This PDF file contains the front matter associated with SPIE Proceedings Volume 9623, including the Title Page, Copyright information, Table of Contents, Introduction, Authors, and Conference Committee listing.

Rapid inspection of a projection optics incorporated to 193 nm excimer-exposure system is important for 90 nm node and beyond IC manufacturing. To overcome the problems of the collimator lens presented in high NA high accuracy wavefront error metrology with Shack-Hartmann wavefront sensor, a pinhole array is used as the illumination source, which produces an array of high NA and high accuracy spherical waves, and form a high brightness source. In this paper, the diffraction of the pinhole array is calculated by using finite-difference time domain method and the theory of partial coherence. The distribution of the pinhole array considered here includes square, hexagonal and random distribution. The results shown that, pinhole diameter and separation in pinhole array have significant influence on the intensity contrast of the diffracted light, and the light intensity diffracted by the random pinhole array is smoother than that diffracted by the square or hexagonal distribution pinhole array, and is preferential in high precision wavefront error metrology.

Recent trends of interferometric wavefront sensing tend to focus on high precision, anti-vibration, compact, along with much more involved of electric and computer technology. And the optical principles employed not only limit to interference but also include diffraction, scattering, polarization, etc. In this paper, some selected examples basing on the research works in our group will be given to illustrate the trends mentioned above. To achieve extra high accuracy, phase-shifting point diffraction interferometry (PS-PDI) is believed to be a good candidate as it employs a nearly perfect point diffraction spherical wavefront as the reference and also takes advantage of the high precision of phase-shifting algorithms. Cyclic radial shearing interferometry (C-RSI) successively demonstrate the anti-vibration characteristic and can diagnose transient wavefront with only one single shot by employing a three-mirror common-path configuration and a synchronizing system. In contrast sharply with those early interferometers, interferometers with very compact configuration are more suitable to develop portable wavefront sensing instruments. Cross-grating lateral shearing interferometer (CG-LSI) is a very compact interferometer that adopts a cross-grating of millimeters to produce lateral shearing of the diffraction wave of the test wavefront. Be aware that, computer technique has been used a lot in all of the above interferometers but the non-null annual sub-aperture stitching interferometer (NASSI) for general aspheric surface testing mostly relies on the computer model of the physical interferometer setup and iterative ray-tracing optimization. The principles of the above mentioned interferometric wavefront sensing methods would be given in detail.

A new encoding method for absolute angular encoder based on optical diffraction was proposed in the present study. In this method, an encoder disc is specially designed that a series of elements are uniformly spaced in one circle and each element is consisted of four diffraction gratings, which are tilted in the directions of 30°, 60°, -60° and -30°, respectively. The disc is illuminated by a coherent light and the diffractive signals are received. The positions of diffractive spots are used for absolute encoding and their intensities are for subdivision, which is different from the traditional optical encoder based on transparent/opaque binary principle. Since the track's width in the disc is not limited in the diffraction pattern, it provides a new way to solve the contradiction between the size and resolution, which is good for minimization of encoder. According to the proposed principle, the diffraction pattern disc with a diameter of 40 mm was made by lithography in the glass substrate. A prototype of absolute angular encoder with a resolution of 20" was built up. Its maximum error was tested as 78" by comparing with a small angle measuring system based on laser beam deflection.

Micro-Doppler effect, which is induced by micro motion of target or any structure on the target, is a frequency modulation that generates sidebands about the target’s Doppler frequency shift, such as mechanical vibration or rotation.

When a target’s motions incorporate micro motions, the radar echo signal will contain micro-Doppler characteristics related to these motions. Therefore, the micro-Doppler effect provides a new approach to obtain the dynamic properties of targets, which can be used to accomplish the detection and identification of targets, such as the identification of different types of helicopters.

Scattering of the laser spot from a target surface modulates the Doppler signal, causes broadening of the signal spectrum, and, adds uncertainty to the signature analysis. A mathematic model of cone spin, which is a typical micro motion, is built first in this paper. Furthermore, an analyzed equation is deduced to predict the micro-Doppler spectral broadening of acquired medium current signals in situations of different laser spot size. It is found that the beam spot size on the target affects the resulting spectral broadening.

Finally, an experiment based on the scaled model is performed to verify the simulation. A narrow-linewidth single frequency fiber laser is employed to detect the cone target at different laser spot size by coherent detection with constant detect distance and laser power.

The experimental result shows that the beam spot size on the target affects the resulting spectral broadening caused by speckle, which corresponds to the simulation result. The experimental broadening was consistently greater than the theoretical broadening due to other effects that also contribute to the total broadening.

Based on the location technique of beacon photogrammetry, Dual Camera Photogrammetry (DCP) algorithm was used to assist helicopters landing on the ship. In this paper, ZEMAX was used to simulate the two Charge Coupled Device (CCD) cameras imaging four beacons on both sides of the helicopter and output the image to MATLAB. Target coordinate systems, image pixel coordinate systems, world coordinate systems and camera coordinate systems were established respectively. According to the ideal pin-hole imaging model, the rotation matrix and translation vector of the target coordinate systems and the camera coordinate systems could be obtained by using MATLAB to process the image information and calculate the linear equations. On the basis mentioned above, ambient temperature and the positions of the beacons and cameras were changed in ZEMAX to test the accuracy of the DCP algorithm in complex sea status. The numerical simulation shows that in complex sea status, the position measurement accuracy can meet the requirements of the project.

Light efficiency uniformity is a very important parameter of medical rigid endoscope. This paper introduces a new system based on image processing to test the light efficiency uniformity of medical rigid endoscope. Employing an electric machinery to reduce the human intervention, so that the precision of measuring and automation degree are improved. We collect the image with a digital CCD camera and display it on the screen of a computer, which can avoid visual fatigue from the direct observation through the rigid endoscope. To perform the image processing on a computer, we adopt a self-developed image processing software, by which the test results can be obtained from PC itself. The processes of our self-developed image processing software include: gray-scale transformation, image pretreatment and image binarization; calculate the center and equivalent radius of the field of view (FOV); plot the curve, through which the ratio of edge and center in different field and the center axisymmetric of light efficiency can be both calculated. It concludes that the relative self-effect of illumination light luminosity is the foremost factor affecting the uniformity, and these endoscopes are all qualified with the max deviation of the center axisymmetric less than 20%. The results of our study prove that this system can test the light efficiency uniformity of medical rigid endoscope quickly, expediently and accurately, and it contains more information instead of only reflecting a particular field of the FOV, what’s more, it applies to different types, length and angles of view of medical rigid endoscope.

The dynamic envelope curve measurement of high-speed train based on linear CCDs has the advantage of high measuring frequency and speed, and the design of cylindrical lens for linear CCD is essential. A design of cylindrical lens for linear CCD is presented according to the actual measurement requirements. A double-Gauss objective is selected as the basic type in ZAMAX. By appropriately changing the surface of the lens, adjusting various parameters and multiple optimizations, the optical structure is defined. The design can fulfill the requirement of the actual measurement system. Furthermore, by analyzing the image distortion characteristics of cylindrical lens, a kind of distortion model is built. According to the distortion cure of the final optical structure, the cylindrical lens distortion formula is defined based on the primary aberration theory, which provides the basis for the distortion correction of one-dimensional camera.

Multiple synthetic aperture imaging can enlarge pupil diameter of optical systems, and increase system resolution. Multiple synthetic aperture imaging is a cutting-edge topic and research focus in recent years, which is prospectively widely applied in fields like astronomical observations and aerospace remote sensing. In order to achieve good imaging quality, synthetic aperture imaging system requires phase extraction of each sub-aperture and co-phasing of whole aperture. In the project, an in-depth study about basic principles and methods of segments phase extraction was done. The study includes: application of sinusoidal extreme strip light irradiation phase shift method to extract the central dividing line to get segment phase extraction information, and the use of interference measurement to get the aperture phase extraction calibration coefficients of spherical surface. Study about influence of sinusoidal extreme strip phase shift on phase extraction, and based on sinusoidal stripe phase shift from multiple linear light sources of the illumination reflected image, to carry out the phase shift error for inhibiting the effect in the phase extracted frame.

An accurate estimation of the point spread function (PSF) is very useful in image restoration. This paper proposes a method of estimating the PSF of space camera based on in-orbit wavefront sensing. Three wavefront sensors are used to measure the wave-front errors of the space camera, with one sensor in the center field and the other two sensors in the two edge fields. The wavefront errors of other fields can be estimated by interpolation. Then, the PSFs of each field can be estimated using the wavefront errors.

For monochromatic light, the PSF can be calculated by Fourier Transformation. For a white light imaging system, the PSF is a weighted integration of the monochromatic PSFs. The weighting coefficient is the product of the sun-light spectrum, spectral reflection factor of the object, spectral transmission factor of the optical system, and the spectral response of the image detector. Because different object has a different spectral reflection factor, to be practical and simple, we use an average spectral reflection factor of typical ground scenes instead.

It will induce error in the PSF estimations by using the average reflection factor instead of the real one. This error is analyzed in the paper which shows that the error is acceptable.

This paper presents a new 3D coordinate measurement method based on linear camera equipped with cylindrical lenses (LCEWCL). The LCEWCL has prominent advantages in high-precision coordinate measurement and dynamic position-tracking owning to the high resolution and outstanding frame rate of linear CCD. Every LCEWCL is a one-dimensional angle-measuring unit which can confirm a plane passing through the light spot. With three or more LCEWCLs arrangement in front of the measurement field, the 3D spatial coordinate of the light spot is reconstructed by multi-angle intersection. Experiments are conducted to validate the accuracy and effectiveness of the proposed method and good results have been obtained.

This paper designs a solar automatic tracking wireless charging system based on the four quadrant photoelectric sensor. The system track the sun's rays automatically in real time to received the maximum energy and wireless charging to the load through electromagnetic coupling. Four quadrant photoelectric sensor responsive to the solar spectrum, the system could get the current azimuth and elevation angle of the light by calculating the solar energy incident on the sensor profile. System driver the solar panels by the biaxial movement mechanism to rotate and tilt movement until the battery plate and light perpendicular to each other. Maximize the use of solar energy, and does not require external power supply to achieve energy self-sufficiency. Solar energy can be collected for portable devices and load wireless charging by close electromagnetic field coupling.

Experimental data show that: Four quadrant photoelectric sensor more sensitive to light angle measurement. when track positioning solar light, Azimuth deviation is less than 0.8°, Elevation angle deviation is less than 0.6°. Use efficiency of a conventional solar cell is only 10% -20%.The system uses a Four quadrant dual-axis tracking to raise the utilization rate of 25% -35%.Wireless charging electromagnetic coupling efficiency reached 60%.

In the research of optical synthetic aperture imaging system, phase congruency is the main problem and it is necessary to detect sub-aperture phase. The edge of the sub-aperture system is more complex than that in the traditional optical imaging system. And with the existence of steep slope for large-aperture optical component, interference fringe may be quite dense when interference imaging. Deep phase gradient may cause a loss of phase information. Therefore, it’s urgent to search for an efficient edge detection method. Wavelet analysis as a powerful tool is widely used in the fields of image processing. Based on its properties of multi-scale transform, edge region is detected with high precision in small scale. Longing with the increase of scale, noise is reduced in contrary. So it has a certain suppression effect on noise. Otherwise, adaptive threshold method which sets different thresholds in various regions can detect edge points from noise. Firstly, fringe pattern is obtained and cubic b-spline wavelet is adopted as the smoothing function. After the multi-scale wavelet decomposition of the whole image, we figure out the local modulus maxima in gradient directions. However, it also contains noise, and thus adaptive threshold method is used to select the modulus maxima. The point which greater than threshold value is boundary point. Finally, we use corrosion and expansion deal with the resulting image to get the consecutive boundary of image.

There are two light sources in Femtosecond laser tracker, the center wavelengths of which are different. In order to achieve precise distance, light beams from the two sources should be combined. In this paper, key technology of light path alignment for femtosecond laser tracker based on double optical wedge is presented. Precise steering of incident light beam can be realized by changing the angle of the double optical wedge. Method for adjusting the angle and translation of light beam using two pairs of double optical wedge is proposed. Also mathematical model on the basis of vector superposition method is established to correct offset of light beam, which is validated with Zemax.

The workshop Measuring Position System (wMPS) based on intersection of optical planes is widely applied in large-scale metrology. However, in guidance areas concerning more about horizontal directions such as in the area of transporting with AGVs, the coordinate of z axis which represents the height of the vehicle is of no particular importance. Also, the installation and parameters calibration of wMPS is complex and time-consuming. In this paper, a new method with single transmitter measuring two dimensional coordinate to guide the moving object (except the vertical direction) is proposed and demonstrated. The three dimensional coordinate of receiver was calculated if its horizontal angle, vertical angle and the coordinate of vertical direction are given. In order to get the receiver’s horizontal and vertical angle, a serious of mathematical formulas was derived from a model of single transmitter with two rotating laser planes. The coordinate of vertical direction was obtained by the laser tracker and mapped from laser tracker coordinates to transmitter coordinates. Concerning that the coordinate of the vertical direction remains almost the same if the object moves in the level ground, a series of vertical-direction coordinates of moving object was measured beforehand and the average value of coordinates was the approximate vertical-direction coordinates of every point. To verify this method, the points acquired by the transmitter were remeasured by the laser tracker. Finally, the coordinates were compared and the results were analyzed. The experiment results show that the method’s measuring accuracy has reached 5mm.

Geometric errors in laser trackers such as light offset and transit tilt have essential influence on the system measurement errors. Thus error detection and calibration are very important for producers and customers to execute error compensation. Different methods are developed to detect and calibrate errors. However, the commonly used methods such as length measurement and two-face measurement are sensitive to several misalignments which cannot calibrate errors directly and separately. In this paper a series of methods for detecting and calibrating geometric errors such as mirror tilt, beam tilt and transit tilt were presented which can calibrate geometric errors individually and precisely. The mirror tilt could be detected with the help of two autocollimators and one polygon. Then the beam tilt and offset errors were calibrated using a CCD camera and condenser lenses. Finally the transit tilt error was calibrated using a gradient and a vertical plane. Experiments and error assessment were executed to show that the accuracy of the calibration methods can meet the user’s demand.

Optical coherence tomography (OCT) technology has been widely applied in the field of ophthalmic diagnosis. As the use of this innovative 3D imaging approach increases, the requirement to characterize its fundamental system performance is in great demand. Resolution capability is considered as the most important parameter for any imaging devices including OCT. Differing from conventional microscopic imaging method, the axial resolution of OCT is governed by full width at half maximum of the source spectrum (FWHM) while its lateral resolution is determined by the system numerical aperture (NA). Here, a miniaturized system is developed to measure the source spectrum and the system numerical aperture of OCT equipment. Both the hardware and the software are custom designed and integrated to measure the two key parameters of an OCT equipment. A clinical OCT machine is tested with the compact measuring system. In the meanwhile, the same parameters are also acquired with the use of commercial but bulky instrument, and a good agreement has been achieved by comparing the measuring results. The measuring mechanism, data processing algorithm as well as the mechanical design are described in detail. It has provided an applicable method to verify and calibrate fundamental parameters of any OCT equipment.

Construction of high-speed railway in China has entered a period of rapid growth. To accurately and quickly obtain the dynamic envelope curve of high-speed vehicle is an important guarantee for safe driving. The measuring system is based on binocular stereo vision. Considering the difficulties in field calibration such as environmental changes and time limits, carried out a field calibration method based on fast reconstruction of three-dimensional control field. With the rapid assembly of pre-calibrated three-dimensional control field, whose coordinate accuracy is guaranteed by manufacture accuracy and calibrated by V-STARS, two cameras take a quick shot of it at the same time. The field calibration parameters are then solved by the method combining linear solution with nonlinear optimization. Experimental results showed that the measurement accuracy can reach up to ± 0.5mm, and more importantly, in the premise of guaranteeing accuracy, the speed of the calibration and the portability of the devices have been improved considerably.

A new calibration method for infrared hyperspectral imaging Fourier transform spectrometer is presented. Two kinds of common materials as Polypropylene (PP) and Polyethylene Terephthalate (PET) films which have special absorption peaks in the infrared band were used in the calibration experiment. As the wavelengths at the sharp absorption peaks of the films are known, an infrared imaging spectrometer can be calibrated on spectra with two or three peaks. With high precision and stability, this method simplifies the calibration work. It is especially appropriate for the measuring condition with a lack of calibration equipment or with inconvenience to calibrate the multiple light sources outdoors.

With the rapid development of modern nondestructive testing technologies, ultrasonic phased array and Ultrasonic array testing technology has been used widely, at the same time the propagation process of ultrasonic in the material becomes more and more complex. In order to make the ultrasonic propagation path become visible and researchers can observe the acoustic field directly, considering the properties of the ultrasonic as a stress wave, according to the theory of polarized light interference, a multi-channel dynamic photoelastic imaging system is developed successfully. The system can generate many kinds of focusing ultrasonic fields in optical specimen by controlling the ultrasonic transmission delay time of each equipment channel, and the system has the ability to simulate the acoustic field’s focusing process of the ultrasonic phased array. The image shot by CCD camera reflects the propagation process of the acoustic field in the specimen, and the dynamic video is formed under control of the timing circuit, and the system has the ability to save the captured image in the computer.

In this paper, a noninvasive photoacoustic measurement setup was established to simple simulate the glucose concentration measurement. The PPA signal excited by a pulsed tunable wavelength laser can be used to determine the glucose concentration in solution. By building the multiple linear regression (MLR) model for the peak valves of the PPA signal at five characteristic absorption wavelengths, the relative error of prediction is less than 20% and the absolute error is less than 33mg/dL.

The swing arm profilometer realizes the measurement of the different surface shape by adjusting the axis of the arm bearing and the axis of the workpiece bearing for different spatial positional relationships,so the high precision positional relationship between the axis of the arm bearing and the axis of the workpiece bearing is the premise to obtain accurate result. This paper presents a way using four-based laser trackers to calibrate the axes of the swing arm profilometer,that satisfies the requirement of the high precision and the dynamic calibration. The four-based laser trackers system only uses the precise distances to obtain the coordinates of points. The coordinates of points in the rotate arc of the axes can fit the axes，and the relationship between the axes can be know. The study of the self-calibration of the four-based laser trackers, the arrangement of four-based laser trackers, the design of the calibration method and the processing of measurement data are included in this paper. Finally, the study is validated by the preliminary experiment.

When using the swing arm profilometer (SAP) to measure the aspheric mirror and the off-axis aspheric mirror, the error of the effective arm length of the SAP has an obvious influence on the measurement result. In order to reduce the influence of the effective arm length and increase the measurement accuracy of the SAP, the laser tracker is adopted to measure the effective arm length. Because the space position relationship of the probe system for the SAP is needed to measured before using the laser tracker, the point source microscope (PSM) is used to measure the space positional relationship. The measurement principle of the PSM and other applications are introduced; the accuracy and repeatability of this technology are analysed; the advantages and disadvantages of this technology are summarized.

A new pose measurement system based on orthogonal beam splitting imaging is proposed in this paper to solve the contradictions between the measurement accuracy and measurement speed in the existing pose measurement method of monocular or binocular vision with multi-linear CCDs. In the system, monocular object lens with beam splitting structure and two linear CCDs are combined to compose the pose measurement sensor. Monocular camera helps the system gain a large field of view. And the two orthogonally placed linear CCDs are equal to one array CCD. Furthermore, linear CCD possesses the advantage of high-resolution imaging, high-speed data capturing and high-efficiency data processing as compared to an array one. The key work of this paper lies in designing the optical structure of the sensor, calibrating the parameters of the camera corresponding to its model, and solving pose of the object by corresponding position algorithm. The experimental results prove that the measurement accuracy (2%) of orthogonally-splitting-imaging pose sensor can be achieved. Hence, this system meets the high-speed and high-precision measurement requirements in wide space and can be applied to pose measurement in aerospace and vehicle field.

To improve the accuracy of coordinate measurement, the precise 3D coordinates of spatial points on the surface of the target object are needed. Based on the stereo vision measurement model, an all-around coordinates measuring system with single camera and a two-dimensional turntable is proposed. By controlling the rotation of objects in two different orientations and by the principle of relative motion, the single-CCD sensor model was imaged as a visual multi-CCD sensor model. In other words, the visual CCD sensors at different but relative positions are used to acquire coordinates information of the measured points. Considering the calibration accuracy of those two shafts affecting the accuracy of the entire system, the mathematical calibration model is built, consisting of virtual multi-CCD sensor measuring system based on the non-orthogonal shafting. The shaft and its calibration method are described in detail. The experimental result shows that the system based on the virtual multi-CCD sensor model can achieve the standard deviation of 0.44mm, and thus proves the feasibility of its multi-angle coordinates measurement for spatial points.

The infrared thermal imager is widely used in infrared radiation measurement, but the accuracy of radiation measurement is greatly affected by the changing environment and self-heating effect. In this article, the influence of self-heating effect is analyzed in a stable environment and the phenomenon of temperature drift caused by the self-heating effect is found. Then the drift rules are summarized by experiment, and a weighted-based compensation method is presented, the result shows that the temperature measurement error is less than 0.7 centigrade after compensation.

According to the aero-thermal effects and aero-thermal radiation effects of the optical window, the thermo-optic effect, the elasto-optical effect and the thermal deformation of the optical window are analyzed using finite element analysis method. Also, the peak value and its location of the point spread function, which is caused by the thermo-optic effect and the dome thermal deformation, are calculated with the variance of time. Furthermore, the temperature gradient influence to the transmission of optical window, the variation trend of transmission as well as optical window radiation with time are studied based on temperature distribution analysis. The simulations results show that: When the incident light is perpendicular to the optical window, image shift is mainly caused by its thermal deformation, and the value of image shift is very small. Image shift is determined only by the angle of the incident light. With a certain incident angle, image shift is not affected by the gradient refractive index change. The optical window transmission is mainly affected by temperature gradient and thus not neglectable to image quality. Therefore, the selection of window cooling methods, needs not only consider the window temperature but try to eliminate the temperature gradient. When calculating the thermal radiation, the optical window should be regarded as volume radiation source instead of surface radiator. The results provide the basis for the optical window design, material selection and the later image processing.

A primary standard measurement facility based on differential spectral responsivity (DSR) method for calibration of reference solar cells was realized at National Institute of Metrology (NIM), China. The primary calibration of the critical spectral parameters and short-circuit current of reference cells, not only with WPVS (World photovoltaic Scale) design but with non-regularly shaped, can be performed by this standard facility. The linearity measurement can be carried out by measuring DSR of the solar cells at different bias levels in the spectral range from 300nm to 1200nm. The characterization and performance of the facility were reported. An uncertainty of 0.9% (k=2) for short-circuit current of WPVS reference solar cells was able to be obtained. A more accurate and better calibration service for solar photovoltaic (PV) cells could be provided to local or international solar cell research community, testing labs and industry users and manufacturers.

Dust aerosol size distribution is an important source of information about atmospheric aerosols, and it can be determined from multiwavelength extinction measurements. This paper describes a stochastic inverse technique based on artificial bee colony (ABC) algorithm to invert the dust aerosol size distribution by light extinction method. The direct problems for the size distribution of water drop and dust particle, which are the main elements of atmospheric aerosols, are solved by the Mie theory and the Lambert-Beer Law in multispectral region. And then, the parameters of three widely used functions, i.e. the log normal distribution (L-N), the Junge distribution (J-J), and the normal distribution (N-N), which can provide the most useful representation of aerosol size distributions, are inversed by the ABC algorithm in the dependent model. Numerical results show that the ABC algorithm can be successfully applied to recover the aerosol size distribution with high feasibility and reliability even in the presence of random noise.

The spectral responsivity is one of the most important technical indicators of infrared detector which has an important significance for radiation thermometry and emissivity measurement. Using a blackbody radiation at multiple temperatures, the calibration for spectral responsivity of the infrared detector is proposed. With the Planck's law, the spectral radiance of blackbody at the different temperature is calculated. The detector captures the radiation and generates output values each of those is the function of spectral responsivity, spectral radiance and environmental radiation. Calibration equation is established by means of the calculated radiance and output values. By solving the equations based on principle of least squares, the calibration of spectral responsivity is implemented. From the comparison experiment of measuring the radiance of blackbody at 850K, radiance value measured by the MCT detector has a good consistency with the theoretical data.

Inorganic mercury (Hg²⁺) produces toxic effects even at very low concentration. High sensitive fluorescent probes for Hg²⁺ detection has been researched and synthesized. A fluorescence detection system is built for Hg²⁺ detection in water environment with fluorescent probes as the detection reagent. Fiber coupled LED with high brightness is developed and used as excitation light source. And the optimized excitation wavelength is about 520 nm. The measurements of fluorescence spectra is obtained by means of optical fiber spectroscopic techniques. Fluorescence detection experiments are carried out for a range of different concentrations of Hg²⁺ in aqueous solutions. The center wavelength of the fluorescence spectra is about 580 nm which is unchanged in the experiments. Relationship between Hg²⁺ concentrations and the fluorescence intensity is studied. A positive correlation exists between the intensity of fluorescence spectrum and the concentrations of Hg²⁺. The fluorescence intensity grows with increasing the concentration of Hg²⁺ for the same excitation light. When the concentration of Hg²⁺ is high enough, the fluorescence intensity increases slowly. And a numerical model is built for the concentration calculating. The detection limit is 0.005 μmol/L in the experiments. The Hg²⁺ detection system reported has many advantages such as small size, rapid response, high-sensitivity, and can be used for on-site testing of the water quality.

Raman spectroscopy has become a very important tool in many fields, including chemistry, material, environmental protecting and etc. While Raman scattering is a weak process, it is often hampered in background noise. Since surface enhanced Raman scattering (SERS) was observed for the first time in 1974, surface enhanced Raman spectroscopy has developed more and more rapidly. Periodic nanostructures have the advantage of reliable and reproducible Raman signal relative to the irregular nanostructures. In this paper, holographic gratings coated by metal are proposed to fabricate SERS-active substrate. The excitation light excite on the gratings with proper grating constant that will lead to plasmon resonant phenomena, which enhance local electric field for Raman scattering. The electric field enhancement of sinusoidal, rectangular and triangular gratings is simulated using a commercially available software finite-difference-time-domain (FDTD). Period, groove depth, duty cycle and coated metal thickness of gratings affecting the electric field enhancement are also discussed. The optimum grating structure for SERS-active substrate is obtained in theory.

The paper proposes a new vision-based inspection of car circlips. Due to the variety of circlips and large quantity, human inspection about its inside diameter, ring width is always subjective, labor-intensive and slow. The detector consists three parts: electromagnetic feeder, vision-based detection system and multi-station workbench. The feeder is customized to accomplish storage, screening, sorting and transmission of circlips. Vision system is made up of bilateral telecentric lens, tablet light and industrial camera. By means of image processing, it can detect dozens of circlips which it maximum outside diameter is less than 25.00mm. And the precision of inside diameter can reach up to 0.02mm. A multi-station workbench method is put forward in order to improve detecting efficiency combined with parallel software. The system can sort 60-80 pieces per minute.

Motion detection retains a fascinating amount of scope for new ideas. Digital holography enables three-dimensional images to be recorded with high resolution and large depth of field. Appropriate design of a holographic target has the potential to unlock significant resolution gains from holographic measurement systems. In this paper, we explore the potential of proposed three-dimensional analogues of Costas arrays for the design of such targets. These innately sparse constructions have the potential to enable the use of additional compressive sensing techniques to unlock further gains in resolution.

Optical photography measurement and three-dimensional (3-D) scanning measurement have been widely used in the field of the fast dimensional and surface metrology. In the measurement process, however, retro-reflective markers are often pasted on the surface in advance for image registration and positioning the 3-D measuring instruments. For the large-scale workpiece with freeform surface, the process of pasting markers is time consuming, which reduces the measurement efficiency. Meanwhile, the measurement precision is impaired owing to the thickness of the marker. In this paper, we propose a system that projects two-dimensional (2-D) array optical markers with uniform energy on the surface of the workpiece instead of pasting retro-reflective markers, which achieves large-range and automated optical projection of the mark points. In order to conjunction with the 3-D handheld scanner belonging to our team, we develop an apparatus of optical marker projection, which is mainly composed of the high-power laser, the optical beam expander system, adjustable aperture stop and Dammann grating of dibasic spectrophotometric device. The projection apparatus can achieve the function of beams of 15 * 15 uniformly light of the two-dimensional lattice. And it’s much cheaper than the existing systems.

Pixel equivalent is an important parameter to describe the relationship between pixels of digital images and actual size of measured piece in a 2D image measuring system. It is mainly calibrated with the standard component method, which is traditionally off-line and requires measuring conditions and attitude of devices to remain constant while measuring and calibrating. To overcome above limitations, a new calibration method is proposed in this paper which is defined as the float equivalent method. This method requires the standard component and measured piece be placed in image measuring system simultaneously. Everytime before measuring, no matter aiming at the same measuring point or not, the pixel equivalent is calibrated for this specific time, specific condition, specific measuring point, and specific object distance. This method has the advantage of reducing the influence of conditions changing on the accuracy without additional calibration equipment or operations. The steel tape verification system is taken as an example to testify the effectiveness of the method.

For normal eyes without history of any ocular surgery, traditional equations for calculating intraocular lens (IOL) power, such as SRK-T, Holladay, Higis, SRK-II, et al., all were relativley accurate. However, for eyes underwent refractive surgeries, such as LASIK, or eyes diagnosed as keratoconus, these equations may cause significant postoperative refractive error, which may cause poor satisfaction after cataract surgery. Although some methods have been carried out to solve this problem, such as Hagis-L equation^[1], or using preoperative data (data before LASIK) to estimate K value^[2], no precise equations were available for these eyes. Here, we introduced a novel intraocular lens power estimation method by accurate ray tracing with optical design software ZEMAX. Instead of using traditional regression formula, we adopted the exact measured corneal elevation distribution, central corneal thickness, anterior chamber depth, axial length, and estimated effective lens plane as the input parameters. The calculation of intraocular lens power for a patient with keratoconus and another LASIK postoperative patient met very well with their visual capacity after cataract surgery.

The influence of acceleration resulting from spacecraft maneuvering on star spot positioning and hereafter dynamic motion compensation technology are addressed. Firstly the pattern of the smeared star-spot image under maneuvering condition and the locating error are investigated. It is found that instead of following a symmetrical shaped pattern, the smeared star spot under acceleration is twisted. Simulation verifies that the position error is far beyond Cramer Rao Lower Bound(CRLB) of photoelectric devices under uniform velocity. Then a novel scheme to derive the more general accurate motion compensation is proposed. In this case, an approximate CRLB is derived to give a baseline to measure the performance of any positioning algorithm and motion compensation technique on star tracker. The theory and corresponding simulations show the novel general compensation approach is better than the conventional compensation strategy and close to the approximate CRLB. Therefore, a CRLB position accuracy of star spot is expected to be realized by using the generalized dynamic compensation method on maneuvering spacecraft.

Laser collimation technology is widely applied in the positioning and measurement. The accuracy is affected by the laser beam drift, so laser beam drift compensation is necessary. Effective compensation depends on the characteristics analysis of laser beam drifts. Spectrums and values of noise signals caused by electronic noise, laser source, and environment, are analyzed in detail. The characteristics of various types of noise signals are gained and the effectiveness of low-pass filter and mean process are verified and compared. This study will provide support for separation of various types of signals and compensation of beam drifts.

Endoscopic imaging quality affects industrial safety and medical security. Rigid endoscope distortion is of great signification as one of optical parameters to evaluate the imaging quality. This paper introduces a new method of rigid endoscope distortion measurement, which is different from the common methods with low accuracy and fussy operation. It contains a Liquid Crystal Display (LCD) to display the target, a CCD to obtain the images with distortion, and a computer to process the images. The LCD is employed instead of common white screen. The autonomous control system of LCD makes it showing the test target designed for distortion, and its parameter is known. LCD control system can change the test target to satisfy the different demand for accuracy, which avoids replacing target frequently. The test system also contains a CCD to acquire images in the exit pupil position of rigid endoscope. Rigid endoscope distortion is regarded as centrosymmetric, and the MATLAB software automatically measures it by processing the images from CCD. The MATLAB software compares target images with that without distortion on LCD and calculates the results. Relative distortion is obtained at different field of view (FOV) radius. The computer plots the curve of relative distortion, abscissa means radius of FOV, ordinate means relative distortion. The industry standard shows that, the distortion at 70% field of view is pointed on the curve, which can be taken as an evaluation standard. This new measuring method achieves advantages of high precision, high degree of intelligence, excellent repeatability and gets calculation results quickly.

When the acousto-optic device worked on the Bragg model, the non-liner affected the diffraction beam. There were some errors between the diffraction beam deflection peak position and the input signal’s frequency, which reduced the frequency measure accuracy of the acousto-optic spectrum analyzer. Under the existing optical experimental platform, we eliminated the CCD background noise by reducing the threshold firstly, and then we processed the data by four methods, the peak value method, the Gaussian fitting method, the squared cancroids method and the Hilbert transform method. The least frequency measure variance is 31.8 KHz², the data processed by the Gaussian fitting method. It provides theoretical support for reducing the frequency measurement variance of acousto-optic spectrum analyzer.

High accuracy automatic measurement of engine box is significant for enhancing the quality and performance of the engine. To complete the fast automatic measurement of the engine box shaft hole diameter, a new non-contact methods for inner hole diameter measuring is proposed in this paper, a mathematic model is built according to this method. A probe based on laser displacement sensors is developed to meet the method by distributing the laser displacement sensors in the probe cross-section uniformly. By this method, shaft hole diameter can be got with single measurement. This method eliminates some defects involved in existing shaft hole diameter non-contact measuring methods, it does not need the rotation of the probe and accurate locating of the probe center and the shaft hole center. Experiments proved that the methods can be used to complete the task of the shaft hole diameter measuring with simple operation and accurate result. Experiments have also shown that the proposed method is an effective method of non-contact high accuracy diameter measurement.

Ion mobility spectrometry (IMS) is a key trace detection technique for toxic pollutants and explosives in the atmosphere. Ultraviolet radiation photoionization source is widely used as an ionization source for IMS due to its advantages of high selectivity and non-radioactivity. However, UV-IMS bring problems that UV rays will be launched into the drift tube which will cause secondary ionization and lead to the photoelectric effect of the Faraday disk. So air is often used as working gas to reduce the effective distance of UV rays, but it will limit the application areas of UV-IMS. In this paper, we propose a new structure of curved drift tube, which can avoid abnormally incident UV rays. Furthermore, using curved drift tube may increase the length of drift tube and then improve the resolution of UV-IMS according to previous research. We studied the homogeneity of electric field in the curved drift tube, which determined the performance of UV-IMS. Numerical simulation of electric field in curved drift tube was conducted by SIMION in our study. In addition, modeling method and homogeneity standard for electric field were also presented. The influences of key parameters include radius of gyration, gap between electrode as well as inner diameter of curved drift tube, on the homogeneity of electric field were researched and some useful laws were summarized. Finally, an optimized curved drift tube is designed to achieve homogenous drift electric field. There is more than 98.75% of the region inside the curved drift tube where the fluctuation of the electric field strength along the radial direction is less than 0.2% of that along the axial direction.

We mainly study on hardware design and implementation of multiplexing photon correlator based on FPGA and the graphical user interface programmed by LabView to control it, and its application in submicron particle size analyzer. The study is based on the verification of the principle of sampling correlation calculation, the implementation of the multiplexing correlation operation, the hardware design of FPGA, and etc. Multiplexing photon correlator can calculate the auto-correlation function of multiplexing photon signals that were received by a single PMT at different times. Multiplexing photon correlator mainly composes of signal control module, photon counter module, shift register module, multiplier-accumulator module, communication module, etc. With appropriate optical set-up, it will change from the traditional measurement of the single point to the 2D or 3D measurement using a single photon detector, greatly expands the application range of photon correlation spectroscopy.

Zonal wavefront reconstruction by use of the well known Southwell algorithm with rectangular grid patterns has been considered in the literature. However, when the grid patterns are nonrectangular, modal wavefront reconstruction has been extensively used. We propose an improved zonal wavefront reconstruction algorithm for Hartmann type test with arbitrary grid patterns. We develop the mathematical expressions to show that the wavefront over arbitrary grid patterns, such as misaligned, partly obscured, and non-square mesh grids, can be estimated well. Both iterative solution and least-square solution for the proposed algorithm are described and compared. Numerical calculation shows that the zonal wavefront reconstruction over nonrectangular profile with the proposed algorithm results in a significant improvement in comparison with the Southwell algorithm.

The triangulation measurement is a kind of active vision measurement. The laser triangulation displacement is widely used with advantages of non-contact, high precision, high sensitivity. The measuring error will increase with the nonlinear and noise disturbance when sensors work in large distance. The paper introduces the principle of laser triangulation measurement and analyzes the measuring error and establishes the compensation error. Spot centroid is extracted with digital image processing technology to increase noise-signal ratio. Results of simulation and experiment show the method can meet requirement of large distance and high precision.

In this paper, taking stability and cost in consideration, a high-power fiber-coupled Light Emitting Diode (LED), instead of a Laser Diode (LD), was adopted as the light source in the measurement of the straightness errors. The calibration experiment showed that the standard deviation was 0.36μm and 0.34μm in X and Y directions, respectively, and the maximum residual was about 0.7μm in X direction and less than 0.5μm in Y direction. The stability experiment indicated that the standard deviation of the position of spot on the detector was 0.246μm in X direction and 0.256μm in Y direction in 30 minutes, respectively. The repeatability experiment was performed by straightness measurement of the linear guide for three times. For one LED with the wavelength of 490nm, the maximum deviation was ±0.9μm in X direction and ±1.4μm in Y direction respectively. For another LED with the wavelength of 565nm, the maximum deviation was ±0.85μm in X direction and ±0.7μm in Y direction. In a conclusion, the system using a LED possesses good stability and repeatability within a limited measurement range, thus proving the feasibility and novelty of the adoption of the LED in collimation measurement, which presents a new approach to enhance the measurement accuracy.

Among temporal phase unwrapping methods based on structured light projection, tri-frequency heterodyne method, with the merits of less projected fringe, high precision and high reliability, has become a practical method in objects three-dimensional (3D) shape measurement. In this paper, a 3D shape measuring system was developed with a digital micromirror device (DMD) and synchronously trigged CCD camera. The 3D shape of a measured object was reconstructed from the deformed fringe patterns based on tri-frequency heterodyne method. The practical experiments were carried on some coins, and the results show that the system can restore their 3D shape on the tested partition with an accuracy of microns. This measurement system is prominent in 3D shape measurement of small or tiny objects, sample testing, and many other application fields.

An experimental system for infrared spectral emissivity measurements is reported in this study, which enables the measurement of spectral emissivity of opaque solid materials in the temperature range between 473K and 1273K and spectral range from 0.8μm to 2.2μm. Emissivity characteristics are investigated for several Al6061 samples with different roughness and temperatures in atmosphere environment. By analyzing various uncertainty sources in this experiment, the combined uncertainty of the system is less than 3.9%. The influences of wavelength, temperature, surface roughness, heating time and oxidation on the spectral emissivity are discussed. The experimental results show that the spectral emissivity decreases slowly with the increasing of the wavelength, then the values at high temperatures are larger than that of low temperatures. The spectral emissivity increases with the increase of surface roughness. At a specified temperature, the influence of the heating time on the spectral emissivity is discussed. The spectral emissivity has a slight increase with the increasing of heating time due to oxidation, and the variation of the emissivity becomes negligible after 400 minutes of heating when the film thickness is stable.

Before using a series of concentric circles as the target, the target needs to be pre-processed to get characteristic parameters. This paper discusses a new method based on Gaussian sub-pixel to detect the edge of concentric circles, and get the coordinate of the center and radius of concentric circles based on the cross ratio invariability with five points which leads to more stable data. In the end, Levenberg-Marquard algorithm is used to approach the results. To verify the results, two methods are used both in the hands of experiment and simulation. These two results illustrate that the method we discusses have advantages on the accuracy.

In this paper, a method to detect internal pocks and bubbles of optical elements based on laser line source scanning is proposed. In dark field environment, a laser line source is used to illuminate from one side of the glass under test, a high-resolution CCD camera is used to take pictures in front of the glass sample. Images which contain information of defects are acquired through rough scanning and accurate scanning. Accurate three-dimensional coordinates of the internal defects are acquired after image processing, which descript the characteristic information of internal defects quantificationally. Compared with the microscope imaging measurement, this proposed detection of defects in optics based on laser line source scanning has a relative aberration smaller than 2%. In addition, the detection time is approximately reduced to 20 minutes from 1 hour dramatically. The analysis indicates that the error of the position of defects is much smaller than the size of them, which means the position of the defects can be acquired accurately by this approach.

Absolute distance measurement using dual femtosecond comb lasers can achieve higher accuracy and faster measurement speed, which makes it more and more attractive. The data processing flow consists of four steps: interference peak detection, fast Fourier transform (FFT), phase fitting and compensation of index of refraction. A realtime data processing system based on Field-Programmable Gate Array (FPGA) for dual-comb ranging has been newly developed. The design and implementation of the interference peak detection algorithm by FPGA and Verilog language is introduced in this paper, which is viewed as the most complicated part and an important guarantee for system precision and reliability. An adaptive sliding window for scanning is used to detect peaks. In the process of detection, the algorithm stores 16 sample data as a detection unit and calculates the average of each unit. The average result is used to determine the vertical center height of the sliding window. The algorithm estimates the noise intensity of each detection unit, and then calculates the average of the noise strength of successive 128 units. The noise average is used to calculate the signal to noise ratio of the current working environment, which is used to adjust the height of the sliding window. This adaptive sliding window helps to eliminate fake peaks caused by noise. The whole design is based on the way of pipeline, which can improves the real-time throughput of the overall peak detection module. Its execution speed is up to 140MHz in the FPGA, and the peak can be detected in 16 clock cycle when it appears.

Absolute distance measurement with dual femtosecond comb lasers has advantages of wide-range, high-accuracy and fast speed. It combines time-of-flight and interferometric measurement. The novelty of ranging method leads to new challenges in designing the data acquisition and processing hardware system. Currently there are no available real-time data processing system for dual-comb ranging. This paper introduces our recent progress on designing and implementing such a platform. Our platform mainly contains four different function modules. First, a clock module that accept a 250MHz maximum reference clock input was introduced to generate the sample clock for A/D converter, and the module’s output clock can be delayed up to 20ns with a resolution of 714ps. Second, a high-speed data acquisition module with a 14-bit resolution and a 125 MSPS maximum sample rate was designed to convert the analog laser pulse signal to digital signal. Third, we built a real-time data processing module that allows an input of 16-bit data in the FPGA to calculate the distance from the digital signal within 83us. Finally, a data transmission module based on a 128MB DDR SDRAM and USB2.0 was added so that we can easily debug the platform in the PC. The performance of our system is evaluated in real-time. The test bench consists of two femtosecond laser sources, an optical fiber interferometer and our data processing system. The repetition frequencies of the two combs are around 50MHz, with frequency difference of 2.5kHz. The center wavelength of laser pulses is 1560nm. The target distance is from 0m to 3m. The experimental results show that our system can output measurement results at the rate of 2500 pts/s, and the measurement deviation is less than 10um.

This paper reported the algorithm for Infrared Hyperspectral Imaging Radiometric Spectrometer Technology. Six different apodization functions are been used and compared, and the phase corrected technologies of Forman is researched and improved, fast fourier transform(FFT)is been used in this paper instead of the linear convolution to reduce the quantity of computation.The interferograms is achieved by the Infrared Hyperspectral Imaging Radiometric Spectrometer which are corrected and rebuilded by the improved algorithm, this algorithm reduce the noise and accelerate the computing speed with the higher accuracy of spectrometers.