Material characterization, particularly three-dimensional (3D) surface-contour measurement, is essential for fully understanding and optimizing the performance of micro- and nano-structured devices. Point scanning confocal microscopy (PSCM) is a well-established 3D measurement technique, but it requires point-by-point scanning. Optical sectioning structured-illumination microscopy (OS-SIM), while faster and more cost-effective than PSCM, faces challenges when measuring samples with complex reflective properties, such as interreflection and subsurface scattering. This paper proposes confocal structured illumination microscopy (CSIM). CSIM uses the single-pixel imaging principle to separate indirect light signals caused by interreflection and subsurface scattering from the direct light signal of the conjugated object point. Subsequently, it applies the confocal imaging principle to extract direct light signals for confocal image reconstruction. Our experimental results demonstrate that, for samples with interreflection, CSIM effectively eliminates the artifacts caused by interreflection and accurately reconstructs the 3D contour of the measured sample, a task that OS-SIM struggles to accomplish. For samples with subsurface scattering, CSIM achieves a signal-to-background ratio (SBR) that is 3.5 times higher than that of OS-SIM. The proposed method enables precise 3D surface contouring of micro- and nano-structured samples with complex reflective properties. It has broad potential impacts in fields such as microelectronics, materials science, and mechanical engineering.

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• Classical optics
• Ghost imaging
• Imaging & optical processing
• Metrology
• Tomography
• Confocal imaging
• Optical microscopy