Recently, the phones with high screen-to-body ratio are popular in the market, and it leads to the demand of in-display fingerprint recognition. The optical fingerprint sensor is based on frustrated total internal reflection (FTIR), and the camera type independent on the panel process is cost-effective and with high yield rate. To meet the volume constraint of the smart phone, a miniaturized compact lens is designed. For maximizing the sensing area in the limited space, the field of view can reach 128°. To increase the accuracy and speed of the recognition, the design has extremely small distortion and low f-number. Mostly importantly, the resolution should be sufficient for the fingerprint extraction algorithm. To achieve the specifications, the lens is designed with three aspheric plastic lenses using injection molding. In this paper, the procedure of optical design, mechanical design, lens fabrication and assembly of the prototype is presented. Finally, the prototype is employed for fingerprint identification.
Since the beginning of this year, the full screen mobile phone has been more and more popular. Because the traditional capacitive fingerprint sensor cannot work under the display, it should be placed on the side or back of the phone. However, it is unfavorable to the consumer experience. Therefore, the demand for in-display fingerprint recognition technology has arisen. The in-display fingerprint identification technology can be divided into optical and ultrasonic fingerprint identification. Because the ultrasonic fingerprint identification is limited by low yield rate and high cost at present, the optical fingerprint identification is more popular in market. The optical fingerprint identification is advantageous for the identification not affected by dry or greasy fingers, higher yield and lower cost. In this study, the miniature wide angle lens under the display is developed for the OLED panel. For optical fingerprint identification, the illumination is inevitable. In comparison with the LCD panel, the OLED panel needs not the backlighting because each pixel has its own light. The optical sensor is based on the principle of the frustrated total internal reflection (FTIR). The ridge of the finger destroys the total internal reflection (TIR), and then the dark pattern appears. On the contrary, the valley of the finger satisfies the TIR condition, and then the bright pattern generates. Because the camera is implemented in the narrow space of the mobile phone, the ultra-wide field of view and extremely short total track length are necessary. In this study, the optical design can successfully meet the requirement for fingerprint recognition.
This paper presents a new thin-film liquid salinity sensor by using the D-shaped fiber and thin-film coating techniques. The D-shaped fiber will enhance optical fiber to generate an evanescent field in sensing applications. Indium-galliumzinc oxide (IGZO) films can produce high attenuation lossy mode resonance (LMR) to make high-sensitivity liquid salinity fiber sensors. IGZO thin film is prepared by a radio-frequency (RF) magnetron sputtering method. The optical fiber thickness is 67.6 μm and IGZO film thickness of 100 nm is deposited on the polished surface of the D-shaped fiber to fabricate LMR-type liquid salinity sensors. The sensitive region was immersed in different sensing liquid salinities from 0 ‰ to 100 ‰, and attempted to investigate the sensitivities of the LMR salinity sensors. The experimental results show that the highest sensitivity of the salinity sensors for the sensing NaCl solutions is 0.80 nm per salinity unit (SU).
Generally, mobile phone use one camera to catch the image, and it is hard to get stereo image pair. Adding a biprism array can help that get the image pair easily. So users can use their mobile phone to catch the stereo image anywhere by adding a biprism array, and if they want to get a normal image just remove it. Using biprism arrays will induce chromatic aberration. Therefore, we design a double biprism arrays to reduce chromatic aberration.
This paper presents a periscope type 3X zoom lenses design for a five megapixel cellphone camera. The configuration of optical system uses the right angle prism in front of the zoom lenses to change the optical path rotated by a 90° angle resulting in the zoom lenses length of 6 mm. The zoom lenses can be embedded in mobile phone with a thickness of 6 mm. The zoom lenses have three groups with six elements. The half field of view is varied from 30° to 10.89°, the effective focal length is adjusted from 3.142 mm to 9.426 mm, and the F-number is changed from 2.8 to 5.13.
The motorcycle headlamp is composed of a white LED module, an elliptical reflector, a parabolic reflector and a toric lens. We use non-sequential ray to improve the optical efficiency of the compound reflectors. Using the toric lens can meet ECE_113 regulation and obtain a good uniformity.
We apply a digital camera with two prism arrays to capture a stereo image of the corrected chromatic aberration and
distortion. The doublet prisms are used to correct chromatic aberration. The camera distortion with two prism arrays can
be increased, and reduced by the lens optimization.
We present an asymmetric condenser with an elliptical solid angle distribution and improves system efficiency of 15.5%.
The proposed system on the DMD achieves the light efficiency of 63.4% and the average deviation of 1.75%.
We present an illustrating method for triplet prisms combination that can minimize the chromatic aberration. The
apochromatic aberration equation, relation between relative partial dispersion and glass V-number can be quickly
analyzed and found the combination.
We present a hybrid sunlight and light-emitting diode (LED) lighting system design for indoor illumination.
Sunlight is collected by a set of sunlight concentrator and then split into visible and non-visible rays by a beam splitter.
The visible rays pass through the light guide into a light box. The sunlight and LED light are combined and made
uniform by the light box, if the sunlight is not bright enough, some of these 140 LEDs can be turned on to maintain
indoor illuminance above the standard level. When nighttime comes, all the LEDs can be turned on to illuminate the
indoor space. The lighting system can let the lighting environment green and comfortable. Our simulation of the
illumination system shows that the efficiency of the sunlight and LED hybrid lighting combination is better than that of
LED and traditional lighting systems.
We proposed a combo design of pick-up head used prism to shorten the geometrical size and reduce the optical components. We apply a rhomboid beam splitter to separate two diodes in the design for the optical pick-up head of DVD and HD-DVD.
We propose a design of a compact HD-DVD pickup head, where a lensed penta-prism is used to replace the mirror and the collimating lens in a conventional one to shorten the geometrical size but keep the whole optical path length unchanged.
A simple and direct method using these equations to correct real aberrations and to find the minimum aberration of the system has been suggested. The calculated third-order aberration can exactly meet the target values at each stage by means of the damped least-squares method. The spherical aberration is first targeted to get the minimal value of an on-axis aberration corresponding to the real aberration. Similarly, the coma and astigmatism target values are adjusted to force off-axis real aberrations at the 1.0 field angle down to the minimum. Finally, the minimum aberration at the field angle of 0.7 is fulfilled by the manual variation of the lens thickness and lens spacing. Two examples of triplet designs are presented.
We presented an efficient method to achieve the optimized design of a doublet lens. Using the third-order aberrations to obtain directly a minimal area from the ray-fan diagram was suggested. We took the specification of F/#=3.333 and a half field of view 1 degree(s) as the design example. The optimization technique was utilized to control the third order aberrations such as spherical aberration and coma, and used the third-order spherical and coma aberrations to correct directly the on-axis aberrations. In order to minimize increasing the tendency of the off-axis aberration at the 1.0 field angle, during the correction of the on-axis aberration a small value, then had a tendency to increase. Our solution is taking the RMS value of spot diagram less than the diffraction limited value of point spread function (PSF) as an evaluated criterion for the on-axis aberrations. Finally, the optimized value of the system design is obtained by adjusting lens thickness and lens spacing. Two design examples of the doublet, one glass lens and one plastic lens, are well presented in this article.
Coddington's equations can be used to eliminate the oblique astigmatic error in the design of ophthalmic lens of spherical or other conicoidal surfaces. But it is difficult to get satisfactory result in the designing of the nonconic aspheric ophthalmic lens. In this paper we present an efficient approach based on optimization of aspheric coefficients, which enables the design program to obtain the minimum aberrations. Many higher order coefficients of aspheric surfaces can easily result in inflection point, which increases the difficulty in manufacturing. We solved the problem by taking it as one of the optimization constraints. The design of nonconic aspheric ophthalmic lens could also make the spectacle lenses well thinner in thickness and well flatter in shape than the design of spherical ophthalmic lens and other conicoidal ophthalmic lens. Damped least square methods are used in our design. Aspherical myopia ophthalmic lenses, aspherical hypermetropic lenses and cataract lenses were designed. Comparisons of design examples' results are given.
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