• Particle and aerosol research
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• v.13 no.2
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• pp.53-63
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• 2017

As semiconductor process was highly integrated, particle contamination became a major issue. Because particle contamination is related with process yields directly, particles with a diameter larger than half pitch of gate should be controlled. PBMS (Particle beam mass spectrometry) is one of powerful nano particle measurement device. It can measure 5~500 nm particles at ~ 100 mtorr condition in real time by in-situ method. However its usage is restricted to research filed only, due to its big device volume and high price. Therefore aperture changeable aerodynamic lenses (ACALs) which can control particle focusing characteristics by changing its aperture diameter was proposed in this study. Unlike conventional aerodynamic lenses which changes particle focusing efficiency when operating condition is changed, ACALs can maintain particle focusing efficiency. Therefore, it can be used for a multi-monitoring system that connects one PBMS and several process chambers, which greatly improves the commercialization possibility of the PBMS. ACALs was designed based on Stokes number and evaluated by numerical method. Numerical analysis results showed aperture diameter changeable aerodynamic lenses can focus 5 to 100 nm standard particles at 0.1 to 10 torr upstream pressure.

• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.135-138
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• 2007

Using a Shack-Hartmann sensor and sub-wavelength sized pinhole point source, we develope an optical testing system that measures the wavefront error of high numerical aperture and small sized optical components. The subwavelength sized pinhole generates perfect spherical waves with large diffraction angle and this makes possible to test high numerical aperture optics. The Shack-Hartmann sensor reconstructs the wavefront and calculates the aberrations. We make a home-made reference plane wave source which generates nearly perfect plane waves and the calibration with this plane source gives the overall uncertainty of the optical testing system 0.010 $\lambda$ rms.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.1-5
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• 2012

According to the paraxial diffraction theory, diffractions of optical systems which have the same wavelength and numerical aperture are always the same, independent of lateral magnification. But the diffractions for optical systems with different magnifications are varied due to the non-paraxial diffraction effect on the imaging of high NA optics. In this study, the non-paraxial diffraction effect is interpreted as a phenomena caused by curved principal planes. Pupil functions and modulation transfer functions of aplanatic conic mirrors are examined as a function of lateral magnification.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.262-267
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• 1998

In Synthetic Aperture Radar(SAR) imaging, the echoed data are collected by moving radar's position with respect to the target area, and this operation actually gives effect of synthesizing aperture size, which in turn gives better cross range resolution of reconstructed target scene. Among several inversion scheme for SAR Imaging, we uses an inversion scheme which uses no approximation in wave propagation analysis, and try to verify whether the collected data with synthesized aperture actually gives the same support as that with physical aperture in the same size. To do this, we make a signal subspace comparison of two imaging models with physical and synthesized arrays, respectively. Theoretical comparison and numerical analysis using Gram-Schmidt procedures had been performed. The results showed that the synthesized array data fully span the physical array data with the same system geometry and strongly support the proposed inversion scheme valuable in high resolution radar imaging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.178-178
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• 2009

High-density optical information storing equipment, which is using Blu-ray, is the next generation information storing equipment that has about form six times to thirty-five times capacities. and high-density optical information storing equipment uses high NA(Numerical Aperture) aspheric glass objective lens as optical pick-up equipment to record and recognize high-density date. Generally this objective lens is developed and produced through a way of GMP(Glass Molding Press) that uses molding core that is performde by Ultra precision grinding, but grinding performing that has high-accuracy is very difficult because objective lens form is high NA. In this research, we preformed Ultra precision turning, using single crystal diamond bite, about WC(Co 0.5%), sintering brittleness material that is used molding core's material for GMP. and we confirmed aspheric glass lens compression of deformities molding core's Ultra precision turning possibility by measuring surface roughness(Ra) and processing surface's condition.

• Korean Journal of Optics and Photonics
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• v.30 no.3
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• pp.94-100
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• 2019

The near-field subwavelength squint-less focusing system of a phased array antenna is designed and demonstrated by numerical simulation. The Huygens-Fresnel principle is applied to numerical simulation for calculation of the phased array antenna at microwave frequency. It was shown that beam squinting can be eliminated, utilizing true-time optical delay lines based on a chirped fiber grating in the proposed system. Furthermore, subwavelength focusing with high numerical aperture can be achieved by considering the fact that the array elements of the phased-array antenna can be treated as diffractive elements in an optical lens system. Also, side lobes can be suppressed by decreasing the distance between element antennas to less than half of the wavelength.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.78-83
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• 2005

The Blu-ray disc as a next generation high density optical medium uses an objective lens of high numerical aperture(NA 0.85) and blue laser in order to increase the recording density. The double layer is also useful for doubling the density. The spherical aberration of Blu-ray disc is very sensitive to the thickness of the disk because of high numerical aperture. This paper suggests a method to compensate the spherical aberration caused by the change of disk thickness, by using the Liquid Crystal lens instead of the Liquid Crystal panel. It was possible to develop both the LC panel generating the optical phase difference and LC lens changing the optical power. In this paper, we analyzed the aberration performance and a position sensitivity of the two type LC elements when the samples deviate from the optical axis of the objective lens. The results of applying this analysis show that the LC lenses rather than the LC panels have a significant assembling tolerance. The theoretical characteristics of the two elements are calculated and compared with the measurement data.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.531-537
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• 2014

Through-silicon vias (TSVs) are fine, deep holes fabricated for connecting vertically stacked wafers during three-dimensional packaging of semiconductors. Measurement of the TSV geometry is very important because TSVs that are not manufactured as designed can cause many problems, and measuring the critical dimension (CD) of TSVs becomes more and more important, along with depth measurement. Applying white-light scanning interferometry to TSV measurement, especially the bottom CD measurement, is difficult due to the attenuation of light around the edge of the bottom of the hole when using a low numerical aperture. In this paper we propose and demonstrate four bottom CD measurement methods for TSVs: the cross section method, profile analysis method, tomographic image analysis method, and the two-dimensional Gaussian fitting method. To verify and demonstrate these methods, a practical TSV sample with a high aspect ratio of 11.2 is prepared and tested. The results from the proposed measurement methods using white-light scanning interferometry are compared to results from scanning electron microscope (SEM) measurements. The accuracy is highest for the cross section method, with an error of 3.5%, while a relative repeatability of 3.2% is achieved by the two-dimensional Gaussian fitting method.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.4
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• pp.34-41
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• 1999

Unlike the traditional radar system, Synthetic Aperture Radar(SAR) system is capable of imaging a target scene to ceertain degree of cross-range resolution. And this resolution is mainly depends on the size of aperture synthesized. Thus, a good system model and inversion scheme should be developed to actually give effect of synthesizing aperture size, which in turn gives better cross range resolution of reconstructed target scene. Among several inversion schemes for SAR imaging, we used an inversion scheme called wavefront reconstruction which has no approximation in wave propagation analysis, and tried to verify whether the collected data with synthesized aperture actually give the same support as that with physical aperture in the same size. To do this, we performed a signal subspace comparison of two imaging models with physical and synthesized arrays, respectively. Theoretical comparisons and numerical analysis using Gram-Schmidt procedures have been performed. The results showed that the synthesized array data fully span the physical array data with the same system geometry. This result strongly supports the previously proposed inversion scheme valuable in high resolution radar imaging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.290-290
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• 2009

Blu-ray Disk, the next generation optical information storing equipment used Blu-ray is the next generation leading storing equipment that has capacity is about from six times to thirty-five times bigger than the existing CDs, DVDs. Especially, we need elaborate optical pick-Up equipment to record and recognize detailed date. Moreover, Blu-ray disk has so narrow track-pitch so it is used high NA(Numerical Aperture) aspheric glass objective lens. In this research, we processed optical pick-up aspheric glass objective lens molding press core by parallel grinding method with ultra precision machining and mold core surface measured form accuracy(PV), surface roughness(Ra).