The domestically produced FIS4 series wavefront sensors are reshaping the future landscape of optical measurement with their high precision, cost-effectiveness, and strong environmental adaptability.

In the fields of optical manufacturing and precision testing, the repeatability and stability of measuring instruments directly determine the reliability of data and the dependability of processes. Since 2006, Professor Yang Yongying's team at Zhejiang University has been dedicated to the research and development of the wide-spectrum FIS4 series of wavefront sensors after 17 years of dedicated research using four-wavefront transverse shearing interferometry phase imaging technology. The sensors have demonstrated outstanding performance in recent repeatability and stability verifications, becoming a 'dark horse' among domestically produced optical sensors.

Background: FIS4-HR-C vs a certain wavefront sensor-HR

To comprehensively evaluate the performance of the FIS4-HR-C sensor, we compared it with a commonly used wavefront sensor in the industry—the HR sensor (measuring wavelength of 940nm). The test samples consisted of six groups of coated discs, and their PV (peak-valley) and RMS (root mean square) values were measured to verify the measurement consistency and reliability of the FIS4 on different samples.

Table 1 Comparison of PV and RMS values measured by FIS4-HR-C and a certain wavefront sensor-HR

The data shows that:

* The maximum PV difference is no more than 17.41 nm, and the minimum is only 0.58 nm;

* The RMS difference is controlled within 5 nm, mostly in the 2–4 nm range;

* The FIS4 measurement results are highly consistent with those of a certain wavefront sensor, demonstrating excellent repeatability and stability.

Comparison of measured spectra

图 1 样品4的某波前传感器-HR测量数据

Wavefront sensor-HR measurement results:

PV: 178.50nm | RMS: 27.15nm

The spectrum shows that the wavefront distribution on the sample surface is uniform and the edges are clear.

Figure 2. FIS4-HR-C measurement data of sample 4

FIS4-HR-C Measurement Results

PV: 179.08nm | RMS: 30.39nm

The spectrum is highly consistent with that of a wavefront sensor, demonstrating strong detail reproduction and natural edge transitions.

In the measurement of sample 4, the PV difference of FIS4 was only 0.58nm, and the RMS difference was controlled at 3.24nm. It maintains high consistency even in complex surface morphologies, exhibiting outstanding stability.

Figure 3. Wavefront sensor-HR measurement data of sample 6

FIS4-HR-C Measurement Results

PV: 179.08nm | RMS: 30.39nm

The spectrum is highly consistent with that of a wavefront sensor, demonstrating strong detail reproduction and natural edge transitions.

In the measurement of sample 4, the PV difference of FIS4 was only 0.58nm, and the RMS difference was controlled at 3.24nm. It maintains high consistency even in complex surface morphologies, exhibiting outstanding stability.

图 4 样品6的FIS4-HR-C测量数据

FIS4-HR-C Measurement Results

PV: 174.50nm | RMS: 25.38nm

The spectrum shows a high degree of agreement with the measurement results from a wavefront sensor, accurately reproducing surface morphology details and exhibiting natural and smooth edge transitions, demonstrating excellent signal consistency.

In the measurement of sample 6, the PV difference of FIS4 was only 4.80nm, and the RMS difference was controlled within 1.98nm, further verifying its strong repeatability and stability in the measurement of complex surface morphology.

Why is FIS4 so remarkably stable?

✅ Four-wave transverse shearing interferometry technology utilizes a single-path interference principle, eliminating the need for phase shifting. This enhances signal stability, suppresses noise interference, and improves the measurement signal-to-noise ratio.

✅ High repeatability design: Hardware and algorithms are optimized in tandem, enabling real-time output of key parameters such as PV, RMS, PSF, MTF, and Zernike coefficients, as well as dynamic acquisition and area analysis. This ensures consistent results across multiple measurements, making it suitable for continuous production line inspection.

✅ Strong environmental adaptability: Requires no reference light, features a compact optical path structure, and exhibits strong resistance to vibration and temperature drift, making it suitable for various scenarios in industrial environments and laboratories.

✅ Fully domestically produced solution: While maintaining accuracy comparable to international brands, it provides a more cost-effective measurement solution.

With its superior repeatability, reliable stability, and comprehensive domestic technological support, the FIS4 wavefront sensor is gradually becoming a new choice in the field of high-precision optical measurement. Widely used in optical lens surface shape inspection, coating uniformity evaluation, microstructure surface morphology measurement, and semiconductor wafer quality monitoring, FIS4 provides reliable, usable, and dependable measurement assurance, whether for sample analysis during the R&D stage or batch inspection in the production line.