• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.3
• /
• pp.277-284
• /
• 2015

Purpose: The study aimed to evaluate the effect of circle contact lens wearing on visual quality of the eyes after a refractive surgery. Methods: The objective visual quality was evaluated for 40 eyes who did not get refractive surgery and 30 eyes who got a refractive surgery after applying plano circle contact lenses on their eyes, respectively. Modulation transfer function (MTF), objective scatter index (OSI) and the focusing ratio on retina (Strehl ratio) were measured by using optical quality analysis system (OQAS) and the correlation between pupil size and objective visual quality was analyzed by measuring the pupil size. Results: When wearing circle contact lens on the eyes after refractive surgery, MTF and Strehl ratio were reduced and OSI was increased compared with the eyes without refractive surgery. The eyes after a refractive surgery showed more significant difference changes in MTF, OSI and Strehl ratio according to the pupil size compared with those without refractive surgery. Conclusions: The results showed that wearing of circle contact lens after the refractive surgery has deteriorated the objective visual quality based on the quality of focused image on the retina. Therefore, we suggest that sufficient understanding and consideration about the deterioration of visual quality is necessary in the case of circle contact lens wearing after refractive surgery.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.27 no.1
• /
• pp.56-74
• /
• 2023

In order to obtain practical and high-quality satellite images containing high-frequency components, a large aperture optical system is required, which has a limitation in that it greatly increases the payload weight. As an attempt to overcome the problem, many multi-aperture optical systems have been proposed, but in many cases, these optical systems do not include high-frequency components in all directions, and making such an high-quality image is an ill-posed problem. In this paper, we use deep learning to overcome the limitation. A deep learning model receives low-quality images as input, estimates the Point Spread Function, PSF, and combines them to output a single high-quality image. We model images obtained from three rectangular apertures arranged in a regular polygon shape. We also propose the Modulation Transfer Function Loss, MTF Loss, which can capture the high-frequency components of the images. We present qualitative and quantitative results obtained through experiments.

• Korean Journal of Optics and Photonics
• /
• v.17 no.2
• /
• pp.149-158
• /
• 2006

We have analyzed various tolerances of the multi-configurative microscopic system for inspecting the wire-bonding of a reed frame by using the Gaussian bracket method and the equivalent lens method. The tolerances for the curvature and the thickness, which are axial symmetric tolerances, are given by varying the back focal length within a fecal depth under diffraction-limited conditions. Moreover, by using the trial and error method, the axial non-symmetric tolerances for decenter and tilt are established by assigning the 5% variation of MTF(modulation transfer function) at the spatial frequency of 50 lp/mm and at the field angle of 0.7 field. As the tolerances with the most probable distribution are distributed within the range of the decay rate of less than 5% independent of the probability distribution of tolerances, we can achieve completely the desired design performances of the multi-configurative microscopic system by using the various ranges of these tolerances.

• Korean Journal of Computational Design and Engineering
• /
• v.16 no.6
• /
• pp.397-406
• /
• 2011

Since tolerance allocation in a mobile phone camera manufacturing process greatly affects production cost and reliability of optical performance, a systematic design methodology for allocating optimal tolerances is required. In this study, we proposed the tolerance optimization procedure for determining tolerances that minimize production cost while satisfying the reliability constraints on important optical performance indices. We employed Latin hypercube sampling for evaluating the reliabilities of optical performance and a function-based sequential approximate optimization technique that can reduce computational burden and well handle numerical noise in the tolerance optimization process. Using the suggested tolerance optimization approach, the optimal production cost was decreased by 30.3 % compared to the initial cost while satisfying the two constraints on the reliabilities of optical performance.

• Journal of Institute of Control, Robotics and Systems
• /
• v.19 no.12
• /
• pp.1094-1098
• /
• 2013

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. Defect detection is not an easy process because of noises from various sources and optical distortion. In this paper the acquired images from a TFT panel are enhanced with the adoption of an HVS (Human Visual System). A human visual system is more sensitive on the defect area than the illumination components because it has greater sensitivity to variations of intensity. In this paper we modified an MTF (Modulation Transfer Function) in the Wavelet domain and utilized the characteristics of an HVS. The proposed algorithm flattens the inner illumination components while preserving the defect information intact.

• Journal of the Optical Society of Korea
• /
• v.18 no.2
• /
• pp.110-117
• /
• 2014

In this study, we objectively determined whether the ReSTOR as a multifocal IOL (intraocular lens) has a multifocal function compared to the IQ as a monofocal IOL in vivo by OQAS (Optical Quality Analysis System). Eighteen patients who had cataract surgery with implantation of ReSTOR (27 eyes) and 15 patients with IQ (21 eyes), were included inthis study. Uncorrected distance visual acuity (UCDVA), corrected distance visual acuity (CDVA), uncorrected near visual acuity (UCNVA)and distance corrected near visual acuity (DCNVA) were measured. After setting the artificial pupil size to 3 mm, we performed 'Optical quality'. We inputted defocus diopters of (objective spherical refraction)(far), (objective spherical refraction-1.25 D)(intermediate),(objective spherical refraction-2.5 D)(near), and (objective spherical refraction-3.5 D)(very near) into 'selected spherical refraction' simulating the optical quality at far, intermediate, and near distance. We changed the pupil size to 5 mm and repeated the same measurements. The UCDVA and CDVA did not show significant differences between the 2 groups. But, the UCNVA and DCNVA of the ReSTOR group were better than those of the IQ group (p=0.000, p=0.000). For 3 mm pupil, at far distance, modulation transfer function (MTF) cut off and point spread function (PSF) width at 50% of ReSTOR were worse than those of IQ (p=0.039, p=0.020). At intermediate distance, MTF cut off, Strehl ratio and PSF width at 50% of ReSTOR were worse than those of IQ (p=0.001, p=0.001, p=0.000). At near distance, MTF cut off of ReSTOR was worse than that of IQ (p=0.033). At very near distance, MTF cut off and Strehl ratio of ReSTOR were worse than those of IQ (p=0.002, p=0.002), but PSF width at 50% of ReSTOR was better than that of IQ. For 5 mm pupil, most parameters at each distance, there was no significant difference between the 2 groups. Only PSF width at 50% of ReSTOR were worse than those of IQ at intermediate distance (p=0.013). It was impossible to show the multifocal function of ReSTOR compared to the IQ byOQAS.

• Current Optics and Photonics
• /
• v.7 no.6
• /
• pp.745-754
• /
• 2023

In order to test the recognition ability and accuracy of a target imaging simulator under the irradiation of solar stray light in a laboratory environment, it needs to be fixed on a five-axis turntable during a hardware-in-the-loop simulation test, so the optical system of the simulator should have a long exit pupil distance. This article adopts a secondary imaging method to design a projection optical system suitable for thin-film-transistor liquid crystal displays. The exit pupil distance of the entire optical system is 1,000 mm, and the final optimization results in the 400 nm-850 nm band show that the modulation transfer function (MTF) of the optical system is greater than 0.8 at the cutoff frequency of 72 lp/mm, and the distortion of each field of view of the system is less than 0.04%. Combined with the design results of the optical system, TracePro software was used to model the optical system, and the simulation of the target imaging simulator at the magnitude of -1 to +6 Mv was analyzed and verified. The magnitude error is less than 0.2 Mv, and the irradiance uniformity of the exit pupil surface is greater than 90%, which meets the requirements of the target imaging simulator.

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.1
• /
• pp.49.1-49.1
• /
• 2018

The MATS (Mesosphere Airglow/Aerosol Tomography Spectroscopy) satellite is the next Swedish science microsatellite. We report optical performance test results of the limb telescope, which is the major payload. This telescope is designed with "linear astigmatism-free" (LAF) off-axis optical system in order to have high optical performance across the wide field of view. We measured Modulation Transfer Function (MTF) and Encircled Energy Diameter (EED) of the limb telescope. Full field imaging tests show expected results without linear astigmatism across the full field of view ($5.67^{\circ}{\times}0.91^{\circ}$). Since the amount of stray light is from the earth and the sun, we also simulated and measured the stray light in the field image.

• Korean Journal of Optics and Photonics
• /
• v.23 no.4
• /
• pp.154-158
• /
• 2012

In this paper, for low cost infrared optical equipment, we design and fabricate an infrared optical system for an uncooled detector using PGM(Precision Glass Molding) lenses. The designed infrared optical system has a good athermalization, and the material of all of its lenses is a chalcogenide glass suitable for the PGM method. In addition, we also fabricate the same infrared optical system using SPDT(Single Point Diamond Turning) lenses in order to measure the optical performance of PGM lenses. We measure the MTF(Modulation Transfer Function) of the two infrared optical systems which use the PGM lenses and the SPDT lenses. And then we compare and analyze the images of them both. As a result, we find that they have only a very small difference in optical performance. If the use of PGM lenses increases, we expect to reduce the cost of infrared optical equipment.

• Korean Journal of Remote Sensing
• /
• v.33 no.2
• /
• pp.159-169
• /
• 2017

The Satellite Electro-Optic Payload System needsspecial requirements with the conditions of limited power consumption and the space environment of solar radiation. The acquired image quality should be mainly depend on the GSD (Ground Sampled Distance), SNR (Signal to Noise Ratio), and MTF (Modulation Transfer Function). On the well-manufactured sensor level, the thermal noise is removed on ASP (Analog Signal Processing) using the CDS (Corrective Double Sampling); the noise signal from the image sensor can be reduced from the offset signals based on the pre-pixels and the dark-pixels. The non-uniformity shall be corrected with gain, offset, and correction parameter of the image sensor pixel characteristic on the sensor control system. This paper describes the SNR enhancement method of the satellite EOS payload using the mentioned noise remove processes on the system design and operation, which is verified by tests and simulations.