This PDF file contains the front matter associated with SPIE Proceedings Volume 8563, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

We investigated the interference amplitude and phase characteristics of a multi-frequency sweeping interferometer with sinusoidal phase modulating technique. A novel multi frequency sweeping light source that generated an interval and center frequency variable frequency comb with a bandwidth of 14 nm was demonstrated. The interference phase and amplitude distributions were investigated by observing the zeroth and first order interference signals. In addition, the zeroth and first order interference phase variations caused by center frequency sweeping were measured.

Absolute distance measurement is essential in large-scale equipment manufacturing and scientific projects. Nowadays, sophisticated equipment manufacture demands for high-precision ranging with a high speed. Several raging methods utilizing the wide spectral range and stable frequency intervals of femtosecond frequency comb laser can achieve a high precision, but most of such systems suffer from relative low speed. Fortunately, the ranging method based on a pair of femtosecond frequency comb lasers can potentially resolve such problem. Combining time-of-flight and interferometry method, the measurement can accomplish rapid raging in a measurement period of 0.2ms, and achieve higher precision by interferometry after averaging of many periods. We performed a simulation of this method in Matlab/Simulink. The precision can achieve ~10nm in ideal simulation environment. By error analysis we estimated the data processing system, and gave the appropriate parameters of detector and A/D sampling. It comes to a conclusion that detector with relative long response time of ~7nm or about can be adopted, and fast Fourier transformation (FFT) of 16384 points contributes to higher precision. With such parameters, it is possible to realize real-time raging performed on field-programmable gate array (FPGA) with high precision.

Phase shifting profilometry (PSP) technique is widely used as a 3-D shape measurement technique due to its robustness and accuracy. However, PSP requires multiple fringe pattern images to be projected onto an object and a reference plane to calculate the phase value, and also the object must maintain motionless when the measurement is taken. If the object moves during the measurement, significant errors will be introduced when calculating the phase value. This paper analyses the relationship between the object movement and the phase value, and proposes a method for compensating the errors caused by two-dimensional movement of object. This method can eliminate the errors caused by two-dimensional movement of object and reconstruct the object shape successfully. The effectiveness of the proposed method is verified by simulations.

Fringe pattern profilometry (FPP) is one of the most promising 3D profile measurement techniques, which has been widely applied in many areas. A challenge problem associated with FPP is the unwrapping of wrapped phase maps resulted from complex object surface shapes. Although existing quality-guided phase unwrapping algorithms are able to solve such a problem, they are usually extensively computational expensive and not able to be applied to fast 3D measurement scenarios. This paper proposes a new quality-guided phase unwrapping algorithm with higher computational efficiency than the conventional ones. In the proposed method, a threshold of quality value is used to classify pixels on the phase maps into two types: high quality (HQ) pixels corresponding to smooth phase changes and low quality (LQ) ones to rough phase variance. In order to improve the computational efficiency, the HQ pixels are unwrapped by a computationally efficient fast phase unwrapping algorithm, and the LQ pixels are unwrapped by computational expensive flood-fill algorithm. Experiments show that the proposed approach is able to recover complex phase maps with the similar accuracy performance as the conventional quality-guided phase unwrapping algorithm but is much faster than the later.

After coarse calibration of the binocular 3D vision system, there still are large systematic errors existed. In order to improve the measurement accuracy, we directly calibrate the existed systematic errors after simple calibration steps of the binocular vision system. The depths of the targets located at different distances are measured at three different field of views(FOVs). After got original results, the relationship between the depth errors, the field of views and the distances is analyzed. The error curves for correction are obtained. The largest error is about 26% and after the correction the error is below 5%. Also a simple matching program is designed to automatically match the feature points at left and right images, and to calculate the depth of the feature points.

In order to validate the detection precision of a three Dimensions Optical Deformation Measure System (3D-OMS), a calibration method of auxiliary coordinate and the optical coordinate base on theodolites has been proposed. The installation method by using theodolites to calibrate the auxiliary coordinate and the optical coordinate has been proposed. Specifically, after the auxiliary mirrors installed, the installation accuracy is detected, then we analyzed the influence of Axis-Error of theodolite under the practical condition of our experiment. Furthermore, the influence of validation precision for the 3D-OMS caused by the misalignment of auxiliary coordinate and optical coordinate is analyzed. According to our theoretical analysis and experiments results, the validation precision of the 3D-OMS can achieve an accuracy of 1″ at the conditions of the coordinate alignment accuracy is no more than 10′ and the measuring range of 3D-OMS within ±3′. Therefore, the proposed method can meet our high accuracy requirement while not sensitive to the installation error of auxiliary mirrors. This method is also available for other similar work.

This paper presents a ball-bar based self-calibration technique for a five-axis point laser optical measurement system. The system is composed of a high accuracy laser point sensor and five motion stages X, Y, Z, B, C. A kinematical system model of the 5-axis measurement system is presented to map the stages and sensor readouts to the target position of the work piece to be measured. With an assumption that each stages’ linearity error, straightness errors, angular errors and sensor linearity error have been calibrated or omitted due to high performance hardware selection, the three squareness angles, laser beam direction and rotary axis position and direction of the two rotary stages are well addressed as the model parameters in the system model. Heuristic methods are introduced to separately calibrate the system squareness, beam direction and rotary axis by using different data acquisition approaches over the ball bar. Parameter estimation methods are applied to obtain the system model parameters via the data set of the ball bar. Experimental studies using a cylinder bar and ball bar demonstrate that the system achieved an accuracy of better than 5 micron.

The traditional structured light binocular vision measurement system consists of two cameras and a projector, which can be regarded to two monocular vision systems composed by the projector and a camera. In this paper, we present a threedimensional (3D) measurement method based on the combination of binocular vision and monocular vision. The common field of view is reconstructed by a binocular vision system, and the missing data area is filled up by two monocular vision systems. In order to improve the measurement accuracy and unify the three world coordinate systems, a calibration method is proposed. The calibration procedure consists of a binocular vision system calibration, the two monocular vision systems calibration and a globe optimization of the three systems for unifying to a common reference. In monocular vision system calibration, a new method based on virtual target is proposed and used to set up the coordinate relations. We use a projector and two cameras to build a vision system for testing the proposed technique. The experimental results show the calibration algorithm ensures the consistent accuracy in the three systems, which is important for data fusion. And it is clear that the proposed method improves the integrity of measurement results and measuring range efficiently.

Lacquer crafts are distributed over Southeast Asia from the East Asia such as China and Korea, Vietnam, Myanmar including Japan. Especially, a Japanese lacquer is well-known traditional crafts. Its color is jet black but people feel different texture because it is made by complicated and multi step manufacturing process such as coating and polishing with different materials. In this report, we focus polarization properties of surface structures on black Japanese lacquer. All states of polarization can be expressed Stokes parameters, which are consisted on four elements as s₀ to s_3. These parameters are effective for the evaluation of the state of polarization. The polarization information of surface structure of Japanese lacquer can be visualized by using an imaging Stokes polarimeter by dual rotating retarder and analyzer. It is possible to evaluate surface character by comparing the degree of polarization. It is effective to evaluate the surface by using the polarization information.

An optical surface profile is measured with a laser diode Fizeau interferometer using a method of absolute measurement. Wavefront aberration in the interferometer causes an undesirable phase distribution in the interference signal. To eliminate this phase distribution, the object surface is shifted in two directions orthogonal to each other and the difference wavefront of the surface profile of the object is obtained. An absolute surface profile is estimated by representing the object surface with a polynomial function and by solving the difference equations with least-squares method.

In the conventional methods to measure radial, axial and angular motions of spindles, complicated artifacts with relative large volume (such as two balls linked with a cylinder) are required. Small volume artifact is favorable from the viewpoint of the accurate and practical measurement of the spindle motion. This paper describes a concurrent measurement of spindle radial, axial and angular motions using concentric circle grating and phase modulation interferometers. In the measurement, the concentric circle grating with fine pitch is installed on top of the spindle of interest. The grating is a reference artifact in the method. Three optical sensors are fixed over the concentric circle grating, and observe the proper positions of the grating. The optical sensor consists of a frequency modulated laser diode as a light source, and two interferometers. One interferometer observes an interference fringe between reflected light form a fixed mirror and 0-th order diffraction light from the grating to measure the axial motion. Another interferometer observes an interference fringe between ±2nd diffraction lights from the grating to measure the radial motion. Using three optical sensors, three radial displacements and three axial displacements of the proper observed position of the grating can be measured. From these measured displacements, radial, axial and angular motions of the spindle can be calculated concurrently. In the paper, a measurement instrument, a novel fringe interpolation technique by sinusoidal phase modulation and experimental results are discussed.

Volume optical computerized tomography (VOCT), which can realize real 3D measurement rather than traditional 2D OCT, has great superiority in quantitatively measuring the thermo physical parameters of transient flow field. Among the refractive index reconstruction techniques, filtered back-projection (FBP) method performs better than algebraic reconstruction techniques (ARTs) with higher accuracy and computationally efficient. In order to apply FBP to VOCT, the radial second-order derivative of projection wave front passes through the tested phase object should be obtained firstly. In this paper, a projection device with two circular gratings is established. In particular, owing to an inherent phase shift exists between moiré fringes of +1 and -1 diffraction orders, a two-step phase-shifting algorithm is utilized to extract the wave front’s radial first-order derivative which is contained in the moiré fringes. The reliability of the two-step phase-shifting algorithm is proved by a computer simulation. Finally, the radial first-order derivative of wave front passing through a propane flame is measured and retrieved by these methods.

Phase Shift Reflectometry has recently been seen as a novel alternative to interferometry since it can provide warpage measurement over large areas with no need for large optical components. To confirm its capability and to explore the use of this method for sub-surface defect detection, a Chinese magic mirror is used. This bronze mirror which dates back to the Chinese Han Dynasty appears at first sight to be an ordinary convex mirror. However, unlike a normal mirror, when illuminated by a beam of light, an image is formed onto a screen. It has been hypothesized that there are indentations inside the mirror which alter the path of reflected light rays and hence the reflected image. This paper explores various methods to measure these indentations. Of the methods test Phase Shift Reflectometry (PSR) was found suitable to be the most suitable both in terms of the sensitivity and the field of view.

Moiré imaging has been used to measure creep in the airfoil section of gas turbine blades. The ability to accurately assess creep and other failure modes has become an important engineering challenge, because gas turbine manufacturers are putting in place condition-based maintenance programs. In such maintenance programs, the condition of individual components is assessed to determine their remaining lives. Using pad-print technology, a grating pattern was printed directly on a turbine blade for localized creep detection using the spacing change of moiré pattern fringes. A creep measurement prototype was assembled for this application which contained a lens, reference grating, camera and lighting module. This prototype comprised a bench-top camera system that can read moiré patterns from the turbine blade sensor at shutdown to determine creep level in individual parts by analyzing the moiré fringes. Sensitivity analyses and noise factor studies were performed to evaluate the system. Analysis software was also developed. A correlation study with strain gages was performed and the measurement results from the moiré system align well with the strain gage readings. A mechanical specimen subjected to a one cycle tensile test at high temperature to induce plastic deformation in the gage was used to evaluate the system and the result of this test exhibited good correlation to extensometer readings.

This article presents a one step geometric calibration for an optical coherence tomography (OCT) which forms part of a medical navigation system. The 3D landmark-based geometric calibration with a self-produced 3D reference structure is based on the identification of a parameterized grey-box OCT model. We show in experimental results by comparing common measurement errors in the field of medical surgery before and after calibration, that the proposed methodology reduces systematic errors by more than one order of magnitude. Due to its simplicity, the calibration can be carried out directly before a surgical intervention enhancing the OCT accuracy.

A displacement sensor that uses a vertical cavity surface emitting laser (VCSEL), which is superior in terms of remediation of the mode-hop issue and modulation efficiency, is proposed. The interference signal in the sensor is processed with the phase-locked technique. This device allows real-time measurement of displacement. No unstable signals due to mode-hop were observed in the experiments. Displacement measurements recorded with this device indicated that it has an rms measurement accuracy of 0.3 μm and 50 nm for displacements of 150 μm and 1.2 μm, respectively.

The requirements of inner profile measurement of pipes and holes become recently larger and larger, and applications of inner profile measurement have rapidly expanded to medical field as well as industrial fields such as mechanical, automobile and heavy industries. We have proposed measurement method by incorporating a ring beam device that produces a disk beam and have developed various probes for different inner profile measurement. To meet request for applying to smaller diameter pipes, we tried to improve the ring beam light source using a conical mirror, optical fiber collimator and a laser diode. At this moment a probe with the size of 5 mm in diameter has been realized.

This paper describes the development of a fiber-optic confocal probe suitable to measuring the central thickness of highcurvature small-diameter optical ball lenses. The confocal probe utilizes an integrated camera that functions as a realtime apex-sensing device. An additional camera is used to monitor the shape of the reflected light beam. Placing the instrument sensing spot off-center from the apex will produce a non-circular image at the camera plane that closely resembles an ellipse for small displacement. By analyzing the shape of the reflected light spot, we are able to precisely determine the focus point of the confocal probe relative to the apex point to better than 2-μm precision for ball lenses with diameters in the range of 3 – 10 mm. The proposed confocal probe offers a low-cost alternative technique for quality control of ball lenses during the manufacturing process.

Optical coherence tomography (OCT), as an interferometric method, has been studied as a distance ranger. As a technology capable of producing high-resolution, depth-resolved images of biological tissue, OCT had been widely used for the application of ophthalmology and has been commercialized in the market today. Enlightened by the emerging research interest in biomedical domain, the applications of OCT in industrial inspection were rejuvenated by a few groups to explore its potential for characterizing new materials, imaging or inspecting industrial parts as a service solution[3]. Benefiting from novel photonics components and devices, the industrial application of the older concepts in OCT can be re-visited with respect to the unique performance and availability. Commercial OCT developers such as Michelson Diagnostics (MDL; Orpington, U.K.) and Thorlabs (Newton, NJ) are actively exploring the application of OCT to industrial applications and they have outlined meaningful path toward the metrology application in emerging industry[3]. In this chapter, we will introduce the fundamental concepts of OCT and discuss its current and potential industrial applications.

Conventional optical imaging systems are limited by a fundamental trade-off between the depth of field (DOF) and signal-to-noise ratio. Apart from a large DOF, a constant magnification within a certain depth range is particularly essential for visual measurement systems. In this paper, we present a novel visual measurement system with extended DOF and depth-invariant magnification. A varifocal liquid lens is employed to sweep its focus within a single exposure of the detector, after which a blurred image is captured. The blurred image is subsequently reconstructed to form a sharp extended DOF image by filtering with a single blur kernel. The experimental results demonstrate that our method can extend the DOF of a conventional visual measurement system by over 10 times, while the change in the magnification within the extended DOF remains less than 1%.

Simultaneous measurement of the birefringence magnitude and direction using Wollaston prism is presented. The sinusoidally modulated laser beam passes through a circular polarizer, the birefringence sample and is split by a Wollaston prism. The measuring beam is then detected by a bi-cell detector and two alternating current signals are detected. Then the Wollaston prism is rotated by 45°, and another two alternating current signals are obtained. By processing the four signals, the birefringence magnitude and direction is resolved simultaneously. In experiments, a wedge waveplate was laterally moved and measured at different birefringence magnitude. The measured birefringence magnitude linearly increased as the wedge waveplate was laterally moved. The maximum standard deviation of the birefringence magnitude and direction is 0.11° and 0.05°The usefulness of this method is verified.

We propose an effective technique for optically detecting images of the inner hole-surface of a hole (hereafter, referred to as the hole-surface) using the polarization property of a 3D television (TV) monitor. The polarized light emitted by the TV monitor illuminates the hole-surfaces present in the test target placed on the screen of the monitor. When the polarizer placed in front of a camera lens is adjusted such that the camera captures a dark image for the transmitted light, only the highlighted hole-surfaces are visible in the captured image.

Measurement of surface finish in industrial manufacturing has traditionally been done by means of either visual comparison with reference plates or by the use of contact stylus based profilers. There are many challenges associated with contact profilers such as stability during measurement in an industrial environment, damage and wear of the tip, measurement in tight spaces or on curved surfaces and just the limited amount of data obtained by a linear scan of the stylus. Many alternative methods have become available such as white light interferometry, focus based systems, and even laser scatter. This paper will present the result of testing of the commercially available methods with particular emphasis on the fine surface finishes demanded in today’s manufacturing, then presents some alternative methods that show strong potential to address some of the challenges mentioned above that are not in wide use today. The analysis will specifically explore some of the physical mechanisms that affect the stylus based measurement, as well as the limitations of many of the optical approaches related to view angle and diffraction limited resolution consequences. The area of confocal imaging will be specifically explored as to how it might be used to obtain more complete data on very fine surface finishes.

Dynamic speckle interferometry using temporal phase analysis has larger measurement range and is easier to setup over phase-shifting based speckle interferometry. Hilbert transform (HT) is a widely used approach to implement analytic method based phase retrieval. To fulfill the requirements of HT based phase retrieval, EMD (Empirical Mode Decomposition) can be applied to remove the bias intensity. With the low noise assumption, the first IMF was taken as the input for HT. However, according to our experiments, some dynamic speckle signals are not as good as assumed. In many cases, the first IMF is not the proper one. To find the proper IMF, we proposed to adaptively find the IMF of largest similarity with the input signal. And the similarity is evaluated by mutual information. Simulation experiments were given to verify the validity of the proposed algorithm.

Laminated structures are increasingly used nowadays in a wide variety of constructions. The proper functioning of such structures has vital importance especially in automotive and aerospace industries. The major problem in their behavior is a possibility of a sudden and irreversible delamination caused by various factors. We propose and study a NDT approach to investigate the dynamics of prolonged layered structures based on the propagation and optical (holographic) detection of bulk strain solitons in them. Results on experimental observation of the evolution of bulk solitary waves in polymeric 2- and 3-layered waveguides with glassy and rubber-like adhesives used for bonding are discussed. Variations of soliton amplitude were shown to demonstrate the existence of delamination areas. The formation of complex wave patterns – soliton trains or radiating solitons became an additional evidence of defects in layered waveguides.

A new design scheme has been proposed that aim to realize real time, on line raw silk diameter measurement based on linear CCD (Charge Coupled Device) and FPGA (Field Programmable Gate Array).In this system, the samples of raw silk are placed in parallel light which reflect light through macro imaging is received by CCD image sensor. The research on how to improve precision of the system from theoretical approach to various functional modules parameter optimization. What’s more, effects are solved in instability of light illumination and raw silk transparency, linear CCD's dark background imaging is chosen to avoid bright background image easily saturation, distortion caused by raw silk jitter is eliminated. system measurement accuracy reaches to±1μm,experimental results prove that research programme has certain feasibility and practicality.

An optoelectronic system is developed to measure the motions and strains of the rotor blades of a helicopter in research. The motion parameters, including the flap, lag and pitch angles, are measured by two-dimensional position sensitive detectors (PSDs) responding to the changes in position of the light emitting points mounted on the surface of blades. The strains on blades are measured by Fiber Bragg Gratings. Test data show that there are good linear relationships between angles and their related voltages. Less than 1% of angle measurement error is achieved within the measuring range. The FBG data are consistent with that of the strain gauge, with linear correlation coefficient of about 0.999. Besides, the strain measurement is reproducible, with relative deviation of only 1.22% between twice strain measurements. It is concluded that the motions and strains can be measured accurately.

High quality images play a key role in inspecting surface defect of rail track. However, image distortion is frequently occurred in traditional detection systems in which exposure frequency of camera are fixed as constant. The system studied in this paper improves traditional systems by combining a speed auto-adaptable (SAA) system, to adjust proper exposure frequency and uniform image quality all the time according to vehicle riding speed. The system mainly consists of a high-speed external controlled camera, a rotary encoder and a signal processing card, with this system, performance in avoiding image distortion both in laboratory test and practical application can be achieved with minimum detection precision of 0.2 mm at relative low speed and theoretically maximum detection speed of approximate 489 km/h.

High sensitivity simultaneous measurements of atmospheric NO₂ and HONO using incoherent broadband cavityenhanced absorption spectroscopy (IBBCEAS) were developed. A near-ultraviolet light emitting diode (LED) peaked at 372 nm was used as light source of the IBBCEAS instrument to measure the absorption of NO2 and HONO in the spectral range of 361-378 nm. Concentrations of atmospheric NO₂ and HONO were retrieved from the absorption spectra recorded in the absence of atmospheric aerosols and the average detection limits of 2.9 ppbv for NO₂ and 1.2 ppbv for HONO with an acquisition time of 5 min were achieved. The results demonstrated high sensitivity of this measurement technique based on IBBCEAS, which is a promising technique for measurements of atmospheric trace gases.

The cables in anchorage zone of cable-stayed bridge are hidden within the embedded pipe, which leads to the difficulty for detecting the damage of the cables with visual inspection. We have built a detection device based on high-resolution video capture, realized the distance observing of invisible segment of stay cable and damage detection of outer surface of cable in the small volume. The system mainly consists of optical stents and precision mechanical support device, optical imaging system, lighting source, drived motor control and IP camera video capture system. The principal innovations of the device are ⑴A set of telescope objectives with three different focal lengths are designed and used in different distances of the monitors by means of converter. ⑵Lens system is far separated with lighting system, so that the imaging optical path could effectively avoid the harsh environment which would be in the invisible part of cables. The practice shows that the device not only can collect the clear surveillance video images of outer surface of cable effectively, but also has a broad application prospect in security warning of prestressed structures.

The Fourier transform method is an analytical method for interferograms with a spatial linear carrier. Interferograms with a spatial linear carrier are analyzed to obtain the phase, by eliminating the noise from the shape components of the interferograms in the Fourier domain. However, when the noise and shape components overlap in the Fourier domain, it is difficult to eliminate only the overlapped noise components using conventional filtering techniques, such as bandpass filtering. Accordingly, a method is proposed to solve this problem using two interferograms with slightly different carrier frequencies. In this method, the Fourier transforms of two interferograms with slightly different carrier frequencies are separately calculated. Both of the spectra resulting from the Fourier transforms of the interferograms contain the same noise components; however, the locations of these components differ slightly for the two spectra. By subtracting the two Fourier spectra, the noise components are removed, and the main components are generated, because the frequency difference between the two components is small. We have named the proposed method the “two-step Fourier transpose method”. The validity of the proposed filtering method is confirmed by experiments in which two color fringes are projected simultaneously onto a scatter object. Images of the color fringes are acquired via a CCD camera under the slow deformation of the scatter object. The images are then analyzed via the proposed method.

We report a novel measurement method, referred to as the multiple pulse train interference (MPTI)-based method, to measure the refractive index of air using a femtosecond optical frequency comb. The temperature change around the region of interest is recorded based on the interference of multiple pulse trains, and this change is reflected as the distance between MPTI fringes via the use of the conventional Fourier transformation method. The proposed method is demonstrated using a sealed 600-mm cell containing a given volume of water. The results of this preliminary experiment reveal the potential of the MPTI method towards obtaining a high-accuracy evaluation of the refractive index of air.

Ellipsometer enables to characterize optical properties of materials and thin films quantitatively via the measurement of the ellipsometric parameters, Psi (Ψ) and Delta (Δ), of the reflected polarized light by specimen. The ellipsometry surgery began to be applied to an increasingly wide range of areas, such as physics, chemistry, materials and biology. The main advantage of the elliptical polarization measurement technique is to measure a long time, take a large wavelength range, the measurement angle, no damage to the sample, measurement results are accurate. By the principle analysis of the ellipsometer, In this paper ellipsometer is used to measurement electric field component amplitude ratio Ψ and electric field component phase difference Δ of the satellite surface coated materials, and then set the angle of incidence and wavelength, the optical constants (index of refractive n and extinction coefficient k) can be obtained. On the measurement results in different incident in an optimization modeling, also has access to more parameters description. The experiments show that the measurement results and fitting results match well within the spectral range 300 nm-1000 nm range. This paper is offer methods of measurement and modeling for characterize optical properties of materials and thin films.

A frequency measurement system for dual frequency He-Ne lasers is set up based on an external cavity diode laser locked to fiber femtosecond optical frequency comb using an Rb clock as a frequency standard. The frequencies of the Zeeman split orthogonal polarized lasers are measured by beating with the locked diode laser at the same time. Locking the diode laser to the 1 894 449th comb tooth, the absolute frequency of the diode laser is 473 612 190 000.0 (2.4) kHz, with a relative frequency uncertainty of 5.1×10^-12. A commercial dual frequency He-Ne laser is measured to test the system, and the results show that the mean absolute frequencies of the horizontal polarized laser and the vertical polarized laser are 473 612 229 934 kHz and 473 612 232 111 kHz, respectively, with a relative Allan deviation of 5.2× 10^-11 at 1 024 s, and the mean split frequency is 2.177 MHz with a standard deviation of 2 kHz.

A new method for phase unwrapping is proposed, which makes the unwrapping of phase images realistic without binary codes or more frequency fringe images produced by projection systems, uses only one additional digital speckle pattern projected to help finding correspondence points. It means that the novel method is by the use of the additional speckle pattern to achieve a unique point correspondence. The proposed method to get unwrapped phase will save images recorded time. Experiment results demonstrated the proposed method is effective and robust.

The conversion efficiency measurement accuracy of solar cell is heavily rely on the measurement uncertainty of pulsed solar simulator. The measurement uncertainty assessment method of pulsed solar simulator is widely analyzed and studied. This paper describes uncertainty assessment method of measurement of irradiance non-uniformity which is one of the three most important factors(spectral mismatch, non-uniformity of irradiance and instability of irradiance) influencing pulsed solar simulator measurement uncertainties. An experiment using a real pulsed solar simulator was performed to testify the validity of uncertainty assessment method. The results provide a theoretical and data basis for further analysis of overall uncertainties of solar simulators.

The increasing developments in Unmanned Aerial Vehicles (UAVs) platforms and associated sensing technologies have widely promoted UAVs remote sensing application. UAVs, especially low-cost UAVs, limit the sensor payload in weight and dimension. Mostly, cameras on UAVs are panoramic, fisheye lens, small-format CCD planar array camera, unknown intrinsic parameters and lens optical distortion will cause serious image aberrations, even leading a few meters or tens of meters errors in ground per pixel. However, the characteristic of high spatial resolution make accurate geolocation more critical to UAV quantitative remote sensing research. A method for MCC4-12F Multispectral Imager designed to load on UAVs has been developed and implemented. Using multi-image space resection algorithm to assess geometric calibration parameters of random position and different photogrammetric altitudes in 3D test field, which is suitable for multispectral cameras. Both theoretical and practical accuracy assessments were selected. The results of theoretical strategy, resolving object space and image point coordinate differences by space intersection, showed that object space RMSE were 0.2 and 0.14 pixels in X direction and in Y direction, image space RMSE were superior to 0.5 pixels. In order to verify the accuracy and reliability of the calibration parameters，practical study was carried out in Tianjin UAV flight experiments, the corrected accuracy validated by ground checkpoints was less than 0.3m. Typical surface reflectance retrieved on the basis of geo-rectified data was compared with ground ASD measurement resulting 4% discrepancy. Hence, the approach presented here was suitable for UAV multispectral imager.

It often needs transfer a reference from one place to another place in aerospace and guided missile launching. At first, principles of several typical optical azimuth transmission methods are presented. Several typical methods are introduced, such as Theodolite (including gyro-theodolite) collimation method, Camera series method, Optical apparatus for azimuth method and polarization modulated light transmission method. For these typical azimuth transmission methods, their essential theories are elaborated. Then the devices, the application fields and limitations of these typical methods’ are presented. Theodolite (including gyro-theodolite) collimation method is used in the ground assembly of spacecraft. Camera series method and optical apparatus for azimuth method are used in azimuth transmission between different decks of ship. Polarization modulated light transmission method is used in azimuth transmission of rocket and guided missile. At the last, the further developments of these methods are discussed.

Optical interferometric phase demodulation algorithm is provided based on the principle of phase generated carrier (PGC), which can realize the optical interference measurement of high-precision signal demodulation, applied to optical fiber displacement, vibration sensor. Modulated photoelectric detection signal is performanced by interval 8 frequency multiplication sampling. The samples calculate the phase modulation depth and phase error through a feedback loop to achieve optimum working point control. On the other hand the results of sampling calculate precision of numerical of the phase. The algorithm uses the addition and subtraction method instead of correlation filtering and other related complex calculation process of the traditional PGC digital demodulation, making full use of FPGA data processing with advantage of high speed and parallel; This method can give full play to the advantage of FPGA performance. Otherwise, the speed at the same time, FPGA can also ensure that the phase demodulation precision, wide dynamic range, and give full play to the advantage of completing the data access by single clock cycle.

In order to obtain an accurate Avogadro constant with a relative uncertainty of 1×10^-8 to redefine the kilogram, the diameter of a perfect single crystal silicon sphere is required with the measurement uncertainty of 0.3 nm using the X-ray crystal density method. To achieve this, phase-shifting interferometers have been developed. A laser frequency tuning system calibrated by a Fabry-Perot cavity is proposed to improve the laser wavelength and the phase-shift accuracy. The laser frequency standard deviation of the beat frequency is 85 kHz with a gate time of 0.1 s. The gap distances in the diameter determination interferometer are measured based on the laser tuning system, which are 275.3 nm and 110.5 nm, respectively.