Piezomechanik Dr. Lutz Pickelmann GmbH. Piezomechanical Stackactuators

Transcription

1 Piezomechanik Dr. utz Pickelmann GmbH Piezomechanical Stackactuators

2 ist of contents Piezostacks 1. Classification of piezostacks Operating principle Stackdesigns Discrete stacking Multilayer structure Bare stacks (without casing, w.o.c.) Stacks with casing Piezoceramic materials Mounting of piezoactuators Operating performance of piezostacks Positioning by piezostacks Force generation by piezoactuators, Interaction with externally applied forces Piezoactuators as force sensors and electrogenerators Notes on technical data Voltage ranges, polarity Electrical capacitance, loss factor Maximum expansion Maximum compressive load (m.c. load) Stiffness Resonance frequency Thermal effects Options Ordering code Custom designed actuators Safety instructions ow voltage actuators Serie PSt 150/4/ Version PSt 150/5/ Version PSt 150/7/ Version PSt 150/14/ High voltage actuators Version PSt 500/10/ Version PSt 1000/10/ Version PSt 1000/16/ Version PSt 1000/25/ Version PSt 1000/5/ Accessories Top cover: 100 kn stack actuators for active vibration control stroke: 220 µm for 150 V thru +700 V operation Coke can for comparison of sizes 2 Piezomechanical Stackactuators

3 Piezostacks 1. Classification of piezostacks 1.1. Operating principle Piezostacks are made from ead(pb)-zirconium(zr)-titanate (Toi) oxide ceramic (PZT), which is available in various formulations. Stacked piezoactuators are using the shape deformation of piezoelectric ceramics under the influence of an electrical field: When a voltage of proper polarity is applied to a simple piezoceramic disc or plate, the thickness of the disc increases slightly. To get a greater expansion, a lot of discs are stacked together, thereby adding the effects of the individual components. Such piezoactuators (piezostacks, piezotranslators) make use of the axial movement of this arrangement, the maximum stroke is (nearly) proportionally related to the stacklength (max. strain approx of stack s length). use of low Curietemperature piezoceramics for different reasons.hereby the operation of multilayers at elevated temperatures or high power operation is limited.the other electromechanical properties like strain, dynamic response, elastic moduli, resonance frequencies are similar to discretely stacked elements. Multilayers are preferentially used with small and medium stacks cross sections Bare stacks (without casing, w.o.c) The ceramic body of the stack is contaced by simple pigtails/leads and then coated with insulting polymers. This simplest version is often used for OEM-purposes. Because of the lack of mechanical protection, following operating conditions are important: low air humidity, protection against shock/tensile stress/side impact, sufficiently high mechanical prestress etc. ceramic endfaces ceramic endfaces piezoceramic layers Insulation coating electrical connection pigtails Fig.1 Principle design of a piezostack actuator The properties of piezoactuators are determined by the dimensions of the stack, the layerstructure and type of PZT material Stackdesigns Discrete stacking Piezoceramic discs are manufactured separately (burning, electroding) and then piled up. Electrical contacting of each PZT layer is achieved by introducing thin metal sheet between the layers and interconnecting them electrically on stacks surface.the thinness of the ceramic layers is limited, so that an elevated voltage is needed to get the required electrical fieldstrength within the stack. Therefore, discrete stacking is mostly related to high voltage operation (500 V, 1000 V). Discrete stacking offers flexibility in designing stack s with regard to shape dimension, use of the widest range of PZT materials. Control of selfheating during power operation (e.g. for vibration control) is superiour to low voltage stacks (see below). Fig. 2 Schematic representation of a bare PZT stack Stacks with casing For a lot of applications, the PZT ceramic stack is mounted in a metal casing for protecting it against unwanted environmental influences and easier handling. Mostly casings are made from stainless steel. But an important aspect of casing s design is the handling of the selfheating power of stacks during highest power operation (e.g. active vibration control, shaker-applications).then other metals are used for improving the heat transfer/cooling performance (ask for Piezomechanik s copperfoot high power stacks). In most cases, mechanical preloading/prestress mechanisms are further included to the casing for highest degree of ruggedizing. Preloading is a prerequisite for dynamic operation of stacks, where high dynamic tensile forces are involved (high frequency, short rise/fall time operation) Multilayer structure For many applications, low driving voltages of actuators are required. It is not possible to handle the necessarily thin layers (typical 0.1 mm) in the above described way. ow voltage stacks are therefore manufactured by co-firing technology, meaning that the complete PZT-layer/electrode structure is built up before burning the ceramic. The complete layerstructure is pressed and burned as a whole. In principle, all available PZT materials can be used for multilayer stacking, but presently, the main emphasis is put on the Piezomechanical Stackactuators

4 Piezo stack moving top end prestress mechanism stainless steel casing coaxial cable bottom piece with thread (fixed end) Fig. : Piezoactuator with casing with internal mechanical prestress 1. Piezoceramic materials Selection of PZT materials for actuator application is mostly making a compromise between aspects like achievable strain (stroke/actuator length), low hysteresis and creep for low dynamic positioning purposes, power consumption, selfheating and resistance to elevated temperatures under dynamic operating conditions (active vibration control, shaker applications). Another aspect is the availability of PZT materials for low voltage/multilayer design of stacks. Please notice,that within feedback controlled systems hysteresis and creep are not really relevant, because these are actively compensated. PM1: highly dielectric ceramic, used for standard low voltage stacks (150 V operating voltage) Curietemperature about 150 C, limits the use of these stacks to a maximum temperature of about 100 C. Highly dynamic cw operation require elevated power levels with tendency of remarkable selfheating. Hysteresis 10 15% PM2: Standard material for discretely stacked HV actuators PSt 500 and PSt Shows one of the highest strain rates together with a rather low hysteresis of about 10%. Despite the higher dielectric constant compared to low capacitance actuators of other origins, under highly dynamic cw-operation, the overall efficiency is much better and selfheating is reduced, because of the better ratio stroke/ capacitance (for same stack dimensions and structure). This results in a lowered driving voltage/ internal field strength to get a distinct mechanical reaction from the actuator. A comparison is given in the application note Material aspects for the thermal balance of piezo stack actuators. The Curietemperature is approx. 220 C, optimum stack operation is up to 120 C, max. operating temperature is 15 C. PM2 material is recommended for high electromechanical power requirements. On special request, PM2 is offered for multilayers (operating voltage up to 200 V). PM: This material is a low dielectric type with high Curietemperature (40 C). It is used, when stack temperatures of 150 C and above are expected. Strain rate is lower than for PM2, but outperforms competitive low capacitance materials of other suppliers. (see material aspects for thermal balance of piezo stack actuators ). PM is only used on special request or when option high temperature is stated. Electrostrictive ceramics: Electrostrictive ceramics is an electromechanically active material, which can be used in a very similar way like piezoceramic. The difference of these effects has to be explained in terms of solid state physics. This is not the purpose of this paper. In practice, electrostriction is discussed because of the much lower hysteresis and creep compared to PZT ceramics. This passive stability is the reason for its application in some optical applications (etalon tuning etc.). The strain rate is about 80 % of common PZT material. The operating temperature range is very limited to about 10 C around optimum temperature/curietemperature of the material (mostly RT) to get the optimum performance. Electrostrictive stack and ring actuators are offered on request. 2. Mounting of piezoactuators bare stacks: Only the axial motion of stacks is used. Mounting of bare stacks has to be done only by the front/ end faces. Clamping of bare stacks by the circumference potentially damages electrodes, insulation and ceramics, and has therefore to be strictly avoided. Stacks with casing: they can be mounted either by the bottom pieces or by clamping at its circumference. The end near the electrical wiring is normally used as fixed end(base). Shear forces acting on the moving top of stacks have to be avoided, because it deteriorates the motion, or, in case of excess forces, the stack will be damaged. Actuators within a preloaded casing are much less sensitive to shear forces, because these are mainly guided to the preload mechanism and not to the ceramic stack. A point contact for force transfer (e.g. by ball contact) to the stack end faces has to be adjusted to the center of the face plates (Fig. 4a). Any coupling between mechanical parts and a PZT-stack should only transfer purely axial forces avoiding any bending/tilting/shear forces, e.g. this is done by combining a (central) ball tip with a plane endface (Fig. 4a). Coupling by a plane-plane contact is only allowed, when a free orientation of one of the components is possible (Fig. 4b). Any misalignment between the contactplanes leads to local mechanical overstress at the stacks edges (Fig. 4c). F F F F allowed a allowed b not allowed c loading of edge Fig. 4a, b, c Coupling conditions of a mechanical component to a piezoactuator 4 Piezomechanical Stackactuators

5 . Operating performance of piezostacks The main applications of piezoactuators include ultraprecise positioning generation/handling of high forces/pressures either static (e.g. high mass loads, elastic forces) or dynamic (acceleration forces).1. Positioning by piezostacks When a piezostack is cycled within a distinct voltage range, the displacement follows the wellknown hysteresis curve as shown in fig. 5. Nonlinearity and hysteresis are a consequence of the ferroelectric properties of PZT materials. stroke stroke Fig. 5: Displacement/voltage diagram of a typical piezostack for different voltage levels (within U max ). U ret returnpoint of voltage for the individual cycle. The hysteresis diagrams for standard actuators are very similar for low voltage and high voltage types and are therefore not a relevant criterion for selection between these stacktypes for a distinct application. The displacement curves are valid for constant force load, meaning that an applied force does not vary during piezostack s travel. Even for very high (but static) load forces, the full extension is achieved. Relative positioning accuracy (positioning sensitivity) Piezoelements show an infinitely high positioning sensitivity: An infinitely small change of the operating voltage (charge content of the actuator) results in an infinitely small change in position. This is a very important feature e.g. for scanning tunnel microscopes to get atomic resolution (by feedback control via the tunnel current). Therefore, piezoactuators show a continuous steady motion with no discrete small steps. The positioning sensitivity of a system consisting of actuator and supply electronics is determined by the stability of the supply electronics and not by the actuator. Absolute positioning Most positioning applications of PZT actuators aim for a travel of a distinct length or a travel to reach a distinct point with highest accuracy. The philosophy to get this is obviously not based on a simple voltage controlled motion by presetting a distinct voltage, because the resolution of this strategy would be limited by the hysteresis as shown in fig. 5. The main point is, that piezostacks are controlled by feedback: the position of interest is defined by some position sensitive effect (e.g. tunnel current of a STM, optical effects, interferogramms) or a position sensor and the voltage is regulated as long as there exist a deviation from the nominal value to eliminate this. The final absolute positioning accuracy is determined again by the precision of the position detection and the stability of the supply electronics (see relative positioning), and not by the PZT..2. Force generation by piezoactuators, Interaction with externally applied forces A lot of applications show varying forces acting on the piezostacks during operation e.g. piezotravel against an elastic counterforce e.g. spring, clamping mechanism etc. acceleration forces during dynamic operation e.g. generation of vibrations, pulsed operation varying massload Under all these conditions, the piezoactuator reacts on the varying force with elastic compression or dilatation according its stiffness and the variation of force (Hooke s law). Piezostacks can be used as force generators where they are operated against a proper counterforce e.g. an elastic clamping mechanism. The produced force depends on the driving voltage and the stiffness relation between actuator and clamping mechanism. The maximum force (blocking force) which can be produced by an actuator is achieved for infinite stiff clamping at maximum voltage. The blocking force can also be defined as the required force to press back a fully elongated actuator to its zero-position. Some general relations between the geometrical dimensions of a stack and its properties are stated below the maximum travel of a stack is proportional to its length: (up to 2 ) load/blocking force is proportional to the stack s cross section the blocking force F B can be estimated according F B = l o x S l o max. travel of stack S stiffness of stack stiffness is related both to the actuators length and cross section. Piezomechanical Stackactuators 5

6 These principle force-travel relations are shown in fig. 6. I 2 I 1; F B (1; 2) F B () Fig.6: Schematic representation of force/travel relations of PZT actuators Actuator 1: showing travel I 1, blocking force F B(1) Actuator 2: double length, same cross section as actuator 1: double travel, same blocking force Actuator : same length, double cross section as actuator 1: same travel, double blocking force Example: an actuator is operated versus an elastic clamping, showing the same stiffness as the actuator: the achieved travel is half the maximum travel, the generated (additional) force is half the blocking force... Piezoactuators as force sensors and electrogenerators Besides the actuator effect, PZT stacks shows normal piezoelectricity, meaning, that a mechanical force generates a voltage signal (electrical charge). Piezoactuators can therefore be used for force sensing, which is very effective due to the high currents involved. Any arrangement incorporating a piezoactuator can be checked for its mechanical resonances or mechanical response by combining the actuator with a signal analyzer and exciting the mechanics by an external mechanical knock/shock. In the widest consequence, PZT actuators can also be used as generators to convert mechanical power to electrical power. 4. Notes on technical data 4.1. Voltage ranges, polarity The actuators shown in the data sheet are specified for 150 V, 500 V and 1000 V respectively. This maximum voltage can only be applied with correct polarity as indicated below. A countervoltage is applicable up to 20% increasing thereby the total stroke of the actuators: 150 V stacks: multilayer design, material PM1 (see 1.4.) operating range : 0 V thru +150 V (eg. use amplifiers SVR 150/) internal fieldstrength at 150 V: 1.5 kv/mm 500 V stacks: discretely stacked actuators, material PM2 (see 1.4.) operating range: 100 V thru +500 V (e.g. use amplifier SVR 500/) internal fieldstrength at 500 V: 1.67 kv/mm F 1000 V stacks: discretely stacked actuators, material PM2 (see 1.4.) operating range: 200 V thru V (e.g. use amplifier SVR 1000/) internal fieldstrength at 1000 V: 1.67 kv/mm Bare stacks are electrically insulated at their front faces and surfaces and can be operated potential free with respect to environment. Notice the polarity of the leads: black, red + For piezostacks with casing, the operating ground reference is connected to the casing, therefore, the polarity of the driving voltage is fixed and is positive for PIEZO- MECHANIK s actuators and supply electronics. This allows free combination of actuators and supplies to match different application needs. On request actuators with casing for negative voltage polarity are available Electrical capacitance, loss factor Piezoactuators are best described as electrical capacitors, when operated nonresonantly. The electrical capacitance is therefore a measure for the power requirements of an actuator, when operated dynamically. The problem is, that the electrical capacitance value of piezoceramics is not constant. The nominal electrical capacitances stated in the data sheet are socalled small signal values, measured with very low excitation voltages (1 2 V) at 1 khz by simple electronic meters. Under the influence of higher voltages, elevated temperature and mechanical load the capacitance values can increase remarkably (up to 200%). The transferred electrical power is partially converted within the PZT ceramic to heat, what is usually described by the loss factor. The loss factor itself depends again on the operating voltage and temperature. This leads to a selfaccelerating situation, where the selfheating leads to a higher powerconsumption and again to a higher selfheating. Where the thermal equilbrium temperature is and what electromechanical response is obtained under these conditions is hard to predict. Therefore it is recommended to use the following check list: Use the frequency/amplitude diagrams shown in the broschure Amplifiers and check for a suitable amplifier using the nominal values of capacitance and required stroke. When this shows,that amplifiers SQV, SVR, E 150/025, E 40/015 are sufficient to cover the desired dynamic range, than there are no big side effects to be expected. For elevated temperature operation take a factor 1.5 for the capacitance value into account. When your selection procedure shows a requirement for one of the high power amplifiers take a capacitance factor of 2 into account and be aware, that remarkable selfheating occurs. The equilibrium temperature depends on a lot of sideconditions e.g. the cooling performance of your mounting etc. These cases have to be discussed individually. Here the discretely stacked HV actuators made from PM2 material outperform other design, because the stroke increases!! with load and temperature and reduces thereby the power requirements to get a desired electromechanical reaction from the system (see application note: Material aspects of the thermal balance of piezo stack actuators ). 6 Piezomechanical Stackactuators

7 The electrical resistance of piezostacks is very high and ranges from of MegaOhm (for large volume multilayers) to Giga- Ohm (for high voltage stacks). An expanded (charged) actuator can be disconnected from the supply and can hold its position for a long time due to the very slow self discharging of the actuators by leakage currents (time constant hours to days). 4.. Maximum expansion The maximum expansion is defined as the stroke for a voltage step 0 V to maximum voltage at roomtemperature. Exceeding the max. voltage ratings will potentially show onset of saturation in actuator s expansion characteristic and reduction of lifetime. The tolerances in the expansion rates are due to variation of materials composition from batch to batch. ow voltage actuators: The maximum voltage is 150 V. Further the 100 V expansion rate is stated to make easier the comparison with multilayer stacks from competitors. Tolerance of the stated ratings is ±10%. Experience shows, that usually the nominal values are reached or slightly exceeded. High voltage actuators: Tolerance of the stated ratings is ±10%. Experience shows, that usually the nominal values are exceeded Maximum compressive load (m.c.load) Piezoceramic resists to high compressive load pressures of about 400 bars or even higher without changing its properties. Some types of PZT ceramic like Piezomechanik s PM2 show an increase! of stroke under loaded conditions. Therefore the absolute force/mass load of an actuator is determined by its cross section and is defined that no adverse change of actuator s properties occur. Exceeding the load does not destroy the actuator, but starts to reduce actuator s performance. A problem are tensile forces, because even for small rates a cracking of the ceramic occurs. This is prevented by preloading/prestressing the stack. Mechanical prestress To handle higher tensile forces, a common trick is to prestress the piezostacks. Tensile forces are allowed as long as they are compensated by the prestress force. For dynamic operation, the prestress is necessary to compensate acceleration forces by overshooting and during the reseting of the actuator. For this case, a minimum prestress force F res is needed, so that the masses coupled to the piezoactuator are sufficiently fast accelerated, that the contracting PZT stack never pulls the external mass load: F res = m l/( t) 2 m = mass load l = max. travel t = minimum reset time 4.5. Stiffness ike any other solid body, piezoceramics show elasticity and therefore stiffness of the piezostacks can be defined. The resonance frequency of a PZT actuator under mass load depends on stiffness and can be estimated according the simple mass/spring-modell. Furthermore, the loss of travel of an activated actuator can be estimated, when in operation against a varying counterforce. The stated data for stiffness are approximate, and were measured at a prestress 10% of the maximum force load. Piezomechanik s stackactuators are manufactured for very high elastic moduli, meaning high stiffness at a minimum cross section of the stack. Hereby, the active volume of the actuator is minimized and therefore the required electrical power to get a distinct mechanical force/stroke response Resonance frequency The stated resonance frequencies are defined for actuators with one side fixed/without external mass/for small electrical signals. The frequencies refer to the basic axial oscillation mode of the actuator. Note, that an actuator shows different oscillation modes and the resonance frequencies of these modes may be lower than those for the axial mode (e.g. radial mode axial mode for a short actuator with large diameter). Additonal mass load applied to the actuator lowers the overall axial resonance frequency. Therefore the resonance frequency of an internally prestressed actuator with casing is lower than that of the bare stack due to the mass of the prestress mechanism. Standard stacks show low resonance gain (high damping) due to the PZT ceramic used and the compound (layer) structure. Resonance has to be kept in mind during the installation of feedback control systems. The onset of phaseshifting between the exciting signal and the mechanical response of the actuator limits the operating frequency range. Note: not only the actuator shows resonance, but also any coupled mechanics. Such parasitic resonances can be excited by the piezoactuator with high efficiency (large gain factor of the mechanics), even when the actuator itself is not operating in resonance. In many applications, resonances are unwanted and the operating frequency of these systems should be well below resonance. However, some applications exists, where resonance is used directly for high power conversion efficiency e.g. to excite large oscillation travels (ultrasonics etc.). Resonantly working actuators and transducers show a different design compared with the standard actuators. 4.7 Thermal effects Operating temperatures: PSt 150 low voltage actuators: 40 C thru +100 C PSt 500/PSt 1000 high voltage actuators: 50 C thru + 15 C. Actuators for cryogenic temperatures, high temperatures available: see options. Thermal expansion: Poled PZT ceramic is anisotropic with respect to thermal expansion: this means that the thermal expansion coefficient differs for the axial and radial direction of the stack. Further there is a difference in thermal expansion to the unpoled ceramic. The thermal expansion coefficient of the standard materials normal to discs plane is slightly negative as seen with the lowvoltage multilayer stacks. HV stacks with their compound structure containing metal and adhesive layers show in total a slightly positive coefficient. Piezomechanical Stackactuators 7

8 The below stated data are measured on short circuited stacks at room temperature. For thermal expansion of actuators with casing the thermal expansion of the metal endpieces has to be taken into account. ow voltage elements: x 10-6 / C High voltage elements: 1 2 x 10-6 / C Temperature dependence of the piezoeffect: The stroke of an actuator for a distinct applied voltage depends on stack s temperature: For low voltage PM1 material, there is a slight decrease of stroke by about 5% at 100 C compared to room temperature. High voltage PM2 material shows a 0% increase of stroke efficiency under the same conditions. This is one of the reasons, why Piezomechanik s HV actuators are excellently well suited for power operation at elevated stack temperatures. Thermal conductivity: The thermal conductivity of poled piezoceramic is again anisotropic, but generally poor. The axial thermal conductivity of pure ceramic is about 2 Watts/m K (compare: copper 90 Watt/m K). The poor thermal conductivity causes problems with determining stack s temperature. Within bulky elements, the actuator core can show significantly higher temperatures than the surface under dynamic operating conditions. Self heating and power application The interest in high electromechanical power conversion by piezoactuators is strongly increasing. Examples are active vibration control with heavy mechanical structures and shaker arrangements. This is supported by the availability of highly efficient switched power supplies, which recycle the reactive part of the power balance instead of wasting it as simple analog amplifiers do (See amplifiers RCV/brochure Amplifiers ). The main limitation for the power balance is now the reaching of the operating temperature limit of the actuator due to selfheating by dissipating partially the operating power. As stated formerly, the dissipated power depends strongly on the driving conditions (field strength, temperature). 5. Options Piezomechanik s actuators can be optimized for distinct applications beyond the described standard technique. Position sensors Piezomechanik offers the application of strain gages in half bridge or full bridge arrangements. Further Piezomechanik offers the PosiCon feedback control for setting up completely closed position control loops (see brochure). Vacuum operation: Piezoactuators are generally not impacted by vacuum operation except the glow discharge region. The better the vacuum, the better for the piezo. The question is in how far the piezo contaminates the vacuum. For UHV applications, Piezomechanik offers stack actuators, where special outgassfree materials are used. Further baking is possible (no voltage applied). Casings are supplied with exhaust orifices for quick evacuation. Increased temperature ranges Piezomechanik offers actuators optimized for cryogenic temperature operation. Further high temperature versions (150 C operation) can be provided. Negative polarity: With cased versions of piezoactuators, the operating polarity (for application of maximum voltage) is fixed. Standard with Piezomechanik s range is positive polarity. Elements for negative polarity are available without additional charge. The strategy for optimizing a power application is rather simple: the power input has to be minimized by using a proper design and material for the actuator to reduce heat. Further the generated heat has to be removed efficiently to keep temperature low, otherwise capacitance increases and this starts a selfaccelerated upheating. Piezomechanik offers the best way for optimum power application of actuators: Especially the HV elements based on PM2 material show highest power conversion efficiency as reported in the application note Materials aspects of the thermal balance of piezo stack actuators. A further contribution is the stack s efficient heatsinking by the copperfoot -design of Piezomechanik s power actuators. Finally, the applier can support the power balance by reducing the strain within the piezoactuator. Notice: the energy content/power requirement of an actuator increases squaric with mechanical strain and voltage. Using a stack of double length (double capacitance, but half strain/voltage level) reduces the power consumption by 50%!! compared to a shorter,but full strain operated element. 8 Piezomechanical Stackactuators

9 6. Ordering code PSt 150/5/50 Gh10/VS 10 xx.yy. PiezoelectricStack for 150 V Stackdiameter/diagonal: 5 mm nominal travel at +150 V: 50 µm with casing diameter 10 mm Gh: without internal prestress VS: with internal prestress options: e.g. VbS ball tip 7. Custom designed actuators Piezomechanik offers a wide range of standard piezoactuators, which display an excellent optimization regarding the wide variety of operating requirements. Piezoactuators are increasingly chosen as innovative solutions for a lot of new applications, which may result in the need for completely new actuator designs. Piezomechanik has a well founded knowledge and offers cooperation in the field of actuators and supplies to find special solutions for your application problem. Contact us. 8. Safety instructions Caution: Depending on the individual application, piezoactuators are electrically connected to voltages and currents, which are potentially dangerous for life and health of the operator. Installation and operation of piezoactuators have to be done only by authorized personnel. Ensure proper and safe connections, couplers, drivers. Caution: Piezoactuators are highly efficient charge storing capacitors. Even when they are disconnected from a supply, the electrical energy content of a loaded actuator can be high and is held for a long time. Ensure always a complete discharging of an actuator (e.g. via a 10 kohms resistor) before handling. (Do not discharge by simple shortcircuiting, because of the risk of damaging the ceramic.) Caution: electrical charges can be generated on disconnected actuators by varying load or temperature. Caution: Discharge an actuator before connecting it to a measuring device/electronics, when this device is not sufficiently voltage proofed. Piezomechanical Stackactuators 9

10 ow voltage actuators Series PSt 150/4/... low voltage multilayer type max. operating voltage +150 V max. compress. load: 100 N Versions without casing (woc), bare stacks End faces: wear resistant corundum (electrically insulating) Ø 5.1 Polymer coating electrical connection: pigtails 4 Type stroke** length capacitance comp. stiffnes resonance frequency 150/2x/5* / /2x/7* 5/7 9 on request on request on request 150/2x/20* 15/20 18 on request on request on request 150/4/7 5/ /4/20 15/ /4/40 0/ * Multilayerstacks with crossection 2x mm for miniaturemechanics, no options ** for 100 V/150 V (see 4..) Options: bs:spherical endpiece additional length: 1.0 mm Ig: endpiece with tapped hole M (for fixed end only) additional length: 6 mm R = 2.5 bs Ig M, depth Ø 7 10 Piezomechanical Stackactuators

11 Versions with casing Gh 9, no mechanical prestress coax-cable length 1 m, BNC connector moving top: plane face, corundum Ø9 Ø5 1± ±0.5 Ø9 R 2.5 Ø Sw 6 mm M, 4 mm depth Type stroke** length capacitance comp. stiffness resonance frequency PSt 150/4/ 7 Gh9 5/ PSt 150/4/20 Gh9 15/ PSt 150/4/40 Gh9 0/ Option: bs: spherical endpiece ** for 100 V/150 V (see 4..) Versions: with casing VS 9, with internal mechanical prestress: prestress force: approx. 0 N coax-cable: length 1 m, BNC connector tapped hole in moving end ±0.5 Ø9 Ø M2, mm Ø9 Ø R1 1 ±0.5 VbS Ø Sw 6 mm M, 4 mm depth Type stroke** length capacitance comp. stiffness resonance frequency PSt 150/4/ 7 VS 9 5/ PSt 150/4/20 VS 9 15/ PSt 150/4/40 VS 9 0/ PSt 150/4/60 VS 9 45/ Options: VbS: spherical end on moving end ** for 100 V/150 V (see 4..) Piezomechanical Stackactuators 11

12 Versions PSt 150/5/... ow voltage multilayer type +150 V Versions without casing (woc), bare stacks End faces: wear resistant corundum (electrically insulating) polymer coating electrical connection: 2 teflon insulated pigtails 0.5 Ø Ø 8 ** for 100 V/150 V (see 4..) Type stroke length capacitance comp. stiffness resonance frequency PSt 150/5/ 7 5/7** PSt 150/5/20 15/20** PSt 150/5/40 0/40** Ø 5.1 R = 2.5 M, 4 depth WC bs Ig Ø 7 Options: WC: plane faces of tungsten carbide (as a counterpice e.g. for spherical micrometer tips) additional length 1.5 mm bs: spherical endpiece additional length 1 mm Ig: mechanical endpiece with tapped hole M (for fixed end only) additional length 6 mm 12 Piezomechanical Stackactuators

13 Version with casing VS10, with internal mechanical prestress: prestress force: approx. 100 N coax-cable: length 1 m, BNC connector or EMOSA OS250 tapped hole in moving end Ø 10 Ø 4 M, 4 mm depth 4±0.5 Ø SW 8 mm M, 4 mm depth Ø 10 Ø 4 Ø 10 Ø 4 Ø 10 Ø 4 M R SW mm 4± ±0.5 VAg Options: VAg: threaded pin on moving end VbS VbS: spherical top piece (steel) on moving end pf pf: plane face on moving end Type stroke length capacitance comp. stiffness resonance frequency PSt 150/5/ 7 VS10 25/7** PSt 150/5/20 VS10 15/20** PSt 150/5/40 VS10 0/40** PSt 150/5/60 VS10 45/60** PSt 150/5/80 VS10 60/80** ** for 100 V/150 V (see 4..) Piezomechanical Stackactuators 1

14 Special versions MPSt 150/5/xx, MPSt-BD 150/5/xx in casing with front mounting thread Operating voltage +150 V The actuators MPSt/MPSt-BD are based on the PSt 150/5/xx low voltage stacks. The stainless steel housing show a fine pitch M 12 x 0.5 thread in the front part. By this fine pitch thread, the actuated component can be prepositioned to define the starting point of the piezo s action. The MPSt/MPSt-BD actuators can be inserted directly to a lot of optomechanical mounts, mirror mounts, stages retrofitting the original micrometers. By using piezoactuators, the positioning sensitivity and dynamics of such arrangements is improved dramatically (eg. for microscanning, laser stabilization by feedback vontrol system PiStab-2). The MPSt actuators are designed for use with the MR P stages. The MPSt/MPSt-BD actuators are not internally preloaded. Preloading has to be done externally eg. by reset springs or magnets as used within common mirror mounts, stages etc. MPSt MPSt-BD Mirror mount S with actuators MPSt-BD Type stroke length capacitance comp. stiffness resonance frequency MPSt(-BD) 150/5/ MPSt(-BD) 150/5/ MPSt(-BD) 150/5/ MPSt(-BD) 150/5/ MPSt(-BD) 150/5/ MPSt(-BD) 150/5/ Max. compressive load: 500 N Electrical connection: 1 m coaxial cable with BNC-connector Actuators with modified threads for longer travels for higher stiffness (based on PSt 150/7/xx stacks) actuators for driving voltages 500 V, 1000 V on request 14 Piezomechanical Stackactuators

15 Versions PSt 150/7/... low voltage multilayer type: 150 V m. c. load: 1000 N Versions without casing (woc), bare stacks End faces: wear resistant corundum (electrically insulating) polymer coating electrical connection: 2 teflon insulated pigtails Ø = ** for 100 V/150 V (see 4..) Type stroke** length capacitance comp. stiffness resonance frequency PSt 150/7/ 7 5/ PSt 150/7/20 15/ PSt 150/7/40 0/ Ø 8.1 R=4 WC bs Ig M, 4 depth Ø 8 Options: WC: plane faces of tungsten carbide (as a counterpiece e.g. for spherical micrometer tips) additional length: bs: spherical endpiece additional length: 2,5 mm Ig: mechanical endpiece with tapped hole M (for fixed end only) additional length: 7 mm Versions: with casing Gh 12, no mechanical prestress coax-cable length 1 m, BNC connector or EMOSA OS250 moving top end: plane face, tungsten carbide Ø12 Ø8 1 Ø12 R4 Ø SW 10 mm M4, 4 mm depth Type stroke** length capacitance comp. stiffness resonance frequency (µm) (mm) (µf) (N/µm) (khz) PSt 150/7/ 7 Gh12 5/7 19 0, PSt 150/7/20 Gh12 15/ , PSt 150/7/40 Gh12 0/40 46, PSt 150/7/60 Gh12 40/ , Options: bs: spherical top end ** for 100 V/150 V (see 4..) Piezomechanical Stackactuators 15

16 Version: with casing VS12, with internal mechanical prestress: prestress force: approx. 150 N coax-cable: length 1 m, BNC connector or EMOSA OS250 tapped hole in moving end Ø12 Ø5 M, 4 mm depth 4 ± 0.5 SW 4 mm Ø SW 10 mm M4, 4 mm depth Type stroke** length capacitance comp. stiffness resonance frequency (µm) (mm) (µf) (N/µm) (khz) PSt 150/7/ 7 VS12 5/7 19 0, PSt 150/7/ 20 VS12 15/ , PSt 150/7/ 40 VS12 0/40 46, PSt 150/7/ 60 VS12 45/ , PSt 150/7/ 80 VS12 60/ , PSt 150/7/100 VS12 75/ , PSt 150/7/120 VS12 90/ ,0 8 4 PSt 150/7/140 VS12 105/ ,0 7 PSt 150/7/160 VS12 120/ ,0 5 2 ** for 100 V/150 V (see 4..) Ø12 Ø12 Ø12 Ø5 M4 Ø5 Ø5 Ø1.5 7± ± ± 0.5 VAg SW 4 mm VbS pf Options: VAg: threaded pin on moving end VbS: spherical top piece (steel) on moving end pf: plane face on moving end 16 Piezomechanical Stackactuators

17 Versions PSt 150/14/... low voltage multilayer stacks: +150 V m. c. load: 4000 N former designation: HA kn/150/ Version with casing VS20, with internal mechanical prestress: prestress force: approx. 700 N coax-cable: length 1.5 m, BNC connector or EMOSA OS250 tapped hole in moving end Ø20 Ø8 M5,5 mm depth SW 6 mm 4 ±0.5 Ø4 5 5 SW 17mm M8, 7 mm depth Type stroke** length capacitance comp. stiffness resonance frequency (µm) (mm) (µf) (N/µm) (khz) PSt 150/14/ 7 VS20 5/7 26 2, PSt 150/14/ 20 VS20 15/20 5 6, PSt 150/14/ 40 VS20 0/ PSt 150/14/ 60 VS20 45/ PSt 150/14/ 80 VS20 60/ PSt 150/14/100 VS20 75/ PSt 150/14/120 VS20 90/ PSt 150/14/140 VS20 105/ ** for 100 V/150 V (see 4..) Ø20 Ø20 Ø20 Ø8 R Ø8 M5 SW 6 mm Ø8 4 ± ± 0.5 VbS VAg pf Options: VbS: spherical top piece (steel) on moving end VAg: threaded pin on moving end pf: plane face on moving end Piezomechanical Stackactuators 17

18 High Voltage actuators Versions PSt 500/10/... discrete stacking, max. operating voltage +500 V Versions PSt 1000/10/... discrete stacking, max. operating voltage V m. c. load: 2000 N Versions without casing (woc), bare stacks End faces: wear resistant corundum (electrically insulating) polymer coating electrical connection: 2 teflon insulated pigtails 0.5 Ø Ø 1 6 Type stroke length capacitance comp. stiffness resonance frequency PSt 500/10/ PSt 500/10/ PSt 500/10/ PSt 500/10/ PSt 1000/10/ PSt 1000/10/ PSt 1000/10/ PSt 1000/10/ Ø 10.1 R=5 M, 6 depth Ø 10 WC bs Ig Options: WC: plane faces of tungsten carbide (as a counterpiece e.g. for spherical micrometer tips) additional length 1.5 mm bs: spherical endpiece additional length: 5 mm Ig: mechanical endpiece with tapped hole M (for fixed end only) additional length: 9 mm Versions with casing Gh 18, no mechanical prestress (on request) 18 Piezomechanical Stackactuators

19 Versions with casing VS18, with internal mechanical prestress: prestress force: approx. 00 N coax-cable: length 1.5 m, BNC connector or EMOSA OS250 tapped hole in moving end Ø18 Ø8 M5, 5 mm depth SW 6 mm 4± 0.5 Ø 5 5 SW 15 mm M5, 5 mm depth Type stroke length capacitance comp. stiffness resonance frequency PSt 500/10/ 5 VS PSt 500/10/ 15 VS PSt 500/10/ 25 VS PSt 500/10/ 40 VS PSt 500/10/ 60 VS PSt 1000/10/ 5 VS PSt 1000/10/ 15 VS PSt 1000/10/ 25 VS PSt 1000/10/ 40 VS PSt 1000/10/ 60 VS PSt 1000/10/ 80 VS PSt 1000/10/100 VS PSt 1000/10/125 VS Ø18 Ø18 Ø18 Ø8 Ø8 Ø8 R M5 4± ±0.5 4 ± 0.5 VbS VAg SW 6 mm pf Options: VbS: spherical top piece (steel) on moving end VAg: threaded pin on moving end pf: plane face on moving end Piezomechanical Stackactuators 19

20 Versions PSt 1000/16/... discrete stacking, max. operating voltage V m. c. load: 6000 N low voltage versions PSt 150/16/ for +150 V operating voltage: on request high voltage versions PSt 500/16/ for +500 V operating voltage: on request Versions without casing (woc), bare stacks End faces: wear resistand corundum (electrically insulating) D1 D2 D 1: 16,1 mm D 2: ca. 20 mm Polymer coating: electrical connection: 2 teflon insulated pigtails D1: 16.1 mm D2: approx. 20 mm 6 Type stroke length capacitance comp. stiffness resonance frequency PSt 1000/16/ PSt 1000/16/ PSt 1000/16/ PSt 1000/16/ On request: stacks for reduced operating voltages, mechanical endpieces, planes faces (hardened steel), longer stacks Version: with casing VS 25, with internal mechanical prestress: prestress force: approx. 700 N coax-cable: length 1.5 m, BNC connector or EMOSA OS250 tapped hole in moving end 4 ± 0.5 Ø25 Ø10 M6, 6 mm depth SW 8 mm Ø4 5 5 Options: VAg: threaded pin on moving end VbS: spherical top piece (steel) on moving end pf: plane face on moving end SW 22 mm M8, 7 mm depth Type stroke length capacitance comp. stiffness resonance frequency PSt 1000/16/ 5 VS PSt 1000/16/ 15 VS PSt 1000/16/ 40 VS PSt 1000/16/ 60 VS PSt 1000/16/ 80 VS PSt 1000/16/100 VS PSt 1000/16/125 VS PSt 1000/16/150 VS Piezomechanical Stackactuators

21 Versions PSt 1000/25/... discrete stacking, max. operating voltage V m.c. load: N Version: PSt 500/25/ for +500 V operating voltage: on request Versions without casing (woc, bare stack) End faces: wear resistant corundum (electrically insulating) Polymer coating D1 D2 D 1: 25.5 mm D 2: ca. 0 mm electrical connection: 2 teflon insulated pigtails D1: 25.5 mm D2: approx. 0 mm 6 Type stroke length capacitance comp. stiffness resonance frequency PSt 1000/25/ PSt 1000/25/ PSt 1000/25/ PSt 1000/25/ On request: stacks for reduced operating voltages mechanical endpieces, plane faces (hardened steel), longer stacks Version: with casing VS 5, with internal mechanical prestress: prestress force: approx N coax-cable: length 1.5 m, BNC connector or EMOSA OS250 tapped hole moving end 8 ± 0.5 Ø5 Ø14 M8, 8 mm depth SW12 mm 6 Ø4 8 8 SW 0 mm M8, 8 mm depth Type stroke length capacitance comp. stiffness resonance frequency PSt 1000/25/ 5 VS PSt 1000/25/ 15 VS PSt 1000/25/ 40 VS PSt 1000/25/ 60 VS PSt 1000/25/ 80 VS PSt 1000/25/100 VS PSt 1000/25/150 VS Piezomechanical Stackactuators 21

22 Versions PSt 1000/5/... discrete stacking, max operating Voltage V m. c. load: 5000 N Versions PSt 500/5/ for V operating voltage: on request Version without casing (woc), bare stacks End faces: wear resistan corundum (electrically insulated) Polymer coating D1 D2 D 1: 5.5 mm D 2: ca. 40 mm electrical connection: 2 teflon insulated pigtails, lenght approx. 150 mm D1: 5.5 mm D2: approx. 40 mm 6 Type stroke length capacitance comp. stiffness resonance frequency PSt 1000/5/ PSt 1000/5/ PSt 1000/5/ PSt 1000/5/ On request: stacks for reduced operating voltages mechanical endpieces, plane faces (hardened steel), longer stacks Version: with casing VS 45, with internal mechanical prestress: prestress force: approx N coax-cable: length 1.5 m, BNC connector or EMOSA OS250 tapped hole in moving end 8 ±0.5 Ø45 Ø20 M8, 8 mm depth 6 SW 17mm Ø4 8 8 SW 40 mm M8, 8 mm depth Type stroke length capacitance comp. stiffness resonance frequency PSt 1000/5/ 5 VS PSt 1000/5/ 15 VS PSt 1000/5/ 40 VS PSt 1000/5/ 60 VS PSt 1000/5/ 80 VS PSt 1000/5/100 VS PSt 1000/5/150 VS Piezomechanical Stackactuators

23 Accessories Piezostacks with casing are supplied with coax-cables. As connectors BNC and EMOSA OS250 are available (other types on request). For orders comprising a complete system actuator + electronic supply, the actuators show plugs corresponding to the supplies connector system. Necessary adaptors/couplers are delivered without further charge. A wide range of extensions cords, couplers and adaptors simplifies the installation and interconnection of PIEZOMECHA- NIK s components and the combination with electronics from other sources. Adaptors, couplers: EMOSA-BNC: for combining actuators/components with BNC connector to a supply with EMOSA sockets. BNC-EMOSA: for combining actuators/components with EMOSA plugs to BNC-sockets BNC-SMC: on request SMC-BNC: on request Extension cables BNC plug-bnc socket EMOSA plug-emosa socket EMOSA plug-bnc socket BNC plug-emosa socket length 2 m/4 m/10 m length 2 m/4 m/10 m length 2 m/4 m/10 m length 2 m/4 m/10 m Piezomechanical Stackactuators 2

24 Piezomechanik Dr. utz Pickelmann GmbH Berg-am-aim-Str. 64 D-8167 Munich Phone xx 49/89/ Fax xx 49/89/ info@piezomechanik.com Stand: Juni 1998