An approach, which is used to fabricate diffractive optical elements (MOEs), is presented by applying reduction
projecting system based on digital micro-mirror device (DMD). In this paper, coding-mask is combined with DMD
which is real-time, flexible and easy for alignment. Pre-distortion according to the non-linear effect in the aerial
image and resist course can be implemented. The accumulation of exposure energy can be obtained through
modulating rotating velocity of mask graphics, and finally distribution of exposure, which is required, can be
achieved. It shows that the method is practical and feasible on the grounds of the results of MATLAB simulation and
experiments.
In order to improve the quality and solve the problem of low speed of image reconstruction in the traditional optical computerized tomography (OCT) when the data acquired is incomplete projection, the multiple constrained of genetic algorithm based on algebraic iterative was proposed. Generally speaking, under the condition of multiple-objective optimization, the common extreme point for all the objective functions doesn't exist. So we can achieve the preferable compromise in the contradictions of multiple objectives. In this article, there are three constrained conditions. The first one is the maximum entropy criterion which is used mostly to solve the problem of OCT image reconstruction when the data acquired is incomplete projection recently. The second one is the minimum criteria of peak value which is introduced to suppress noise effectively and ensure the gliding property of the image reconstruction, because of the first one leading to noise amplification during the iterative process. The last constrained condition is the minimum criteria of the difference between the projection again of image reconstruction and the original projection. The concept of penalize-function is introduced into the genetic algorithm, which would transform the constrained optimization problem to unconstrained. It is clearly demonstrated from the experiment results that the algorithm reconstruction technique can efficiently improve the quality of images reconstruction of the incomplete projection data.
In the course of selective laser sintering (SLS), transient temperature has directly effect on protyping mechanism and quality. According to the analysis of transient temperature, infrared thermograph test method is proposed in this paper. Point and line temperature is measured immediately, and the test result is compared with numerical simulation. The result indicates that the test agrees with theory, and the proposed method provides steady base for selecting sintering parameter reasonable.
On the basis of close analysis of the drawback in conventional fabrication techniques of binary optical element, this paper presents a new method for fabricating optical element. This method can be called transverse-adding fabrication technique(TAFT), and it is developed from the rapid prototyping technique used in microelectronic processing and micro-machining. The principal objective developing this technique is to realize the compatibility of micro-optics with microelectronics and micro-machining technique to provide technical support for the integrated single-chip micro photo-electromechanical system. An explanation for the technological principle and process of this technique is stated. By analyzing experimental data, the selection of materials and corresponding process parameters for implementing this technique were determined. The main process error of this technique, alignment error, was analyzed and calculated. In addition, a computerized simulation was carried out. Analysis shows that this technique can not only fabricate continuous phase component, its diffraction efficiency is insensitive to the alignment error as well. It is therefore clear that the transverse-adding fabrication technique is a feasible technique for fabricating binary optical elements and has an advantage over conventional techniques in fabricating precision.
In this paper, a method, using the spectrum tomography combining with the principle of numerical calculation to rebuild two-temperature of plasma flow, is proposed. Heavy particle temperature of plasma flow is reconstructed based on numerical calculation and the electron temperature measured in experiment using the method. It is not the same as traditional one that reconstructs electron temperature and heavy particle temperature of plasma flow by calculating iteratively electron and heavy particle energy transfer equations with pure numerical simulation. The spatial distribution characteristics about electron temperature and heavy particle temperature of plasma flow and the factors that influence local-temperature equilibrium(LTE) are completely analyzed .In the diagnostic process, as is shown that the method omits multifarious boundary conditions and it is more feasible than that of pure numerical simulation for those plasma flows of which boundary conditions are difficult to confirm.
A novel device and corresponding techniques are proposed, which are the transverse element of binary optics and transverse-adding technique. The transverse-adding technique of binary optics can be used to fabricate microelectronic elements and micro-mechanical elements very well. By using this technique, the micro-photoelectric-mechanical systems can be integrated on a single chip. The fabrication model and method of Fresnel diffractive lens with Transverse-adding technique are presented. It is demonstrated that the diffractive efficiency of Fresnel diffractive lens fabricated with this technique can reach 100% by theoretic analysis. In addition, the diffractive efficiency of this kind of Fresnel diffractive lens is independent of technique error.
A novel self-adaptive volume reconstruction technique (SVRT) based on multiobjective optimization is proposed. Its reconstruction results for asymmetrical 3-D single-peak cosine emission coefficient fields are studied with the numerical simulation of a computer. The results show that this algorithm has faster convergences and higher reconstruction precision, and can reconstruct asymmetrical single-peak cosine emission coefficient fields perfectly with only two views. (The average error is 0.18% with no noise data.) In the experiment of argon-arc plasma diagnosis, the 3-D reconstructions of temperature and ionization coefficient fields are fulfilled with this algorithm combined with the spectrum relative-intensity method.
Optical Computed Tomography is a useful tool for plasma diagnostics. But in plasma physics, viewing access is very limited, which leads a highly undetermined inversion problem. Two major approaches to this problem are compared in this paper: Maximum Entropy (ME) method and Simultaneous Iterative Reconstruction Technique (SIRT). The results of numerical simulation and experiments illustrate that both two algorithms can yield good qualities of reconstruction with limited views when some prior information has incorporated into calculation. Especially, in the case of two views, with prior information, a good result can even be achieved by ME algorithm.
The accuracy of the micro-displacement feed detection and control is decided by the calibration of the system. On the basis of laser interference principle, a new scaling method is introduced. Combining hardware subdivision and software subdivision, the scaling system can calibrate the micro-displacement effectively. The scaling system is composed of optical interferometer, signal processing circuits and microprocessor. Experiments proved that it is feasible to rectify the micro-displacement system with laser interference. The resolution of the micro-displacement is better than 0.1 micron after it was revised.
Being supposed that the target is greybody in the principle of two-color pyrometry, the color temperature is regarded as the true temperature. The main cause of the error is emissivity. In published literatures on emissivity ε, the wavelength λ was taken into account but the temperature T was neglected. The curve of ε(λ) against λ could be obtained in certain temperature. In this paper the emissivity is considered that it relates not only with wavelength but also with temperature, and the expression of ε(λ,T) can be gained. Therefore, a series of ε(λ) against λ curves under different temperature can be united into the form of ε(λ,T).
A new type of isosceles blazed grating with compensated phase on the obverse side (abr.IBGCPOS) is designed. The problems of double-sided fabricating alignment are solved. The theoretical model of diffraction intensity is founded and simulated. The difference between IBGCPOS and the isosceles blazed gratings with compensated phase on the inverse side (abr. IBGCPIS) is analyzed. Typical distribution patterns of diffraction intensity are given. In addition, the method of binary optics fabrication for the new type grating is simply discussed.
A convenient, efficient and real-time experiment setup has been applied to measure the light intensity of Argon plasma. The effects of airflow rate and discharge current on the light intensity and on the electronic Temperature (Te) are investigated. The profiles of Te and the number density of electron (ne) are obtained.
The formula of bi-wavelength-thermometry is given, which is used for characteristic signal process of arc plasma thermometry and its distribution. The principle of spectrometer is introduced simply. Through experiment research of the three kinds of current measuring ways, a method of spectrum measurement using multi-wavelength scan is presented, which is in favor of studying the spatial distribution of the thermal plasma field thoroughly.
In this paper, the diffractive efficiency in Ce:SBN photorefractive crystal was measured using two-wave coupling light path. The light-induced scattering resistance was gained through observing the transmitted light spot. Furthermore the other holographic storage properties such as the quality of the stored image and preservation time were studied. Finally using Ce:SBN photorefractive crystal as the storage medium, storing and reconstructing the holographic image were realized.
A new technique with a one-step rainbow hologram for recording 2-dimension or 3-dimension images is presented. In this method, not only can we realize to record rainbow hologram in the same recording material with multiplex angles, but also obtain laminated result. The hologram has a low speckle noise and a high diffraction efficiency when it reconstructed with white light.
In this paper, we consider a promising method of pattern recognition based on Texture Features (TF) to classify cancer cell. With this technique, the TF characters are calculated among different cells or different regions of cells. Then these texture features are transmitted to the input neurons of the Back Propagation (BP) neural network. After training phase of neural network, the structure is determined. At last, we design an opto-electronic neural network to complete the cancer cells recognition.
This paper introduces the design of optics, power driver and control system of a high power semiconductor medical laser. The instrument adopts 980nm laser with maximum power output of 2W as therapeutic beam and 670nm laser of 3mW as aiming beam. The laser beams, after being collimated , can either be transmitted directly or be coupled through an optical fiber. In the driver of therapeutic laser, there exist current supply, protection circuit , temperature controller and light power feedback loop. The whole system is controlled by a microprocessor. With appropriate hardware and software, we've achieved , in our driver ,a variety of protection features including the ability to suppress transients and reduce noise, relay shorting protection , soft turn-on , current limit and overvoltage shut-off ,which keep the laser diode from damage. Meanwhile, we've also obtained a continuously adjustable optical power output with high accuracy and stability , both of which are vital to a safe and reliable
In the testing and control of electricity system, Magnetism-photo optical fiber electricity sensor modules based on Faraday Effect of the main electricity wire can be made. We can play these sensor modules at the spots where the electricity need to be tested and controlled real-timely and make use of the Wavelength Division Multiplexing (WDM) technique of optical fiber network to transmit the real time data from all spots to the central computer, so the system of distributed optical fiber electricity current supervision and control is constructed.
This paper discusses an optical fiber acousto-optic phase modulator coated with piezoelectric ZnO. The geometry of optical fiber using ZnO coating has firstly been presented and the basic theory of piezoelectric resonator of this geometry been analyzed. Also, the equivalent network model for the optical fiber acousto-optic phase modulator coated with piezoelectric ZnO has been given. And then, the reflection coefficient Rf has been obtained by this model. Finally, calculation of Rf has been made in great detail according to the practical parameters.
KEYWORDS: Holograms, Signal to noise ratio, Refractive index, Water, Modulators, Image quality, Temperature metrology, Californium, Holography, Signal processing
The experiment has indicated in this paper that dichromated gelatin (DCG) holograms after the first development can be reprocessed. The quality of over exposed of multi-exposed DCG holograms can be improved by reprocessing. This is especially beneficial for the DCG hologram with short developed time in the first development processing.
In this paper, the reconstruction precision of Radon transform iteration based on beam-deflection optical tomography, which is used for 3-D temperature fields, has been studied by computer simulation on the prior knowledge of these fields. As an example, the method has been used to reconstruct the arc temperature fields.
This paper presents the application of optical epoxy resin as transfer medium to duplicate the relief hologram onto the hard base material. Experiments have been conducted on photo sensitive and thermal sensitive resins in relief hologram duplication. The results have shown that the diffraction efficiency and spatial frequency of the duplicated hologram are approximate to those of the original ones, and its environmental stability is satisfactory. The new one-time transfer duplicating technique, its simple process and low investment offer a practical value in mass-duplicating production.
This paper presents a new method to diagnose the welding arc temperature field on the basis of plasma physics, Talbot effect and moiré techniques. This method has advantages of immunity to mechanical shock and vibration, tunable sensitivity and considerably simple optical system.
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