The objective of the present work is to demonstrate the efficiency and feasibility of NBR (Nitrile Butadiene Rubber)
based conducting polymer actuator that is fabricated into a micro zoon lens driver. Unlike the traditional conducting
polymer that normally operates in a liquid, the proposed actuator successfully provides fairly effective driving
performance for the zoom lens system in a dry environment. And this paper is including the experiment results for an
efficiency improvement. The result suggested by an experiment was efficient in micro optical zoom lens system. In
addition, the developed design method of actuator was given consideration to design the system.
Aspherical glass or plastic lenses are usually adapted in the camera module of handheld phone. Recently, slimmer
cameras are required according to reducing thickness of handheld phone. In this paper, we present an ultra slim camera
module using multiple freeform off-axis imaging lenses. New optical concept of multiple lens system introduces the
planar optics with freeform shaped aspherical lens surface on the wafer, which can achieve the thickness of 50%
compared to the conventional symmetric lens system. In order to achieve the resolution specification, we separate the
field of view in camera module. As the result, two inverted images are produced on a same imaging sensor and the
acquired inverted images are processed by photo stitching algorithm so as to combine them. Finally, in order to verify
the new imaging system, we manufacture the new slim lens through the UV embossing replication process. We found the
new imaging system is feasible for VGA resolution and it can be expandable to the high resolution system.
Trichromatic LED backlights render higher color gamut and panel transmittance to the liquid crystal displays (LCDs) than yellow phosphor-converted white LED backlights can possibly do at their best. In realization, however, several technical challenges arise, such as color mixing, minimizing the total number of chips, and maintaining the color balance. We designed and demonstrated a backlight unit for 2.2 inch TFT LCD using two RGB 3-chip LEDs to assess the feasibility and the technical hurdles to overcome. The average brightness of the backlight is 2509cd/m2 at the input power of 200mW. The power efficiency is lower than but comparable to commercially available white LED backlights. The color gamut of the LC panel is increased from 53% to 78% when its conventional white LED backlight is replaced by the trichromatic LED backlight. Panel transmittance is expected to be enhanced as well by about 8%. The ambient temperature change was found to be the most significant cause of the color shift of the trichromatic LED backlight. The forward bias voltage can be used in the feedback, since it changes linearly with temperature.
We have developed a compact and cost-effective camera module on the basis of wafer-scale-replica processing. A multiple-layered structure of several aspheric lenses in a mobile-phone camera module is first assembled by bonding multiple glass-wafers on which 2-dimensional replica arrays of identical aspheric lenses are UV-embossed, followed by dicing the stacked wafers and packaging them with image sensor chips. This wafer-scale processing leads to at least 95% yield in mass-production, and potentially to a very slim phone with camera-module less than 2 mm in thickness. We have demonstrated a VGA camera module fabricated by the wafer-scale-replica processing with various UV-curable polymers having refractive indices between 1.4 and 1.6, and with three different glass-wafers of which both surfaces are embossed as aspheric lenses having 230 μm sag-height and aspheric-coefficients of lens polynomials up to tenth-order. We have found that precise compensation in material shrinkage of the polymer materials is one of the most technical challenges, in order to achieve a higher resolution in wafer-scaled lenses for mobile-phone camera modules.
A novel image quality evaluation method, which is based on combination of the rigorous grating diffraction theory and the ray-optic method, is proposed. It is applied for design optimization and tolerance analysis of optical imaging systems implementing diffractive optical elements (DOE). The evaluation method can predict the quality and resolution of the image on the image sensor plane through the optical imaging system. Especially, we can simulate the effect of diffraction efficiencies of DOE in the camera lenses module, which is very effective for predicting different color sense and MTF performance. Using this method, we can effectively determine the fabrication tolerances of diffractive and refractive optical elements such as the variations in profile thickness, and the shoulder of the DOE, as well as conventional parameters such as decenter and tilt in optical-surface alignments. A DOE-based 2M-resolution camera lens module designed by the optimization process based on the proposed image quality evaluation method shows ~15% MTF improvement compared with a design without such an optimization.
There are many proposals and studies for the high density optical data storages with a data capacity over 150GB. Multi-layer recording is consider as one of the best candidates for the next generation optical data storage since it can be realized with an addition of a few optical components in the current Blu-ray (BD) optical pickup. Of course, it is required to compensate the spherical aberration between the recording layers in the multi-layer disk. A novel liquid crystal (LC) lens is proposed and designed to compensate the spherical aberration occurred by the difference of substrate thickness. New structure of liquid crystal (LC) lens includes both concave and convex surfaces which can compensate the spherical aberration with a relatively long range. Since previously developed LC panel showed very low tolerance to the shift of objective lens, new design was proposed with a special LC lens structure to improve both characteristics of the shift tolerance and compensation range. The refractive index of LC lens is changed by applying a voltage on the ITO electrodes prepared with a curvature surface. Therefore, a focal point of the transmitted light can be changed with a careful control of applied voltage, resulting in a compensation of the spherical aberration. Several types of LC lens, including spherical and aspherical surfaces, were designed and their performance was simulated theoretically. With an optimized curvature control with the spherical LC lens, the aberration of BD optical pickup can be kept under 0.018λRMS even for the thickness variation of ±25μm.