ByoungChang Kim

3D shape measurement using curvature data

We present a method of three dimensional shape measurement from the curvature data, which are obtained from the subaperture topography along the diagonal direction of artifact by using white-light scanning interferometry. The curvature is an intrinsic property of the artifact, which does not depend on the positioning errors of measuring sensor. Experimental results prove that the proposed method is useful, especially for large-scale optical surface profile measurement with nanometer accuracy. The current version of this paper has had a correction made to it at the request of the author. Please see the linked Errata for further details.

An in-situ monitoring system on the grinding process

We present a non-contact type monitoring system specially devised to control the cutting depth on the grinding process. This system comprises a one axis scanning stage and the imaging system using line camera and collimated white light source. Experimental results prove that the proposed system is useful, especially for the monitoring system in grinding the piston groove on the cylinder with a few micrometers accuracy in the dozens of millimeter area.

Aspheric measurement based on the curvature sensing method

We present a method of aspheric surface profile measurement based on the principle of curvature sensor, which measures the curvature of subaperture topography along a line and then reconstructs the entire profile from the measured local curvature data. The subaperture topography is obtained by using white-light scanning interferomtery to avoid the optical alignment error along an optical axis. Test measurement results demonstrate that the proposed method and system is well suited for the aspheric surface profile measurement.

White Light Scanning Interferometry for Nano Surface Metrology

Extended Abstract Polymer nanofiber composites for the treatment of hazardous compounds are of considerable scientific and technological interest. In this study, polyamide nanofiber for organic pollutant removal and chemical warfare protection is discussed. The effect of position of functional materials in nanofiber matrix on the photocatalytic activity was studied by comparing the AgTiO2-decorated nylon nanofiber composite (AT-sur-NF) and Ag-TiO2-embedded nylon nanofiber composite (AT-in-NF) [1]. We find that AT-sur-NF shows better photocatalytic activity compared to the photocatalytic activity of AT-in-NF. Based on these results, nylon and meta-aramid nanofibers decorated by various functional nanomaterials were fabricated. The electrospun meta-aramid nanofiber composites exhibit poor chemical stability because of the salt molecules remaining between meta-aramid chains [2]. The chemical stability of meta-aramid nanofiber composites were improved by removing salt molecules during washing and additional thermal treatment. The polyamide nanofiber composites were stacked to enhance mechanical properties and resistivity to chemical warfare agents (CWAs). By controlling the stacking of polyamide nanofiber composites, thickness, weight density, and cool/warm feeling are optimized. In addition, the assemblies exhibit enough resistivity to CWAs while still maintain water vapor transmission to allow evaporation of sweat on the skin. Further study on the thermal properties and microstructure of nylon nanofibers reveals that the chains rigidity and thermal stability increase with decreasing diameter of nylon nanofibers.

Subaperture method for aspheric surface metrology using curvature data

We present a profilometry for measuring aspheric surface, which determines the curvature from the sub-aperture topography along two orthogonal directions and then reconstructs the entire surface profile from the measured curvature data. The entire surface was divided into a number of sub-apertures with overlapping zones. Each sub-aperture was measured using white-light scanning interferometry to avoid any optical alignment error along an optical axis. Simulation studies are also presented based on the mathematical model. The proposed mathematical model was also experimentally tested on freeform surfaces using white-light scanning interferometry under deveolpment.

Aspheric surface reconstruction from curvature data along two orthogonal directions

We present a method of aspheric surface reconstruction from the curvature data along two orthogonal directions. The curvature is an intrinsic property of the artifact, which does not depend on the positioning error of a measuring sensor. In this paper, we showed that the curvature method is suitable for aspheric surface reconstruction along one direction and expanded this algorithm to two directions. Computer simulations were undertaken to explore the possibility of three-dimensional surface reconstruction. The simulation results and the position error diagnosis showed that the curvature method is robust against various positioning errors.

Large free form measurement using slit beam

In heavy industry, 3D surface measurement of large-scale hull pieces is needed for fabrication and assembly. Until now, there is not such an efficient method as a standard ruler on 3D profile measurement of large-scale curvature plates. We suggest an efficient method of 3D profile measurement to obtain the xyz-coordinates of curvature plates. The measurement system comprises a few slit beam lines and performs profile measurement by projecting structured light source on the object surface.

3D profile measurement of large-scale curvature plates using structured light source

In heavy industry, especially in the shipbuilding process, 3D profile measurement of large-scale hull pieces is needed for fabrication and assembly. Currently, using many kinds of templates made of wood or plastic still do an important role as a standard ruler. We suggest an efficient method of 3D profile measurement to obtain the xyz-coordinates of curvature plates. The measurement system comprises multiple line structured laser sources and performs profile measurement by projecting structured light source on the object surface. The measurement results show that measurement accuracy is within the boundary of accuracy required in the shipbuilding process.

The curvature profile measurement using white-light scanning interferometry

We present a method of curvature profile measurement using White-light Scanning Interferometry. This method is based on the principle of curvature sensor which measures the local curvature under test along a line. The profile is then reconstructed from the curvature data on the each point. Unlike subaperture-stiching method and slope detection method curvature sensing have strong points from a geometric point of view in measuring the free-form surface profile. Curvature is related to second derivative terms of surface profile and an intrinsic property of the test piece, which is independent of its position and tip-tilt motion. The curvature is measured at every local area with high accuracy and high lateral resolution by using White-light scanning interferometry.

GPS Methods for 3-D Surface Profile Measurement on Light Scattering Surfaces

In this paper, it is proposed that GPS (Global Positioning System) methods are used for 3-D surface profile measurement of light scattering surface. This method is a new way that use the diffraction interference diverged from multiple two-point-diffraction sources made of a pair of single-mode fiber