In precision engineering labs, high-resolution surface metrology is essential. At the Design for Precision Engineering laboratory of Eindhoven University of Technology (TU/e), PhD researcher Bas Huisman needed exactly that - a way to visualise tiny out-of-plane deformations on actively deformable substrate tables. His work, carried out in collaboration with ASML, explores piezoelectric actuation concepts that are conceptually similar to deformable optical mirrors, but with the added requirement of controlling in-plane deformation as well.
To demonstrate their research at conferences, the team previously used an array of capacitive probes to show deformations. However, there was a need for a measurement method with much higher spatial resolution. They wanted something far more visual and continuous: a full-aperture interferometric map that could show even the smallest deformations live.
The Search for a Practical Solution
Bas first discovered Wavefront Pro after watching a video by Jeroen Vleggaar of Huygens Optics on making a deformable mirror. Intrigued by the software’s near real-time surface analysis capabilities, he contacted Jaco Verster at Wavefront Pro to discuss hardware options. At the time, budget constraints made a brand-new commercial interferometer unrealistic. Wavefront Pro therefore suggested a more pragmatic path: source a second-hand Fizeau interferometer and convert it with a modern camera kit.
Shortly afterwards, Jaco mentioned the project to Jeroen. It turned out he already had a potentially suitable candidate - a Zygo PTI-02 from 1986 that he had recently acquired second-hand. Jaco introduced Bas and Jeroen, and the project was set in motion.
Bringing a 1986 Zygo Back to Life
The Zygo PTI-02 arrived in poor cosmetic and mechanical condition. The exterior was worn, the wiring and electronics were outdated and unreliable, and the original imaging system consisted of an analogue RCA tube camera paired with a black-and-white CRT monitor. Fortunately the internal optics remained clean and free of mold or coating damage. The helium-neon laser, already replaced in 2008, was still in excellent working order.
Jeroen completely rebuilt the instrument. The system was stripped down, the optics carefully cleaned, and the entire electronics package was replaced, including power supply, wiring and switches. The exterior was spray-painted to restore a professional appearance. The original mechanical aperture stop that limited the evaluation area from 100 mm to 30 mm diameter was removed, because the new camera would provide more than enough resolution for very high digital zoom levels and high fringe densities.
In its place Jeroen installed a Basler a2A5060 25-megapixel USB 3.0 camera, carefully specified in collaboration with Wavefront Pro so that both the hardware and software requirements would be optimally matched. The refurbished interferometer now delivers high-resolution interferograms directly to a PC running Wavefront Pro.
Modern Software Meets Vintage Optics
Once digitised, the classic Fizeau optics could finally be used with contemporary analysis tools. Wavefront Pro processes the camera images in near real-time, performing Zernike fitting and generating live surface-shape plots, residual maps and other optical metrics. What was previously a static, qualitative fringe pattern on a CRT has become a quantitative, interactive measurement system.
At the Design for Precision Engineering lab the combination is already proving its value. Using Wavefront Pro’s live surface shape plots, Bas and his colleagues can now clearly demonstrate even the smallest deformations of their piezoelectric substrate tables in near real-time.
A Successful Collaboration Model
This project is an excellent example of how older, self-owned or second-hand interferometers can be given a new lease on life. Huygens Optics supplied the Zygo PTI-02 and performed the complete hardware conversion and camera integration. Wavefront Pro specified the camera, ensured software compatibility, and provided the real-time analysis platform. The Design for Precision Engineering lab at TU/e now has a high-performance metrology tool that fits both its technical needs and its budget.
Whether you already own an older interferometer or are considering a cost-effective upgrade path, the same approach is available: modern high-resolution cameras + Wavefront Pro software can turn existing interferometer hardware into a powerful, real-time surface metrology system.
---
Credits
Hardware conversion, Zygo PTI-02 supply & photos: Huygens Optics (Jeroen Vleggaar)
Camera specification & software integration: Wavefront Pro (Jaco Verster)
Application: Design for Precision Engineering lab, TU/e (Bas Huisman)
Writing assistance, document review and language polishing: Grok 4.5 (xAI)