• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.10 s.115
• /
• pp.1044-1049
• /
• 2006

The vibration exciter with the accurate calibration requires a low distortion along a single axis over a wide range of frequency. The fabricated piezoelectric exciter was composed of a base, piezoelectric element(Venitron PZT 5A), electrode and seismic mass. Its performance characteristics is evaluated the Mach-Zehnder optical fiber interferometer. The phase of the optical wave passing through the optical fiber around the piezoelectric element was related the vibrational amplitude with a change of the applied sinusoidal voltage on the piezoelectric element. The dynamic characteristics of vibration exciter can be obtained by measuring the vibrational amplitude with a sinusoidal applied voltage on the piezoelectric element. The sensitivity of the fabricated piezoelectric exciter had a 0.4 nm/V which was uniform up to 20 kHz.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.11a
• /
• pp.136-137
• /
• 2002

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.11a
• /
• pp.134-135
• /
• 2002

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.05a
• /
• pp.105-108
• /
• 2004

The effect of thermal deformation of optical pick-up due to laser diode(LD) and LD driving integrated circuit on the optical performance of digital versatile disk(DVD) optical system was analyzed using the finite element analysis with initial surface residual stress conditions, and results were compared with the measured results with holographic interferometry. Ray tracing was performed using the deformed configuration of optical system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1998.04a
• /
• pp.227-232
• /
• 1998

This work focuses on the analysis of dynamic characteristics of an optical disk drive, Dynamic performance of the drive plays an important role in the design of a mechanism where the quality of servo mainly affected by the quality of controlling focus error and tracking error, A finite element model of the optical disk drive is presented to demonstrate its dynamic behaviors. Experimental results for the drive are presented and compared to predictions from the finite element model for verification. Using the finite element model, dynamic responses are predicted under internal and external excitations. Some design parameters of the vibration isolators are presented, satisfying the requirements of DVD drive system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.45-46
• /
• 2013

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.12 s.177
• /
• pp.100-107
• /
• 2005

The present work covers a new ray tracing scheme of an injection-molded plastic lens linked with finite element analysis fur injection molding processes. The traditional ray tracing schemes have been based on the assumption that optical property of the lens is homogeneous throughout the entire volume. However, this assumption is quite unrealistic for injection-molded plastic lenses since material properties vary at every point due to injection molding effects. In order to consider non-homogeneous property of a lens, a modified ray tracing method is proposed in connection with finite element analysis of injection molding. Through the analysis of the injection molding process, the distribution of refractive indices can be obtained. This information is then utilized in the proposed ray tracing scheme based on finite element meshes so as to take into account variation of the refractive indices. The effect of mold temperature is also investigated through finite element analysis, and the relevant optical quality is evaluated through the proposed ray tracing simulation.

• Current Optics and Photonics
• /
• v.7 no.2
• /
• pp.213-221
• /
• 2023

The optical window, as a part of the collimator system, is the connector between the outside light source and the optical system inside a vacuum tank. The temperature and pressure difference between the two sides of the optical window cause not only thermoelastic deformation, but also refractive-index irregularities. To suppress the influence of these two changes on the performance of the collimator system, thermo-optical analysis is employed. Coefficients that characterize the deformations and refractive-index distributions are derived through finite-element analysis, and then imported into the collimator system using a user-defined surface in ZEMAX. The temperature and pressure difference imposed on the window seriously degrade the system performance of the collimator. A decentered and tilted lens group is designed to correct both field aberrations and the thermal effects of the window. Through lens-interval adjustment of the lens group, the diffraction-limited performance of the collimator can be maintained with a vacuum level of 10^-5 Pa and inside temperature ranging from -100 ℃ to 20 ℃.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1288-1293
• /
• 2007

The present study covers the design and analysis of a thermionic scanning electron microscope (SEM) column. The SEM column contains an electron optical system in which electrons are emitted and moved to form a focused beam, and this generates secondary electrons from the specimen surfaces, eventually making an image. The electron optical system mainly consists of a thermionic electron gun as the beam source, the lens system, the electron control unit, and the vacuum unit. In the design process, the dimension and capacity of the SEM components need to be optimally determined with the aid of finite element analyses. Considering the geometry of the filament, a three-dimensional (3D) finite element analysis is utilized. Through the analysis, the beam emission characteristics and relevant trajectories are predicted from which a systematic design of the electron optical system is enabled. The validity of the proposed 3D analysis is also discussed by comparing the directional beam spot radius. As a result, a prototype of a thermionic SEM is successfully developed with a relatively short time and low investment costs, which proves the adoptability of the proposed 3D analysis.

• Current Optics and Photonics
• /
• v.3 no.3
• /
• pp.227-235
• /
• 2019

With slimmer, lighter and all-reflective imaging systems in high demand for consumer and military applications, coaxially folded optical image systems are widely considered because they can extend focal length and reduce track length. Most of these systems consist of multiple surfaces, and these surfaces are machined on one element or grouping processing on two elements. In this paper, we report and first experimentally demonstrate an all-aluminum all-reflective optical system which consists of two optical elements, with two high order aspherical surfaces in each element. The coaxially folded system is designed with Seidel aberration theory and advanced optimization with Zemax. The system is made of all-aluminum material processing by single point diamond turning (SPDT). On this basis, we completed the system integration and performed an imaging experiment. The final system has the advantages of short track length and long focal length and broad application prospects in the micro-unmanned aerial vehicle field.