.

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[22] K. Torashima, T. Teshima, Y. Mizoguchi, S. Yasuda, T. Kato, Y. Shi-mada, and T. Yagi, “A micro scanner with low power consumptionusing double coil layers on a permalloy film,” in Proc. IEEE-LEOSConf. Optical MEMS 2004, Takamatsu, Japan, 2004, pp. 192–193.

[23] H. Schenk, P. Durr, D. Kunze, H. Lakner, and H. Kuck, “A resonantlyexcited 2d-micro-scanning-mirror with large deflection,” Sensors Ac-tuators A, vol. 89, pp. 104–111, 2001.

[24] H. Miyajima, “Development of a MEMS electromagnetic opticalscanner for a commercial laser scanning microscope,” J. Microlithogr.Microfabrication, Microsyst., vol. 3, no. 2, pp. 348–357, 2004.

[25] H. Urey, A. D. Yalcinkaya, T. Montague, D. Brown, R. Sprague, O.Anac, C. Ataman, and I. Basdogan, “Two-axis MEMS scanner for dis-play and imaging applications,” in Proc. IEEE Optical MEMS Conf.,Oulu, Finland, 2005, pp. 17–18.

Arda D. Yalcinkaya received the B.S.E.E. degreefrom the Electronics and Telecommunication Engi-neering Department, Istanbul Technical University,Istanbul, Turkey, the M.Sc. and Ph.D. degreesfrom theTechnical University of Denmark (DTU),Mikroelektronik Centret, Kgs. Lynby, Denmark, allin electrical engineering, in 1997, 1999, and 2003,respectively.

Between 1999 and 2000, he was a Research andDevelopment Engineer at Aselsan Microelectronics,Ankara, Turkey. He had short stays as a Visiting

Reseacher at Interuniversity Microelectronic Center (IMEC), Leuven, Belgium,and Centro Nacionale de Microelectronica (CNM), Barcelona, Spain, in 2000and 2003. Since 2003, he has been a research associate at Koç University,Istanbul, Turkey, where he is engaged with start up of a cleanroom facility. Heis also working as a part-time ASIC Designer for Microvision Inc., Seattle,WA. His research interests include design, fabrication and characterizationof MEMS, CMOS-MEMS integration, nanotechnology and design of analogASICs. He was a Sabanci Foundation (VAKSA) scholar between 1992 and1997, and a Turkish Education Foundation (TEV) scholar between 1997 and1999.

Hakan Urey received the B.S. degree from MiddleEast Technical University, Ankara, Turkey, in 1992,and M.S. and Ph.D. degrees from the Georgia Insti-tute of Technology, Atlanta, in 1996 and in 1997, re-spectively, all in electrical engineering.

He is currently an Assistant Professor at KoçUniversity, Istanbul, Turkey, where he has beenseince 2002. He joined Microvision Inc., Seattle,WA, in 1998. He has published more than 50 journaland conference papers, five edited books, two bookchapters, and he has nine issued and several pending

patents. His research interests are generally in the area of information opticsand microsystems, including micro-optics, optical system design, microelec-tromechanical systems (MEMS), and display and imaging systems.

Dr. Urey is a member of SPIE, OSA, and IEEE-LEOS, and Vice-President ofthe Turkey chapter of IEEE-LEOS. He is the Chair of Photonics West MOEMSDisplay and Imaging Systems Conference and Photonics Europe SymposiumMEMS, MOEMS, and Micromachining Conference.


Dean Brown received the B.S. degree in mechanicalengineering from the University of California, SantaBarbara, in 1974.

His experience includes mechanical engineeringanalysis and design in a wide variety of industries,including electronics, ocean engineering, nuclearpower generation, hazardous materials handling,and transportation. He has spent the last nine yearsdesigning and analyzing MEMS devices, and iscurrently a Principal Engineer for Microvision, Inc.,Seattle, WA, performing MEMS optical scanner

design and analysis.

Tom Montague received the B.S. degree in aeronautical and astronautical en-gineering and the M.Sc. degree in physics, both from the University of Wash-ington, Seattle, in 2000 and 2005, respectively.

Over the past nine years, he has worked as a Research and Development En-gineer of laser scanning instruments and display systems. From 1996 to 1999,he worked for Laser Sensor Technology, Redmon, WA, developing laser- basedparticle size measurement systems for applications ranging from the monitoringof cell growth to petroleum processing and for operating environments fromcryogenic to high temperature. Since 2000, he has been with Microvision Inc.,Seattle WA, USA where he is currently the Manager of the MEMS design group.He has developed two generations of the MEMS scanners used in Microvision’sdisplay products.

Randy Sprague, photograph and biography not available at the time ofpublication.

Documents

786 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. … · 786 JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 4, AUGUST 2006 Two-Axis Electromagnetic Microscanner for High