title: Digital holographic microscopy based on a modified lateral shearing interferometer for three-dimensional visual inspection of nanoscale defects on transparent objects.
abstract: A new type of digital holographic microscopy based on a modified lateral shearing interferometer (LSI) is proposed for the detection of micrometer- or nanometer-scale defects on transparent target objects. The LSI is an attractive interferometric test technique because of its simple configuration, but it suffers from the so-called 'duplicate image' problem, which originates from the interference of two sheared object beams. In order to overcome this problem, a modified LSI system, which employs a new concept of subdivided two-beam interference (STBI), is proposed. In this proposed method, an object beam passing through a target object is controlled and divided into two areas with and without object information, which are called half-object and half-reference beams, respectively. Then, these two half-beams make an interference pattern just like most two-beam interferometers. Successful experiments with a test glass panel for mobile displays confirm the feasibility of the proposed method and suggest the possibility of its practical application to the visual inspection of micrometer- or nanometer-scale defects on transparent objects.
authors.affiliation: HoloDigilog Human Media Research Center (HoloDigilog), 3D Display Research Center (3DRC), Kwangwoon University, 447-1 Wolge-Dong, Nowon-Gu, Seoul 139-701, Korea.
authors.forename: Kwang-Beom
authors.initials: KB
authors.lastname: Seo
authors.affiliation: HoloDigilog Human Media Research Center (HoloDigilog), 3D Display Research Center (3DRC), Kwangwoon University, 447-1 Wolge-Dong, Nowon-Gu, Seoul 139-701, Korea.
authors.forename: Byung-Mok
authors.initials: BM
authors.lastname: Kim
authors.affiliation: HoloDigilog Human Media Research Center (HoloDigilog), 3D Display Research Center (3DRC), Kwangwoon University, 447-1 Wolge-Dong, Nowon-Gu, Seoul 139-701, Korea.
authors.forename: Eun-Soo
authors.initials: ES
authors.lastname: Kim
keywords: Defect detection of transparent materials; Depth and phase measurement and metrology; Digital holographic microscopy; Lateral shearing interferometer; Three-dimensional visual inspection