• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.996-999
• /
• 2008

Aspheric polymer lens fabrication using isothermal compression molding is presented in this paper. Due to increasing definition of an image sensor, higher precision is required by a lens which can be used as a part of an imageforming optical module. Injection molding is a factory standard method for a polymer optical lens. But achievable precision using injection molding has a formidable limitation due to the machining of complex mold structure and melting and cooling down a polymer melt under high pressure condition during forming process. To overcome the precision requirement and limitation using injection molding method, isothermal compression molding is applied to fabrication of a polymer optical lens. The fabrication condition is determined by numerical simulations of temperature distribution and given material properties. Under the found condition, the lens having a high precision can successfully be reproduced and does not show birefringence which results often in optical degradation.

• Ceramist
• /
• v.21 no.4
• /
• pp.427-432
• /
• 2018

In this study, the aspherical lens for optical communications produced not with an one-step pneumatic type of external pressurization system (existed GMP process) but a constant weight of self-loaded mold put up to upper core. So the lens is molding with self-loaded weight molding and it calls Weight Molding process. In self-loaded molding process, we measured changes of center thickness molding lenses with each variable molding temperatures and time to find the effect of center of lens thickness to search key factors. As experimental results, the center thickness reach to targeted lenses step time value was changed drastically and it depends by molding temperature. If the molding temperature gets higher, the targeted lens that is reaching to the center thickness step time value was decreased. To find the effect of life improvement on mold core by imposing the self-loaded molding process we molded with GMP(Glass molding press) method and self-loaded molding method for 9,000 times and measured the lenses shape accuracy and surface roughness to evaluate the core life. As a result the self-loaded molding method core has 2,000 times longer that GMP (Glass molding press) method. If we adopt self-loaded molding method of the optical aspherical lens molding in the future, we expect that it would reduce the expense of changing the molds by molding core life improvements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.487-488
• /
• 2006

As DLC coating possesses such features as, high hardness, high elasticity, abrasion resistance and chemical stability, there have been exerted continuous efforts in research works in a variety of fields, and this technology has also been applied widely to industrial areas. In this research work, the optimal grinding condition was identified using Microlens Process Machine in order to contribute to the development of aspheric glass which is to be used for mobile phone module having 2 megapixel and $2.5{\times}$ zoom, and mold core (WC) was manufactured having performed ultra-precision machining and effects of DLC coating on shape accuracy(P-V) of mold core and surface roughness(Ra) as well were measured and evaluated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.307-308
• /
• 2008

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1091-1096
• /
• 2007

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of a electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, and the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.2
• /
• pp.57-64
• /
• 2008

This paper describes the development of a small lens molding system for manufacturing the small lens like lens of a cellular phone, a small digital camera and so on. In order to manufacture a small lens, firstly, the raw material for lens with spherical shape should be manufactured by processing a glass material, secondly, the mold inserted the raw material for lens should be heated till its molding temperature in the electric furnace, finally, the small lens is manufactured by applying the force using pressuring control system. In this paper, the small lens molding system with the function of force control and velocity control was developed. It is composed of an electric furnace and its temperature control system, a pressuring control system, a body, and so on. The temperature characteristic test of the electric furnace, the force and velocity characteristic test of the pressuring control system were carried out. It was confirmed that the developed system had good functions for manufacturing a small lens.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.04a
• /
• pp.15-19
• /
• 2003

Polymeric micro lens arrays with diameters of $13\~96\;{\mu}m$ fabricated using the micro-compression molding with electro formed mold inserts. In the present study, the electro forming process was used to make the metallic micro-mold insert for micro-molding of microlens array. The wettability property of the fabricated mold insert was examined by measuring the contact angle of the polymer melt on the mold insert. Microlenses were compression-molded with the fabricated mold insert. The effects of the molding temperature and wettability property on the replication quality of the molded lenses were analyzed experimentally.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.2
• /
• pp.31-36
• /
• 2003

Electronic or measuring instruments equipped with aspherical lens have recently been used since aspherical lens is more effective than spherical one. for the mass production of aspherical lenses, specific molds with precisely machined cores should be prepared. Some researches on the aspherical lens machining have been carried out to date. However, ultra-precise finding of aspherical or mold core has not been fully studied. In this study, the ultra-precise grinding and evaluating system were established to investigate the finding characteristics of aspherical lenses. Unlike conventional grinding process, since a highly-precise lathe were operated in a clean room without vibration the experimental results can be very useful for further studies on ultra-precise grinding process.

• 연구논문집
• /
• s.25
• /
• pp.105-113
• /
• 1995

Fresnel lenses are developed for flat optics with the optical characteristics close to aspherical lens such as sharp focusing and dispersion instead of spherical or aspherical surface. Usually, these fresnel lenses and diffraction gratings are machined by high-energy beam such as electron beam machining, but recently with the development of ultra precision machine tool and machining technology, 3-dimension micro machining becomes preferable. This study on the micro machining of fresnel lens is carried out to develop the basic technology of ultra precision micro machining. The machined lens mold will be used for the manufacturing of fresnel lens with 120mm focal distance using synthetic resin material with 1.49 refractive index(PMMA), and the shape of lens is 48mm diameter, $300\mum$ pitch and about $5-700\mum$depth of groove in brass.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.1
• /
• pp.1-6
• /
• 2021

In this study, we investigate the injection molding of f-theta lens, an important element of the laser scanning unit of laser printers and scanning systems. The f-theta lens is an aspherical plastic lens that must be molded with a precision of seconds. An injection molding method is often used for mass producing aspherical plastic lenses at a low cost. In the injection molding process, costs related to forming and injection are included. Therefore, in this study, to determine the shrinkage and deformation of injection molded f-theta lens, we predict the pressure and temperature distributions. Further, based on the analysis of the predictions, we maximize the design efficiency and verify the cost and development period reduction.