ASC500 Full Version

ASC500 Full Version

fully digital SPM controller with xy-scan generator and z feedback control, phase locked loop (PLL)

The ASC500 is attocube’s flagship microscopy controller with a very generic hard- and software concept compatible with almost any scanning probe microscopy technique. All desirable functions and high-end specifications for conducting the experiment of your choice in AFM, MFM, KPFM, PRFM, CFM, SHPM, SNOM, STM, and many more measurement techniques are available. The ASC500 features optional closed loop functionality, fully supporting attocube’s FPS interferometric sensors.

Cryogenic Tablet

Specifications

Size and Dimensions
chassis19" rack, 2 rack units, 9 x 45 x 40 cm³
weight10 kg
Controller Hardware
power supply100/115/230V, 50 .. 60 Hz
power consumption [W]max. 80
connectorIEC inlet
Output Signals
frequency range1 kHz .. 500 kHz
Detection
measurement bandwidth50 kHz
Interfaces
xy scan voltage output2 x -10 .. +10 , 16 (+16) bit, 5 MHz with programmable tilt correction uni-/bipolar, output limiter, slewrate control
z voltage output-10 .. +10 V, 18 bit, 200 kS/s uni-/bipolar, output limiter, slewrate control
analog ADC inputs6 x -10 .. +10 V, 18 bit, 400 kS/s ADC with programmable offset and gain compensation
analog DAC outputs4 x -10 .. +10 V, 16 bit, 200 kS/s DAC switchable 2nd order low pass 3 kHz / 100 kHz noise: 16 µVrms (10 Hz..100 kHz)
analog modulation inputs-10 .. 10 V, DC .. 50 kHz for DAC 1, DAC 2, and Z-Out
high frequency section2 x 16 bit, 50 MS/s ADC with continuous signal amplification, 2 x 16 bit, 50 MS/s DDS-DAC, oscillation excitation, 2 x monitor output of preamplified signal, 2 x SYNC output with fixed 10 V amplitude
general purpose digital interface8 bit LVTTL trigger input, 8 bit LVTTL trigger output, e.g. pixel-, line-, frame-clock, for optional programmable in / out sync, counter
digital serial interface (RS232)connection to ANC300 for coarse movement
digital serial interface (NSL)connection to ANC350 for closed loop coarse movement
host computer interfaceUSB 2.0 high speed, LAN 100 Mbit
auxiliary power outlet+/-5 V (0.2 A) and +/-15 V (0.1 A)
Resolution
frame view display modes2 frame views, 2 line views, easy generation of additional frames possible
frame view optionsoversampling, autosave (png, ASCII, bcrf), line subtraction line view with up to 16 subsequent lines
frame view selection toolsframe alignment, frame centering, zoom function, path mode, grid mode
Scan Generation
pixel clock [kHz]312.5
resolution20 bit (16 bit, 16x oversampling)
features (scan)slope compensation, switchable uni-/bipola, software rotation and zoom, slew-rate controlled movement
scan speed1 pm/s .. 2 mm/s
frame ratemax. 20 Hz @ 100 x 100 pixel
Sample Positioning
sensor typeinterferometric (FPS 19” SLIMLINE) or position triggered scanning
closed loop sensor range5 mm x 5 mm
closed loop scan resolution (steady state, 100 ms sample time)down to 1 nm (usually limited by noise & vibration levels)
Z Controller
z feedbackdigital P/I, anti wind-up
z resolution18 bit, up to 34 bit for small control range
input control signalany internal signal channel
features (z controller)external modulation input, setpoint modulation, invertable, feedback gain and output polarity, P/I gains in physical units
Phase Locked Loop (PPL)
features (PLL)2 P/I controllers with graphical interface
frequency resolution [µHz]0.14
Q Control
q feedabck typeelectronic, phase controlled
efficiency of Q controldecrease or increase of Q by factor 10 typical
Spectral Performance
spectroscopy modespoint/line/grid spectroscopy (up to 1024 x 1024 pixel)
spectroscopy typez-spectroscopy, bias spectroscopy, soft spectroscopy (all GUI parameters), dI/dV with internal Lock-In
averaging25 µs up to 160 ms per data point
spectroscopy parameterscontrol loop off, signal limiter
Second Pass Mode
second pass mode - working principle2nd pass with height offset or different scan parameter set
second pass mode - parametersheight offset, wait time, slew rate, alternative DAC, alternative setpoint
application for second pass modeMFM, SGM
Lock-In
low frequency Lock-In1 mHz .. 20 kHz
modulationall DAC channels & any internal signal
high frequency Lock-In1 kHz .. 500 kHz
integration timeup to 128 periods (low frequency Lock-In), up to 512 periods (high frequency Lock-In)
lock-in usageAFM cantilever signal, tuning fork signal etc. (high frequency Lock-In), spectroscopy, vibrational analysis, Hall probe etc. (low frequency Lock-In)
Optical Data
oscilloscopearbitrary channel vs. time; time base 2.5 µs .. 150 ms, 32000 pixel max. trigger: amp/edge/auto/single
FFTsfor every channel, 0 .. 200 kHz range, 1 .. 128 x averaging, windowing options, scaling: magnitude/power density/power spectrum
Path Mode
path mode working principleaction executed along user defined path
path mode functionalityuser definable, spectroscopies, manual handshake, TTL handshake
Options and Upgrades
features (transfer function)ADC/DAC offset adjustment, linear transfer function programming, preamp for each ADC channel (1 .. 64 x gain)
features (crosslink)two generic P/I loops, input/output for all ADC/DAC channels, map any internal signal to any arbitrary output channel
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Hardware

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microscopes, controller, ASC500, hardware, rear

Software

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Scan Engine

The ASC500 uses a dedicated hardware with a 4 MHz scan generator to create the voltages necessary for the raster motion. Further features are:

  • software rotation of the field of view
  • slope and drift compensation
  • fully software integrated control
  • LabVIEW™ interface
microscopes, controller, ASC500, software, z controller

Z Controller

The z scanner output is controlled by a digital PI algorithm with a bandwidth of 50 kHz. The z output DAC has a resolution of 18 bit, yielding a 4 pm resolution on a 1 µm scan range.

  • highly versatile; all signal channels can be used as control inputs
  • physical units of PI gain
  • setpoint modulation for PI fine tuning
  • inversion of feedback gain
  • inversion of output polarity
microscopes, controller, asc500, software, closed loop

Closed Loop (optional)

The ASC500 now supports closed loop scanning at low temperatures as an upgrade option. With different sensors closed loop positioning ranges up to 5 mm are possible with extremely high resolution. This unique concept provides not only compensation of scan non-linearities, but also full repeatability/recovery of positions over the full coarse range with nm resolution. Switching back and forth between different hot spots on the complete sample has never been easier. The ASC500 is fully compatible with the FPS3010/FPS 19“.

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Lithography (optional)

The ASC500 also offers a lithography mode. Any geometrical shape composed from convex polygons and single dots can be scanned with full control over scan speeds and line spacings for each shape unit. Shape definition is done via text files for full flexibility. Furthermore, a shutter can be controlled via TTL pulses for each shape unit. Lithography can operate in both open and closed loop mode.

  • scanning of arbitrary shapes composed from polygons and dots
  • full speed control for each shape unit
  • very flexible shape definition
  • shutter controller via TTL
microscopes, controller, ASC500, software, DAC/ADC

Digital/Analog Converters (DAC/ADC)

The outstanding input and output capabilities of the ASC500 are the key to highest precision measurements. Its analog-digital converters use state-of-the-art hardware with lowest possible noise. On-board preamplifiers and switchable low-pass filtering allow for maximum signal-to-noise ratio. The high frequency in- and output section of the ASC500 allows for sophisticated measurement concepts. Additional features include:

  • oversampling and offset compensation
  • analog modulation inputs for the most important channels
  • 6 ADC inputs with 400 kS/s, 18 bit
  • 2  high frequency ADC inputs with 50 MS/s, 16 bit
  • 4 DAC outputs with 200 kS/s, 16 bit
  • software defineable transfer function
microscopes, controller, ASC500, software, q control

Q Control

The ASC500 provides full control over the Q factor of any driven oscillator system by means of electronic Q control. The natural Q factor can be varied by typically more than one order of magnitude in each direction.
Benefits are:

  • to gain sensitivity due to increased Q factor
  • to gain scan speed in ultra-high Q setups by reducing the Q factor
  • to use well-known room temperature scan parameters also for low temperature         experiments with help of Q reduction
microscopes, controller, ASC500, software, pll

PLL

A fully digital phase-locked loop is implemented into the ASC500. It uses the high frequency inputs / outputs with 50 MHz bandwidth. A high-speed Lock-In demodulator and two PI control loops are used to control the amplitude of an oscillator and to follow any resonance shifts. The frequency resolution is below 0.2 μHz in a range of 1 kHz up to 2 MHz. Therefore, it is possible to gain access to a direct measurement of force gradients by means of measuring ∆f. Besides, all all data streams in the PLL chain are accessible for a deeper analysis.

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Supported Microscopy Modes

  • AFM: contact mode, amplitude modulation, frequency modulation (PLL)
  • Conducting-tip AFM
  • MFM: constant height (with tilt correction), dual pass mode
  • Piezoresponse Force Microscopy (PFM)
  • Kelvin Probe Microscopy (KPFM; optional upgrade)
  • Scanning Hall Probe Microscopy
  • Confocal Microscopy: constant height, point/path/grid mode spectros copy
  • Scanning Gate Microscopy (SGM)
  • STM: constant height (with tilt correction), constant current
microscopes, controller, ASC500, software, data processing

Data Processing

Collection of data is the most important task in every experiment. The ASC500 was built to give the user every possibility to view, process, and save all data streams. Data can be visualized in 1D, 2D, or 3D displays. Furthermore, the ASC500 features are:

  • real-time FFT calculation
  • full control over all raw and processed data
  • global snapshot functionality: a user definable collection of data can be saved with only one mouse click
  • saving of parameters in a text file
microscopes, controller, ASC500, software, labview control

LabVIEW™ Control

The LabVIEW™ interface provides full control over all ASC500  features with the following benefits:

  • measurement automatization
  • user-defined experiments
  • easy integration with 3rd party instrumentation

The full package of LabVIEW™ drivers is included in every unit at no extra price.

microscopes, controller, ASC500, software, spectroscopy

Spectroscopy

The ASC500 features advanced spectroscopy techniques such as z spectroscopy and bias voltage spectroscopy. These measurements are supported by an internal Lock-In and a limiter functionality which drastically reduces the likelihood of a tip crash. Spectroscopy measurements can be automatically triggered on line, grid, or point-by-point paths. Combinations of spectroscopies can be defined in action lists.

Customer Feedback

Dr. Benjamin Bryant

London Centre for Nanotechnology

The attocube low-temperature AFM is a versatile instrument which provides a good balance between the flexibility of a user-built setup and the reliability and ease of installation of a commercial instrument. I particularly recommend the ASC500 SPM controller, as it allows for advanced control modes such as phase lock loop (PLL), but still provides a great deal of flexibility in configuration, and ready access to all signals.

Lior Embon

Group of Prof. Eli Zeldov, Weizmann Institute of Science, Israel

Working with an evolving self-developed technique means our needs constantly and rapidly change. It is thus very important for us to have a controller with high flexibility and versatility. The ASC500 allows us to easily and smoothly adjust our measurement scheme to meet the needs of the moment. It has proven to be a powerful tool for scanning probe microscopy.