50 Years of Precision
by Dr. Peter de Groot, Executive Director, R&D, Zygo Corporation

"We need to establish criteria for the name of the new company," suggested Carl Zanoni. "Short, not our names or initials, ...but it must be pronounceable in foreign languages, something like Kodak or Xerox." Paul Forman and Carl each took a dictionary. Paul started from the front and Carl started from the back. Carl found `zygo,` which means "bridge" or `connecting link,` symbolic of the cooperation between academia and industry represented by the two major investors, Wesleyan University in New England and Canon in Japan. So it was that Paul, Carl and Sol Laufer found the name for their new company, and on June 23, 1970 Zygo Corporation and its trademark Zygo® logo were born.

Zygo started life in three rooms on the second floor of a house on High Street, on the Wesleyan University campus in Middletown, Connecticut. Every day that first summer of 1970, Sol would load the air conditioner from his bedroom into the trunk of Paul`s Volvo to be used during the day at the High Street house, then bring it back home again each night. Success demanded continuous expansion, and just three years after the Company`s founding, 16 ZYGO employees moved a brand-new 1000 square-foot facility in the pleasant rural countryside of the neighboring town of Middlefield. Today the Middlefield corporate campus is 160,000 square feet, with 10 additional offices and manufacturing sites worldwide, accommodating more than 500 employees.

Zygo was founded with the goal of creating optical components well beyond the state of the art at the time. As Paul put it, "our vision is to be the best at whatever we set out to do." One of the Company`s first major projects was a machine to product aspheric lenses at an unprecedented speed and precision. The aspheric generator used air bearings, a rigid structure between the grinding wheel and the work piece, and innovative closed-loop computer control. The machine-generated surface was so smooth that it was hard to tell it wasn`t polished. The Canon FD55 mm f/1.2 AL was the world first interchangeable 35 mm SLR camera lens employing an aspherical optical element to achieve sharp definition over the maximum aperture, thanks to Zygo`s aspheric generator.

A priority for Zygo has always been to build world class optical fabrication facilities for producing the highest precision plano surfaces.

Zygo began as a maker of optical components of unparalleled high quality. The tradition continues with these planar amplifiers for high energy lasers.

In 1980, Zygo received a contract from Lawrence Livermore National Laboratory (LLNL) to fabricate plano elements for the NOVA laser project. Capabilities continued to advance, and in 1997, the LLNL National Ignition Facility awarded Zygo a contract for thousands of meter-class flat optics, including windows and laser doubling crystals, for the largest laser fusion project ever attempted. This resulted in a major expansion in the 1990`s of Zygo`s planar polishing capability, using custom-designed machines and test facilities in Middlefield. Today Zygo is the premier supplier of high fluence optics for the world`s most powerful lasers.

It wasn`t long after the founding of the Company that Zygo introduced the first practical laser Fizeau interferometer for testing optical components as an additional product line to supplement the fabrication business. The "Interferometer System Model GH" brochure issued on December 6, 1972 describes the product`s unique operating features: interchangeable reference flats, a quick and easy setup, simultaneous viewing and photography, and an unrestricted test workspace. The system could "...perform virtually all the measurements required of coated and uncoated optical components, surfaces, and systems."

In 1977, Zygo introduced ZIPP – the Zygo Interference Pattern Processor – as the first commercially available method of quantitative interferogram data reduction, either from an interference pattern displayed on a video monitor or from a Polaroid® print.

By 1989 the Mark-IV laser Fizeau was fully automated, with computer control of data acquisition and analysis using the HP-windows based MetroPro™ software. The laser interferometer product line has continued to evolve and grow, with introductions of the GPI™ and Verifire™ Asphere platforms, covering working apertures from 10 mm to 800 mm, and establishing Zygo as the gold standard in optical testing.

In the 1980`s, Zygo decided to address the challenge of stage positioning for demanding applications in photolithography equipment for semiconductor manufacturing. The foundational technology is heterodyne line-of sight laser interferometry, which has the critical advantages of high precision while nearly eliminating Abbe offset errors. Working with strategic partners, Zygo introduced the original Axiom 2/20 and became a major supplier of metrology systems for integration into the most advanced photolithography systems.

The modern ZMI product line continues this legacy, with Zygo-built stabilized lasers and proprietary acousto-optic crystal modulators, complex optical systems for simultaneous monitoring of linear displacement, tilt and tip angle, and high-speed electronics capable of monitoring reticle and wafer stage motions with nanometer precision at speeds of several meters per second.

The early 1990`s represented an exciting time in the development of interference microscopy. Long considered a technology with very limited applications to smooth optical or polished metal surfaces, new methods with white-light microscopes liberated the technique from these constraints, making it possible to measure nearly any surface type. Zygo`s first coherence scanning system, the NewView™ 100, measured machined, ground, or highly textured surfaces as well as super-polished surfaces with speed and precision. By the beginning of the 2000`s, Zygo was pioneering the application of high precision non-contact interferometry for automotive components, improving fuel efficiency and reducing air pollution in manufacturing environments previously considered inappropriate for such instruments. The product line has continued to grow and there are now thousands of ZYGO optical profilers installed worldwide, addressing markets from semiconductor manufacturing to precision machining.

The project history of the E-O Group includes beam line optics for the first laser-based corneal cutting equipment, a 3D imaging system for teeth, and athermal polychromatic imaging lenses. The E-O Group developed one the earliest examples of a high-performance mixed reality system – the advanced helmet mounted display (AHMD). – which overlays computer-generated scenery on the real-world environment in flight simulator applications In addition to these achievements, the Zygo E-O Group today is the single largest supplier of telescopes for compact, space-based, earth imaging satellites.

Progress in building the company was not always a continuous upward path. In the early 2000`s, like many high-tech companies, Zygo launched itself into the telecommunications boom with the TeraOptix® Division. Soon the stock price climbed to vertiginous heights and there seemed to be no limit to profitability and growth. The bubble burst, of course, and all hands were called upon to restructure and recover. Another initiative aimed at front-end semiconductor wafer metrology confronted the worldwide financial crisis of 2008, when capital equipment purchases in the sector fell precipitously, and Zygo scaled back this aggressive initiative to a modest OEM business. These setbacks helped to forge a resilient Company that has survived with valuable lessons learned.

Beginning in 2010, new opportunities revitalized the markets served by Zygo and it was a time to reinforce and expand the product lines. The industry standard Zygo MetroPro™ software was completely revised and upgraded to the new Mx™ platform for all the interferometric metrology products. The flagship Nexview™ interference microscope significantly expanded the range of applications for optical non-contact metrology on complex structures, including surface on additive manufacturing components and partially-transparent thin-film layers.

Zygo optical profiler technology is at the heart of the new Compass™ system for measuring micro-aspheres for consumer electronics, including cell phone cameras and emerging digital immersive displays. The latest laser Fizeau Verifire™ MST wavelength-tuned interferometer separates multiple surfaces for thin transparent glass optics, while new optical testing platforms offer both software vibration mitigation as well as "single shot" dynamic data acquisition based on digital holography.

The Zygo Extreme Precision Optics (EPO) Division was formed in 2010 from former ASML assets in Richmond, California. EPO produces some of the most accurately-made optical components in the world, from EUV projection lenses for lithography to the test masses for the Laser Interferometer Gravitational-wave Observatory (LIGO).

The continued demands on the semiconductor photolithography industry created an opportunity for the Precision Positioning Systems Group to introduce in 2013 a new product line based on innovative optical heterodyne encoders, designed to solve the air turbulence problem in semiconductor photolithography systems. Zygo`s new ZPS fiber-based interferometric position sensor, offering up to 64 channels of absolute distance measurement with 10 pm/Hz noise levels and drift of a few nanometers per day, is being deployed on the adaptive optics of advanced synchrotron sources for real-time X-ray beam conditioning.

After the retirement of the Founders, it was time for Zygo to look to the next generation of leadership and position itself for the future. In 2014, Zygo joined the Ultra Precision Technologies Division of AMETEK. The UPT Division includes sister metrology companies Taylor Hobson, Solartron, Reichert and Creaform, as well as precision engineering leaders Precitech, Sterling Ultra Precision and TMC. The Zygo tradition continues with new products and innovations, building on a solid tradition while enjoying mutually-beneficial collaborations with its new AMETEK sister companies.

From the beginning, Zygo`s business plan has been founded on the ambition to take on the tough problems that address critical unmet needs in industry. In Sol`s words, "We can do it... There are no boundaries, there are no limitations." This means hiring top-notch employees, including leading engineers that can drive new solutions from idea to product introduction. The patent literature has over 8,200 citations to Zygo`s portfolio of 875+ issued US patents. Scientific journals, textbooks and conference proceedings includes hundreds of papers, book chapters and review articles authored by Zygo employees. Zygo scientists are actively engaged in professional societies, standards committees, university collaborations, and professional publication activities in applied optics and precision manufacturing disciplines.

From small beginnings grew a company that is today a recognized institution in precision optics fabrication and interferometric metrology. The Zygo name has become synonymous with instruments that measure surface form and texture, and optical components and systems that define the state of the art. Zygo has also stayed true to the idea of forming a bridge between international markets and centers of excellence worldwide. The mission of the company continues to be to "enable customer success by delivering innovative precision optical and metrology solutions." This spirit remains strong as we set our sights on the challenges ahead. It`s amazing to think that after 50 years, we still feel like we`re just getting started.

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