Compact DUV reflective Fourier ptychographic microscopy for high-throughput surface measurements

High-throughput surface measurements and inspection are crucial for a wide range of applications, from reflective optical components to very large-scale integrated (VLSI) circuits. Reflective Fourier ptychographic microscopy (RFPM) has been previously reported as a solution for imaging reflective surfaces at high resolution. Prior approaches have used epi-illumination for bright-field and either a ring array or parabolic mirror for dark-field illumination, which can be bulky and require demanding calibration compared to standard transmission FPM setups. In this work, we present a novel, to the best of our knowledge, deep ultraviolet (DUV) RFPM method that utilizes a single LED matrix as the illumination source. The system achieves a simpler and more compact reflective FPM setup, enabling a 1.6 mm field of view, 690 nm spatial resolution, and nanometer-scale height profiling using a 5×, 0.12 NA DUV objective lens. We demonstrate the DUV RFPM experimental setup and present measurement results on wafer standards and a machined concave mirror surface.