High numerical aperture (NA) microscope objectives are critical in semiconductor wafer defect inspection. Conventional wavefront measurement approaches are limited by the precision of reference wavefronts and inherent systematic errors, which restricts their performance in high-precision metrology. To address these iss...
Coherence scanning interferometry is a non-contact optical measurement technique used for high-resolution, three-dimensional surface topography characterization. The physical principle of this technique allows to measure the shape of an object, whether its surface is smooth or rough. The measurement system is basically...
High-accuracy characterization of optical grating pitch is increasingly important for the quality control of diffractive optical elements, particularly in the emerging augmented reality optics. To address the limitations of conventional measurement methods, such as AFM and diffractometry, we present a snap-shot interfe...
This paper investigates the feasibility of measuring wedge and decentre of an aspheric optic using a multiwavelength interferometer in a single, unified setup where surface form, wedge, and decentre are measured in succession. Wedge and decentre errors of an aspherical lens were measured on a multiwavelength interferom...
The 7-Dimensional Telescope (7DT), developed by Center for the Gravitational-Wave Universe at Seoul National University, is a multi-telescope array designed to identify the electromagnetic counterparts of gravitational-wave events. 7DT consists of twenty 50cm telescopes equipped with CMOS cameras, each providing a 1.25...
Abstract We present a laser interferometric measurement system for absolute distance measurements based on currentmodulated laser diodes in the telecommunications wavelength range. The sensor system described here uses two lasers with slightly different wavelengths in a point-wise measuring interferometer and enables t...
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