DOE-based Multi-spot Confocal InterferenceMicroscope

Diffractive lens arrays are used to enhance the resolution of a low-numerical-aperture objective to perform high-resolution large-area measurements. However,the axial resolution of such setups is still fundamentally limited by the objec-tive[4]. This work introduces the concept of utilizing the reflected conjugatewave of the diffractive optical elements (DOEs) for interference measurements.A traceable step height target is measured and the experiment result showsthat the proposed setup can improve the accuracy and reduce the measurementuncertainty in the axial direction.