WHITEPAPER – Fast Alignment Technology comes to ACS controls | Enabling Large-Format Industrial Productivity-- Scott Jordan --Enabling Large-Format Industrial Productivity
Award-Winning PI Fast Alignment Technology Comes to ACS Controls

Physik Instrumente (PI) GmbH & Co. KG, Auf der Römerstr. 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, E-Mail info@pi.ws , www.pi.ws

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WHITEPAPER – Fast Alignment Technology comes to ACS controls | Enabling Large-Format Industrial Productivity-- Scott Jordan --1 Introduction
PI’s award-winning fast optimization technology has provento dramatically improve production economics in processes
as diverse as photonics wafer probing, device packaging, andchip testing and even laser and optical equipment
manufacturing. The combination of blazing speed, nanoscale
performance and industrial robustness is reducing costs andimproving yield worldwide.

Now the flexible combination of PI´s industrial stages andnew alignment-enabled controls from ACS address additional
tough throughput and yield challenges for photonics
production. Large-format production processes can now beaddressed, with each mechanism contributing intelligentalignment for test and assembly. This opens new possibilities
for hyper-efficient systems architectures.

PI’s unique, fifth-generation optimization technology, now
well-proven in the field after its 2016 introduction, allows
simultaneous alignment across channels, I/Os and DoFs, evenwhen they interact due to optical or geometric crosstalk. The
dazzling throughput improvement of this parallelism canoften exceed a factor of 100, as PI routinely demonstrates inlive demonstrations at conferences. So, for example, anarray-device alignment that previously took a few minutes
can often now be achieved in a second or less.

PI’s first implementations of this technology were in fastpiezo stages and hexapods. Now its key functionality has
been extended to ACS controls, bringing the benefits ofground-breaking productivity to large-format applications asdiverse as photonics wafer probing, device packaging, andchip testing and even laser and optical equipment
manufacturing.

PI’s unique optimization functionality is firmware-based,
offers the unique option of parallel alignment across multiple
inputs, outputs and degrees-of-freedom, and can improve
process throughput by a factor of 100 or more compared tolegacy approaches.

2 Background
Alignment automation emerged three decades ago. In an era
dominated by single-mode pigtailing applications, it was anenabler that helped eliminate costly manual submicronalignment processes during device test and assembly.

The photonics world has advanced, though. Wafer-based
photonics now drives the industry. Adoption volumes areorders of magnitude higher than in the 1997-2001 photonics
boom, and the devices are quite different: for example,
multiple I/Os necessitating multiple degree-of-freedom
optimization, with each coupling frequently presenting nonGaussian multimode cross-sections and interactions acrosschannels, inputs and outputs, and DoFs. While thesechallenges can often be met with legacy alignment
techniques, the minutes-scale times required present serious
challenges for production economics.
Physik Instrumente (PI) GmbH & Co. KG, Auf der Römerstr. 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, E-Mail info@pi.ws , www.pi.ws

Abb. 1The double sided fibre alignment systems from PI enablessimultaneous positioning of input and output fibers for chip
testing and wafer probing

Moreover, the algorithms offer seamless compatibility withtoday’s photonic devices, which often prove challenging forlegacy approaches. For example, there is no implicit
assumption of circular symmetry embedded in thealgorithms. That posed no issues in 1997 but can be highly
sub-optimal for latter-day photonic devices. It can practicallybe stated that these systems can virtually “optimizeanything,” which is definitely not the case for the decades-old
approaches still commonly offered.

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WHITEPAPER – Fast Alignment Technology comes to ACS controls | Enabling Large-Format Industrial Productivity-- Scott Jordan --3 A deeper diveTwo alignment techniques are most useful today: area scans,and gradient searches for fast optimization and tracking.

3.1

Area scans

A good example of a legacy approach to an area scan is aclassical raster or serpentine scan, which sweeps one axis,
then increments its orthogonal axis, and repeats until thearea is covered. Variations on this theme are common,including stepwise hill-climbs. But these approaches pose
fundamental issues today. The stopping-and-starting adds
settling time and causes vibration throughout the system, andthe linear acquisitions can lead the system to actually de-alignin common situations of asymmetric coupling profiles.
By comparison, PI’s firmware-based area scans use smooth,
continuous sinusoidal and spiral patterns of selectablefrequency. So system resonances can easily be avoided,
allowing the non-stop scan to proceed without vibration. The
result is considerably higher speed. Add built-in modelling insome controllers, and the system can determine the peak (oreven the centroid of a top-hat coupling) with good accuracy
and speeds down to a few hundred milliseconds.

Abb. 2In the case of the sinusoidal scan routine the defined surface isscanned continuously without vibration-inducing acceleration ordeceleration phases. Surface, starting point, line distance, andsuccess criteria can be defined by the user.

Physik Instrumente (PI) GmbH & Co. KG, Auf der Römerstr. 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, E-Mail info@pi.ws , www.pi.wsAbb. 3

In the case of the spiral scan routine, a defined area is scanned
helically, whereby either a constant angle or a constant pathvelocity is maintained. Its selectable operating frequency helps
to avoid system resonances.

3.2

Gradient search

The digital gradient search was first developed in 1987 and,
until now, has been mostly unchanged in its implementation
through four subtle generations of the technology. A small,circular motion causes the coupling signal (or other figure-ofmerit) to vary, and this variation can be analysed in phase andamplitude to determine the instantaneous gradient. This
allows a fast and direct path to optimum, with tracking
possible for appropriate mechanisms.

Abb. 4Ground-breaking results can be achieved with the uniqueimplementation of the gradient search algorithm. If the lightsignal is present, this gradient search makes it possible to findthe signal maximum in typically less than 1 second.

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WHITEPAPER – Fast Alignment Technology comes to ACS controls | Enabling Large-Format Industrial Productivity-- Scott Jordan --PI’s radical fifth-generation approach builds on this classicalfoundation to enable multiple gradient searches to proceed inparallel. For example, this allows an XY lock-on to be
performed at the same time a theta-Z optimization runs— anessential combination for any array-device alignment. This
fast, parallel execution replaces the time-consuming iterative
loop of separate XY and theta-Z alignments that was formerlyrequired. One step instead of dozens!

3.3

PI´s latest breakthroughSince 2016, firmware-based fast area scan, gradient searchand parallel gradient-search technologies have been
implemented in PI’s powerful piezo nanopositioner andhexapod controllers. Now fast alignment functionality isavailable for ACS controls. Combined with PI’s large industrialstages (including spindle-driven and linear-motor stages,
gantries and air-bearing assemblies), this forms a foundationfor especially high-throughput applications involving largearea processing, such as when devices are processed in trays,or across several stations, or on an indexing platform orconveyor.

Abb. 5

Example automation subsystem for multi-channel automatedphotonic-device assembly tools, based on the proven doublesided F-712 HA2 alignment system and PI´s multi-axis gantrysystem, offers an idea for further workflow automation.

ACS controls lead the industry in modularity andperformance. Based on an EtherCAT open, distributedarchitecture, they support absolute encoders, minimizing
system start up times, easing initialization approaches andreducing collision risks. ACS’ yaw control (combined with PI’s
highly optimized joint construction) provides industry-leading
orthogonality correction and minimizes risk of axis binding—adistressingly common issue for older architectures. True

Physik Instrumente (PI) GmbH & Co. KG, Auf der Römerstr. 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, E-Mail info@pi.ws , www.pi.ws

MIMO gantry control plus dynamic cross axis control yields
uniform performance over the gantry area, eliminating gridbased approximation methods and their consequent lowestcommon-denominator approach to tuning over large areas.
Together, these mean higher performance and reproducibility
in your application.
These benefits come with PI’s and ACS’ rich offering of global
support options, ranging from on-site Quick Start andtraining, to extended warranties and service plans, toconsulting and co-engineering, to application and software
consultation and quick-port approaches for key customers
transiting from other architectures.

Abb. 6This conceptual demo shows how PI’s fast alignment can apply
to large-area applications such as pick-and-place, and thescreening, assembling, and testing of photonic devices. From thewafer, through coupon and chip, to the packaged product.

3.4

Summary

Photonics today is serious business, with a rapid rate ofinnovation and churn and broad adoption by important
semiconductor and networking players. Manufacturing andtesting these devices demand flexibility and high performancefrom production systems and tooling. Multiple studies havespotlighted alignment time as the highest cost contributor tophotonic device fabrication, both from the lengthy process
times formerly required and from the repeating requirement
for alignment throughout the production process. PI’s
revolutionary fast alignment technology is unmatched formeeting these challenges, and now it is deployed in largearea mechanisms based on a modular, open-architecture
approach ideal for systems integration and tooling platforms.

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WHITEPAPER – Fast Alignment Technology comes to ACS controls | Enabling Large-Format Industrial Productivity-- Scott Jordan --4 Author

WP4023E Fast Alignment Technology comes to ACS Controls 06/2019 Subject to change. © Physik Instrumente (PI) GmbH & Co. KG 2019

Scott Jordan is head of the photonics market segment in the
globally active PI Group, and a PI Fellow. He lives in Silicon
Valley and has been with PI for over 20 years; he was active
as director of NanoAutomation technologies and made adecisive contribution to continued technological developmentof the company. A physicist with an MBA in Finance/NewVentures, Scott is well known in the community for hispassion and engagement.

5 About PI
Well known for the high quality of its products, PI (PhysikInstrumente) has been one of the leading players in the global
market for precision positioning technology for many years. PI
has been developing and manufacturing standard and OEM
products with piezo or motor drives for 40 years. All key
technologies are developed in-house. This allows thecompany to control every step of the process, from design toshipment: The precision mechanics and electronics as well asposition sensors.
By acquiring the majority shares in ACS Motion Control, aworldwide leading developer and manufacturer of modular
motion controllers for multi-axis and high-precision drive
systems, PI has made a major step forward in providing
complete systems for industrial applications with the highest
demand on precision and dynamics. In addition to four
locations in Germany, the PI Group is represented
internationally by fifteen sales and service subsidiaries.

Physik Instrumente (PI) GmbH & Co. KG, Auf der Römerstr. 1, 76228 Karlsruhe, Germany
Phone +49 721 4846-0, Fax +49 721 4846-1019, E-Mail info@pi.ws , www.pi.wsPage 5 of 5