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Low-Voltage Shear Piezoelectric Chips and Stacks
Chip with Two Flat End Plates
Discrete Shear Stack Translates along One Lateral Direction
One Longitudinally- and Two Laterally-Translating Stacks Bonded Together for 3D Positioning of Top Surface
Segment Displacement is Parallel to:
Chip with Bare Gold Top and Bottom Electrodes
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Shear Piezoelectric Chips and Stacks provide lateral displacement. The relationships between voltage bias (±V), piezo polarization (P) and electric field (E) are shown. The green side on our chips indicates displacement direction. See the Operation tab for details.
Thorlabs offers Shear Piezoelectric Chips and Stacks as well as Multi-Axis Positioners that incorporate our shear piezo stacks. Our shear piezo chips provide up to 1.3 µm of displacement along one lateral axis, while our shear piezo stacks achieve a lateral stroke up to 7.0 µm. Our multi-axis positioners achieve 7.0 µm displacement per axis. For a complete list of specifications, please see the tables below.
Please see the Operation tab for information on interfacing piezoelectric actuators with loads and special operational considerations. Piezoelectric chips with custom dimensions, voltage ranges, and coatings are available; please contact Tech Support for details.
Shear Piezo Chips
Shear Piezo Stacks and Multi-Axis Positioners
Shear vs. Axial Strain
Shear Chips and the PN5FC1 single shear stack offer displacement along one lateral direction, the PN5FC2 comprises two bonded shear stacks and provides displacement along both lateral directions, and the PN5FC3 enables 3D positioning by bonding a longitudinally-translating stack to two laterally-translating shear stacks.
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Figure 1: A green bar indicates the lateral motion direction of the shear piezos. The surface electrode that has a positive voltage applied to it will be laterally displaced towards the painted green bar.
Electrical Bias and Shear Strain
These shear piezo chips have identical electrodes on their top and bottom surfaces, and the induced shear strain is symmetrical. Therefore, these chips can be driven by bipolar symmetrical electrical supplies. We recommend Thorlabs' HVA200 High-Voltage Amplifier, which is available below.
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Figure 2 Example plot illustrating that the stroke for a ±100 V driving voltage range is approximately 30% that for a ±200 V range. Relative hysteresis under both operating conditions is also shown.
Hysteresis and Lateral Displacement
Adding an Electrical Connection to the PL5FB External Electrodes
Soldering Wire Leads to the PL5FBP3 Electrodes
Interfacing a Piezoelectric Element with a Load
Some correct and incorrect approaches to interfacing loads with piezoelectric chips are shown in the diagrams below.
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Figure 3 Correct mechanical clamping methods include using a spring to apply force. Note that the incorrect example on the right is missing an end plate between the chip and load.
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Figure 4 The piezo should be held in place using adhesives as shown on the left. Note that applying glue as shown on the right will impede the lateral translation of the piezo.
HVA200 High-Voltage Amplifier Specifications
Firmware for the HVA200 Amplifier
The available firmware updates can be downloaded by clicking on the link below.
Each piezo chip is fabricated from a single layer of piezoelectric ceramic with chemically deposited gold electrodes on the top and bottom of the chip. The driving voltage is applied across these electrodes. The PL5FBP3 includes flat end plates (Item # PKFEP4) with copper plates and leads glued to the top and bottom of the piezo. The end plates spread the contact force of the load over the entire mounting face of the piezo while the copper leads, which are extended beyond the footprint of the chip, facilitate making electrical connections.
Applying a voltage less than -200 V or greater than 200 V to either electrode will decrease the the life of these chips and may cause mechanical failure.
Our multi-axis positioners provide displacement along the axes of an orthogonal coordinate system, with each integrated stack providing displacement along a single axis. The translation axes of the individual stacks and the stacks built into our multi-axis positioners can be identified from the wire configuration.
All positioners include one or two shear stacks. Applying a voltage less than -200 V or greater than 200 V to either electrode of a shear stack will decrease its lifetime and may cause mechanical failure. Our PN5FC3 also includes a longitudinally-translating stack, which provides displacement in the Z-axis direction. Applying a voltage greater than 150 V to this longitudinally-translating stack will decrease the life of the stack and may cause mechanical failure, and, unlike the shear stacks, applying a reverse bias may cause this stack to mechanically fail.
Cross talk between the two shear stacks bonded together in the PN5FC2 and PN5FC3 is no more than 5%.
The Thorlabs HVA200 High Voltage Amplifier is ideal for driving our Shear Piezo Chips. While it is possible to also use the HVA200 to drive the longitudinally-translating stack incorporated in the PN5FC3 multi-axis piezo positioner, the relatively low current provided by the HVA200 combined with the high capacitance of the stack limits the maximum driving voltage frequency. In addition, care must be taken not to exceed the driving voltage limits of this stack.
The amplifier has many features, including a ±200 V output, a continuous current output of 100 mA, a 1 MHz bandwidth, and low noise. The voltage gain of -20 boosts the input up to the high voltages needed to drive our lithium niobate broadband modulators and shear piezos. An adjustable bias allows for precise DC offset control. The HVA200 is also a preferred driver for our Electro-Optic Modulators; however, there are some limitations on the operational wavelength ranges of some of the modulators when the HVA200 is used as the driver. Please see the electro-optics modulators page for additional details.
The HVA200 uses a high voltage, wideband, high slew rate output amplifier to achieve the desired output. The input amplifier includes a summing junction, which allows an adjustable DC bias to be added to the input modulation. This composite signal is then boosted by a fixed voltage gain of 20 by the output amplifier up to a maximum output of ±200 V. For example, if the HVA200 is sweeping from -200 to 200 V and a 10 V DC Bias is applied, the output of the HVA200 will be from -190 to 200 V (i.e., the sweep is clipped because the maximum voltage output was reached). If, however, the HVA is swept from -100 to 100 V and the same 10 V DC Bias is applied, the output will sweep from -90 to 110 V.
For added safety, a front panel HV Enable button must be pressed to connect the HV output to the output BNC. The DC Bias control consists of a rotary encoder, which allows precise control and repeatability. The bias adjustment is typically used to shift the DC level of the output as needed by the application. A voltage monitor output is provided to allow real-time monitoring of the high voltage output. The monitor has a scaling of 20:1 (when used with high impedance detectors) so that an output of 200 V results in a 10 V monitor voltage.
The HVA200 includes an SMA-to-BNC cable for connection to our free-space electro-optic modulators, a USB 2.0 Type A to B cable for remote operation, and a power cord. Custom cables will need to be used to connect the HVA200 to one of our shear piezos.
This Alumina Flat End Plate is designed to spread the force at the contact point over the entire surface of the piezo chip. It is used on the top and bottom surface of the PL5FBP3 piezo chip above and has a dimensional tolerance of ±0.04 mm.