EssentOptics used its presence at Laser World of Photonics 2025 in Munich to showcase breakthrough technology to address a key challenge in deep ultraviolet coating metrology – delivering absolute measurements with polarisation control at any angle, without the traditional compromises that have limited the industry.
The company's enhanced PHOTON RT spectrophotometers represent a significant advancement in DUV coating measurement capability, offering what the company describes as unparalleled reliability and superior repeatability for characterising interference mirrors and diffraction gratings at wavelengths down to 185 nm.
"Unlike any other system on the market, our enhanced PHOTON RT spectrophotometers deliver absolute measurements with polarisation at any angle up to 75 deg, offering seamless, step-free spectra from 185 nm," explains Taras Lisouski, Head of Business Development at EssentOptics. "Our unique optical design ensures excellent reliability and repeatability, and virtually noise-free, fully automated performance for EUV interference mirrors and even diffraction gratings."
The technology addresses a critical gap in the market, where deep ultraviolet mirrors operating at wavelengths such as 193 nm, 213 nm, and 248 nm are mission-critical components in semiconductor manufacturing, laser micromachining, and cutting-edge inspection systems. These applications demand ultra-high performance and the ability to endure extreme fluences, yet reliable measurement of such coatings with angle and polarisation control has remained challenging.
Real-world solution for industrial environments
What sets EssentOptics apart is its focus on practical, industrial-grade solutions for optical coaters rather than for chemistry applications. The dispersive-type PHOTON RT system performs fully automated, absolute transmission and reflection measurements, including both S- and P-polarisation, across critical DUV wavelengths without requiring vacuum chambers or nitrogen purging.
"This is not a lab prototype – it is a robust, industrial-grade platform validated over years by leading customers," says Lisouski. The company's confidence in its technology was validated early in development when the first customer to receive results from the prototype responded with a single word of approval.
"The first customer to receive results responded with one word: 'Congratulations,'" Lisouski recalls, highlighting the immediate recognition of the system's capabilities within the industry.
The enhanced system delivers accurate angle- and polarisation-resolved measurements down to 185 nm, with fully automated absolute reflection and transmission scans for the sensitive range from 185 nm to 260 nm. This capability is particularly crucial given that many coatings are still qualified based on single-angle, unpolarised measurements, or rely solely on simulations.
Expanding applications beyond mirrors
The versatility of the PHOTON RT platform extends beyond interference mirrors to encompass diffraction gratings, offering true polarisation-resolved spectral characterisation up to 5200 nm and recently to 14,000 nm with other grating-based PHOTON RT instruments. This includes both reflective and transmissive gratings, whether flat or concave, ruled or holographic.
"Beyond mirrors, the same measurement system enables true absolute, polarisation-resolved spectral characterisation of diffraction gratings," explains Lisouski. "Grating manufacturers can now replace guesswork with data, eliminating the need to rely on relative and averaged values, or solely on simulation."
EssentOptics also showcased its LINZA 150 spectrophotometer at the exhibition, which the company describes as "the most tailored tool for characterisation of coatings on lenses." This instrument can handle lenses from 10 mm to 150 mm diameter, whether convex, concave, spherical, aspherical, or cylindrical, and features unprecedented capability to profile lens reflection distribution.
The EssentOptics LINZA 150 spectrophotometer
Addressing market evolution
The development of enhanced DUV measurement capabilities reflects broader market evolution towards more demanding applications. In semiconductor manufacturing, for example, inspection systems optimised at 213 nm can detect impurities as small as 5 nm – comparable to a single feature on a wafer. Such precision requirements demand equally precise measurement and qualification tools.
"For too long, reliable DUV coating qualification – absolute, with polarisation, at angle, – has remained out of reach for most production environments," says Lisouski. "EssentOptics offers a real, scalable solution.”
The company's approach combines years of experience with targeted innovation. For over a decade, PHOTON RT spectrophotometers have been used worldwide for precise measurement of thin-film coatings across transmission, reflection, angle-resolved, and polarisation-sensitive applications from 185 nm to 5200 nm and extending to 14,000 nm.
Partnership approach to innovation
EssentOptics' philosophy centres on eliminating measurement limitations that constrain innovation. The company positions itself as an enabler of advanced coating development rather than simply an equipment supplier.
"Stop guessing. Start measuring. Don't let measurement limitations hold back your innovation," emphasises Lisouski. "Select the powerful technology designed for coaters only."
This approach has resulted in the development of what the company describes as practical tools ready for factory floor implementation, addressing real-world manufacturing challenges with industrial-grade reliability. The enhanced PHOTON RT systems represent the culmination of customer-driven development, responding to specific market needs for comprehensive DUV coating characterisation.
"We've stopped guessing. And we invite you to do the same," concludes Lisouski, reflecting the company's confidence in its technology and commitment to advancing the state of DUV coating metrology across critical applications.
