김대우 교수

Computer controlled polishing requires accurate knowledge of the tool influence function (TIF) for the polishing tool (i.e. lap). While a linear Preston's model for material removal allows the TIF to be determined for most cases, nonlinear removal behavior as the tool runs over the edge of the part introduces a difficulty in modeling the edge TIF. We provide a new parametric model that fits 5 parameters to measured data to accurately predict the edge TIF for cases of a polishing tool that is eit

Optical surfaces can be accurately figured by computer controlled optical surfacing (CCOS) that uses well characterized sub-diameter polishing tools driven by numerically controlled (NC) machines. The motion of the polishing tool is optimized to vary the dwell time of the polisher on the workpiece according to the desired removal and the calibrated tool influence function (TIF). Operating CCOS with small and very well characterized TIF achieves excellent performance, but it takes a long time. Th

We report an adaptive interferometric null testing method for overcoming the dynamic range limitations of conventional null testing approaches during unknown freeform optics metrology or optics manufacturing processes that require not-yet-completed surface measurements to guide the next fabrication process. In the presented adaptive method, a deformable mirror functions as an adaptable null component for an unknown optical surface. The optimal deformable mirror's shape is determined by the stoch

This paper describes a operating characteristics of contactless power transfer (CPT) system from normal conducting coil to HTS coil based on the electromagnet resonance coupling. The basic principle is that two separate coils with same resonance frequency are possible to form a resonant system based on high frequency magnetic coupling and exchange energy in a high efficiency. The CPT technique with the electromagnetic resonance coupling has been expected as a useful option for contactless charge

This review paper addresses topics of fabrication, testing, alignment, and as-built performance of reflective space optics for the next generation of telescopes across the x-ray to far-infrared spectrum. The technology presented in the manuscript represents the most promising methods to enable a next level of astronomical observation capabilities for space-based telescopes as motivated by the science community. While the technology to produce the proposed telescopes does not exist in its final f

We present a novel model-free iterative data-processing approach that improves surface reconstruction accuracy for deflectometry tests of unknown surfaces. This new processing method iteratively reconstructs the surface, leading to reduced error in the final reconstructed surface. The method was implemented in a deflectometry system, and a freeform surface was tested and compared to interferometric test results. The reconstructed departure from interferometric results was reduced from 15.80 μm R

The control of surface errors as a function of spatial frequency is critical during the fabrication of modern optical systems. A large-scale surface figure error is controlled by a guided removal process, such as computer-controlled optical surfacing. Smaller-scale surface errors are controlled by polishing process parameters. Surface errors of only a few millimeters may degrade the performance of an optical system, causing background noise from scattered light and reducing imaging contrast for

Contactless power transfer (CPT) technology is an available option to realize the possibility of power delivery and storage with connector-free devices across an air gap. The CPT system based on a strong resonance coupling, which consists of four separate coils with the same resonance frequency, can possibly exchange energy within 2 m. We propose a combination CPT technology with HTS receiver coils, and call it the superconducting contactless power transfer (SUCPT) system. The SUCPT technique is

The Giant Magellan Telescope (GMT) primary mirror consists of seven 8.4 m light-weight honeycomb mirrors that are being manufactured at the Richard F. Caris Mirror Lab (RFCML), University of Arizona. In order to manufacture the largest and most aspheric astronomical mirrors various high precision fabrication technologies have been developed, researched and implemented at the RFCML. The unique 8.4 m (in mirror diameter) capacity fabrication facilities are fully equipped with large optical generat

Computer controlled optical surfacing (CCOS) requires accurate knowledge of the tool influence function (TIF) for the polishing tool. The linear Preston's model for material removal has been used to determine the TIF for most cases. As the tool runs over the edge of the workpiece, however, nonlinear removal behavior needs to be considered to model the edge TIF. We reported a new parametric edge TIF model in a previous paper.** This model fits 5 parameters to measured data to accurately predict t

Control of mid-spatial-frequency errors on precision optical surfaces is very important for next-generation optical systems. We present results of smoothing experiments and of polishing runs utilizing figuring and smoothing for the 8.4m GMT off-axis segment.

This paper lays out the trail onto a closed-loop polishing process of optical elements enabling the application of the optimum polishing time needed. To that aim, an in-process testing method for monitoring an inclusive microsurface quality (e.g., comprising surface roughness and scratch-and-dig) within the polishing spot is analyzed, and its applicability to closed-loop polishing for classical loose-abrasive full-aperture polishing as well as for computer-controlled laser polishing is experimen