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.
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 study proposes a Fresnel lens with multiple focus modes by combining the technology of polymer stabilized liquid crystals (PSLC) with the novel electrode design, which contains the Fresnel zone electrodes and complementary electrodes. The device was fabricated according the methods including the photolithography for the electrode patterns, the LC cell assembly, and the UV exposure for the PLSC curing. Experimental results show that the diffraction effects of the lens can be switched under different operation modes. It can accordingly provide three focal lengths of 25 cm, 32 cm, and 39.5 cm.
A new liquid refractive index sensor using double-sided polishing long-period fiber gratings (DSP-LPFG) is presented.
The influence of residual cladding thickness on the sensitivity of measuring liquid refractive index is investigated. The
proposed sensor response to external liquid refractive indices varying in the range of n=1.330 - 1.375 has been carried
out by measuring the transmission wavelength changes. Experimental results show that well-controlled polishing
parameters can significantly increase the sensitivity. The sensitivity of -143.396 nm/RIU can be obtained in this study.
Simultaneous measurement of the bending curvature and axial stress by using dual fiber Bragg gratings and a sidepolished
technique is presented. Curvature measurement, using side-polished fiber Bragg gratings with different
thicknesses ranging from 93.94 to 70.66 μm shows corresponding sensitivities from 0.096 to 0.402 nm/m-1 for bending
curvatures in the range of 0 - 3 m-1. The simultaneous axial stress is measured based on the shift in the Bragg
wavelength and ranges from 0.008 - 0.128 GPa. A maximum sensitivity of 13.83 nm/GPa is demonstrated.
We present a new magnetic field sensor based on D-shaped long-period fiber grating (D-LPFG). Iron thin-film was
coated on the polished surface of an LPFG to function as a sensing head. Different levels of magnetic field caused a shift
in the grating loss-dip wavelength shift. The sensing section of a D-LPFG causes a change in the effective refractive
index both of the core mode and co-propagation cladding modes in response to the different levels of the applied
magnetic field. The maximum shift in wavelength of 36 nm was obtained in the case of a magnetic field of 153 kA/m.
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.
KEYWORDS: Digital signal processing, Wavelet transforms, Detection and tracking algorithms, Wavelets, Interferometry, Linear filtering, Discrete wavelet transforms, Signal processing, Software development, 3D image processing
This paper presents a DSP-base defect recognition system by using wavelet transform and the gray level co-occurrence matrix (GLCM). It can be used to detect the texture image of wafer surface which is captured from a laser interferometer. Wavelet analysis associated with the entropy criterion appears to be a good method for recognizing automatically the defects of the interferometric patterns. Three-dimensional plots of the GLCM for various captured
images have been compared and discussed. The parameter of entropy has been calculated from the GLCM and can be used as an indicator for surface flatness.
We demonstrated that a high-sensitivity fiber sensor based on a superstructure fiber grating (SFG) can simultaneously measure the pressure and temperature by encapsulating the grating in a polymer-half-filled metal cylinder, in which there are two openings on opposite sides of the wall filled with the polymer to sense the pressure. The mechanism of sensing pressure is to transfer the pressure into the axial extended-strain. According to the optical characteristics of an SFG composed of a fiber Bragg grating (FBG) and long period grating (LPG), the various pressure and temperature will cause the variation of the center-wavelength and reflection simultaneously. Thus, the sensor can be used for the measurement both of the pressure and temperature. The pressure sensitivity of 2.28×10-2MPa-1 and the temperature sensitivity both of 0.015nm/°C and -0.143dB/°C are obtained.
The induced cladding-mode performance in a tilted superstructure fiber grating (SFG) is first experimentally demonstrated. As a slanted SFG is heated to shift wide-band loss dips for obtaining the multi-narrow-band reflection moved at various positions of the loss dip, the strength and central wavelength of the induced cladding-mode depend on the loss depth and the positive/negative sides of the dip, respectively. The characteristics may provide the third physical-parameter measurements in a simultaneous multi-parameters fiber sensor.
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.
Most microelectronic devices and sensors are fabricated by using thin film deposition. Understanding metal oxide films is important in the electronic applications. We report an improved interferometric method based on a phase shifting technique to determine the mechanical properties of metal oxide films. Thin films were prepared by ion-beam sputter deposition at low substrate temperature. Quantitative determination of the mechanical properties such as the internal stress, the biaxial elastic modulus and the thermal expansion coefficient were investigated. A phase shifting Twyman-Green interferometer wiht the phase reduction algorithm was set up to measure the stress in thin films. Two types of circular glass plates, with known Young's moduli. Poisson's ratios and thermal expansion coefficients, were used as coating substrates. The temperature-dependent stress behavior of the metal oxide films was obtained by heating samples in the range from room temperature to 70 degree C. The stresses of thin films deposited on two different substrates were plotted against the stress management temperature, showing a linear dependence. From the slopes of the two lines in the stress versus temperature plot, the intrinsic stress, the biaxial elastic modulus and the thermal expansion coefficient of metal oxide films are then determined.
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.