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BPC301

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BPC301 Rear Panel

Features

• Variable Output Selection: 75 V, 100 V, or 150 V
• Closed-Loop PID with Advanced Control Algorithm
• Strain Gauge or Capacitive Sensor Feedback Options
• High-Resolution Position Control for Very Fine Positioning Applications
• Voltage Ramp/Waveform Generation Capability for Scanning Applications
• High Bandwidth (10 kHz) Piezo Positioning
• Auto-Configure Function for Thorlabs Ident-Equipped Piezo Actuators
• User-Controlled Digital I/O Port
• USB Plug-and-Play – Multiaxis Expansion
• Motor Control I/O Port (Jogging, Interlocks)
• Full Software Control Suite Supplied
• Intuitive Software Graphical Control Panels
• Extensive ActiveX® Programming Interfaces
• Fully Software Integrated with Other apt™ Family Controllers (Integrated Systems Development)

These single- and 3-channel, high-power (150 V) benchtop piezo controllers provide open- or closed-loop nanometer position control. They have been designed to drive our full range of open- and closed-loop piezo-equipped nanopositioning actuators and stages. In addition, flexible software settings make these units highly configurable and therefore suitable for driving a wide range of third-party piezo elements. A waveform generation capability combined with triggering outputs make these units particularly suitable for piezo scanning applications.

Manual controls are located on the front face of the unit to allow manual adjustment of the piezo position using the digitally encoded adjustment pot. The display is easy to read and can be set to show either applied voltage or position in microns. Open- or closed-loop control and zeroing of the piezo can also be selected from the front panel.

USB connectivity provides easy plug-and-play" PC operation. Multiple units can be connected to a single PC via standard USB hub technology for multi-axis motion control applications. Coupling this with the user-friendly apt™ software allows the unit to get up and running quickly. For example, all relevant operating parameters are set automatically for Thorlabs' piezo actuated products. Advanced custom motion control applications and sequences are also possible using the extensive ActiveX® programming environment, which is described in more detail on the Software tab.

Flexibility

The BPC300 Series are the latest generation piezo controllers to be added to the apt™ motion control family. They have been designed for use in critical alignment applications where manual or automated nanometer level motion control is required. These high power yet low noise units deliver up to 150 V per channel and are compatible with all piezo-actuated nanopositioning actuators and stages in the Thorlabs range. They combine the latest high speed digital signal processors (DSP) with low-noise analog electronics and ActiveX® software technology for effortless software controlled piezo motion.

To support such a wide range piezo actuators these apt™ piezo units are fully configurable through software accessable key parameter settings. Intuitive easy to use software graphical panels allow immediate control and visualization of the operation of the piezo controller – adjustment of many key parameters is possible through direct interaction with the graphical panel. Open or closed loop operating modes can be selected 'on the fly', and in both modes the display can be changed to show drive voltage or position (in microns). In the closed loop operation mode, both the P & I (proportional and integral) components of the feedback control loop can be altered to adjust the servo loop response. The output drive voltage or position can be adjusted by rotating the software-pane" control knob.

Note that all such settings and parameters are also accessible through the ActiveX programmable interfaces which allow the user to build automated alignment routines. Refer to the Software tab for further information on the apt™ software support for the BPC200 Series.

Waveform Output/Triggering

Over and above open and closed loop piezo positioning the DSP controllers within the BCP300 Series offer additional and useful functionality. Through software it is possible to program in a voltage (or position) ramp or waveform as a table of values and then instruct the controller to output (clock out) this table either 'single shot' or continuously. It is possible to specify a hardware output trigger to be generated at a specific point during the waveform output in order to control third party equipment as a function of the piezo voltage (position). Alternatively an external system can trigger the piezo unit to initiate the waveform output in the reverse scenario. This functionality is particularly useful for piezo scanning applications.

Full Software GUI Control Suite & ActiveX® Controls Included

A full and sophisticated software support suite is supplied with the BPC300 controller. The suite includes a number of out of the box user utilities to allow immediate operation of the unit without any detailed pre-configuration. All operating modes can be accessed manually and all operating parameters changed and saved for next use. For more advanced custom motion control applications, a fully featured ActiveX® programming environment is also included to facilitate custom application development in a wide range of programming environments. Note that all such settings and parameters described above are also accessible through these ActiveX® programmable interfaces. For further information on the apt™ software support for the BPC300 units refer to the Software tab. Demonstration videos illustrating how to program the apt™ software are also available for viewing.

The ActiveX® apt™ system software shipped with these units is also compatible with other apt™ family controllers including our multi-channel rack-based system and smaller optical table mountable 'Cube' controllers. This single unified software offering allows seamless mixing of any apt™ benchtop, table top and rack based units in any single positioning application.

The key innovation of the apt™ range of controllers and associated mechanical products is the ease and speed with which complete automated alignment/positioning systems can be engineered at both the hardware and software level. All controllers in the apt™ range are equipped with USB connectivity. The 'multi-drop' USB bus allows multiple apt™ units to be connected to a single controller PC using commercial USB hubs and cables. When planning a multichannel application, simply add up the number and type of drive channels required and connect together the associated number of APT controllers.

Software Developers Support CD

A developers’ kit is shipped with all of our apt™ series controllers. This additional software support is intended for use by software developers working on large, system integration projects that incorporate apt™ products. The kit contains an extensive selection of useful code samples as well as a library of Video Tutorials.

The APT (Advanced Positioning Technology) family covers a wide range of motion controller products ranging from small low powered single channel optomechanical motor drivers (the 'Cube' drivers) to high power multi-channel modular 19" rack nanopositioning systems (the APT Rack System).

All controllers in the APT family share a common software platform, the APT System Software. The software CD supplied with all controllers contains an installation of this system software, together with a wealth of support information in the form of handbooks, help files, tutorial videos, FAQs and other relevant information on using and programming these Thorlabs products.

By providing this common software platform, Thorlabs has ensured that users can easily mix and match any of the APT controllers in a single application while only having to learn one single set of software tools. In this way it is perfectly feasible to combine any of the controllers from the low powered single axis to the high powered multi-axis systems and control all from a single PC based unified software interface.

The APT System Software allows two methods of usage - graphical user interface utilities (supplied) for direct interaction 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 progammed in the development language of choice.

Detailed information on both usage modes is provided on the CD. Also of particular interest, is the inclusion on the software CD of a range of software video tutorials (see the Video Tutorials tab). 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++. 

Click here to go direct to the Thorlabs Download Area to access the full APT software CD. Experiment with the software using the simulator mode - refer to the Tutorial Videos for the APTConfig utility to learn how to select simulator mode.

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.

Click here to view the video tutorial

To further assist programmers, a guide to programming the APT software in LabView is also available.

Click here to view the LabView guide

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:

1. The maximum amount of current the controllers can produce. This is 0.5 A for our BPC Series Piezo Controllers, which is the driver used in examples below.
2. The load capacitance of the piezo. The higher the capacitance, the slower the system.
3. The desired signal amplitude (V), which determines the length that the piezo extends.
4. The absolute maximum bandwidth of the driver, which is independent of the load being driven.

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 that is needed.

So for example, for a 100 µm stack, having a capacitance of 20 µF, 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.

Sinusoidal Signal

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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 V_pp, 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:

Thus,

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.

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Triangle Wave Signal

For a piezo actuator driven by a triangle wave of max voltage V_peak and minimum voltage of 0, the slew rate is equal to the slope, or:

or, since f = 1/T:

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Square Wave Signal

For a piezo actuator driven by a square wave of max voltage V_peak and minimum voltage of 0, the slew rate limits the minimum rise and fall time. In this case, the slew rate is equal to the slope while the signal is rising or falling. If t_r is the minimum rise time, then:

or