• Journal of Sensor Science and Technology
• /
• v.30 no.3
• /
• pp.148-153
• /
• 2021

During the manufacture of a ZnS lens with excellent transmittance in the mid-infrared region (3-5 ㎛) by the hot-press process, a single-layer sintering method is used in which one lens is manufactured in one process. Additional research is required to improve this single-layer sintering method because of its low manufacturing efficiency. To solve this problem, the variation in optical properties of ZnS lenses with change in sintering temperature was investigated by introducing a Stack sintering method that can sinter multiple lenses simultaneously. A carbon paper was placed between the molded lenses and sintered into five layers. The average permeability of 67% at medium infrared wavelengths of 3-5 ㎛ was excellent under the following sintering conditions: pressure of 50 MPa and temperature of 850℃. This value is 1% less than the average permeability in the case of single-layer sintering of the ZnS lens. It was confirmed that the stack sintering method developed in this study can be used to manufacture a large number of lenses with excellent characteristics in a single process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.525-528
• /
• 2003

The aspherical lens are used as objective lens of optical pickup. The sample product is made before manufacturing the injection mould of lens to examine the design factor. The optimum cutting conditions of the main spindle speed, the depth of cut, the feed rate are found when we cut PMMA and PC lens sample with ultra-precision SPDT. The demanded surface roughness 10 nm Ra. aspherical form error 0.5 ${\mu}{\textrm}{m}$ P-V for aspherical lens of optical data storage device are satisfied for PMMA. but not satisfied for PC.

• Korean Journal of Optics and Photonics
• /
• v.28 no.2
• /
• pp.75-82
• /
• 2017

We present a new type of receiver-transmitter optical system that can be adapted to the sensor head of a displacement-measuring interferometer. The interferometer is utilized to control positioning error and repetition accuracy of a wafer, down to the order of 1 nm, in a semiconductor manufacturing process. Currently, according to the tendency of scale-up of wafers, an interferometer is demanded to measure a wider range of displacement. To solve this technical problem, we suggest a new type of receiver-transmitter optical system consisting of a GRIN lens-Collimating lens-Afocal lens system, compared to conventional receiver-transmitter using a single collimating lens. By adapting this new technological optical structure, we can improve coupling efficiency up to about 100 times that of a single conventional collimating lens.

• Publications of The Korean Astronomical Society
• /
• v.7 no.1
• /
• pp.79-87
• /
• 1992

New and improved data on the gravitational lens systems discovered so far are compared with the theoretical predictions of Gott, Park, and Lee (1989, GPL). Systems lensed by a single galaxy, compatible with assumptions of GPL, support flat or near-flat geometry for the universe. But the statistical uncertainty is too large to draw any definite conclusion. We need more lens systems. Also, the probability of multiple image lensing and mean separation of the images averaged over the source distribution are calculated for various cosmological models. Multiple-image lens systems and radio ring systems are compared with the predictions. Although the data reject exotic cosmological models, it cannot discriminate among conventional Friedmann models yet.

• Journal of the Optical Society of Korea
• /
• v.8 no.2
• /
• pp.72-78
• /
• 2004

We propose an improved stereovision scheme using a composite lens array and single camera. The use of a composite lens array makes it possible to construct a compact stereovision system and to improve the quality of the results by adopting image processing method. The principle of the proposed system is explained and the simulation and the experimental results are also presented.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.1
• /
• pp.49-54
• /
• 1997

We proved the feasibiltiy of a parallel optical interconnection technique using single GRIN (graded-index) rod lens as an intermediate coupling device, which increases the working distance and makes packaging easy. The proposed technique shows relatively less dependency on misalignments. In this paper, for convensience of experiments, we applied this method to 4-channel coupling between two fiber arrays, and compared it with butt-coupling and the method of using ball lens. The comparison shows the feasibility of adopting the proposed method to the parallel interconnection between a laser diode array and an optical fiber array.

• Journal of the Optical Society of Korea
• /
• v.18 no.1
• /
• pp.23-31
• /
• 2014

Recently, the number of camera companies that produce commercializing interchangeable lens systems such as digital single lens reflex (DSLR) and compact system camera (CSC) lenses has been gradually increasing. These interchangeable lenses have various kinds of lenses with distinct specifications. In particular, the distance window among these specifications is the function most preferred by customers. Mechanical manual zoom and manual focus in these high end camera lenses with a distance window are in particular desirable specifications and are required for product quality. However, the AF lens group is linked to the zoom cam and moves. Because the AF lens group moves along with the object distance, we can not realize the distance window with only zoom locus calculation. In this paper, in order to solve the problem, we suggest an optical calculation method for a corrected AF zoom cam for an interchangeable lens with a distance window to achieve product differentiation and analyze the error in the calculation.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.4
• /
• pp.501-509
• /
• 2015

Purpose: To evaluate the reliability of refractive power by comparing the marked refractive power in an automatic phoropter and actually measured spherical/cylindrical refractive power. Methods: Actual refractive power of minus spherical lens and cylindrical lens in an automatic phoropter was measured by a manual lensmeter and compared with the accuracy of marked refractive power. Furthermore, combined refractive power and spherical equivalent refractive power of two overlapped lenses were compared and evaluated with the refractive power of trial lens. Results: An error of 0.125 D and more against the marked degree was observed in 70.6% of spherical refractive power of spherical lens which is built in phoropter, and the higher error was shown with increasing refractive power. Single cylindrical refractive power of cylindrical lens is almost equivalent to the marked degree. Combined spherical refractive power was equivalent to spherical refractive power of single lens when spherical lens and cylindrical lens were overlapped in a phoropter. Thus, there was no change in spherical refractive power by lens overlapping. However, there was a great difference, which suggest the effect induced by overlapping between cylindrical refractive power and the marked degree when spherical lens and cylindrical lens were overlapped. Spherical equivalent refractive power measured by using a phoropter was lower than that estimated by trial glasses frame and marked degree. The difference was bigger with higher refractive power. Conclusions: When assessment of visual acuity is made by using an automatic phoropter for high myopes or myopic astigmatism, some difference against the marked degree may be produced and they may be overcorrected which suggests that improvement is required.

• Design & Manufacturing
• /
• v.16 no.3
• /
• pp.9-15
• /
• 2022

In order to reduce the manufacturing costs of the glass lens, it is necessary to manufacture a lens using a UV curable resin or a thermosetting resin, which is a curable material, in order to replace a glass lens. In the case of forming a lens using a thermosetting material, it is necessary to form several lenses at once using the wafer-level lens manufacturing technologies due to the long curing time of the material. When a lens is manufactured using a curable material, an error in the shape of the lens due to the shrinkage of the material during the curing process is an important cause of defects. The major factors for these shape errors and deformations are the shrinkage and the change of mechanical properties in the process of changing from a liquid material during curing to a solid state after complete curing. Therefore, it is necessary to understand the curing process of the material and to examine the shrinkage rate and change of physical properties according to the degree cure. In addition, it is necessary to proceed with CAE for lens molding using these and to review problems in lens manufacturing in advance. In this study, the viscoelastic properties of the material were measured during the curing process using a rheometer. Using the results, Rheological investigation of cure kinetics was performed. At the same time, The shrinkage of the material was measured and simple mathematical models were created. And using the results, the molding process of a single lens was analyzed using Comsol, a commercial S/W. In addition, the experiment was conducted to compare and verify the CAE results. As a result, it was confirmed that the shrinkage rate of the material had a great influence on the shape precision of the final product.

• Korean Journal of Optics and Photonics
• /
• v.5 no.2
• /
• pp.252-259
• /
• 1994

The method of calculating overlap dispersion caused by group velocity mismatch between uv and visible pulses in ultrafast pump-probe experiments is presented to discuss limitations of the time resolution and signal intensity. The calculations show arrangements using a single focusing lens shall result in undesirable time resolution and low signal intensity. Achromatic doublets result in unrealistic solutions. However, dramatic improvement in the time resolution and signal intensity is expected in the optical arrangements using separate lens for each pulse and in the arrangements using a cutoff secondary lens with a main lens. lens.