VarioS®-Microscanner user manual - Scanner
Contents
1. axis 1V 200 V device speci dynamic deformation 1 nm 100 nm 1 nm 100 nm device speci RMS value calculated from the deflection field of the deformed in respect to the undeformed mirror mirror reflectance shock resistivity 2000g 2000g Typically at wavelength of 633 nm without glass cover mounted to chip housing at least chip size 5370 um x 4540 um 5370 um x 4540 um fixed chip housing Fb046 08 USER MANUAL doc DIL 14 ceramics carrier with glass cover DIL 14 ceramics carrier with glass cover glass cover features broadband anti reflection coating in visible range 12 of 14 Cover Glass Transmission The transmission of the ARC glass window depends on the wavelength of the light source and the incidence angle Figure 7 shows typical transmission of the coated cover glass 100 95 90 65 transmission 80 75 400 500 600 700 600 900 1000 1100 wavelength nm Figure 7 Transmission of the broadband ARC glass with 90 incidence angle Typical Mirror Reflectance The reflectance of the mirrors reflective aluminium coating depends on the wavelength of the light source Figure 8 shows typical reflectivity of the mirror coating eo Reflectivity oO o o ROO eo N ceo e eoo 220 320 620 720 20 520 Wavelength A nm Figure 8 Reflec2. 9 of 14 Connecting Scheme All VarioS microscanner demonstrators bonded to a DIL14 housing share the same bond pad and pin configuration Nevertheless the electric chip domains connected to the bond pads depend on customer specific design and layout Check the characterization report delivered for the type of used electric connecting scheme Then use the Table 1 for identification of the reguired bond pads or pins For 1D microscanners the driving potential mirror U M and ground Gnd is reguired For 2D microscanners an additional potential U MF is needed to drive the movable frame perpendicular to the mirrors axis When contacting the microscanner make sure that pins whose potentials are marked in grey are provided Table 1 Pin configurations for VarioS 1D microscanners 1D microscanners 2D microscanners U_M Drive Voltage Mirror U MF Drive Voltage Movable Frame Gnd Ground Colour Scheme Required optional Fb046 08 USER MANUAL doc external 1DPG1 2 1DPG3 4 2DPG1 DIL 14 pin Electric Potential Electric Potential Electric Potential 1 U M U M U M 2 Gnd Gnd U MF 3 Gnd Gnd Gnd 4 Not connected 5 Gnd Gnd Gnd 6 U M Gnd U M 7 U M U M Gnd 8 Gnd Gnd Gnd 9 Gnd Gnd U MF 10 Gnd Gnd Gnd 11 Not connected 12 Gnd Gnd Gnd 13 Gnd Gnd Gnd 14 Gnd Gnd Gnd Potentials 10 of 14 Connecting to a Function Generator To safely connect the m
3. a a a so as 3 Scope of Deliyety erbe meds atus 4 Chip Handling ien e e D TREAT RETE RR TR HG t TEC ai 4 How the System WOEkS cess uve aote dietus geb un ie ERU ERU 5 Microscanner Operation iei o RU GNI RU NOR RERO NN O 6 Starting an Open Loop Oscillation ree teta eene eec e dec PEINE TEN ETE aa 7 Comments on Closed Loop Operation sss ener nnne nnne ntn en aaa aaa een enn enne nn 8 Bond Pad oet ee oat e ta dee a ease 9 DLIA Cerami os Housing iue nia woe iden nit edite state e netta aed 9 Connecting Scheme ornans ione r TRO RE RUNS RS VR RE ORC NORUNT TEX eee den 10 Connecting to a Function Generator nene eee re eR e E 11 echnical Data 3 tinea i Et duit nte ue i ao aaa toc ortis cde iesu eM ass 12 Coverelass LransmisslOn desi asi a geiitu Debe Uu te E OU 13 Typical Mirror Reflectance onset eee Re RENNES IRI QR dius 13 Trouble Shooting x eee RAE RI AI t i Td EH In a A T e ts 14 Fb046 08 USER MANUAL doc 3 of 14 Scope of Delivery Delivery of a VarioS microscanner demonstrator set includes 1 microscanner demonstrators bonded to a DIL14 housing sealed with a protective broad band anti reflective coated glass cover Cover glass is removable 2 Characterization report with device specific technical data 3 This user manual Chip Handling Fraunhofer IPMS Microscanners are very robust Nevertheless the following precautions should be followed 1 The microscanners resists acceleration
4. 50 Fb046 08 USER MANUAL doc 6 of 14 Starting an Open Loop Oscillation 1 Use pin connection table and connect relevant pins of the DIL14 housing with a function generator Ground other pins as indicated by pin connection table Focus laser to the centre or the microscanners mirror plate Set the function generator to a square wave function with a pulse duty factor of 50 See characterization report for appropriate drive voltage 4 Set function generator to start the sweep at an excitation frequency f as shown in the characterization report If characterization report is not at hand start oscillation with fa approximately 2 1 times the specified scan frequency natural frequency f and stop at a value slightly higher than 2 times the natural frequency Set the sweep duration to 5 10 s 5 Power on voltage output of the function generator and start sweep 6 Fine tune drive voltage and drive frequency to set desired amplitude manually after sweep has stopped Do not exceed Uma at any time Comments Mechanical structures have several natural frequencies and related oscillation modes Therefore oscillation of a mirror tilting motion may be excited more than once after starting the sweep and suddenly break down until the desired tilting mode is found In this case start the sweep closely above f 2 x f In case of 2D devices the above described procedure is started independently for each axis All electric chip domains have to b
5. Y ZA Fraunhofer IPMS FRAUNHOFER INSTITUTE FOR PHOTONIC MICROSYSTEMS IPMS USER MANUAL VarioS Microscanner Demonstrators last revision 2014 11 14 Fb046 08 USER MANUAL doc Introduction Thank you for purchasing a VarioS microscanner demonstrator from Fraunhofer IPMS Fraunhofer IPMS has a long and successful track record in developing and fabricating customized highly miniaturized resonantly operated MEMS scanners Devices feature large scan angles high scan frequencies excellent optical mirror interfaces and superb long term stability 1D and 2D micro scanning devices are fabricated with a qualified CMOS compatible bulk micromachining process that can be applied to small and medium size volumes as well VarioS microscanner demonstrators are made for quick cost effective and easy effort application testing With customized microscanners based on the VarioS construction kit we hope to support you in bringing tomorrow s products to market Please do not hesitate to contact us for further questions on VarioS or other products and services Fraunhofer Institute for Photonic Microsystems IPMS Maria Reiche Str 2 01109 Dresden Phone 49 3 51 88 23 0 Fax 49 3 51 88 23 266 Email info ipms fraunhofer de Web www ipms fraunhofer de www micro mirros com Fb046 08 USER MANUAL doc 2 of 14 Table of Contents Mitr GUC tH ONS Ys sack RN 2 Table of Contents oye skin chasse Ei sa o i oi o a as es a a si
6. e connected to the required potential Floating potentials must be avoided Fb046 08 USER MANUAL doc 7 of 14 Comments on Closed Loop Operation To keep the amplitude steady fine tuning of the excitation freguency is reguired whenever environmental conditions such as temperature or pressure change significantly Therefore a closed loop excitation might be more appropriate for some applications Therefore the excitation frequency can be synchronised with the natural frequency of the tilting axis as is shown in Figure 3 Unfortunately capabilities to sense the mirror tilt angle a controller and driving circuitry have to be provided Please contact Fraunhofer IPMS if you are interested in the development of a driving circuitry for your micro scanning device 0 25 0 50 0 75 1 00 1 25 time mechanical period Figure 3 Mechanical mirror oscillation and synchronized drive signal Fb046 08 USER MANUAL doc 8 of 14 Bond Pads If the microscanner is delivered as a bare die the following bond pad naming scheme is required for connection 4540 pm al 5370 um Figure 4 Bond pad naming scheme for VarioS microscanner demonstrators DIL14 Ceramics Housing If not specified otherwise the microscanner demonstrator will be delivered in a DIL14 ceramics housing The pins are named according to Figure 5 Figure 5 Scheme of a VarioS microscanner demonstrator bonded to a DIL14 ceramics housing Fb046 08 USER MANUAL doc
7. icroscanner to a function generator plus voltage amplifier insert a protective resistor of R 100 200 O between the amplifier output and pin connector of the DIL14 housing as shown in Figure 6 The protective resistors suppress the high voltage spikes temporarily occur on the amplifiers output DIL14 socket Gnd function voltage generator amplifier um Figure 6 Connecting a VarioS 2D microscanner with a function generator Fb046 08 USER MANUAL doc 11 of 14 Technical Data Technical properties of the micro scanning device are listed in Table 2 Depending on customer specifications technical properties may vary Please see quotation and characterization report for detailed technical information on device specific properties Table 2 General properties of VarioS microscanner demonstrators VarioS Microscanners mirror type 1D microscanner 2D microscanner remarks mirror plate circular lt 3 mm circular gimbal mounted J lt 2 mm device specific scan frequency 1 axis 0 1 kHz 47 5 kHz 0 1 kHz 10 kHz device speci scan frequency 2 axis 0 1 kHz 47 5 kHz device speci maximum mechanical deflection 1 axis 1 30 f device speci maximum mechanical deflection 2 axis maximum drive voltage 1 axis 1V 200 V 1 30 1V 200 V E device speci device speci maximum drive voltage 2
8. s of more than 2000 g Nevertheless dropping the chip from small altitudes of a few centimetres on hard ground can lead to shock causing even higher accelerations and mechanical failure of the mirror structure 2 Store microscanners within a temperature range of 50 C 120 C Do not operate the device at temperatures exceeding 10 C 70 C 3 If cleaning is required dip chip in distilled water bath and gently pan chip Let chip dry on air afterwards 4 Do not expose microscanners to airflow Do not blow at the mirror for particle removal Air flow can cause the mechanical flexures to fail Fb046 08 USER MANUAL doc 4 of 14 How the System works The micromechanical 1D and 2D scanning mirrors see Figure 1 in the following called microscanner are designed for the periodic deflection of light A 75 um thick plate of single crystalline silicon acts as the light deflecting element The reflection coefficient is enhanced by a thin layer of aluminium 1D Scanner 2D Scanner Figure 1 Left Photograph of 2D microscanner in DIL14 ceramics housing Right Mechanical scheme of the light deflecting mirror The mirror plate of the microscanner performs a continuous harmonic oscillation The oscillation is excited electrostatically and utilizes planar electrostatic comb drives The oscillation frequency has to be close to the natural frequency of the scanning axis Adjusting the driving voltage or the driving frequency allows
9. setting and controlling the oscillation amplitude For 2D devices the mirror plate is gimbal mounted The resonance frequency of each axis is determined by design independently Each axis is excited individually Thus the ratio of the oscillation amplitudes and the phase difference can be set and controlled arbitrarily Fb046 08 USER MANUAL doc 5 of 14 Microscanner Operation deflection angle f exc Figure 2 Typical frequency response curve showing hysteresis When exciting the oscillation of the mirror plate with help of a function generator it is recommended to carry out a sweep from high to low frequencies A typical response curve is shown in Figure 2 The response curve shows a hysteresis Therefore different parts of the curve are obtained dependent on the direction of the frequency sweep The maximum deflection angle is achieved when the excitation frequency matches twice the mechanical resonance frequency of the tilting axis The sweep should stop at a frequency which is slightly higher than f and maintain that value Otherwise the amplitude may abruptly break down This excitation scheme allows easy operation of Fraunhofer IPMS microscanners with standard laboratory equipment e Function generator for square wave signal e Voltage source with frequency controlled switch e or High Voltage Amplifier additional for microscanners with excitation voltage gt 10V for instance TEGAM High Voltage Amplifier Mod23
10. tivity of aluminium mirror coating depending on the wavelength of the light source Fb046 08 USER MANUAL doc 13 of 14 Trouble Shooting Effect Recommended Procedure Oscillation instable a Adjust square function duty factor to a lower value Pulse time period Make sure the oscillation frequency is equal to the indicated natural frequency or slightly higher Mirror started up properly but after an oscillation break down it does not start up again Potentially comb fingers are jammed Send microscanner back to Fraunhofer IPMS for support Mirror does not oscillate at indicated oscillation frequency Start to excite the mirror at a higher excitation frequency and then slowly decrease the excitation frequency towards the indicated value Extend the sweep time Perform optical inspection to assure the torsional mirror support flexures have not been broken Fb046 08 USER MANUAL doc 14 of 14
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