Papers by Keyword: Aspheric Lens

Abstract: According to the principle of optical design, two kinds of 2 Mega-pixel cell phone camera lenses are proposed. One is made up of three plastic (3P) lenses; the other is made up of two plastic lenses and one glass (2P1G) lens. The shapes of all lenses are aspheric. By comparison, the overall length of 2P1G lens is much less than that of 3P lens. Furthermore, in FOV the former is 5 degrees larger than the latter. At the same time, in distortion of the maximum field angle, the former is much less. The other aberrations of 2P1G lens are almost same to those of 3P lens. Therefore, in cell phone camera lens design, it’s recommended to adopt one aspheric glass lens to improve the performance and compactness though the cost will become a little higher due to the introduction of aspheric glass lens. However, the cost of aspheric glass lens could be reduced tremendously by a new cost-effective manufacturing method  compression molding technology.

Abstract: With the rapid development of opto-electronics communications, optics, aerospace and other industries, ultra-precision aspheric glass lenses are widely used in middle/high-grade optical opponent because of its high resolution and imaging quality. To achieve ultra-precision molding pressing of micro-lens, ultra-precision mold must be fabricated firstly. In this paper, some key new technologies were proposed for fabricating ultra-precision mold of small-size aspheric optical lens. A method of finite element simulation was employed to predict mould pressing process of the glass lens for correcting molds and improving the formation efficiency. An ultra-precision inclined-axis grinding and error compensation technology was also used to improve form accuracy of micro lens mold.

Abstract: In this paper, an on-machine profile measuring system for aspheric ground surface was presented, which involved data processing with improved two-dimensional weighted mean filtering and free form surface fitting. To verify the reliability of this system, a calibration experiment was done by comparing the measuring results of Ф320mm mirror between the WYKO 24 inch interferometer and the on-machine measuring system. The experiment results show that the on-machine measurement is effective and it can provide foundation for compensation machining. By comparing the measurement experiment results of the Keyence LC2430 with the WYKO interferometer, it is demonstrated that the deviation of PV is better than 0.23μm and the deviation of RMS better than 0.08μm.

Abstract: The key of qualities of optical lens created by injection molding are geometric errors and distribution of residual stress. This study analyses a mobile phone camera lens with aspheric optical lens created by one mold and 16 cavities. Mold flow analysis was used to simulate geometric shapes of different gates and design cooling systems to control mold temperatures. Mold temperature was controlled during the actual injection process and simulation results were used as the basis for mold design. The effects of cold-wall-mold on lens residual stress are discussed. The experiment result showed that higher mold temperatures are helpful to reduce residual stress. An aspheric mould measurement system was used to measure both the mold and the product. The results showed that the replicating capacity is satisfactory with a molding error of 3.604μm.

Abstract: Contact stylus instrument has difficulties in tracing large slope angle (LSA) lens for surface profile measurement due to the dilation of measured profile image by the shape of stylus tip. This research is to develop a surface profile reconstruction method for tip profile with LSA lens and then verified the result by estimating the form error. Experimental set-up is configured of a surface profile and roughness analyzer, Panasonic Ultra Accuracy 3-D Profilometer (UA3P), and the feasibility of the developed program is compared with the results of a commercial operation software, UA3P software. The figure form error (FFE) is used to evaluate the developed method. Experiments have been performed by measuring the LSA lens of a s55ml spherical gage with measuring ranges increasing from ±30°, ±45° to ±60° and measuring an aspheric lens with range ±50°. Experimental results showed that the FFE of the developed method has smaller FFE values than those obtained by the UA3P software as the measuring range of ±30° and ±45. Similar result of FFE is obtained as 0.891 μm for the aspheric lens by the developed method than FFE 0.896 μm by the UA3P software. Therefore, the developed method has been verified for estimating the FFE of LSA lens with variant measuring ranges. Future work is to develop related compensation methodology of FFE for LSA lens measurement and also to find appreciated tip profiles for measuring LSA lens of higher order nonlinear terms.