A freeform mirror profiler with a very wide dynamic range and a high precision

We have developed a new non-contact profiler which can measure aspherical mirrors including freeform surfaces. One of the best feature of this instrument is its very wide dynamic range of 10 nm to 100 μm, while maintaining interferometer-level measurement precision. It utilizes Computer-Generated Holograms (CGH) for generating the arbitrary wavefront. The wide dynamic range is achieved by integrating two modes, “Interferometer Mode" and "Hartmann Mode," which can be switched by changing the internal optical path without the need to move the measurement target. The measurement accuracy is 5.3 nm RMS in Interferometer Mode and 0.055 µm RMS in Hartmann Mode. The Interferometer Mode provides a measurement range from 0.0053 µm to 31 μm, while the Hartmann Mode extends from 0.055 to 625 µm when measuring the test surface of F-number 1.0.