Optical Convergence Smart Device Solution Lab.

The applicability of a polyether ether ketone locking compression plate (PEEK LCP) fabricated using FDM (fused deposition modeling)-based 3D printing to treat actual patients was studied. Three different tests—bending, axial compression, and axial torsion—were conducted on tibial non-osteoporotic comminuted diaphyseal fracture samples fixed with the commercial titanium alloy LCP and 3D-printed PEEK LCP. Comparing the outcomes of these tests revealed that the commercial titanium alloy LCP underwent plastic deformation in the bending and axial torsion tests, though the LCP did not fail even when an external force greater than the maximum allowable load of the tibia fixture of the LCP was applied. Elastic deformation occurred in the 3D-printed PEEK LCP in the bending and axial torsion tests. However, deformation occurred even under a small external force, and its stiffness was 10% compared to commercial titanium alloy LCP. Thus, 3D-printed PEEK LCP can be applied to the fracture conditions in non-weight-bearing regions. The experimental results reveal detailed insights into the treatment of actual patients by considering the stiffness and high toughness of 3D-printed PEEK LCP.

A dual-layer near-field recording (NFR) optical system with a high numerical aperture (NA) of 1.84 was designed by appropriate cover and spacing layer selection, using layers with refractive indices of 2.0. The designed aplanatic imaging optics exhibited additional aberrations in the multi-layered stack, mainly due to the air-gap and spacer layer. Given optics designed only to compensate for aberrations caused by a 2-μm-thick cover-layer, a 3-μm-thick spacer layer induces 96.2 mλrms and 6.5 mλrms of spherical aberration and defocus, respectively. A complete electric field calculation analysis for the inside of the multi-layer stack verified that diffraction-limited spot quality can be ensured on the recording layer with phase-only correction. As the aberration caused by the multi-layered stack cannot be corrected perfectly, due to the high oscillation of the aberration function along the radial direction in the exit pupil, three different types of liquid crystal (LC) electrodes were considered for practical implementation. Of the three phase-correction methods, the approximate linear phase-correction method was the most tolerant of axis decenter from the optical axis, providing acceptable diffraction-limited correction performance.

We designed compatible optics for a solid-immersion-lens (SIL)-based near-field recording (NFR) system and a Blu-ray disc (BD). The working distance, numerical aperture (NA), and cover layer thickness of the SIL-based NFR system differ from those of BD. Therefore, for the compatibility of a cover layer incident type NFR system of whose NA is 1.46 and BD, we use a relay lens that is composed of two lowNA lenses. The optical tolerances such as decenter, tilt, and SIL thickness tolerances are considered to ensure manufacturability. The decenter and tilt tolerances of each optical component are greater than 1.0 mm and 0.1, respectively. The tolerance of the SIL thickness range is 14 mm at the criterion of the wavefront aberration of 0:035 rms. We design the optical layout and simulate each focus error signal of BD and the SIL-based NFR system. From the practical design results, we confirm that the SIL-based NFR system can be compatible to BD with a simple relay lens. # 2009 The Japan Society of Applied Physics

종래의 spot형 UV경화기는 복수의 렌즈를 이용한 collimator 광학계를 구성하여 광속을 광케이블로 입사하도록 하고 있다. 전달 광 효율을 높이기 위해 3매 이상의 렌즈로 구성된 collimator 광학계가 필요하며 이에 따라 광학계 정렬에 어려움이 있고, 시스템을 컴팩트하게 구현하기 어렵다. 본 연구에서는 3매 렌즈로 구성된 collimator 광학계와 동등한 수준의 spot 직경 및 광 효율을 구현할 수 있는 단일 TIR 렌즈 collimator 설계하였다. 이를 통해 최소 조도 편차를 갖는 경화 위치에서의 광 효율이 33.2 % 수준으로 참조 collimator 광학계의 성능과 유사한 수준을 확보하였고, 경화면에서의 조도 편차는 18.8 % 수준으로 양호한 성능을 확보하였다. 또한, field flattening 기능을 갖는 fly-eye lens를 condensing 렌즈 앞단에 배치함으로써, TIR 렌즈만 적용한 경화 광학계와 비교할 때, 유효 경화영역 직경이 5.0 mm에서 3.0 mm 로 줄어 보다 높은 경화 에너지 밀도를 구현할 수 있었으며, 조도 편차는 14.4 % 수준으로 현격히 개선할 수 있음을 확인하였다.

We analyzed the effect of an annular aperture on solid immersion lens (SIL)-based near-field recording (NFR) to verify the feasibility of applying an aperture to SIL-based NFR. SIL-based NFR with an annular aperture, which blocks the propagating waves, shows good characteristics such as a beam profile on the recording layer and beam propagation inside a medium. By introducing the annular aperture, the focused beam spot size and its sensitivity to the gap between SIL and the surface of the medium can be decreased, and the axial confined beam distribution can be obtained inside the medium. We also show that the general gap control method can be applied to SIL-based NFR with an annular aperture through the calculated exit pupil intensity distribution of the reflected electric field.

A numerical study has been performed to secure temperature uniformity of printing chamber for the development of a FDM type 3D printer using high melting point materials. In order to improve the temperature uniformity of the air inside the chamber, it is appropriate to discharge the high-temperature air from the upper part of the chamber. In addition, the temperature uniformity can be improved when there is a macroscopic flow mixing inside the chamber. Finally, effect of a porous plate was investigated by applying perforated plate to the front of the outlet. These results are expected to be applicable not only to the printing of industrial materials, but also to the printing of popular materials such as ABS and PLA