- Customer Interview: Patrycja Paruch and Iaroslav Gaponenko - Novel Functionalities at Domain Walls
- Reduce lab setup complexity: The first lock-in amplifier with digitizer option
- Reduce lab setup complexity: Arithmetics for All
- Detailed Application Know-how: New Application Notes
- Premium Customer Care: LabOne 14.08
- Tips and Tricks: Sweep parameters in Application Mode
It's great to see big instrumentation manufacturers making a feature of how many instruments they combine into one single box. For instance, Tektronix likes to talk about its 6-in-1 scope and Keysight invites the reader to 'experience the integration'. The trend is clear, laboratory users prefer multi–functional instruments, and the interoperability between the functional units will be an area of ongoing innovation. Of course, this is something that Zurich Instruments has been doing for many years, and the development continues - in this newsletter I am pleased to introduce two new functional units: the first ever digitizer option for a lock-in amplifier, and a powerful unit for arithmetic operations on demodulated samples.
Patrycja Paruch and Iaroslav Gaponenko - Novel Functionalities at Domain Walls
Patrycja, your laboratory focuses on multiferroic thin films, what are the main field of applications?
[PP] For magnetoelectric multiferroic research, the holy grail is energy-efficient, potentially multistate memories with electric-write and magnetic-read capabilities. We’re looking a lot further upstream from that, at the fundamental physics of domain walls in these materials - at the sample level, they can be used to enhance functionalities such as dielectric or piezoelectric response - and perhaps in a more distant future, themselves be used as nanoscale active device components.
Which are your international research partners?
[PP] We work with many different groups, both theoretical and experimental. Right now, we are investigating a large library of ferroelectric thin films from the group of Lane Martin, UC Berkeley, focusing specifically on localized electrical conduction at domain walls. On the theory side, our closest international collaborators are from Centro Atomico Bariloche in Argentina - Sebastian Bustingorry and Alejandro Kolton. However, we also work closely with our colleagues here in Geneva, especially the groups of Jean-Marc Triscone and Thierry Giamarchi.
Could you mention two of your publications that best summarize your research?
[PP] For the novel domain wall functionalities: J. Guyonnet, I. Gaponenko, S. Gariglio and P. Paruch, Conduction at domain walls in insulating Pb(Zr0.2Ti0.8)O3 thin films, Adv. Mat. 23, 5377 (2011).
And for the work on domain walls as pinned elastic interfaces, a recent review P. Paruch, J. Guyonnet, Nanoscale studies of ferroelectric domain walls as pinned elastic interfaces, C. R. Acad. Sci. Paris, Ser. IV 14, 667 (2013).
But we also work on optimizing the performance and quality of the tips we use for AFM imaging: Y. Lisunova, I. Levkivskyi, and P. Paruch, Ultra-high currents in dielectric-coated carbon nanotube probes, Nano Lett. 13, 4527 (2013).
Many of the measurements, such as DFRT are bimodal by nature. Do you consider multi-frequency AFM as an enabler for successful measurements?
[IG] In a sense, yes. DFRT / PFM allows us to track the contact resonance peak, allowing for a much cleaner phase signal despite the changing tip-sample interaction. The same can also be said for Kelvin Probe AFM, where a bimodal measurement will lead to an increase in the quality of the obtained results. The true strength of multi-frequency measurements lies in the possibility to excite and measure at different harmonics simultaneously - increasing the possibilities of functional AFM.
What are the major trends that you foresee for the further development of AFM?
[IG] In my opinion, AFM measurements will get even faster: this can already be seen in the proliferation of high-speed AFMs and techniques. The second observed trend is the quest for functional and property measurements in materials. From local microwave impedance measurements to electrochemical potential mapping - the leading scientists in the field don't stop innovating!
[PP] A big, already developing area is the interface with life sciences, with coupled AFM and optical/confocal microscopy. Here, innovation not only in terms of speed, but also tailoring of the probes themselves (for example for low damage intracellular probing) will play a big role. Also, an auxiliary development to all the band excitation and other “big data” generating measurements is that the community has to better deal with large throughput image/information processing.
What is your favorite thing to do in Geneva? How do you enjoy both lake and mountain between Switzerland and France?
[PP] I’m more of a mountain person. I love hiking, rock and ice climbing, skiing - or just wandering around the nearby forests looking for mushrooms. The lake is a lovely spot for a lazy summer walk and a cool glass of wine on an outdoor “terrasse” - the local seagulls, ducks and swans might want to share your meal though!
[IG] Geneva is probably one of the nicest places in the world: it is a careful balance of urban and rural, lake and mountain, flat and hilly, quiet and animated. What I really enjoy, on a sunny Saturday, is to take my bike out for a ride along the lakeside, then sit down at the terrace of a café overlooking the Jet d'Eau and eat some tasty ice cream.
Patrycja Paruch [PP] is group leader and Iaroslav Gaponenko [IG] is PhD Student of the Paruch Lab at Université de Genève.
Reduce lab setup complexity
The first lock-in amplifier with digitizer option
What happens with all the data that is being digitized by a digital lock-in amplifier? An HF2LI 50 MHz lock-in amplifier has two 14-bit ADC converters at 210 MSa/s. What follows is a number crunching machine that processes 735 MB of data each second.
When users measure a modulated signal, the relevant information is the temporal variation of its amplitude and phase. Amplitude and phase can be acquired with the help of a lock-in amplifier, where a relatively small part of the signal spectrum is retained while wide-band noise is rejected. Demodulation increases the signal noise ratio but also limits the signal bandwidth - lower and higher harmonic signal components are lost for good. We believe that the next cornerstone in lock-in measurements will be the capability to overcome this situation and acquire demodulated samples at the same time as the raw temporal signal, without losing any signal components, up to the input bandwidth of the lock-in amplifier itself.
Our users have remarked many times how useful it is to capture the raw digitized signal. Indeed, for 6 years Zurich Instruments has provided an oscilloscope as standard tool for all its lock-in amplifiers as part of the ziControl user interface. The supported sampling rates and memory depths are no match to any high-end scope, but for most practical purposes people simply wonder whether there is any signal on the BNC. An integrated oscilloscope is a handy debugging tool that removes the need to add another box connected with a T-connector to the setup. While the oscilloscope and lock-in amplifier combination remains fairly unique, we have been looking for the next evolutionary step.
Today we introduce the first lock-in amplifier available with a digitizer option, and we do this by extending the capability of our integrated oscilloscope.
We have always aimed to provide research laboratories with the most inspiring and useful instruments, in terms of their performance and usability. We do this by learning from your measurement challenges and understanding the reasons for combining instruments in the way that you do. The new combination of lock-in amplifier and digitizer in one box aims to enable a wide range of opportunities for new innovative instrument use. The UHF-DIG Digitizer option for the UHFLI Lock-in Amplifier addresses 5 main topics:
- fast scope shot acquisition: the segmented memory can acquire up to 60'000 shots per second
- large memory: 512 MB to store more and longer shots
- dual channel: both signal inputs can be captured at the same time, which is an upgrade from the standard LabOne oscilloscope
- high-resolution FFT: an FFT on 128 MSamples is readily available on an suitable PC
- extended cross-domain triggering and synchronization architecture
Reduce lab setup complexity
Zurich Instruments is introducing another powerful and "first of its kind" feature to the world of lock-in amplifiers: the arithmetic unit or AU. The AU enables operations based on the various internal signals such as the results of lock-in measurements (X, Y, R, Θ) or the two auxiliary inputs in real-time. For the UHFLI, with its two fully symmetric signal inputs and a total of 8 dual phase demodulators, there is the possibility of connecting more than 50 different input parameters to this AU. The possible operations include addition, subtraction, multiplication, division, and calculation of absolute values and phase angles of complex numbers (e.g. X1 + i*Y2). The AU is available to all UHFLI Lock-in Amplifiers users installing the newly released LabOne 14.08 - it is not necessary to purchase any product options.
The use of the AU is particularly attractive for applications where the result of the arithmetic operation is directly used as feedback to the experimental setup, hence it can also be combined with one of the PID controllers (UHF-PID option) whose outputs are directly available on any of the four auxiliary outputs. The interplay between AU and PID provides a massive boost of functionality for high-performance applications.
Let’s consider four application examples:
- Differential measurements: for example, auto balanced detection for convenient laser noise suppression and dual frequency resonance tracking.
- Relative measurements: dividing a signal by a reference signal allows direct measurement of an optical absorption line independent of laser amplitude fluctuations.
- Absolute sensing and control of the phase of interferometers where the phase angle between the results of different demodulator data is needed along with a scaling factor (see A.A. Freschi, J. Freijlich, Optics Letters, Vol. 20, Issue 6, pp. 635-637 (1995), http://dx.doi.org/10.1364/OL.20.000635).
- Manipulation of signals modulated with multiple frequencies: for example, those with sidebands such as frequency and phase modulated signals - sidebands can be added, subtracted and normalized to the carrier signal.
In addition the signals derived from the AU can be streamed in real-time to the host computer, where they can be further analyzed with LabOne's time and frequency domain toolbox as well as used with any dedicated user programmed utilities.
Detailed Application Know-how
New Application Notes
Regular visitors to our website will have noticed that we have recently added a number of new application notes to the Applications section. In these publications we focus on a particular application but with the intention of making them accessible to the reader who may not be working in a similar area. They also show how, with the support of our Application Scientists and sometimes with the addition of options, our instruments can be adapted to the exacts requirements of the user.
Drawing on results from a collaboration with the University of Basel, the Dye-sensitized solar cell impedance spectroscopy application note shows how the HF2LI Lock-in Amplifier can be used to measure both the power efficiency and impedance characteristics of this promising technology.
The Parametric feedback cooling note looks at the use of lock-in amplifiers in laser cooling, and how the integration of PLLs and PIDs into our HF2LI and UHFLI Lock-in Amplifier offers a powerful and convenient integrated implementation of such techniques.
In Multi-angle Light Scattering Detection of Engineered Nanoparticles we show how, by using a multiplexer developed by CSEM in Switzerland, the HF2LI Lock-in Amplifier can measure 4 detector signals, in this case for MALS measurement of absolute molar mass and nanoparticle size.
We welcome any comments you might have about these latest publications. If you have any suggestions for new application notes, or would like to collaborate with Zurich Instruments on a new note, we'd be happy to hear from you.
Premium Customer Care
We're pleased to announce LabOne 14.08, again showing our committment to offering more features and better usability than anyone else in the industry. It's now available for download, for both the HF2 and UHF Instruments (user and password authentication is required), by clicking on the above link. A wealth of new features have been added over the last couple of months and the best part of it: it's free of charge. Updating is highly recommended not only to enjoy the new functionality but also to make sure that you can continue to receive the best possible support from our customer service team.
The improvements range from Zurich Instruments' unique new Arithmetic Unit to double-click XY rescale for all graphs, which is a significant usability improvement. All the highlights are mentioned hereafter:
- Arithmetic Unit: four arithmetic units for real-time post-processing of demodulator outputs
- Sinc filter for Sweeper: increases speed of sweeps at low frequencies
- Scope: trigger performance, functionality and display have been further improved
- Sweeper: now supports data provided from the PID, boxcar and arithmetic unit
- Sweeper: simultaneous display of multiple traces
- UHF-PID PID option: low pass filter for the D part now accessible in the user interface
- Auxiliary outputs can now output also the PID shift, e.g. frequency adjustment in a PLL
- UHF-MOD Modulation option: full access to phase, time constant, and filter order for the side bands
- UHF-BOX Boxcar: averaging replaces integration, provides better usability and more intuitive behavior
- New Harmonic Analyzer for UHF-BOX Boxcar: bar chart display for FFT of periodic waveform analyzer
HF2LI and HF2IS users who update their software to LabOne 14.08 will also benefit from several improvements such as:
- Sweeper: Sinc filter speed improvement
- Improved locking range for PLL and ExtRef
- Improved programming APIs
Tips and Tricks
Sweep parameters in Application Mode
The LabOne Sweeper is a versatile tool that enables the user to perform fast and precise signal demodulation as a function of physical parameters such as the frequency, AC+DC signal output and DC voltage bias. Many other internal units can also be taken as a sweep parameter: PID set point, boxcar averager gate width and modulation index, just to name a few. The points in the chosen sweep range can be measured either sequentially (forward or reverse) or not (binary scanning provides fast previews of the full range), and bi-directionally to account for non-linear systems (e.g. hysteretic behavior). As the freedom to choose the parameter space is vast, it is easy to fall into traps and make mistakes. Therefore we have implemented several application modes with a subset of the settings in order to allow the user to focus on the results rather than on the instrument control. In these modes appropriate mathematical operations (e.g. averaging, standard deviation) and filter settings are applied to the acquired data set. Let's briefly look at the provided modes:
- Parameter Sweep provides fast and robust operation. With filters set to auto bandwidth and single sample acquisition per sweep point, measurement speed can be as fast as 5ms/p. An example of this mode is a quick scan of a resonance circuit's amplitude and phase as a function of frequency.
- For better signal to noise ratio, additional averaging and settling time is used in the Parameter Sweep Averaged mode.
- Noise Amplitude Sweep provides an optimized algorithm for measuring the noise spectrum to characterize a device under test: the demodulation bandwidth is automatically adapted and the standard deviation is calculated on a large data set and normalized by the bandwidth.
- Frequency Response Analyzer (FRA) can be used for precise network analysis. In this mode a narrow band measurement is targeted, with more averaging and longer settling time to account for additional system delays. For low frequency measurements, the FRA (Sinc Filter) mode also adds a Sinc filter.
- The 3-Omega mode is used, for instance, in thermal conductivity measurements where higher sensitivity is needed to measure a small signal at the 3rd harmonic of the drive frequency. Filters are set to the 8th order and averaging is enabled. To speed up the measurements, Omega is suppressed by up to 100 dB in order to allow for higher filter bandwidth.
All sweeps can further be optimized for speed or accuracy by toggling between low and high precision operation with pre-defined settling times. If the application modes are not sufficient, the user can chose the Advanced Mode with completely adjustable parameters space. Finally, once a sweep has been tuned to the needs of the user, it can easily be transferred to a user program (e.g. MATLAB, LabVIEW or Python) since the APIs share the same code basis with the user interface.