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Delving Into the Science Behind Zygo’s Latest Interferometer

Following the recent launch of Zygo’s Qualifire laser interferometer we sat down with Erin McDonnell the laser interferometer project manager to delve deeper into the background and technology behind the new product.

Q: What motivated Zygo to develop the Qualifire laser interferometer, and how does it address the specific needs of various industries?

A: One of the main factors that motivated Zygo to develop the Qualifire was the need for a smaller, more user friendly, laser interferometer compared to our existing laser interferometer product line. Additionally, Zygo has been making and selling the same interferometer form factor for over twenty years and while it has served us well, moving to a modern design and manufacturing techniques allowed us to more easily implement the latest technological advancements. We have introduced a number of new features, such as Smart Accessories, Stable Zoom and Flying Spot, to expand our current capabilities while maintaining the robust feature set our customers have come to expect from Zygo metrology tools.

Qualifire’s versatile design and core technologies allow it to adapt to different measurement requirements across various industries, ensuring that it remains a valuable asset in the most diverse applications.

Q: The Flying Spot module is highlighted as a significant enhancement to the Qualifire, actively reducing or eliminating artifacts in measurements. Can you elaborate on how the Flying Spot combines Ring of Fire and Coherent Artifact Reduction technologies to enhance the reliability and repeatability of measurements?

A: The Flying Spot Module, available with the new Qualifire, gives a level of confidence and flexibility not seen with other coherent noise reduction systems. By removing coherent spatial noise and annoying bullseye artifacts from the cavity, the Flying Spot gives the best signal to noise ratio for high precision measurements. The Qualifire system with a Flying Spot Module enabled takes the best of Zygo’s patented Ring of Fire and Coherent Artifact Reduction System (CARS) technologies: it includes a quick, single shot measurement mode reminiscent of Ring of Fire and a separate mode that performs the “stop and stare” and continuous ring functionality of CARS that’s compatible with dynamic measurements. Flying Spot also provides novel improvements of its own.

The Flying Spot Module also allows for a phase-based autofocus method. This means that a very precise focus can be set on perfectly specular surfaces, without the need for edges, fiducials, reticles, or other physical artifacts necessary for manual or intensity-based focus methods. In fact, precise focus can be achieved without operator intervention at all, providing improved ease of use, more reproducible data, while guaranteeing that the instrument delivers the best achievable imaging performance and Instrument Transfer Function.

Q: Erin McDonnell mentions the improved ergonomics and portability of the Qualifire. How do these features contribute to its ease of use, and in what ways does the smaller, lighter-weight design impact the performance of the interferometer, especially in applications that require frequent movement or adjustment?

A: The Qualifire features a smaller instrument footprint and reduced weight along with improved structural design around the device’s most sensitive components. The smaller mainframe, available in either 4” or 6” native aperture, measures less than 500 mm (20 in) in length and weighs approximately 22 kg (50 lbs).  This makes it the smallest 6” aperture commercial laser interferometer available on the market. Equipped with ergonomic lift handles and a protected, integrated phase measuring receptacle (PMR), the Qualifire can be moved easily between different measurement setups or brought to large test parts without worrying about damaging your sensitive instrument. The lighter weight and handles on all sides make it significantly easier to place the interferometer on raised platforms or towers as some applications demand.  All this is achieved with no performance or stability compromises.

The interferometer’s optical path is sealed for ultimate optical cleanliness and ease of servicing adjacent components such as electronics. Even the laser source can be swapped without exposing sensitive optics, ensuring peak performance with minimum down time for our customer’s most sensitive applications. Move forward and backwards seamlessly as Qualifire is compatible with all existing transmission elements, receptacles, and mounts. The same optical centerline and aperture options are retained so all your existing configurations simply work.

Q: The Qualifire introduces the Smart Accessory Interface, recognizing “smart accessories” and automatically applying system error files and lateral calibration. How does this feature enhance the adaptability of the interferometer to different applications, and can you provide examples of smart accessories that users can leverage?

A: To complement the new Qualifire’s improved performance, the new line of “smart” interferometer accessories will allow for superior metrology quality while reducing setup time and user involvement. Install a smart transmission flat or sphere and the Qualifire recognizes the optic and interfaces directly with Zygo’s Mx software. With one click, Mx will perform lateral calibration and subtract the supplied calibrated system error file. Using this system calibration file, the interferometer’s measurement uncertainty can be minimized to provide improved performance beyond the normal limitations of the hardware, to achieve 100th wave metrology with a 20th wave optic.

Q: The Press Release states that Qualifire maintains Zygo’s high standards in metrology while delivering the highest level of precision. Can you provide specific examples of how the Qualifire will deliver precision, reliability, and user experience in real-world applications within demanding environments?

A: The Qualifire laser interferometer system by Zygo promises to uphold Zygo’s renowned standards in metrology while offering exceptional precision, reliability, and user experience in challenging environments.

Robust Design: The Qualifire is designed to operate reliably in demanding environments. Designed from the bottom up to fit the needs of our most demanding customers, the Qualifre’s robust engineering and construction ensure that you can maintain precision performance even in the most challenging conditions such as fluctuating temperatures, vibrations, or mechanical disturbances. This feature makes it suitable for use in various industrial settings where environmental conditions may not be ideal.

User-Friendly Interface: The system is equipped with a user-friendly interface, making it easy for operators to set up measurements, interpret data, and optimize performance. Smart Accessories makes extreme precision measurements straightforward and accessible for any environment and any application. Intuitive controls and the robust Zygo Mx software feature set streamlines the measurement process, enhancing user experience and productivity.

Versatile Applications: The Qualifire is suitable for a wide range of real-world applications, including precision manufacturing, metrology laboratories, research and development, and quality control processes. Its adaptability enables it to cater to varied measurement needs across a spectrum of industries, ensuring its continued relevance and value across diverse environments.

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