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APT Piezo Control Module
Full Suite of
The APT™ MPZ601 piezo driver module is a dual channel high power (75 V, 500 mA) piezo controller. It has been designed to drive the full range of open and closed loop piezo equipped nano-positioning actuators and stages offered by Thorlabs (see Related Items tab). Equipped with strain gauge feedback circuitry on each channel this unit is able to provide closed loop positioning to the nanometer regime when operated with Thorlabs actuators. In addition flexible software settings make these units highly configurable and therefore suitable for driving a wide range of piezo elements in third party products. A waveform generation capability combined with triggering outputs makes this unit particularly suitable for piezo scanning applications.
This module incorporates the latest high speed digital signal processing (DSP) and low-noise analog electronics technology and has been designed specifically to fit the highly flexible APT MMR601 Motion Control 19" Modular Rack System. Multiple MPZ601 piezo modules can be fitted to this rack system (providing up to 12 channels of operation per rack) to support larger scale critical alignment applications where nanometer level motion control is required with a high axis count.
USB connectivity via the MMR601 Rack Enclosure provides easy plug and play PC operation - multiple modules can be connected to a single PC via standard USB hub technology for multi-axis motion control applications. Coupling this with the very user friendly APT software allows the user to very quickly get up and running in a short space of time – for example all relevant operating parameters are set automatically for Thorlabs piezo actuator products. Advanced custom motion control applications and sequences are also possible using the extensive ActiveX® programming environment described in more detail on the Motion Control Software and APT Tutorials tabs.
User I/O Controller
Ext In (+) and Ext In (-)
Differential Inputs. The output from the HV amplifier circuit can be set to be controlled, in part, by the differential signal on these two inputs. If the Input Source is set to include a BNC option, the unit sums this differential signal with any other input sources selected (voltage set using the GUI panel 'Output' control and voltage from an external potentiometer).
0 to 75 V, 0 to 250 mA. Provides the drive signal to the piezo actuator.
These videos illustrate some of the basics of using the APT System Software from both a non-programming and a programming point of view. There are videos that illustrate usage of the supplied APT utilities that allow immediate control of the APT controllers out of the box. There are also a number of videos that explain the basics of programming custom software applications using Visual Basic, LabView and Visual C++. Watch the videos now to see what we mean.
To further assist programmers, a guide to programming the APT software in LabView is also available.
Piezo Driver Bandwidth Tutorial
Knowing the rate at which a piezo is capable of changing lengths is essential in many high-speed applications. The bandwidth of a piezo controller and stack can be estimated if the following is known:
To drive the output capacitor, current is needed to charge it and to discharge it. The change in charge, dV/dt, is called the slew rate. The larger the capacitance, the more current needed:
For example, if a 100 µm stack with a capacitance of 20 µF is being driven by a BPC Series piezo controller with a maximum current of 0.5 A, the slew rate is given by
Hence, for an instantaneous voltage change from 0 V to 75 V, it would take 3 ms for the output voltage to reach 75 V.
Note: For these calculations, it is assumed that the absolute maximum bandwidth of the driver is much higher than the bandwidths calculated, and thus, driver bandwidth is not a limiting factor. Also please note that these calculations only apply for open-loop systems. In closed-loop mode, the slow response of the feedback loop puts another limit on the bandwidth.
The bandwidth of the system usually refers to the system's response to a sinusoidal signal of a given amplitude. For a piezo element driven by a sinusoidal signal of peak amplitude A, peak-to-peak voltage Vpp, and frequency f, we have:
A diagram of voltage as a function of time is shown to the right. The maximum slew rate, or voltage change, is reached at t = 2nπ, (n=0, 1, 2,...) at point a in the diagram to the right:
From the first equation, above:
For the example above, the maximum full-range (75 V) bandwidth would be
For a smaller piezo stack with 10 times lower capacitance, the results would be 10 times better, or about 1060 Hz. Or, if the peak-to-peak signal is reduced to 7.5 V (10% max amplitude) with the 100 µm stack, again, the result would be 10 times better at about 1060 Hz.
Triangle Wave Signal
For a piezo actuator driven by a triangle wave of max voltage Vpeak and minimum voltage of 0, the slew rate is equal to the slope:
Or, since f = 1/T:
Square Wave Signal
For a piezo actuator driven by a square wave of maximum voltage Vpeak and minimum voltage 0, the slew rate limits the minimum rise and fall times. In this case, the slew rate is equal to the slope while the signal is rising or falling. If tr is the minimum rise time, then
For additional information about piezo theory and operation, see the Piezoelectric Tutorials page.
Thorlabs offers two platforms to drive our wide range of motion controllers: our Kinesis® software package or the legacy APT™ (Advanced Positioning Technology) software package. Either package can be used to control devices in the Kinesis family, which covers a wide range of motion controllers ranging from small, low-powered, single-channel drivers (such as the K-Cubes™ and T-Cubes™) to high-power, multi-channel, modular 19" rack nanopositioning systems (the APT Rack System).
The Kinesis Software features .NET controls which can be used by 3rd party developers working in the latest C#, Visual Basic, LabVIEW™, or any .NET compatible languages to create custom applications. Low-level DLL libraries are included for applications not expected to use the .NET framework. A Central Sequence Manager supports integration and synchronization of all Thorlabs motion control hardware.
Kinesis GUI Screen
APT GUI Screen
Our legacy APT System Software platform offers ActiveX-based controls which can be used by 3rd party developers working on C#, Visual Basic, LabVIEW™, or any Active-X compatible languages to create custom applications and includes a simulator mode to assist in developing custom applications without requiring hardware.
By providing these common software platforms, Thorlabs has ensured that users can easily mix and match any of the Kinesis and APT controllers in a single application, while only having to learn a single set of software tools. In this way, it is perfectly feasible to combine any of the controllers from single-axis to multi-axis systems and control all from a single, PC-based unified software interface.
The software packages allow two methods of usage: graphical user interface (GUI) utilities for direct interaction with and control of the controllers 'out of the box', and a set of programming interfaces that allow custom-integrated positioning and alignment solutions to be easily programmed in the development language of choice.
A range of video tutorials is available to help explain our APT system software. These tutorials provide an overview of the software and the APT Config utility. Additionally, a tutorial video is available to explain how to select simulator mode within the software, which allows the user to experiment with the software without a controller connected. Please select the APT Tutorials tab above to view these videos, which are also available on the software CD included with the controllers.