• Title/Summary/Keyword: Lens power

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Design of a Linear Ultrasonic Actuator for Small Lens Actuation (초소형 렌즈 구동을 위한 선형 초음파 구동기 설계)

  • Kwon, Tae-Seong;Choi, Yo-Han;Lee, Seung-Yop
    • Transactions of the Society of Information Storage Systems
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    • v.2 no.4
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    • pp.251-256
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    • 2006
  • There is a great demand of micro-actuators for mobile information devices such as SFF optical drives and mobile phone cameras. However, the magnetic coils used in conventional electromagnetic motors are a major obstacle for the miniaturization because of their complicated structures and large power consumption. In this paper, a linear ultrasonic motor to actuate focusing lens of mobile devices is proposed. The new actuator uses a ring type bimorph piezoelectric material, and $d_{31}$ mode is adopted for applying linear motion. The interaction between inertia force and friction force makes linear motion by high-frequency saw signal input. The saw signal gives steady forces on the one direction by asymmetric inclination property of the signal itself on time domain. A commercial FEM(ANSYS) was used in this investigation for simulating structural analysis, identification of dynamic property, such as resultant displacement and coupled analysis with piezoelectric material. To evaluate the performance of the new design, a prototype was manufactured and experiments were carried out. Experimental results show the actuator motion of 5.4 mm/s at 10V saw signal of 41 kHz.

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Development of an Equipment for measuring the MTF of Camera Phone Lenses (카메라폰 렌즈의 MTF 측정장치 개발)

  • Hong, Sung-Mok;Jo, Jae-Heung;Lee, Yun-Woo;Lee, Hoi-Yon;Yang, Ho-Soon;Lee, In-Won
    • Korean Journal of Optics and Photonics
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    • v.18 no.1
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    • pp.31-36
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    • 2007
  • In order to evaluate the performance of phone camera lenses, we have developed equipment for measuring the modulation transfer function(MTF) for small size lenses. The equipment is composed of an an image analyzer, object generator, and a lens mount. The object generator is rotated for on and off-axis measurement. The lens mount is of horizontal type and tiltable for precise alignment to the optical axis. After the initial alignment process, the measurement is done within 10 seconds automatically

A Design of Standing Human Body Sensing System Using Rotation of a PIR Sensor (초전형 적외선 센서 회전방식을 이용한 정지 인체 감지 시스템에 관한 연구)

  • Cha, Hyeong-Woo;Cho, Min-Yyeong
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.1
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    • pp.129-136
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    • 2016
  • A novel sensing system for standing and moving human body using PIR(pyroelectric infrared) sensor was development. The system consists of power supply, interface circuit of PIR sensor, small stepping motor, and digital control. The detecting principle for stop human body is detecting the human body when the stepping motor sticking the PIR sensor and the fresnel lens has rotated by 180 degree at six second and has stopped the motor for no detecting signal of human body. We developed control algorism for proposed the detection system. The experimentation shows that the detector system had detected length and angle were 6m and 30 degree against as standing and moving human body with $37^{\circ}C$.

Predicting Powers of Spherical Rigid Gas-permeable Lenses Prescription (구면 RGP 렌즈의 처방 굴절력 예측)

  • Yu, Dong-Sik;Yoo, Jong-Sook
    • Journal of Korean Ophthalmic Optics Society
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    • v.15 no.3
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    • pp.219-225
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    • 2010
  • Purpose: Usefulness in predicting the power of spherical rigid gas-pearmeable (RGP) lenses prescription using dioptric power matrices and arithmetic calculations was evaluated in this study. Noncycloplegic refractive errors and over-refractions were performed on 110 eyes of 55 subjects (36 males and 19 females, aged $24.60{\pm}1.55$years) in twenties objectively with an auto-refractometer (with keratometer) and subjectively. Tear lenses were calculated from keratometric readings and base curves of RGP lenses, and the power of RGP lenses were computed by a dioptric power matrix and an arithmetic calculation from the manifest refraction and the tear lens, and were compared with those by over-refractions in terms of spherical (Sph), spherical quivalent (SE) and astigmatic power. Results: The mean difference (MD) and 95% limits of agreement (LOA=$MD{\pm}1.96SD$) were better for SE (0.26D, $0.26{\pm}0.70D$) than for Sph (0.61D, $0.61{\pm}0.86D$). The mean difference and agreement of the cylindrical power between matrix and arithmetic calculation (-0.13D, $-0.13{\pm}0.53D$) were better than between the others (-0.24D, $0.24{\pm}0.84D$ between matrix and over-refraction; -0.12D, $0.12{\pm}1.00D$ between arithmetic calculation and over-refraction). The fitness of spherical RGP lenses were 54.5% for matrix, 66.4% for arithmetic calculation and 91.8% for over-refraction. Arithmetic calculation was close to the over-refraction. Conclusions: In predicting indications and powers of spherical RGP lens fitting, although there are the differences of axis between total (spectacle) astigmatism and corneal astigmatism, Spherical equivalent using an arithmetic calculation provides a more useful application than using a dioptric power matrix.

Fabrication of Artificial Sea Urchin Structure for Light Harvesting Device Applications

  • Yeo, Chan-Il;Kwon, Ji-Hye;Kim, Joon-Beom;Lee, Yong-Tak
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.380-381
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    • 2012
  • Bioinspired sea urchin-like structures were fabricated on silicon by inductively coupled plasma (ICP) etching using lens-like shape hexagonally patterned photoresist (PR) patterns and subsequent metal-assisted chemical etching (MaCE) [1]. The lens-like shape PR patterns with a diameter of 2 ${\mu}m$ were formed by conventional lithography method followed by thermal reflow process of PR patterns on a hotplate at $170^{\circ}C$ for 40 s. ICP etching process was carried out in an SF6 plasma ambient using an optimum etching conditions such as radio-frequency power of 50 W, ICP power of 25 W, SF6 flow rate of 30 sccm, process pressure of 10 mTorr, and etching time of 150 s in order to produce micron structure with tapered etch profile. 15 nm thick Ag film was evaporated on the samples using e-beam evaporator with a deposition rate of 0.05 nm/s. To form Ag nanoparticles (NPs), the samples were thermally treated (thermally dewetted) in a rapid thermal annealing system at $500^{\circ}C$ for 1 min in a nitrogen environment. The Ag thickness and thermal dewetting conditions were carefully chosen to obtain isolated Ag NPs. To fabricate needle-like nanostructures on both the micron structure (i.e., sea urchin-like structures) and flat surface of silicon, MaCE process, which is based on the strong catalytic activity of metal, was performed in a chemical etchant (HNO3: HF: H2O = 4: 1: 20) using Ag NPs at room temperature for 1 min. Finally, the residual Ag NPs were removed by immersion in a HNO3 solution. The fabricated structures after each process steps are shown in figure 1. It is well-known that the hierarchical micro- and nanostructures have efficient light harvesting properties [2-3]. Therefore, this fabrication technique for production of sea urchin-like structures is applicable to improve the performance of light harvesting devices.

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Study of the Axial Length/Corneal Radius Ratio in Determining the Refractive State of the Eye (굴절이상과 안축장/각막곡률반경 비와의 관계에 관한 연구)

  • Seo, Y.W.;Choe, Y.J.
    • Journal of Korean Ophthalmic Optics Society
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    • v.4 no.2
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    • pp.23-31
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    • 1999
  • The purpose of this study is to evaluate the relationship between axial length/corneal radius ratio and refractive error for human eye. Ocular components were measured Baush & Lomb keratometer, Holden-Payor pachometer, and Stoz Compuscan. Refractive error was measured by subjective refraction. The results were as follows; 1) Spherical equivalent refractive error and axial length/corneal radius ratio was very highly correlated with the correlation coefficient for -0.89. 2) Axial length/corneal radius ratio and axial length, vitreous chamber depth were highly correlated that the correlation coefficients were 0.82, 0.80 respectively. 3) Axial length/corneal radius ratio and anterior chamber depth, corneal power, corneal radius, lens power were correlated with the correlation coefficients for 0.57, 0.40, -0.39, -0.35 respectively. 4) There were no significant correlation between axial length/corneal radius ratio and lens thickness, and corneal thickness.

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The Influence of the Variation of Conic Coefficient of the Front Surface on RMS Spot Diameter (전면의 conic 계수 변화가 착락원 크기에 미치는 영향)

  • Park, Seong-Jong;Ju, Seok-Hee;Sim, Sang-Hyun
    • Journal of Korean Ophthalmic Optics Society
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    • v.8 no.2
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    • pp.77-83
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    • 2003
  • To investigate the influence of the variation of conic coefficient of the front surface on the RMS SD(Root Mean Square Spot Diameter) in a back focal plane, we use programs which are Cove V and LOSA 2.0. We consider a spectacle lens with back vertex power of -4.00D, diameter of 70 mm, the front surface powers which are 2.00D, 4.00D, 6.00D, and 8.00D, and the indices which are $n_d$=1.498, 1.523, 1.586, and 1.660, respectively. The RMS SD in the back focal plane and the thickness of an aspherical tens having the optimized conic constant are smaller than those of a spherical lens. The RMS SD in the back focal plane decreases as the front surface power decreases. From these results, we determine the optimized conic constant to improve the optical image quality and decrease RMS SD in the back focal plane.

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Miniaturized Conically Stepped COBRA for High Power Electromagnetic Generator (고출력 전자기파 발생 장치용 소형화 된 원뿔 계단형 COBRA)

  • Ahn, Ji-Hwan;Lee, Sang-Heun;Yoon, Young-Joong;Kim, Jun-Yeon;Lee, Woo-Sang;So, Joon-Ho;Han, In-Hee
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.9
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    • pp.947-956
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    • 2008
  • In this paper, miniaturized conically stepped COBRA is proposed. In order to prevent electrical breakdown, COBRA, which consists of hem and lens, has to get bigger if it is designed with conventional method. Because of the phase error increase, shortening the length of the antenna without changing the aperture size leads to the reduction of the antenna gain. To avoid this, the phase error at the aperture is compensated by transforming the COBRA lens into conically stepped form. The simulations result shows that the proposed antenna has higher gain than the conventional COBRA in spite of the size reduction from 1,300 mm to 600 mm. The fabricated and measured COBRA has the gain of 26.2 dBi.

LED Fiber-Optic Lighting Devices Developed for Medical Assistance for the Local Treatment Retractor (국부치료를 위한 Retractor용 LED 광섬유 의료보조조명 장치 개발)

  • Eo, Ik-soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.2
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    • pp.666-671
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    • 2016
  • This paper introduces a device providing close local lighting to the affected part, where the operation-purpose astral lamp alone cannot shed light directly, in an operation room of hospitals or clinics, which helps clinical doctors perform safe treatment of the affected part deep inside a human body. This medical assisting lighting is a device necessary to prevent fatal operation failures, which can occur with minute operation processes, such as tumor removal or angiorrhaphy. The components, such as the light source and power supply were designed to be low power consuming and small in size, have a narrow angle lens was used to increase the light spreading effect and focused illumination. The end-caps of the light transmission device using an optical cable and the lighting device were designed in the waterproof type to enable disinfection of these devices after use for the next patients. According to the measurement of the light source properties made after development of the retractor lighting device, the illumination intensity was 490 lux, the brightness was $11,550cd/m^2$, general color rendering index was 78, color temperature was 11,000K, and the intensity distribution was even, which were confirmed to be adequate for medical assisting local lighting.

Prediction of Agricultural Wind and Gust Using Local Ensemble Prediction System (국지앙상블시스템을 활용한 농경지 바람 및 강풍 예측)

  • Jung Hyuk Kang;Geon-Hu Kim;Kyu Rang Kim
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.26 no.2
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    • pp.115-125
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    • 2024
  • Wind is a meteorological factor that has a significant impact on agriculture. Gust cause damage such as fruit drop and damage to facilities. In this study, low-altitude wind speed prediction was performed by applying physical models to Local Ensemble Prediction System (LENS). Logarithmic Law (LOG) and Power Law (POW) were used as the physical models, and Korea Ministry of Environment indicators and Moderate Resolution Imaging Spectroradiometer (MODIS) data were applied as indicator variables. We collected and verified wind and gust data at 3m altitude in 2022 operated by the Rural Development Administration, and presented the results in scatter plot, correlation coefficient, Root Mean Square Error (RMSE), Normalized Root Mean Square Error (NRMSE), and Threat Score (TS). The LOG-applied model showed better results in wind speed, and the POW-applied model showed better results in gust.