FIS4 wavefront sensor: High-precision measurement, a shining example of domestic technology comparable to Zygo!

In the field of optical measurement, accuracy is a core indicator for evaluating instrument performance. The FIS4 wavefront sensor, developed over 17 years by Professor Yang Yongying's team at Zhejiang University, is becoming a new benchmark for high-end domestically produced optical measurement instruments due to its outstanding performance. Through comparative accuracy tests with a Zygo interferometer, the FIS4 wavefront sensor's superior performance in various phase plate measurements has been fully verified.

A summary of verification results

Three typical samples—circular stepped plate, square stepped plate, and continuous phase plate—were selected for testing. PV (peak-to-valley value) and RMS (root mean square value) were measured using Zygo and FIS4, respectively. The results are as follows:

Real-world case comparison: FIS4 vs Zygo

Test 1: Comparison of circular stepped plates

The circular stepped phase plate was measured using a Zygo interferometer (wavelength 632.8 nm). The measurement results are shown in Figure 1. As can be seen from the figure, the measured PV is 0.113λ (equivalent to a length of 71.51 nm) and the RMS is 0.043λ (equivalent to a length of 27.21 nm).

Figure 1. Zygo measurement data of the circular stepped phase plate

The results of the measurement using the FIS4 wavefront sensor are shown in Figure 2. The PV is 73.03 nm and the RMS is 24.64 nm.

图 2 圆形台阶相位板的FIS4测量数据

Conclusion: The wavefront morphology of the two samples is highly consistent, with a PV value deviation of only 1.52 nm. FIS4 accurately reproduced the step characteristics of the samples.

Test 2: Comparison of square step panels

The square stepped phase plate was measured using a Zygo interferometer (wavelength 632.8nm). The measurement results are shown in Figure 3. As can be seen from the figure, the measured PV is 0.109λ (equivalent to a length of 68.98nm) and the RMS is 0.033λ (equivalent to a length of 20.88nm).

Figure 3. Zygo measurement data of the square stepped phase plate

The results of the measurement using the FIS4 wavefront sensor are shown in Figure 4. The PV is 69.37 nm and the RMS is 23.08 nm.

Figure 4. FIS4 measurement data of the square stepped phase plate

Conclusion: For regular square structures, FIS4 exhibits exceptional edge reproduction capability and surface accuracy, with a PV deviation as low as 0.39nm.

Test 3: Comparison of Continuous Phase Plates

The continuous phase plate was measured using a Zygo interferometer (wavelength 632.8 nm). The measurement results are shown in Figure 5. As can be seen from the figure, the measured PV is 0.624λ (equivalent to a length of 394.87 nm) and the RMS is 0.169λ (equivalent to a length of 106.94 nm).

Figure 5. Zygo measurement data for continuous phase plates

The results of the measurement using the FIS4 wavefront sensor are shown in Figure 6. The PV is 387.58 nm and the RMS is 103.99 nm.

图 6 连续相位板的FIS4测量数据

Conclusion: When faced with complex continuous aspherical surfaces, FIS4 can stably capture both the global contour and local details, with PV and RMS deviations controlled within a reasonable range, thus verifying its reliability.

PS: FIS4 software has a phase reversal function. In test results, all core data such as feature contours, PV values, and RMS values are completely consistent; only the phase is reversed.

FIS4 Core Advantages

✅ High-Precision Measurement, Comparable to International Brands

In tests with three different phase plates, the PV and RMS deviations of the FIS4 were controlled at the nanometer level. Particularly on the square stepped plate, the PV deviation was only 0.39 nm, demonstrating measurement accuracy comparable to Zygo.

✅ Strong Adaptability, Widely Applicable to Various Samples

Whether for regular shapes (circular, square) or complex continuous phase surfaces, the FIS4 can stably output reliable data. Its single-path design provides excellent vibration resistance, making it suitable for diverse optical component testing scenarios.

✅ Domestic Substitute, Superior Cost-Effectiveness

As a domestically produced high-end optical sensor, the FIS4 maintains high precision while offering superior cost-effectiveness, providing reliable and economical optical measurement solutions for domestic research and industrial users.

The FIS4 wavefront sensor, with its excellent measurement accuracy, strong adaptability, and excellent cost-effectiveness, is gradually becoming a new benchmark in the field of optical measurement. As shown in the comparison chart above, its measurement results are highly consistent with those of top international equipment. Whether it's quality control during the R&D phase or online inspection during the production process, FIS4 provides reliable and accurate wavefront measurement support.