Proceedings Volume 4927

Optical Design and Testing

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Proceedings Volume 4927

Optical Design and Testing

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Volume Details

Date Published: 20 September 2002
Contents: 12 Sessions, 139 Papers, 0 Presentations
Conference: Photonics Asia 2002
Volume Number: 4927

Table of Contents

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Table of Contents

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  • Design of Optical Systems and Instruments I
  • Design of Optical Systems and Instruments II
  • Optimization Algorithms for Lens Design
  • Infrared Optics
  • Interferometry I
  • Interferometry II
  • Aspheric Surface Testing
  • Optical Testing
  • Testing with Optical Technology I
  • Testing with Optical Technology II
  • Thin Film Design and Optimization
  • Poster Session
  • Optical Testing
  • Poster Session
  • Optical Testing
  • Design of Optical Systems and Instruments I
Design of Optical Systems and Instruments I
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Importance of international standards at all levels of optical instrument production
This paper briefly reviews the standards produced by ISO TC172/SC1, whose remit is 'Optics and Optical Instruments', both those already published and those currently under development.
Catadioptric omnidirectional system with undistorted imaging for horizontal scene
Xianyu Su, Jiyong Zeng
A complete method based on the perspective-imaging model is established to design catadioptric omnidirectional systems with un-distorted imaging for horizontal scene. A mirror has been designed, and a catadioptric omnidirectional system with un-distorted imaging for horizontal scene has been developed. The image taken by this catadioptric omnidirectional system is compared with the real image taken by hyperboloidal omnidirectional system and its perspective omnidirectional image.
Optical design and analysis of 2D spectrograph for space solar telescope
Yanxun Wu, Yuesong Jiang, Guoxiang Ai
In a study by the National Astronomical Observatory Center (NAOC) for Space Solar Telescope (SST) laboratory, an One-meter aperture SST is being developed for measuring solar vector magnetic. This paper introduces its optical design of 2-Dimension Spectrograph (2DS), which depends their action on the interference of polarized light and are designed to transmit very sharp bands with very high resolution (0.075Å at 5324Å). It can be tunable for one spectral line to obtain part of the line profiles of 2-dimension field of view with 8 channels. The 2DS is also called Birefringent Filter with 8-Channel. Four forms of the filters which are used in 2DS are described in details. Analysis of the characteristic of those filters chose the 2DS has significant advantages in both transmission and profile shape. Finally, the transmittance of the filters will be discussed.
Design of Optical Systems and Instruments II
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Semiconductor laser scanning optomechanical system in an integrated machine vision sensor
Dawei Tu, Caixing Lin, Sheng Cheng, et al.
The design of a two-dimensional x-y scanner for an integrated machine vision sensor, which innovates a synchronized spot scanning triangulation imaging system for precision data within the near range and a laser radar (lidar) to get the coarse image at the far field, is discussed in this paper. To support the new idea of layer and modular structure of machine vision structure, the two set of imaging systems have in common with the same scanner for emitting and returning optics with one laser source, to ensure that the data from two imaging systems respectively are coordinated in time and space. After expounding the basic principle of laser triangulation range imaging system based on synchronized scanner, system parameters involving the optics, the electronics are determined according to the active range, image resolution, frame frequency, and the range accuracy.
Optmization design of zoom lens systems
A zoom lens system is usually composed of several components. Some of the components can be moved to change the focal length or magnification. Zoom lens system design is more complicated than fixed-focus lens design due to the moving of some components. In this paper, an optimization method that is used to design zoom lens systems is presented. Using this method, the Gaussian parameters of zoom lens systems are optimized at first, and then the initial structure parameters in each component are generated and optimized. At last the aberration balance is made using multi-configuration. In this paper the flowchart of optimization design for such complex optical systems is showed and the algorithms are described. As a conclusion, the relationship between power distribution, initial structure and the aberrations is considered at the beginning, the evaluation criteria are reliable and efficiency for designing zoom lens systems.
Head-tracked dome display technology
Liping Liu, Yongtian Wang, Lin Li
A combat fighter simulator requires a visual display system with a large field of view, high resolution and good luminance. The technology of head-tracked dome display provides a good solution to these contradictory requirements that are hard to accommodate with other display methods. The structure and technical characteristics are described for the first head-tracked dome display system in China.
Standardization of acousto-optic tunable filter NIR spectrometric instrument
Wenbo Wang, Yixiong Su, Chengzhi Jiang, et al.
By employing an Acousto-optic Tunable Filter (AOTF) as the spectroscopical device, a Near-infrared (NIR) spectrometer that is compact, rugged and having random wavelength access has been built. In this paper, the working principle of Acousto-optic Tunable Filter and the schematic design of the instrument are described in details. As a spectrometer for on-site use, the instrument adopts a double beam scheme for self-calibration, modulation of light intensity is employed to reduce interference of noise, and different configurations of the probe offer more versatility in measurement. Specifications for the instrument are quantified. After the instrument’s performance is qualified for wavelength accuracy and scale precision, glucose solution samples are prepared and transflectance spectra are sampled on the instruments. PLS model has been set up through the spectra of aqueous solution of glucose and cross-validation is used to test its predictability. Calibration transfer is attempted between instruments. Direct Standardization (DS) and Piecewise Direct Standardization (PDS) algorithms are briefly described here. It should be noted in this experiment that the proper determination of rank of transformation matrix plays an important role in estimating the quality of spectra transfer. Calibration transfer is performed between instruments and a satisfactory prediction error of 1.5~2 times larger is achieved by applying DS and PDS method.
Artificial neural network and application in calibration transfer of AOTF-based NIR spectrometer
Wenbo Wang, Chengzhi Jiang, Kexin Xu, et al.
Chemometrics is widely applied to develop models for quantitative prediction of unknown samples in Near-infrared (NIR) spectroscopy. However, calibrated models generally fail when new instruments are introduced or replacement of the instrument parts occurs. Therefore, calibration transfer becomes necessary to avoid the costly, time-consuming recalibration of models. Piecewise Direct Standardization (PDS) has been proven to be a reference method for standardization. In this paper, Artificial Neural Network (ANN) is employed as an alternative to transfer spectra between instruments. Two Acousto-optic Tunable Filter NIR spectrometers are employed in the experiment. Spectra of glucose solution are collected on the spectrometers through transflectance mode. A Back propagation Network with two layers is employed to simulate the function between instruments piecewisely. Standardization subset is selected by Kennard and Stone (K-S) algorithm in the first two score space of Principal Component Analysis (PCA) of spectra matrix. In current experiment, it is noted that obvious nonlinearity exists between instruments and attempts are made to correct such nonlinear effect. Prediction results before and after successful calibration transfer are compared. Successful transfer can be achieved by adapting window size and training parameters. Final results reveal that ANN is effective in correcting the nonlinear instrumental difference and a only 1.5~2 times larger prediction error is expected after successful transfer.
Design of compact high-resolution optical system for space and stray-light analysis
Jun Chang, Zhicheng Weng, Xiaojie Cong
This paper describes the results of the design effort for a three-mirror anastigmatic system (TMAS) and its stray light analyzing. The system’s focal length is 4000mm and the relative aperture is f/10, it’s total length is nearly f’/3~f’/4 and field of view (FOV) is 30 × 10. The final optical system is a three-mirror unobscured telescope. It is telecentric and achieves diffraction-limited imagery at visible wavelengths. After analyzing the stray light used the Light Tool software, finally We can draw two conclusions: 1) design of unobscured optical system is still best approached using fundamental optical design principle; 2) time spent in careful analyzing the stray light and a higher probability of success for the assembled system.
Optimization Algorithms for Lens Design
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Critical view of three lens design methods: damped least squares, Spencer's and Glatzel's
Juan L. Rayces, Martha Rosete-Aguilar
A lens system can be represented as a point in the N-dimensional parameter space. There is a set of quantities called merit functions associated with points in this parameter space that define the performance of the lens system. Ideally this set can be reduced to a single quantity called the merit function. Lens design iterations consist of transferring from one point in parameter space to another where the merit function indicates an improvement. By repeating this process the designer may eventually reach a satisfactory solution. Even when the functions involved are theoretically continuous, the transferring in parameter space may never be strictly continuous because it is a numerical process. Yet, it should be possible to take arbitrary short steps on going from one point to another. Long steps, or leaps, can abruptly lead to undesirable regions from where it may be difficult to return to the previous, more desirable region. There are three common methods to set up the merit function: Levenberg’s damped least squares (DLS), G. Spencer’s constrained damped least squares (CDLS) and E. Glatzel’s automatic adaptive correction (AAC). This paper reviews the pros and cons of these methods. A discontinuity found in Spencer’s method will be discussed in detail.
Study on automatic optical element addition or deletion in lens optimization
Two lens form parameters, quantifying the symmetry of the optical system and the optical power distribution among the individual lens elements, are used as the criteria for automatic element addition or deletion in lens optimization. The scheme based on the criteria is described in this paper. Design examples are provided, which demonstrate that the scheme is practicable.
Simulated annealing algorithm for unwrapping noisy phase map
Zhenjun Peng, Xiangzhao Wang, Feng Qian, et al.
We have proposed an improved regularized phase-tracking (RPT) technique for unwrapping two-dimensional principal phase maps. Simulated annealing (SA) algorithm is applied to RPT technique for finding the global optimum values. Further, the size of the neighborhood selected for plane approximation at each pixel is adjustable according to local noise quantity. In the area of low noise, the size of neighborhood is small to improve processing speed. On the contrary, a neighborhood with large size is selected to enhance the noise-reduced ability in the high-noisy area. Numerical simulation proves that this technique is highly robust to noise and experimental results show the feasibility of this technique.
Infrared Optics
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Design and fabrication of infrared hybrid refractive/diffractive optical system for 3- to 5-um band
Jian Bai, Xiyun Hou, Yibing Shen, et al.
An infrared hybrid refractive/diffractive optical system for 3 to 5μm band, which is composed of four refractive elements and one binary optical element (BOE), has been designed and manufactured. The BOE, whose chromatic behavior is opposite to that of the refractive element, has made it possible for us to design the diffraction limited optical system with field of 40× 40, aperture of 60mm, F number of 2.46, total track of 140mm and temperature range from minus 30°C~70°C. A polar coordinate laser direct writing system (PLDWS) and a reactive ion beam etching (RIBE) device have been established to manufacture the BOE. The imaging performance of our optical system has been tested by Ealing IR MTF equipment, which shows that the diameter of spot is less than 80μm when the energy within the spot is 90% of the total.
Low-temperature blackbodies and facility for calibration of them
The calibration of IR sensors, thermal imagers, instrumentation for remote earth sensing, signature recognition, and low background spacebome radiom-eters requires development of low- and near-ambient-temperature reference standard sources capable of operating in vacuum at low or medium background conditions. The paper contains the characteristics of blackbodies (BB), developed at the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI). A novel Medium Background Facility (MBF) intended for calibrating IR sources has been developed at VNIIOFI. The MBF used for the calibration under vacuum conditions (10-3 Pa) and medium background temperatures includes a Ga Fixed-Point Blackbody (29.76 °C), Variable Temperature Blackbody (-60 °C ~ +80 °C) and Filter Radiometer. A brief description of the operating principles and specifications of the MBF is presented. The results of a comparison of the Variable Temperature Blackbody and Ga Fixed Point Blackbody in the Medium Background Facility are given. The measurement uncertainties radiance temperature associated with spectral bandwidth are discussed.
Application of harmonic diffraction in infrared
Qiang Sun, Zhaoqi Wang, Wei Quan, et al.
Harmonic diffractive surface element is successfully introduced to the system of infrared dual band in this paper. It has been simultaneously accomplished that the rectification of the Transverse ray, Lateral color and Longitudinal aberration in both band, wave front aberration less ¼ wave length and Modulation Transfer Function of dual band approaching or attaining the diffraction limit. The properties of action spectrum of harmonic diffractive are between refractive element and diffractive, which debased the demand for technical level. The practical design not only shows that the system is compact, few elements and high rates of transmission but also has better weaken-ray aberrations character and 100% cool diaphragm efficiency. The harmonic diffractive element offers a new component for optics designs.
Calibration method of three-band infrared integrated radiometer
Xia Wang, Zhiyun Gao, Jianyong Zhang, et al.
A three band infrared integrated radiometer was developed for field measurement. The composition and work theory of the radiometer are described in this paper. The detailed calibration methods are analyzed for extended source and point source, and corresponding measurement results are given. With test data, the experimental results and instrument performance are analyzed in detail, in respect of the equivalent temperature of inter reference blackbody, linearity with target temperature, measurement error of point source and extended source. To lessen the influents of calibration for measurement, the attentive problems in actual calibration of extended source and point source are summarized, and satisfied results are acquired.
Study for the MTF of photovoltaic and photoconductive infrared detector cells
Moying Tong, Ji Tang, Benkang Chang, et al.
This paper firstly discussed respectively the transform mechanism of photons-to-electron of photoconductive and photovoltaic infrared detector cells from the point of the micro-mechanism, then makes the macro-analysis about the equation relation between the irradiation area and the output signal of infrared detector cells under the condition of uniform irradiation. According to the result, this text consolidates the relation between the input irradiation area and the output voltage of photovoltaic and photoconductive infrared detector cells. In the middle part, this paper illustrates the physics meaning of the modulation transfer function of photovoltaic and photoconductive infrared detector cells which produced by the scanning movement of the cell. This text puts forward the method of measuring the MTF of infrared detector cells. This text names it the knife-edge scanning method. Last part, the text calculates the MTF of infrared detector cells in the ideal condition that detector cells in the ideal condition that detector cells are homogeneous and the geometry of cells is the regular rectangle. At last the paper sums up the factors, which affect the MTF of photovoltaic and photoconductive infrared detector cells.
Some developments on fractional Fourier optics
Daomu Zhao, Shaomin Wang
Some developments on fractional Fourier optics are reported in this paper. First, a thick lens can be regarded as a fractional Fourier transformer. Second, relations between the Collins formulae and the fractional Fourier transform or fractional Hankel transform are bridged, we show that the Collins formulae in spatial domain or in spatial-frequency domain can be described by the fractional Fourier transform or fractional Hankel transform. Third, connections between the multi-element resonators and the scaled fractional Fourier transforms are established, it is shown that there exists twice scaled fractional Fourier transform for beams in completing one round trip, the beam oscillation in resonator can be viewed as a process of consecutive implementing scaled fractional Fourier transform. Finally, some extensions of the fractional Fourier transforms to misaligned optical systems are simply reviewed.
Interferometry I
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Advances in interferometric metrology
Modern electronics, computers, and software have made interferometry an extremely powerful tool in many fields including the testing of optical components and optical systems. This paper will discuss some of the recent advances in reducing the sensitivity of phase-shifting interferometers to vibration.
Arbitrary angle measurement by grating wedge-plate interferometer and the calibration technique
Wei Tao, Zhaobang Pu, Zhitao Zhuang
A new method of arbitrary angle measurement with a grating wedge-plate interferometer is described here. A grating wedge-plate is introduced to the dual-frequency laser interference angle measurement system to enlarge the angle measurement range from ±10 to 360° or more in this system. The optical path and the structure of the interferometer are introduced and its advantages are analyzed. The calibration of the system and absolute zero-point determination of dynamic measurement by relative measurement method using 360° natural angle standard is also provided. Experiments of the repeatability of arbitrary angle measurement without and with self-calibration, the calibration error and the repeatability of zero-point of dynamic measurement under different rotating rates are given. The angle measurement range of the system is up to 360° and the measurement accuracy of arbitrary angles is better than 1” and can reach 0.5” for the best. The largest calibration error of the calibration curve is 0.5” and the repeatability of zero-point in dynamic measurement is related to the rotating rate of the wedge-plate for which the best is 0.3”. High precision, stability, immune to errors and self-calibration are the distinguished features of this angle interferometer.
Surface roughness measurement using infrared phase-shifting digital interferometer
Yong He, Lei Chen, Qing Wang, et al.
The design of far infrared phase-shifting Twyman-Green interferometer is described in this paper. An IR interferometric method is used to evaluate the surface roughness of ground glass. It is conducted that a rigorous mathematical analysis to describe the contrast of the interference fringes patterns and surface roughness. The experiment is run at the instrument of self-developed interferometer which aperture is Φ 30mm with accuracy better than λ/50 (λ=10.6μm). The mathematical derivation is verified with experimental data obtained from various values of roughness.
Interferometry II
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Simple lateral shearing interferometer using phase-shifting interferometry technique
Jae Bong Song, Yun Woo Lee, In Won Lee, et al.
In order to use phase shifting interferometry(PSI) in lateral shearing interferometer, piezoelectric transducer(PZT) is mainly used. But because PZT has many error sources and the moving distance for required phase shifting is very short, the phase shifting quantity has always considerable errors. We present a simple phase shifting technique without PZT. Moving the wedge plate parallel to the first wedge surface changes the phase difference between the original wavefront and the sheared wavefront. This method makes the shearing interferometer very simple in spite of using PSI technique. We derive the phase shifting relations originated from the moving wedge and discuss some error factors.
Tolerance analysis and test of focus' coincidence with last surface's curvature center for reference lenses
Zhishan Gao, Jinbang Chen
Reference lenses play an important role in test of spherical surfaces. In this condition, the ray reflected from the tested spherical surface goes the same way as that from the last surface of the reference lenses. If the two rays go different way, the focus of the reference lenses is not coincidence with its last surface’s curvature center, and system error is produced. The deviations between the focus and the curvature center of the last surface for a series of reference lenses are studied in this paper.
Optical quality and frequency response of an interferometer analyzing with optical design software
Zhishan Gao, Jinbang Chen
The optical quality and frequency response of an interferometer is influenced by its primary parts, for example its collimating input system, its reference lenses, its reference flat, its stop, etc. An interferometer is set up with optical design software to study the full view of influence by them in this paper. The data and curve is also given in this paper making sure the system error induced by them is less than 0.01λ (λis wavelength).
Imaging performance evaluation for fiber optical plates with modulation transfer function
Weijian Tian, Wei Zhang, Weihong Ma, et al.
In this paper, a measuring method utilizing Modulation Transfer Function (MTF) to evaluate the imaging performance of fiber optical plates, is proposed. As a kind of relay optical component in optical imaging systems, optical fiber transfer image plates have become more important and more available. By digital simulating the discrete MTF values, algorithm for MTF measure of fiber plates is studied. And MTF experimental results for the performance evaluation of fiber plates with knife-edge effect compared CCD test, are also discussed.
Aspheric Surface Testing
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Recent developments in the measurement of aspheric surfaces by contact stylus instrumentation
Paul Scott
Contact stylus instruments with sufficient range to resolution that could measure and analyze aspheric surfaces first appeared in the 1980s. These where limited to the measurement of a single profile over a rotationally symmetric aspheric surface. Although limited in use they proved to be very useful for the characterization of both optical and non-optical aspheric surfaces, correction of tool paths for aspheric generators etc. The work described here reviews recent developments in the measurement and characterization of aspheric surfaces by contact stylus instrumentation and includes measurement over an area rather than a single profile and measurement and the characterization of non-rotationally symmetric aspheric surfaces. Some of the challenges involved in the areal measurement of aspheric surfaces by contact stylus instrumentation will be described together with the techniques and considerations used to overcome these challenges. Specifically we will describe the mathematical models used to describe the aspheric surfaces and how these can be used to eliminate measurement set-up errors. How the finite size of the stylus can be corrected using techniques developed for image analysis. The automatic detection and removal of asperities using wavelet technology will be described. Finally the benefits and limitations of data fusion techniques to improve the range of the instrument will be reviewed.
New long trace profiler for aspheric optical surface metrology
Tiqiao Xiao, Shaojian Xia
A long trace profiler (LTP) is specially designed for the metrology of long aspheric optical surfaces and has been widely used in the fields of synchrotron radiation and astronomy. An LTP with an innovative design has been successfully developed at SSRF. An f-θ system based on phase plate diffraction collimation is employed for the first time. Effect of source instability and ambient factors on the precision is greatly reduced, compared to other LTPs now available. The scanning range is 350mm, precision better than 0.5μrad, static repeatability 0.1μrad. The profiler has been calibrated by a standard mirror from Chinese National Institute of Metrology.
Optical Testing
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Automatic testing of optical multiparameter based on CCD camera and LCD graph generator
Xusheng Zhang, Shengye Huang, Mailing Xing, et al.
A novel means to measure optical multi-parameter is overviewed in this paper and an integrated measurement system consisting of CCD camera, LCD graph generator, testing software and computer is described. Based on this system, novel methods of measuring focal length of lens and visual magnification of infinite conjugate system are given. In addition, the measurement of other parameters such as MTF, parallax, distortion, etc. is also discussed. Three automatic focusing criteria are proposed and selectively used to locate CCD target accurately in the image plane.
Novel approach to measure the linear birefringence in bulk optical glass sensing head of current sensors
Zheng Ping Wang, Qingbo Li, Huili Wang, et al.
In this paper, a novel approach to measure linear birefringence in bulk optical glass sensing heads of current sensors is reported. The theoretical analysis based on Jones matrix, the formula of uncertainty and applied examples are also given. The main advantages of this method are simple structured, practical and that the devices needed are easy to obtain.
Method to measure reflection-induced retardance without compensator
Zheng Ping Wang, Qingbo Li, Huili Wang, et al.
The measurement of reflection-induced retardance of optical devices is the usual case encountered in optical research, development and engineering. This kind of measurement usually can be completed using a linear polarizer and a retarder. A novel method used for the measurement of reflection-induced retardance employing a polarizer and an analyzer is proposed in this paper, the theoretical analysis of the method and an application example are given.
Optical analysis for light intensity distribution in EPR with different light sources
Xiangning Li, Liner Zou, Longyun Xu, et al.
Eccentric photorefraction is an objective refraction technique that, by taking a picture of the pupil of the subject, can measure refractive errors in human eyes. The method assessing the refractive errors is mainly from the size and orientation of the crescent of the pupil image. Because of the effects of the light source and the vignetting of the optical system’s aperture, the boundary of the crescent is not sharp so as to accurately determine its size. This uncertainty reduces the accuracy of the EPR system and limits its extensive application. In this paper, analysis on the light intensity distribution across the pupil is presented. It aims to determine the size of the crescent based on the aperture opening in the form of straight edge, rectangle and slit are also included in discussion. The analysis shows that the EPR system with a line source and a rectangular aperture opening will give a good linear light distribution profile across the pupil, which may be helpful to automatically determine the size of the crescent. The method will effectively improve the measurement accuracy of EPR.
Analysis of light field of waveguide grating couplers using the FDTD method
Jing Liu, Xiuhua Yuan, Chongqing Huang, et al.
The scalar two-dimensional finite difference time domain (FDTD) method is applied to the simulation of light field distribution of waveguide grating couplers. The mode patterns of TE0, TE1, TE2 and TE3 are obtained by using planar optical source as a stimulin. A few important problems are studied carefully, such as: the effect on field distribution with different grating parameters and waveguide structures, the absorbing boundary conditions, etc. The procedure for calculating is compiled in MATLAB. The calculating results are analyzed carefully.
Vision coordinate measurement technique using stereo-probe imaging
Jin-yao Jin, Zhi-jiang Zhang
A new method of vision coordinate measurement using stereo-probe imaging is presented. The system consists of a CCD camera, a stereo-probe and a personal computer. It realizes the three-dimensional coordinate measurement of the contacted points by utilizing the stereo-probe to contact with measurement surface and analyzing the imaging changes of the known characteristic points on the objective-probe. It can realize not only most of the present vision coordinate measurement, but also the measurement of hidden surfaces. In addition, it does not depend on light characteristic of measurement surface and has a larger measurement range. At first, the paper sets up the nonlinear measurement equations of the vision coordinate measurement system by special coordinate translation. Following, the paper describes the Newton nonlinear initiation method to resolve the measurement equations. Finally, the paper analyzes the effect factors of the system accuracy. In addition, the paper also brings forward an auto-calibration approach of important parameter---effective focus. Furthermore, the article validates the correctness of measuring model and feasibility of resolving the nonlinear measurement equations.
Testing with Optical Technology I
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Study on a distributing Fabry-Perot measurement system
Zhiquan Li, Zhibin Wang
A distributing Fabry-Perot measurement system is introduced in this paper. The theory analysis indicates that if the lengths of the cascaded and paralleled Fabry-Perot sensors are properly selected, the crosstalk can be well restrained, and the experiment simulations agree to the theory analysis.
Research on the linear continuous attenuator technique of large caliber
Jiaming Lin, Qingsheng Zheng, Taogeng Zhou, et al.
The key technology that the attenuators of the continuous values are designed, manufactured and calibrated to calibrate the range of Laser Range Finder is discussed in this paper. The transmittance control technology of designing the continuous attenuator with a large caliber and 0.2dB-10dB attenuation continuously is sets forth, and the means of orthogonal polynomial surface fitting for continuous attenuation values are analyzed, the utility calibrating results are also presented.
Detection of distributed polarization coupling in high-birefringence fibers
White light interferometry has been adopted to measure the distributed polarization coupling in high birefringence fibers. A superluminescent diode is adopted as the optical source in the white light interferometer. To enlarge the measurement range, the light beam in the scanning arm of the Michelson interferometer is reflected three times. Thus the scanning range of the interferometer is doubled. The full-width half-maximum spectrum of the SLD is 50 nm, and the central wavelength is 1300 nm. If the modal birefringence of the HBF is 5×10-4, a spatial resolution of 70 mm can be achieved. A high sensitivity photo detector and a high-resolution analog to digital converter have been adopted. The polarization coupling intensity measurement accuracy can be up to -75 dB.
Tiny gallium arsenide probe for electro-optic sampling
Hailan Li, Xiaoting Zhang, Zhanguo Chen, et al.
Several fabrication methods of electro-optic probe are introduced and the wet chemical etching technique is the most promising to fabricate a tiny probe. The experimental material is Gallium Arsenide crystal whose dielectric constant is small and stability is good. A pyramidal electro-optic probe has been achieved which whole size is smaller than conventional probes and surface is very smooth. So the influence of probe on the measured electric field can be reduced remarkably which will improve the measurement accuracy, and at the same time good spatial resolution would be obtained.
Measurement of motionless water surface shape using laser scanning and optical project methods
Qun Hao, Keiji Kawachi
In order to study the possibility of machinery of small size using surface tension of liquid, the water surface shape should be measured precisely. When the object on water is relatively light, then the deformation of water surface would be somewhat small. In this case, a laser scanning method is proposed. By this method, we can get the shape of water surface through the measuring of slope of water surface. In order to get the shape of water surface, and also escape from precise calibration of measurement system, we proposed an iterative algorithm through which we can compute the shape of water surface precisely. If the object on water is relatively heavy, which can produce somewhat large deformation of water surface. In this case, we proposed to measure the shape of water surface by optical projection. Using an ordinary lamp as the background light, a numerical camera to collect the image of water surface from the side of transparent water vessel. Through image processing, the shape of water surface can be gotten. Comparing with theoretical calculation, the experiment results exhibit that the two methods all coincide with the theoretical one very well.
New design to detect vibration
Zhiquan Li, Huiqing Chen, Sui Wang
A design uses micro-cantilever beam with matching twin long period optic fiber grating which are sensitive to the strain and the vibration as the sensor head. And the difference amplifies the micro-displacement of wavelength which caused by strain or vibration. Special cladding material is used to eliminate the interference which temperature brings. The design has the good capability to detect the micro-information and smooth the bias lighting.
Testing with Optical Technology II
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Improving the measuring accuracy of laser autocollimator used over long distance
Meirong Zhao, Yuchi Lin, Ping Zhang, et al.
The methods of how to improve the measuring accuracy of the autocollimator used over long outside distance are introduced in this paper. Pulse diode laser is adopted as a light source and CCD is used as signal receiver. By the optical design of common-path and the signal processing such as smoothing filtering, interpolating image center, eliminating anomaly data and identifying false points, a higher stability of 2.5” and a better repeatability of 5.6” are achieved in the positioning measurement over ten meters. The principle of auto-collimation, the optical system design, the signal processing and the experimental results are expatiated in this paper.
Normal spectral emissivity changes of tungsten at 633 nm in the range from room temperature to melting point under pulse-heating conditions
Chengwei Li, Fan Yi, Jingmin Dai
The classical steady-state technique for the measurement of thermophysical properties at high temperatures suffer from many limitations (for example, chemical reaction, evaporation, loss of mechanical strength, etc. may exist). These problems may be overcome by transient techniques of sub-second durations. Pulse-heating experiments were performed on tungsten strip specimen, taking the specimen from room temperature to the melting point based on rapid resistive self-heating of the specimen. The normal spectral emissivity of the specimen was measured by integrating sphere reflectometry developed at HIT. At the same time, the radiance temperature is measured by high-speed pyrometer from 1200K to the melting point. Details of the measurement technique, measurement apparatus and of the calibration technique are described. Results of the normal spectral emissivity of tungsten at 633nm from room temperature to melting point are presented and discussed.
Detection and A/D conversion for 10GHz microwave signals using optical sampling
Hongming Zhang, Minyu Yao, Can Peng, et al.
A simple optical sampling scheme for ultra-high speed optical A/D conversion is demonstrated. 10GHz microwave signal is sampled using 10ps optical pulses generated by a mode lock laser, and 6 bits resolution is achieved.
Logic circuit design using optically controlled MESFET
Garima Bandhawakar, B. B. Paul
Since their introduction in 1970's GaAs MESFETs have shown their outstanding performance in various high frequency applications, especially in upper microwave and millimeter range. After a decade in 80's research efforts in GaAs OPFET development came in to focus and gained rapid foothold in high-speed arena. The most attractive feature for development of GaAs MESFET IC's under optically controlled condition is to persue the highest possible switching speed and the other is to realize very low power dissipation, so as to make large-scale integration possible. These devices exhibit multifunction such as optical amplification, bistability and switching. Optoelectronic integrated circuits (OEICs) are of great interest and widely applied for high speed integrated circuits (IC's). Such as optical fiber communication systems, telecommunication and computer industries. In present paper we have presented a DCFL (Direct Coupled Field Effect Transistor Logic) using OPFET's. Several set of analytical equations have been derived, which relates the inverter parameter to the parameter of switching transistor and saturated load. For both the switching transistor and saturated load, MESFETs have been used and gate of switching transistor has been illuminated optically, thus a photovoltage (Vop) develop at gate. Furthermore, the photogenerated electrons in the depletion and channel region contribute to excess current which is added to dark channel current to give the total channel current. All the inverter parameters such as the load saturation current, the switching transistor threshold voltage and inverter turn - on and off time show better performance under illumination rather than under dark condition.This device using OPFET can be a useful tool in the areas of optical communication and can be used as switches and/or logic gates in OEICs.
Unwrapping phase map by estimating regions containing phase jumps
Feng Qian, Xiangzhao Wang, Zhenjun Peng, et al.
We present herewith a phase unwrapping technique by estimation of regions containing 2π phase jumps based on their phase-distribution features. The more the neighbors around a pixel have phase values near π and -π, and the smaller the number difference between the neighbors near π and -π, the more possibly the pixel locates near a phase jump. The pixels with high possibility forms the phase-jump regions, which can then be eliminated by compensating the pixels with a multiply of 2π to minimize the phase difference between them and their neighbors. After removing phase jumps, one can utilize ordinary filtering operations to postprocess the noisy unwrapped phase map. Computer simulation and experimental results from the surface profile measurements of a transparent plate are presented.
Multiwavelength high-thermometry using spectrum analysis
Xinmin Qi, Yiqing Gao, Huanming Chen, et al.
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.
Comparison of trap stiffness between a solid-mode optical trap and a donut-mode optical trap
H. T. Chen, Zan Gong, Y. M. Li, et al.
Do-nut Mode Optical Trap is the kind of Optical Trap that the laser distribution in the center part of the beam is approximately zero. Because the trapping effect of an Optical Trap correlates closely with the distribution of optical field, the scattering force of Do-nut Mode Optical Trap is markedly reduced. We realized Do-nut Mode Optical Trap by rebuilding wave front. Then we studied the trapping effect and trap stiffness of Solid Mode Optical Trap and Do-nut Mode Optical Trap in the cases of upright microscope and inverted microscope. We measured the stiffness of the Optical Trap near the focus with Boltzmann statistics method. The distribution of the optical field of Do-nut Optical Trap is like aura. And the trapping effect changes with the diameter ratio of the aura.
Thin Film Design and Optimization
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Genetic arithmetic global optimization design of optical thin film used in fiber optic communication
Minghong Yang, Jinsong Liu, Bo Zhang, et al.
Thin film filter design method based on genetic arithmetic is provided in this paper. Theoretical analysis model is built up. A 50Ghz filter is optimized according to the programme. Optimization aims can be selected as different requirements.
Optimization of optical multilayer based on genetic algorithm and nonlinear least square method
Zhigang Fan, Hongbing Li, Aihong Zhang
Study on the combination of different optimal algorithms to improve the performance of the algorithm is crucial to design optical multiplayer. A method based on GA (Genetic Algorithm) and NLSM (nonlinear least square method) is presented in this paper. GA is used to optimize the refractive index of the optical multilayer to get the original structure parameters. Then the NLSM is used to optimize the thickness of the optical multilayer based on the previous result. The algorithm model is explained in detail and the optimization design examples prove that the result is better. The results also indicate that the method is simple, effective and general for the optical multilayer design.
Design of the filter with flattening spectral transmittance
Juan Zhang, Liren Liu, Yu Zhou, et al.
A new method to produce flattening spectral transmittance for birefringent chain filter based on the interference of polarized light is presented. In previous publications, each birefringent crystal must be of equal thickness and only one group of azimuth angles of the crystals was obtained. Besides, the shape of spectral transmittance is not enough flat and the flatness width of the passband and the stopband is not wide enough. Our method is more advantageous than that of the previous publications. It is based on Fourier transform. The thickness of each crystal can be different. We can obtain all the numerical solutions of the azimuth angles of the crystals when ripples are relative small in both the relative wide passband and stopband. In this paper, three birefringent crystals are used and all the azimuth angles of the crystals are obtained when ripples are limited to a uniform 0.1% in both the passband and the stopband with the widths of greater than 2/11 period. The influence of the change of the azimuth angles and thickness of the crystals on the spectral transmittance of the system is discussed as well.
Broad-linewidth bandstop filters with multilayer grating structure
Ya Nie, Zhiheng Wang, Chengjun Lai
A novel type of bandstop filters according to multilayer grating structure is presented. This device is based on guided-mode resonance effect of waveguide grating structure and interference effect of multilayer structure. The multilayer thin-film stacks consist of Si and SiO2 layer alternantly. This device is designed for an operating wavelength of 1.55 μm. Calculated examples show that high efficiency and broad reflectance can be achieved with a few layer pairs. Provided that the number of the layer pairs reaches to a certain value, the total-reflection phenomenon can be found. The low angular sensitivity, another important property, is also discussed. It is found that the total-reflection maintains during a relative large changing range of incident angle.
Design of highly flat-output gain equalizers
Yu Zhou, Liren Liu, Juan Zhang, et al.
Birefringent filters in which several unequal-length birefringent crystal plates are located between two polarizing devices are used to flatten the gain spectrum of erbium-doped fiber amplifiers. The intensity transmission function of birefringent filter is a cosine series containing a finite number of terms. Because the desire intensity function can be transform into a cosine Fourier series which is truncated after an appropriate number of terms, the thickness and the relative rotation angles of each element can be acquired by comparing the intensity transmission function with the cosine expanding series of the desire function. Since the rotation angles of each element are easy to control, the desired function can be realized accurately. With this device, an amplifier can be given with <0.1dB gain variation in 1550nm-1562nm spectrum band. Furthermore, the use of a polarization beam-splitter and a polarization beam-combiner makes this device polarization-independent.
Poster Session
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Optimum baffle design of star sensor
Wei Lu, Zhan Li
Along with the gradual development of CCD-star sensor, exactly extracting star point has been becoming more and more important. The background noise of CCD will affect the extracting accuracy badly. The baffle designed in the old way couldn’t satisfy the high precision requirement of CCD-star sensor nowadays. A kind of optimum baffle design method is expounded in this article. The old design of baffle uses vanes to absorb and attenuate the stray lights, which would be eliminated by scattered and absorbed in the baffle. Whereas, in new method reflex surfaces would replace vanes, the light would be removed by reflected and absorbed.
Polar-coordinate laser writer: analysis of exposure dose distribution
In the single point laser direct writing (LDW) process, there are differences between the exposure dose distribution and the light intensity distribution, and the differences will bring the line profile errors. In this paper, the equations to calculate the exposure dose distribution for the polar coordinate laser direct writing system are presented. The differences between the exposure dose distribution and the light intensity distribution are discussed. The line profile in the photoresist after development is predicted. The experimental results agree well with the theoretical forecast.
Vibration-resistance technology of phase-shifting interferometry
Dong Wu, Jinbang Chen, Lei Chen, et al.
A vibration-resistance phase-shifting interferometer (PSI) was recently constructed and demonstrated. In this instrument, we have developed a method for actively compensating for vibration using a closed-loop phase servo system. An essential feature of this is phase modulating interference fringes fractionizing technology. This method can detect the fringe movement at 1/400 fringe interval, so fringes phase can be locked by the closed-loop feedback within 0.005 π. And the instrument implements phase shifting with the same piezoelectric transducer (PZT) that also compensates for vibration as feedback device. A microprogrammed control unit (MCU) is used to process phase information from photoelectric receiver, and then output the control signal to PZT driver. Experiments show that this solution is unique.
Laser moire deflectometry system used for fire science research
Qiang Xu, Guangxuan Liao
An improved laser Moire deflectometry system is designed for fire safety science research. It has larger scope than conventional system. Relatively larger scale experimental simulation can be carried out with this system. It was used to study the flow procedure of ceiling jet and propagation of fire on solid combustible material. Research of ceiling jet illustrates flow procedures of ceiling jet of different ceiling constructions. The procedure of hot buoyant plum propagating across barrier was clearly displayed. It provides reference to ceiling construction design and dynamic performances evaluation of fire detect system. Detection time lag is one of three distinct time lags that contribute the effectiveness of fire detection systems and fire mitigation strategies. Two sets of photographs are present corresponding to ceiling jet with different cross girders.
Reflecting optical system to increase signal intensity in confocal microscopy
In fluorescence mode confocal microscopes, only 0.02% of emitted signal can be detected in best case. So, we proposed reflecting optical system to increase signal intensity detected in photon detector. In this paper, we evaluate the proposed reflecting optical system using optical transfer function. To evaluate the proposed system, we used the modeling method based on wave optics. We first calculated point spread function of total system, and calculated optical transfer function of total system. When we use the proposed reflecting optical system, we can increase the signal intensity detected in photon detector. Amount of increased signal intensity depends on the ratio of NA of objective in the original confocal microscopy to NA of objective in reflecting optical system. We also simulated axial response of total system. FWHM of axial response increased a little when using reflecting optical system. The amount of increased FWHM also depends on the ratio of NA, mentioned above. Maximum increase in FWHM of axial response is about 5%.
Polychromatic modulation transfer function analysis of color LCD
The analysis of the polychromatic modulation transfer function (PMTF) for evaluating the image quality of the color LCD monitor is presented. The PMTF is easily calculated from the values of the MTF weighted by the overall spectral response of the system. To obtain the spectral response of the monitor, the chromaticity (x, y) and luminance are measured with a spectroradiometer. The variations of the luminance, chromaticity (x, y), and MTF of the color CRT and LCD monitors for different viewing angles are measured. We designed a synthetic equipment that could obtain the chromaticity (x, y), luminance, and MTF of the color monitor simultaneously. The experimental results of several color monitors made in Korea are presented.
Alternative method for simulating IPSF in two-photon laser scanning microscopy
YongJun Zhou, DeQiang Chen, Wenhao Huang, et al.
The refractive-index mismatch induced by coverslips will lead to the distortion of two-photon laser scanning microscopy (TPLSM) images. Such distortion will result in the elongation of the intensity point spread function (IPSF). In order to predict the trend and extent of the distortion, we develop a new data proceeding method which combines Torok’s theory with the experimental value. This method considers the fluorescence quantum efficiency of the sample together with the detection efficiency of the system. By calculating IPSF and using our method to proceed the data, the simulation results are quite consistent with experimental results.
Analysis of resolving power in linear optical image systems
Jiwu Chen, An Chen, Zhineng Li
The two-point resolution of optical image system has long been introduced in several literatures. The process was not only based on diffraction effects, but also on the sine condition in spherical centred system, which is not held in ideal optical system according to Gaussian optics. In the paper, the view point is used that image point determined by Gaussian optics, is formed by diffraction effects resulting from the exit pupil according to Rayleigh theory. The viewpoint could be regarded as basing on linear system, as diffraction-limited imaging system is essentially in accord with linear system theory. The two-point resolution formulas of linear optical image system are derived under the viewpoint, and one of the conclusions is that even if the diameter of the exit pupil, or the entrance pupil, is infinite, 0.61λ is the distance between two object points which can be just resolve.
Appreciation method for the maximum acting distance of infrared TV goniometer
Zhibin Chen, Yan Liang, ShuLi Long, et al.
The maximum acting distance of infrared TV goniometers is a key index to appreciate its overall performance. By means of the theoretical research on the transmission equation of the infrared wave in the atmosphere and the technical analysis on the receiving property of the infrared TV goniometers, an auto-appreciating system for the maximum acting distance of infrared TV goniometers is presented which is controlled and processed by computer. The system uses advanced high-power infrared LED (light emitting diode) source driving technique, adjustable driving voltage technique controlled by DAC and image process technique. In addition, compared with the experiments of the firing ground, the validity of this method has been proved. Results from the system can also offer the reference to appreciate the effective acting distance of similar instruments such as laser ranging and laser navigation. As a result, this research is very valuable in the infrared wave application.
Automatic testing method on the consistency of optical axis for the continuous vari-focus laser communicating system
Zhibin Chen, Yong Zhang, ShuLi Long, et al.
The consistency of optical-axis between aiming and transmitting of continuous vari-focus laser communicating system is the important factor influencing the effective distance of communication. Therefore, the research for the consistency of optical-axis is very important. Based on the analysis of the defects of the present testing method which examine the deviating extent of the aiming light spot from the reticle by eye observation, The paper provides a new testing method for the continuous vari-focus communicating system such as the application of advanced image-sampling technique by CCD and image-processing technique by computer, especially close-cycle adaptive controlled image-processing technique. Meanwhile, the paper designs a advanced automatic testing equipment. The result of experiment proves the feasibility of the project and shows the broad applying prospects.
Computerized testing equipment for the resolution of night vision instrument with faint light
Zhibin Chen, Yan Liang, ShuLi Long, et al.
Based on the analysis of the present testing principal and methods, a novel testing design for the resolution of night vision instrument with faint light is presented. According to the principle technical design including the programmed resolution chart with adjustable pattern, Cathegreen collimator and CCD image sampler, this paper provides a unique testing equipment to the resolution of night vision instrument with faint light which can all be controlled, processed and displayed by computer. This testing equipment overcomes many defects of the traditional testing methods such as the harsh request of the testing field and environment, the inconvenience of changing the resolution chart and the influence of the subjective factor etc. Because of its small volume, light weight, high computerization and simple operation, the testing efficiency is improved greatly. Also, with its high accuracy and low cost, this research work can be reference to much more accuracy resolution testing of other optical instruments. It has a good prospect to be popularized and applied.
Design of new type of isosceles blazed grating
Yiqing Gao, Tingzheng Chen, Haibao Lu, et al.
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.
Non-contacted instrument for measuring the error of NC cutter holder
Xibo Ding, Jianyin Guo
NC cutter holder is one of NC machine’s important accessories. Now index gauge still was used to measure the angular indexing error and repeated location error of NC cutter holder. A few mechanical instruments have been developed, which are more accurate than index gauge, but the requirement of high accuracy and convenient operation can not be fulfilled. To solve the problem, we develop a new photoelectric non-contact displacement instrument, the non-contacted instrument for measuring the error of NC cutter holder is designed based on it. It has many advantages, such as simplify structure, low manufacture cost and high accuracy. The instrument’s discrimination can achieve 0.1 μm, the results showed the instrument’s accuracy is about ±0.3μm.
Laser-level sensor with high precision
Jingwei Dong, Xin Li, Jing Liu, et al.
Aimed at difficulties of measuring level of the cans storing high viscidity liquids, the paper puts forward a new method to measure liquid level, whose principle is using laser to measure distance. Two signals with different frequencies superpose each other and drive a laser launcher. The laser beam with two frequencies launched at the same time was reflected back at liquid surface (tiny bead reflector needed). The reflected laser beam is received by a laser receiver and then is divided into two signals to input to two mixers. After enlarged in time scale, outputs of mixers are input to phase discriminators. After data processing, high part and low part of the liquid level with different precision can be worked out. The analysis of measuring principle of this method and experiments on the field show: the general measuring error of liquid level is less than ±2mm, the measuring range is 1~25m.
Measuring method on relative image stabilization accuracy
Yuegang Fu, Zhijian Wang, Chunyan Wang
The testing system for the image stabilization accuracy of the optical stabilizing system is presented. In this paper a measuring method on relative image stabilization accuracy is given, which use a micrometer adjustment. The object lens of micrometer adjustment designed on the method of wave aberration. The analyses of precision also are given.
Method of adjustment and examination of optical axis' parallelism of laser rangefinder
Yuegang Fu, Huilin Jiang, Zhijian Wang
This paper primarily studies the project of adjustment and examination of optical axis’ parallel of a visual device, especially to laser rangefinder’s three axes’. One way which uses either big aperture collimation mirror of off-axis paraboloidal mirror or of coaxial paraboloidal mirror is put out and outdoors examination method is also given. Use a tool that can measure the parallelism of optical axis.
Emission spectral reconstruction of arc temperature fields
Yuehong Gan, Yiqing Gao, Xinmin Qi, et al.
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.
Optical involute aspheric surface
Shujie Geng, Wencheng Wang
Involute aspheric surface is a new type of optical aspheric surface. In this article, the involute aspheric surface’s general equation is discussed, and the characteristics of its aberration and technology are analysed. The conclusion that involute aspheric surface is axial symmetrical rotation aspheric surface, and it has second level aberration and fine characteristics of aberration and technique can be drawn here. Involute aspheric surface has practical value in optical system design, and it can provide a new degree of freedom to the designers of optical system.
Algorithm for automatic interpretation of interference fringes
Yunhua Gong, Ping'an He, Lin Zhou
Concerning automatic interpretation of interference fringes, current algorithms, such as typical hit-or-miss transform, always extract the characters by binary images, which are sure to lose some available information. Hence a new automatic interpretation algorithm of interference fringes is proposed, which uses their own gray characters and designs an appropriate weight function, then solves a series of curves to which the integrals of the square of the distance from each point of the fringes is minimal, that is to say, resolves expectations of fringes under the weight function designed. Furthermore the new algorithm has the functions of extracting the multiplicity of fringes as well as image processing. And the algorithm is insensitive to the random noise when the weight function is an odd function of gray.
Orbit environment analysis of the spaceborne imaging spectrometer
Linghua Guo, Xin Zhang, Xiaojie Cong
This paper summarizes the technical specifications of the Space-borne Imaging Spectrometer. The remote sensor consists of 20 bands including visible, near infrared, short wave infrared and thermal infrared channels. The engineering model (EM) was completed. Using the software CODEV, we discuss the influence of the space-borne environment, different temperature, especially different assembling material on this instrument. Data show that the main optical system is sensitive to the space-borne temperature; the space image quality is affected heavily by the assembling material and etc. The orbit environment analysis is of great advantage to the optical set-up, environment experimentations and cost saving.
Design of Fourier transform lens and its use in optical correlation detection
Yangxue Guo, Wensheng Wang, Ye Zhang, et al.
High accuracy correlation detection technology of object signal is to search and detect objects by optical correlation, and it can detect in real-time, recognize automatically and orientate precisely. Optical correlation processes images at light speed and its device is simple, and Fourier transform can be realized. In this article, we mainly study how to design optical Fourier transform system which can realize optical correlation.
Autotesting method of angle of optical fiber endface based on principle of geometric projection and mathematical morphology
Ping'an He, Aijun Zeng, Yunhua Gong
Optical fiber connection with beveled endface is applied to enhance return loss in optical fiber communication, so the angle of endface is an important parameter of the optical fiber that needs to be tested before connection. Perfect optical fiber endface is an area in an intersection plane across a cylinder of the optical fiber and the projection of the area is an ellipse or line relative to the beveled angle. Because imaging of microscope objective follows the principle of geometric projection, when the optical fiber endface is imaged in CCD by a microscope objective, the image is the amplified projection of the optical fiber endface. With a video capture card, the digital image is formed in the computer. The equation of the projection is resolved by means of digital image processing, and then the angle degree is calculated. In course of image processing, edge detection and thinning of the image is based on mathematical morphology and curve fitting is based on least square method. It is shown by the result that the precision of the angle degree is between 0.2° in the method.
Modern aspheric manufacturing technology
Geng Jian, Changshun Hui, Jian Zhang
Aspheric optical elements have been applied in many kinds of advanced optical systems especially in military and space optic fields accompanied by the development of the optic science. Ultra-precision aspheric surface can improve the optical performance effectively. It also can reduce the dimensions and the weights of the systems, which is the major advantage of it. In order to achieve the high-precision aspheric surfaces, some methods of the aspheric fabrication and metrology have been generated such as the diamond turning, molding, holography and some other special polishing manners based on the traditional craft production and measurement. In this article we described the manufacturing methods of aspheric element in brief and then we posed one way of the production about the aspheric surface. We introduce not only the manufacturing machine and measuring instrument about this kind of element but also the optical and mechanical parameters about the grinding and polishing, as well as technology of the process control. All devices compose a cycle of the production that is flexible and convenient to generate aspheric elements. It attribute to the high-speed production and improvement of efficiency in the factory.
Digital research on using CCD to detect the performance of optical device
Gang Li, Bing Zhou, Wengang Hu, et al.
This paper introduces some new methods for measuring parameters of the telescope system with CCD device such as OTF, parallax, diopter and so on. It doesn’t need man’s subjective judgment. The computer accomplishes the assignment to display, print and save the results automatically. So, these methods have some advantages: high accuracy, digital display, and autoimmunization. Basing on the mentioned theory analysis in the paper, we have realized the digitization checkout of a lot of parameters on same instrument.
Time-space filtration research on CCD static image retrains the noise
Gang Li, Shou-Cheng Cheng, Chunmei Xu, et al.
Against those problems discovered using single-slit to measure OTF, this paper puts forward the time space filtration method to restrain these noise. Experiments verify that the method has gained better effects. Using CCD to measure other parameters, it also has very good reference value. Increasing the sample times can gain better filtration effect. But the time space filtration of long time and multiposition is not very meaning to the raising of measurement. Compare many filtration times, we find that average of time filtration for 8 frames pictures and space filtration for 20 lines is suitable. This experiment results accord with related theory.
Research on the portable photoelectric railway ruler
Xin Li, Jingwei Dong, Jing Liu, et al.
This paper presents a new method to test horizontal levelness of railway and gauge based on principle of photoelectric conversion. The paper emphasizes structure and operating principles of sensor and solves problems of the difficulty of zero calibration in measuring levelness and lowering power waste in portable instrument. Fundamental of whole design of the instrument is presented; error is analyzed; prototype is developed and calibrating experiment is accomplished. The result of experiment follows: prototype’s resolution power is 0.1mm, its non-linear error is less than 0.05%, its delaying error is less than 0.1%, its repeated error is less than 0.1%, its error coefficient of temperature stability is less than 0.015%, and precision of whole system is higher than 0.2%.
Modulating transfer function used for fiber endoscope testing
Meirong Lin, Fang Fang, Yu Guo, et al.
The modulation transfer function (MTF) has been used to evaluate the image quality of the optical system. There are no papers discussing the MTF of the endoscope system. This paper discusses the image quality of the fiber endoscope system by MTF. We found that the defocus error and the discrete pixel structure of the image fiber bundle are the two main factors of influencing the system resolution. The theoretical MTF values of the fiber endoscope system at the different working distances were calculated. The highest spatial frequencies that can be distinguished by the system at the different working distances were gotten through the MTF. The theoretical results were compared with the system resolutions that were measured experimentally. We found that the agreement between theory and experiment was excellent. Finally, we suggest that the system resolutions are determined by different factors in different cases.
Digitalized detection of optical axes' parallelism in multi-optical axes system
Bingqi Liu, Jun Ling, Bing Zhou, et al.
Automation and intelligent function in performance testing of optical instrument are the key problems in modern detection technology. In this paper a testing system based on the detection in laboratory is proposed and has successfully realized the detection of multi-optical axes’ parallelism. This system is on the base of optics, mechanics and electricity, and combines the modern computer technology to gather and process the data obtained in the experiment, finally high-precision quantified results can be gotten, so these results can provide reliable data for the alignment of optical axes. The paper introduces the whole testing system’s design options, system composition, operational principle and software design in detail, and it’s technical difficulties and emphases are also analyzed and discussed.
Real-time measuring system for veiling glare index of optical system
Binqi Liu, Xilin Zhao, Yanzhong Han, et al.
Based on the principle of black-spot measuring method for veiling glare index of optical system, we put forward realizing the research and design of real-time measuring system towards veiling glare index of optical system with CCD camera. In the course of experiment the handling technology to digital image is adopted. It can eliminate the effect of non-measurement signal. The measurement results can be digitally displayed with real time, and they can provide quantized reference for judging the severity of faulty work on the optical surface. The method can possess the higher measurement precision. In this paper, we introduce particularly the design plan, system composition, and flowchart of software.
Optical-electrical measuring technology of multibarrel parallelism of the multibarrel rocket launcher
Hong Ma, Ye Wang, Suping Bai
This paper describe the principle of a system that use the laser collimation system and coder to measure the parallelism of long-range multi-barrel rocket launcher. This measuring technology and this system can measure the variety multi-barrel’s parallelism that with diameter of between Φ100mm~Φ350mm and length under 10m, its measuring error σ≤10”.
Study on a laser inspecting device for straightness of bore
Hong Ma, Ye Wang, Suping Bai
This paper describe a kind of measure instrument and its mechanism and composing that apply laser collimation technique and photoelectric detect technique to measure the linear error of cannon barrel, it can instead of the traditional optics measure method, and realize the scathe less automatic measure.
CCD instrument of Newton's ring
Li Ma, DaoFu Han
CCD micrographic optical system is applied to observing and measuring Newton’s rings. The reduction of the resolving power for the micrographs can be compensated by image processing. Contrasting with the JXD-1 microscope, on condition that the measuring precision is alike, CCD instrument of Newton’s ring has the better observing effect, its visual field is enlarged to 2.5 times, the date can be collected more conveniently and there are no outside disturbs. By setting up the rule, this instrument can be more suited to the demands of the optical experimental teaching for today’s university.
Research on polarization parameters testing system
Caihong Mao, Xiaowu Shu, Chen Liu, et al.
Polarization controlling is crucial to increase the accuracy of the fiber-optic gyroscopes. In this paper, a new method and testing device measuring the polarization characteristics of the optical components such as SLD light source, polarize maintain fiber, coupler and polarizer was introduced. This system has good qualities of low cost, easy to operate, high accuracy. Extinction ratio of fiber components can be tested up to 55dB. Tested with that device, Panda PM fiber’s extinction ratio is 25dB.
Research of measurement system of oil tank liquid level based on differential capacitance sensing
Jian Miao
Oil tank liquid level is one of the most important measurement parameters in storing and transmitting crude oil technology, but it is not easy to obtain in severe environment, especially when the measurement site is under inflammable and explosive condition. In order to realize high precision and automatic measurement of the oil liquid level, in this paper a method combining the idea of hydrostatic tank gauging (HTG) with the technology of fiber-optic transmission is described and the mathematical model of measuring liquid level is established. Meanwhile, the characteristics of differential capacitance and thermistor are investigated, and the relationship between pressure and capacitance is deduced. The experiments on oil tank liquid level measurement system based on differential capacitance sensing, such as experiments of pressure-capacitance relationship, calibration of temperature and liquid levels, are performed, and parameters calculation and display are accomplished by hardware and software. All results obtained demonstrate that the system has high accuracy and stability, and is immune to electro-magnetic interference. It is hoped to help us to promote the automatic measurement and calibration and information management of oil tank liquid level.
Design of 3D measuring system of mongline structural light
Yujing Qiao, Xiaoyang Yu, Jun Zhao, et al.
In this paper, a 3-D noncontact measuring method using single-line structural light is put forward. First, the light path for measuring is designed according to the principles, then the mathematical model is derived, in which necessary parameters are defined. Finally the implementation of the system is given out, and the experimental testing results as well.
Combination of a vision system and a coordinate measuring machine for rapid coordinate metrology
Yufu Qu, Zhaobang Pu, Guodong Liu
This paper presents a novel methodology that integrates a vision system and a coordinate measuring machine for rapid coordinate metrology. Rapid acquisition of coordinate data from parts having tiny dimension, complex geometry and soft or fragile material has many applications. Typical examples include Large Scale Integrated circuit, glass or plastic part measurement, and reverse engineering in rapid product design and realization. In this paper, a novel approach to a measuring methodology for a vision integrated coordinate measuring system is developed and demonstrated. The vision coordinate measuring system is characterized by an integrated use of a high precision coordinate measuring machine (CMM), a vision system, advanced computational software, and the associated electronics. The vision system includes a charge-coupled device (CCD) camera, a self-adapt brightness power, and a graphics workstation with an image processing board. The vision system along with intelligent feature recognition and auto-focus algorithms provides the feature point space coordinate of global part profile after the system has been calibrated. The measured data may be fitted to geometry element of part profile. The obtained results are subsequently used to compute parameters consist of curvature radius, distance, shape error and surface reconstruction. By integrating the vision system with the CMM, a highly automated, high speed, 3D coordinate acquisition system is developed. It has potential applications in a whole spectrum of manufacturing problems with a major impact on metrology, inspection, and reverse engineering.
Improving method of estimating autocorrelation function in PCS technique
Jin Shen, Gang Zheng, Mengchao Li, et al.
Particles suspended in a fluid exhibit Brownian motion. This motion is due to collisions of the fluid molecules with the suspended particles. The smaller the particles are, the higher their frequency is. The laser light scattered by particles exhibiting Brownian motion will also fluctuate with time. The fluctuation frequency of the intensity of the scattered light will therefore depend on the size of the particles. Therefore the measured light signal contains information about the particle size. Photon correlation spectroscopy (PCS) is an important method for studying fluctuation frequency of the intensity of the scattered light, in which autocorrelation function estimation plays a key role. Accurate particle size measurements are possible only when the autocorrelation function is of high quality. Based on the character of software correlation, two measures, subtracted average from the signal and adopted non-bias estimation, were taken in this paper to improve the quality of software estimation. The results indicate that it is feasible for getting better autocorrelation estimation using the software autocorrelation method.
Measure passive incident laser beam's space direction by use of the PSD
XueJu Shen, Yanxiong Niu, Chu Zhang, et al.
The principle of measuring passive incident laser beam's space direction by use of the PSD (photoelectric site detector) and structural design of system are presented. Theory and experiment show passive incident beam's space direction can be determined accurately and quickly.
Algorithmic analysis of single-ring absolute coder
Haibing Su, Enhai Liu, Qin Zhang Wu
Single Ring Absolute Encoder is a mostly lately encoder technique. The angle measuring method which use black-white stripe to encode in Single Ring Absolute Encoder break through the encoding principle in the conventional grating signal process. The achievement of the Absolute Encoder interinfiltrate many techniques including the sensor, image processing, computer control, hardware integration and so on, and adapt encoder progressive demand on miniaturization and intellectualization. Closely centered on the most lately encode mode of Absolute Encoder, the paper systematically expatiated the plate encoding principle and location algorithm. A binary incising algorithm is applied to district number; and an adaptive edge fetch algorithm is offered for sub-pixel division of image signal on the border characters to calculate the center lines location of every stripe on the plate; and the perfect software filter is applied to lessening the noise during image collection. In this paper, the fundamental principle and theoretical basis of Single Ring Absolute Encoder is specified, and the system hardware design is illustrated. The experimental results fully demonstrate the correctness of system and theoretical basis.
Automatic examination and correction of optic-axes error in impluse laser range finder
Meikai Su, Zhiyun Gao, Fang Zuo, et al.
The impulse laser range finder has been used broadly in military affairs. The “optic-axes” of the laser range finder usually refers to the white light aim axes, laser emitting axes and laser receival axes. The three axes must be parallel to each other. As the range finder is designed, in general, it make sure that the white light aim axis and the laser receival axis is parallel each other in structure. Therefore, to examine and correct the three axes of the device becomes to examine and correct the two axes of the white light aim axes and the laser emitting axis. When the laser ranger finders are used in field operations, there is often a misadjustment of the axes, so the range finding ability is declining. In this paper, By using the image of CCD, we have obtained the error of the two axes and calculated the error by computer. We can adjust the eccentricity ring of the finder according to the calculated error. Automatic examination and correction of the optic-axes error of the finder are realized.
Preparation and properties of inorganic-organic infrared window hybrid material
Jing Sun, Xiaoxian Guan, Jinghe Liu, et al.
In this work, excellent property infrared (IR) window composite materials was obtained by inorganic-organic compound method. Scanning Electron Microscopy (SEM) observation found that inorganic particles were distributed uniformly in the organic matrix, and good combination between inorganic and organic phase were obtained. The measurement of vitrification point showed that glass temperature of composite materials were higher than that of pure plastic matrix, so the temperature range of application of this kind of composite materials was expanded and its transmittivity was about 80% when wave length was before 30μm.
Linear CCD based novel visual sensor for intelligent spherical tank welding robot
Zhenguo Sun, Junbo Wang, Qiang Chen, et al.
In order to fulfill autonomous climbing and automatic weld seam tracking, a novel visual sensor has been developed for intelligent spherical tank welding robot. Composed of a high-resolution linear CCD, an optical system (including light source, filter, lenses and so on), and an all hardware photoelectrical signal processing circuit, the designed visual sensor could avoid the interference of the arc light during welding and provide the seam track signal precisely in real time. In this paper, the construction and working principle of the linear CCD based visual sensor have been illustrated, then principle of weld seam track detecting has been introduced thoroughly. Equipped with the visual sensor, the spherical tank welding robot could move along the weld seam autonomously, could align the welding torch with weld seam automatically. Therefore, the requirements of multi-layer, multi-pass welding process for spherical tank manufacturing have been met.
Analysis and design of a pulsed-light emitter for time-resolved fluoroimmunoassay
Zhen Tian, Zhouyi Guo
This paper deals with a pulsed-light emitter, which is a perfect source for time-resolved fluorescence immunoassay (TRFIA). Using a time-controlled circuit and an energy-controlled circuit, the set can emit high frequency pulsed-light. The frequency is 1000Hz. The wavelength range is from 280nm to 280nm, the pulse width is 54μs, and the output power of ultraviolet radiation is more than 200μw.
Study of limited-view tomography algorithms for plasma diagnostics
Xiong Wan, Yiqing Gao, Shenglin Yu
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.
Design for a kind of infrared target
Yuefeng Wang, LiWei Zhou, Wei Zhang, et al.
This paper analyses the performance needed of the infrared target in the testing of features of infrared thermal imager. The method of design and its theoretic foundation is presented.
Design of infrared collimation converter in temperature distrubance
Yuefeng Wang, LiWei Zhou, Wei Zhang
The Minimum Resolvable Temperature Difference (MRTD) is a key performance of thermal imaging system that is determined by the use of infrared collimation converter. The performance of the infrared collimation converter affects the accuracy of the measurement much.
Total performance measurement of infrared thermal imager
Yuefeng Wang, LiWei Zhou, Feng Huang, et al.
In the past, the measurement of MRTD, MTF of Infrared thermal imager usually used the eye subjective method. This method is more applicable, but its result is hard to decide and easy to induce dispute because of the effect of eyes’ subjective factor. The purpose of searching objective method is to eliminate these adverse factors and to present a unitary and objective judging standard. Nowadays several countries, denoted by English, have worked on this field and made big progress. China is on the starting step now. The key of objective measuring method is using computer to draw out the characteristics of infrared image and identify, then describe or judge the identified result.
Gaussian optical analysis for a "3+2"-model zoom lens
Chengliang Wang, Xiangning Li, Liqing He
We introduce a Gaussian Optical analysis method for a common five-components zoom lens, namely “3+2”. This model has covered a great many type of zoom lens forms by regarding some of components as dummy ones. Taking each component as a paraxial one, “3+2” program calculates the geometric optics through the whole zooming range. The output report will show the moving curve of each element. “3+2” can mutually share the information with ZEMAX through the extension feature of ZEMAX.
Power allocation for varifocal lens of two groups
Chengliang Wang, Xiangning Li, Liqing He
The inverted telephoto lens consisting of two groups is required when a long back focal length and a wide field of view are needed. Varying the air space between these two groups would change the effective focal length. In this paper, power allocation for this varifocal lens affected by aperture, field of view and amount of variation of air space is analyzed. The solution of power allocation is introduced, from which large aperture, wide field of view, and small volume is benefit. Six equations, i.e. power region equation, aperture equation, field of view equation, back focal length equation, movable region equation, speed equation, are derived to guide power allocation of this kind of optical system.
Measuring system of cannon's static direction precision
Chunyan Wang, Zhijian Wang, Qingcai Zhou, et al.
Cannon is important force of shock for modern times warlike. In order to put out enemy and save ourselves, we hope it can hit the target of enemy in first deliver. So the precision of the cannon is concerned important by the national defense project at present. In this paper, we will introduce the method of measuring about artillery static directional precision, choosing laser collimation photo-electricity theodolite, designing the accessories of measuring and building an intact testing system. Using this system we can measure the straight angle and height angle of the artillery and work out the actual error. On this basement, we will analysis this measurement’s precision, draw out the bend line of precision. The result of measuring indicated that this system’s measuring precision has reached 0.06 mil.
Testing of the SR5000 spectroradiometer performance
Jun Wang, JiaoBo Gao, Ling Ma, et al.
The SR5000 spectroradiometer addresses a wide variety of military, industrial and scientific applications that demand real-time, noncontact, highly accurate and highly sensitive measurements of object’s radiometric properties. It covers the waveband from 0.207~14.5m, has spectral resolution as fine as 2% and records over 30 spectra per second. In this paper, we describe the testing process and present results of the SR5000 spectroradiometer performance, for InSb/MCT/CVF8 infrared waveband (1.3~14.5m). We present testing data of the FOV flatness and symmetry, the spectral resolution and accuracy, the effective temperature and the noise equivalent temperature difference.
Radial shearing interferometer for aspheric surface testing
Ming Wang, Bin Zhang, Shouping Nie, et al.
In this paper, aspheric surface testing technique with radial shearing interferometer has been developed. Zone plates are proposed to construct radial shearing interferometer because of its stability and simplicity. Zone plates were designed and fabricated by photographic processing, which is used as radial shearing devices. Radial shearing interferogram are detected by a CCD camera and processed by a PC computer. Fringe phase of shearing interferogram is evaluated by Fast Fourier transform (FFT) algorithm. Wave aberration estimation method of aspheric surface is also presented, which is depended on polynomial expansion fitting. Some errors of interferometer are discussed. Finally, theoretical analysis and experimental results are compared, which shows its accuracy is less than λ/20.
Study on a new MTF automatic measure instrument
Ye Wang, Jing Wang
This paper study on a new scanning mini MTF automatic measure instrument and introduce the method of scanning the imagination point by grating and Fourier transformation to get the MTF, and designed a kind of MTF automatic measure instrument that could test the lens with caliber Φ<90mm, 28mm≤f≤250mm. This automatic measure instrument used CCD camera as the photoelectric detector, then use computer and its mightiness memory and processing function to realize auto test. This instrument is small and have high accuracy.
Research on photoelectric test and measurment for form and position error
Jinsong Xie
Structure and principles of a photoelectric test and measurement system for form and position error are described. A special optical system using laser beam characteristics was designed to ensure the uniformity of the scanning speed. To meet the requirements of the system a precision mechanical system a servo-control system and an computing and data processing system are designed. As a result a high-speed efficiency and high precision non-contact auto-test is realized. This is a promotion to the development of “advanced manufacture technology”.
Numerical study of two-dimensional turbulent flow field and the corresponding optical path difference
Wenke Xie, Wenyu Li, Zongfu Jiang
The optically active, turbulent flow field was investigated to simulate a low speed two-dimensional heated jet. Dynamic spatio-temporal index-of-refraction distribution and velocity profile of the turbulent flow field were obtained by applying computational fluid dynamic methods, the corresponding optical path difference numerical results were educed by optical computational methods. Some relationships between the flow large-scale structure and corresponding optical path differences are inferred.
Limitation of collimating ability for aspheric lenses
Nannan Xu, Zhongxing Shao
The limitation of collimating ability for aspheric lenses is set forth in this paper. The equations for analyzing the limitation are obtained by ray tracing method. By programming the equations we calculate the limitation as a function of focal length and index respectively.
Method of 3D curved surface profile measuring and figure processing
Xiping Xu, Guoyu Zhang, Hongmei Xu, et al.
Based on the principle of laser triangulation and the technology of modern photoelectric sensor, a laser scanning optical triangulation measuring system which is used to measure 3-D curved surface profile is presented, the system uses a semiconductor laser probe and combines with 2-D grating displacement measuring systems and servo-control systems to realize scanning many points for the measured curved surface. Through the Fourier transform profile detection algorithm with the frequency field low-pass filter performing, computer finishes the real time data processing, the profile of 3-D curved surface is given with high accuracy and high speed. In this paper, the mathematical model of the measuring system is introduced and the jump-error processing method of the objects with large gradient change is discussed in detail. The measuring result shows that the 3-D figure is simple in use, convenient in parameter adjustment, especially, is suitable to measure the objects surface with large gradient and low reflecting ratio.
Near-infrared spectroscopic measurement system of the constituent concentration based on acousto-optic tunable filter
Qingbo Li, Chengzhi Jiang, Kexin Xu
The near-infrared spectroscopic measurement system of constituent concentration based on acousto-optic tunable filter (AOTF) is investigated in this paper. However, the diffracted beam is often mixed with zero order beam in AOTF optical system. In order to obtain high wavelength resolution and spectral signal-to noise ratio (SNR), the solutions to improve the purity and efficiency of the diffracted light are proposed. The orthogonal polarizing method and the combine modulation method of optics and electronics are discussed. The results show that both methods can effectively eliminate the inference of zero order light. Especially, the combined modulation method not only can increase wavelength resolution and spectral signal-to-noise ration but also simplify the optical system structure and reduce costs. The application concerning the determination of the milk principal constituents verifies the validity of this measuring instrument and analytical method. The results show that the speed is 30 seconds/sample. The milk principal constituents concentrations are determined with root mean square error of prediction (RMSEP): 0.1~0.2 g/dL. Correlation coefficients between prediction values and reference values are higher than 0.9. Moreover, the results are reliable with coefficient of variation (Cv) of repeatability below 0.02. Obviously, the individual component’s prediction accuracy and repeatability can meet practical measurement requirement.
Error forecast and model optimization of laser measurement system
Bing Ye, Yetai Fei
We improved the measurement precision of the original measurement system, combining the optic measurement system and the error measurement forecast system. We have done parameter-operation control over the error forecast model of NN by using the Genetic Algorithm of Chiasma, Reciprocation and Aberrance. By doing so, we effectively prevented the local astringency of the forecast model. We have got error measurement information from the more economical discrete standard source according with the signal-sampling theorem of the error forecast system. The standard source and the workpiece measured are two framework systems on the same conditions. We can do real-time forecasting and correcting of the measurement error.
Production for superpositions of the orbital angular momentum of photons by fork-like grating
Fengwei Ye, Yongping Li
Laguerre-Gaussian (LG) mode carries a well-defined orbit angular momentum. We design a fork-like grating to produce the superposition of two LG modes. It is useful in the high-dimensional quantum communication.
Theory and error analysis of 3D measure system of structural light
Xiaoyang Yu, Yujing Qiao, Jing Lu, et al.
In this paper, the 3-D measuring system based on structure-light, which principle is that its distortion can be transformed into the height change in the direction of the stripe if a single-stripe light is emitted and observed sideways and a generator emitting a single-stripe light and a camera can make up of a 3-D measuring system, was designed in order to inspect the shape of product surface on-line in the industrial production. At first, this paper introduces the structure of the 3-D measuring system using the single-stripe structured-light and its buildup. At second, its operating principle is introduces, its mathematical model is established and the calibrating method for it is put forward. At last, its prototype is produced and calibrated. The experimental result shows that the mathematical model put forward in this paper is suitable for engineering, the system calibration method suggested in this paper becomes more simple than other calibration methods, the system prototype has the range of 630mm(Depth)×400mm(Height) and the accurate of 0.3%(Depth)×0.5%(Height).
Numerical correction of infrared two-color thermometry
Lihua Yuan, Juning Zhou, Yiqing Gao, et al.
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).
Classification and quantification for boiler dust
Zhoumo Zeng, Yi Liang, Qing Yang, et al.
A non-intrusive optical technique for the study of moving particles and their statistics, laser phase Doppler anemometry (PDA), is used in on-line inspecting and quantifying boiler dusty. PDA collects and processes Doppler signals from moving scattering particles and provides a deterministic measure of particle velocity and statistical information about particles’ size and size distribution. Furthermore, PDA is superior to the traditional intensity based optical particle analyzer, as Doppler frequency or phase shift is less susceptible to electronic noise than intensity. These features are important for reliable results, especially at in-situ application. The present system operated successfully in inspecting soot letting of coal-fired boiler, which leads to an active structure that can be applied in the conditions of limited optical access. The measuring results of soot parameters, as well as the statistics of soot are presented in this paper.
Double-diameter laser-scanned measuring system
Guoyu Zhang, Xiping Xu, Xiuhua Fu, et al.
Based on signal direction laser-scanned measuring technology, a double diameters laser-scanned measuring system is presented. The system adopts laser-scanned measuring technology combining with the special spectroscopic optical systems to form double directions laser-scanning beams, and to simultaneously realize high speed and accuracy non-contact automatic measurement of the diameters of two perpendicular directions at one section of measured workpiece. In this paper, the mathematical model of the measuring system is established. The working principle and overall structure of the system are introduced. The semiconductor laser beam transferred optical system, the scanning emitting and receiving optical systems; the optoelectronic transformation electronic system and microcomputer real-time control and data processing system are discussed in detail. The possibility of the system has been verified by experiments and errors analysis.
Research and manufacture of two-photon response Si photodetector
Xiaoting Zhang, Hanlan Li, Gang Jia, et al.
The physical mechanism of two-photon response was studied in this letter by measuring characteristic of the two-photon response Si photodetector sample. And the conclusion was drew that field induced double frequency absorption was dominant in two-photon response, which established the foundation of fabricating high sensitivity two-photon response Si photodetector.
Laser profile converted device
Xinming Zhang, Jingfeng Wang, Jiandong Yang
A new optical expander is developed in this paper. It converts a beam of light from an Ar+ laser which has a diameter of 0.8 mm to a rectangular collimated light beam which has a height of 50~150mm and width of 1~10mm. This collimated light beam can be shifted 0~100 mm and convert 90° continually. The system is used in measuring fluid motion distribution. Its luminous energy utilization radio can reach 90%, much higher than 12.5% ratio of traditional expanding method.
Illumination system design applied to LC rear projective TV system
Zengbao Zhang, Zhicheng Weng, Jun Chang, et al.
Based on analyzing the LC rear projective TV system, a fly-eyes lens array telecentric illumination system has been designed, which can magnificently improve the optical performance. The modeling result by means of the LightTools software shows that the uniformity can reach (+4.8%, -6.0%). And the effective energy can be above 91%. At the same time this paper also explicates the method of coupling of illumination system and projection lens system.
Real-time far distance microvibration measurement using an external cavity semiconductor laser interferometer with a feedback control system
Weirui Zhao, Pengfei Jiang, Fuzeng Xie
An external cavity semiconductor laser interferometer used to measure far distance micro-vibration in real time is proposed. In the interferometer, a single longitudinal mode and excellent coherent characteristic grating external cavity semiconductor laser is constructed and acted as a light source and a phase compensator. Its coherent length exceeds 200 meters. The angle between normal and incidence beam of the far object is allowed to change in definite range during the measurement with this interferometer, and this makes the far distance interference measurement easier and more convenient. Also, it is not required to keep the amplitudes of the first and second harmonic components equal, and then the dynamic range is increased. A feedback control system is used to compensate the phase disturbance between the two interference beams introduced by environmental vibration.
New type of thermal imaging radiometer
Bing Zhou, Gang Li, Bingqi Liu, et al.
A new type of design for the thermal imaging radiometer is presented in this paper. The new system has many advantages, such as that the apparent temperature configuration of the measured object is showed with image manner, that measure results and parameters of system status is displayed with graphics intuitively, that measure data can be saved easily and conducted further process, etc. Besides these, it has very nicer imaging radiation measure capability, high automatization degree. Its orientation is easy, and field experimental operation is convenient. With so many advantages, it offers an effective method to realize the spatial distributed measure for a target’s infrared radiation, the measure for its variation per hour and the measure for its intensity and dynamic range of the radiation.
Scaling method using laser inteference for microdisplacement measurement system
Xiaojin Zhu, Xinmin Qi, Yiqing Gao, et al.
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.
Application of neural networks in photogrammetry of dynamic targets
Ping Li, Xiaofeng Mu, Yuqi Zhao
The photogrammetry system can provide the coordinate, speed and acceleration of a flying target in space. Its background is disorderly and interference sources are many in number, so that the target recognition and signal processing are difficult. This paper adopts multiple front freeback neural networks to replace traditional mode recognition methods. It has the features of high parallel arithmetic capacity, distributive information storation and parallel proceeding. According to the features of flying targets, useful signals are extracted from various information, therefore, the sampling and recognition can be realized. The combination of artificial neural network techniques, photo recognition and artificial intelligence techniques, improves the speed of photo processing and recognition, and increases the exactness.
Hybrid diffractive-refractive head-mounted display with reflective relay system using micro-liquid-cyrstal on silicon
Huijue Zhang, Zhaoqi Wang, Qiuling Zhao, et al.
As the micro-display applied to head-mounted display, the optical system not only suits for the small size of the micro-display, but also provides sufficient eye relief and exit pupil, and it becomes perplex. For settling this problem, a head-mounted display, which combines a hybrid diffractive-refractive eyepiece with a reflective relay system using a liquid crystal on silicon (LCOS) with the diagonal size 18mm, was designed. Basing on a Zeiss (60°) eyepiece, and replacing the doublet of it of a diffractive-refractive doublet, a hybrid eyepiece with 20mm eye relief and 10mm exit pupil was designed. The weight greatly reduced and the optical performance improved of the eyepiece compared with the Zeiss one. Considering the space for illuminating source of LCOS, a reflective relay system was used, which includes a flat half mirror and a concave mirror. The magnifying power of the relay system also makes the optical system suitable for the small size of LCOS. The system is with high performance, sufficient exit pupil and eye relief, and reasonable size and weight in the specific application of head-mounted display.
Methods for enhancing the resolution of AOTF as a NIR spectrometer
Yong Ni, Kexin Xu, Chengzhi Jiang, et al.
AOTF (acoustic-optic tunable filter) has been widely used in spectrum detecting because of its particular advantages. The spectrum resolution is the most important parameter of AOTF spectroscopy. The resolution of AOTF is mainly determined by the purity of diffractive light, the side-lobe and the bandwidth. In this paper the foregoing parameters are analyzed systematically. The following methods are put forward to enhance the resolution. A new theory of equivalent point for the AOTF designing is introduced. The purity of diffractive light can be improved by either optical modulation and electrical demodulation or bipolarization. By altering shape of the acoustic transducer, the side-lobe can be cut down for energy distribution of supersonic passing AOTF has been changed. Fourier self-deconvolution method is adapted to decrease the bandwidth. Highly resolution can be gained with the help of these methods. Compared with usual AOTF system, the performance of enhanced one is greatly improved. The conclusions have been verified by experiments with using higher accurate FT-IR system.
Method of multi-white-light-beam interfering and its application in fusion-sensitve measurement of distributed optical fiber
Jie Sun, Tiegen Liu, Yimo Zhang, et al.
Comparing with interfering of laser beam used in the position measurement, the method of white light interfere can be used in the measurement of absolute position. As the zone of white light interfering is very small, so the limitation of relative measurement by using laser can be avoid. The equipment for interfering measurement of multi white light beam with one referent white light under the law of white light interfering is presented in this paper. The original light in this equipment is divided into several parts, and each part is made as one incident source of one sensor. The optical fiber sensor modulated the light above in phase and then the output light will interfere with the reference light. As the range of white light interfere occurred is very small, so the optical path of multi white light beams can be measured within one step of scanning by the equipment described in this paper. The method given in this paper is one of the most proper methods for fusion measurement in distributed optical fiber sensor.
Hyperboloid catadioptric omnidirectional imaging system
Jiyong Zeng, Xianyu Su
A method based on the field of view is put forward to design hyperboloid catadioptric omnidirectional imaging systems. The re-projection formulae about this kind of system are derived, thereby the coordinate mapping between the virtual image plane and the real image plane is established, which offer a essential model and a calculation method to deal with video images. According to our design method, a hyperboloidal mirror is developed, and a hyperboloid catadioptric omnidirectional imaging system is established.
Degradation of image quality caused by vibration in push-broom camera
Peng Xu, Qun Hao, Chanqning Huang, et al.
It is important to analyze the degradation of image quality caused by camera vibration in order to determine the tolerance of the stabilization in the satellite attitude. We have proposed an improved model for calculating the MTF of a push-broom CCD camera, and constructed two kinds of experiment system to measure the degradation of the MTF caused by vibration. The calculated MTF with respect to low-frequency vibration agree with the experiment results, indicating the model is valid for studying the stabilization of satellite attitude.
Physical simulation system for studying contrast transfer function of remote sensor
Peng Xu, Qun Hao, Changning Huang, et al.
Studying the characteristics of target and background is very important to determine the parameters of the remote sensor and the light condition. We have established a physical simulation system for studying the contrast transfer function (CTF), allowing us to change light condition; camera parameters, such as relative aperture, TDI factor, incline angle; the target and background. We measured the CTF with different target and background, and compared the results with calculated CTF.
Virtual testing technique applied in aspheric surface testing
Mengxia Liu, Huilan Liu, Jun Li, et al.
The new generation’s so-called intelligence “virtual testing”, the combination of computer technique and testing technique, comes into being. Virtual testing makes use of advanced virtual instrument technique, changes the original work that can be completed by traditional optical instrument hardware. Virtual testing can decrease the request of hardware, simplify the instrument construction, decline cost and increase testing precision at the same time. Aspheric surface plays an important role in modern optics. But the accuracy of traditional testing methods can’t meet the demand. Testing methods become the key of application of aspheric surface. In the paper virtual testing technique is applied at aspheric surface testing and the result shows that the technique can improve the testing precision.
Some design problems of the monochromatic system using AOTF as dispersive element
Zhendong Sun, Qiaofeng Duan, Feng Wan
The principle of AOTF (Acousto-Optic Tunable Filter) is first described. Some design problems of the monochromatic system using AOTF as dispersive element is in detail discussed. These design problems include the design of AOTF driver and the design of optical system. In AOTF driver system, the DSP (Digital Signal Processor) is used as a controller, the DDS (Direct Digital Synthesizer) is used as frequency scanner. In the optical system, the paralic cylinder is used as collimating reflector.
Design on monitor system of sulfur dioxide concentration by UV fluorescence method
The UV fluorescence method for real-time monitoring concentration of sulfur dioxide is advanced method in the world at present. Some technical details of its sensor are interesting problems for instrument specialist and user. This paper introduces some design problems of Opto-electronic system with center wave 213.8nm of excitation light source and picking up signal over a range of wavelength 250-400nm. There problems include of spectrum optimal matching, elements characteristic, optimization of sensor system and analyze of experiment result. This research outcome will use to monitoring sulfur dioxide of smoke emitted from power plant.
Design problem of measurement instrument for dust emitting quantity by light scattering
Guanling Yang, Zhenjiang He, YongChang Yu, et al.
The measurement of the dust emitting quantity is one of the important target in the environment monitoring of polluted sources. The design problem of measurement instrument for dust emitting quantity by light scattering principle are discussed in this paper. We have been investigated size distribution of dust particle emitting from thermal power plants. Light energy contribution of dust particle is studied by simulative experimental equipment. And we used a Self Scanning Photodiode Array (SSPA) in multi-ring cuneal to detect and transform the scattering energy and studied the influence of the size distribution of dust on scattering energy at small angle. We think that when design an instrument for dust emitting quantity by light scattering principle, we must consider that the size distribution of dust has influence on the light energy contribution and side scattering caused by small particles has influence on forward received single.
Research on optical system of airborne infrared search and tracking with stared array sensor
Hua Liu, Yongsheng Wang, Chunjie Guo
Infrared Search and Tracking (IRST) system is, by longer detect range, fine camouflage and lower error probability etc., becoming the first above all airborne warfare equipments in modern battles. Stare focal plane array (FPA) coming out, liberates the optical design idea on this system thoroughly. A kind of pure refractive optics, which dispenses with opto-mechanical scan, improves detective method and finishes target tracking in a wider field of view. The fundamental idea and main strategy is developed. In optimized design, damped least squares method and adaptive procedure are used to get higher spectrum range, wider field of view, lower distortion and appropriate MTF. And the project of this integrated multi-sensor electro-optical system is validated by simulation results in CODE V and so on.
Optical Testing
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Scatter analysis for particle contamination of a bisymmetric reflective system
Andrew Cheng
We demonstrate a step-by-step procedure of conducting a straylight scatter analysis due to particle contamination study using ASAP (Advanced System Analysis Program), a versatile, time-tested commercial software for modeling in optical and illumination systems, including wave effects, diffractive and scattering phenomenon. We hope to demonstrate that scalar optical modeling technology is mature and is highly suitable for commercial applications that are beginning to show higher demands in Signal-to-Noise ratios. Other systems that can be modeled include photonic fiber coupling systems, liquid crystal display technology, MEMS devices, as well as high intensity arc sources.
Poster Session
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Length and weight measuring system for steel pipe in fieldwork
Guixiong Liu, Jingrong Yi, Yan Xiao, et al.
Considering the diameter of steel-pipe is from 910mm to 1500mm, the weight is from 1000Kg to 10000Kg, the length is above 6 m and the request of factory, this paper presented the length and weight measuring system for steel-pipe in fieldwork. The relative measuring method with double CCD (Charge Coupled Device) cameras, capturing and processing the images and acquiring the length of steel-pipe with industrial control computer is put foreword. With emphasis on the system structure, measuring principle, demarcating technology and method how to improve the system reliability are investigated. Comprising simple hardware this system is easy to build and demarcate, and the info-benchmark determining and specially the image recognition are depended on software technology, which choosing homologous equivalent image cell weight to convert the length and get higher measuring precision by studying the character of the shape and placement of the pipe termination point image. Via locale run, this system was proved to be firm and the measuring error is less than 10/00.
Driving and controlling circuit for phase modulation of liquid cyrstal panel
Xiaogai Hu, Wei Xue
Using commercially available liquid crystal displays, through redesigning the drive circuit of the LCD, the dynamic range for phase-only modulation is enlarged, and the linearity of the phase response to the addressing voltage is getting better. In this paper, liquid crystal screen driving and controlling circuit principle and designing ideas have been demonstrated, and the principle figure has also been given. Using complex programmable logic device, we completed the entire circuit kernel control problem, and using the circuit to drive and control liquid crystal screen, we attained the experimental results that the maximum phase shift is proximately 1.5π.
Tunable filter with micromachine F-P cavity on the silicon
Yi Ou, Fang Cui, Yunan Sun
In the paper the electric controlled optical tunable filter as a MOEMS device based on the FP resonant cavity on silicon, which will be potentially used in the dense wavelength division multiplexing (DWDM) system, is introduced. It can be used mainly as a wavelength division multiplexer in a DWDM system, and can be used as a optical add-drop multiplexer (OADM) in an all-optical switch system. Its basic operation principle is that one of the two mirrors is made into an elastic membrane structure, then the cavity length is varied under the driving of the electric field force, and the wavelength tuning be realized. The parameters of its characters, the working principle and the basic structure of the device are analyzed and calculated, including the optical properties, for instance, the tunable spectral range, the 3 dB bandwidth, the finesse, and the insertion loss, the structural properties, for instance, the deformation of the elastic membrane under the electric field force, the mechanics property and the couple performance, for instance, the electromechanical couple between the membrane of the FP cavity and the applied electric field. According to the required performances of the device and the subsystem, the preliminary design is performed combining the technique condition. From the analyzed results, the advantages of minuteness volume, low insertion loss, and high adjustment precision are clearly known.
Optical Testing
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Theoretical model of Er-doped Al2O3 waveguide amplifier
Shufeng Li, Changlie Song, Chengren Li, et al.
The large refractive index changes can provide a strong confinement of the electromagnetic field on the active region of erbium-doped Al2O3 rib waveguide amplifiers on silicon substrate with SiO2 buffers. The finite element technique is used to calculate the dispersion characteristics for different rib waveguide geometry. The propagation constants of the quasi-TE and quasi-TM mode and magnitude distributions of electromagnetic field components are presented at both signal and pump wavelengths. A suitable waveguide amplifier transverse cross-section sizes are determined in order to assure the single mode operate at least at the signal wavelength. Bessel distribution field in fiber excites the modes in waveguide amplifier considering fiber-waveguide coupling. The mode excitation fraction is given as a function of fiber core radius. Normalized pump and signal intensities are obtained.
Design of Optical Systems and Instruments I
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Optimize design of the parabolic gradient-index coupling lens for a laser diode to single-mode fiber
Yantang Huang, Chao Chen
In this paper, we theoretically study the optimize design of the parabolic gradient-index lens used as laser diode to single mode fiber coupling lens. In order to enhance the coupling efficiency between the LD and the SMF, we have calculated the aberration (longitudinal spherical aberration (LSA), offense against sine condition (OSC) and optimized the parameter of the parabolic gradient-index coupling lens by solving the ray equation with the standard Runge-Kutta method. From analysis of the parabolic GRIN coupling lens, it turns out as follow: i) axis GRIN constant L can affect the aberration, ii) the plane-convex parabolic GRIN coupling lens with small end towards LD is the best design, iii) we obtain groups of optimized biplane, plane-convex parabolic GRIN coupling lens.