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The signal processing of the grating encoder has a great impact on its accuracy and resolution. We proposed a new type of signal processing method for a grating encoder using a two-phase differential algorithm based on the two-phase physical structure. The interference signal could be divided into two phases with 90 degrees phase delay, capable of effectively reducing the number of optical devices and the space occupied by the reading head. Owing to the rapid elimination of the DC component in the measurement signal, the measurement displacement was solved swiftly by the two-phase signal using the algorithm. In the experiment, a 660 nm laser and a 1 µm-period grating were used, and the scale grating was actuated at a speed of 1 µm/s by a linear stage. With a sampling rate of 20 kHz, the system resolution of the grating encoder was enabled to reach 50 pm. Simultaneously, there was a measurement error of ±1 µm at a stroke of 4 mm, and the error within a single cycle was 2 nm. Compared with the four-phase algorithm, our proposed two-phase differential algorithm exhibits a compact physical structure and fast solution without reducing the accuracy and resolution, which will be of great significance to the real-time measurement and miniaturization of grating encoders.

Spectral reflectance plays an important role in the evaluation of the object surface, such as the color, the roughness. A new method is proposed to measure the spectral reflectance at a fixed incident angle. The chromatic confocal displacement sensor is modified with an annular stop to generate a hollow cone beam of incident light on the to-be measured sample surface. With self-reference strategy, the upper and lower envelops are derived from the axial scanning of the dispersion probe, whose minus is named as self-reference spectrum. Thus, the reflectance at every wavelength among the valid dispersion bandwidth can be achieved by comparing the self-reference spectra of the sample surface and a standard mirror with known spectral reflectance. With the proposed method and experimental setup, the spectral reflectance of several metal surfaces is obtained and compared with their theoretical spectral reflectance within ±0.04. It proves that the modified chromatic confocal can provide feasible results for the spectral reflectance measurement.

Thickness measurement for the optical thin films is very important for the industries of mechanics, printing, battery and so on. Infrared transmittance method is a very useful method to achieve the physical response, which is related to the film thickness according to the Lambert-Beer law. A detail measurement system is designed with two light paths of reflectance and transmittance, consisting of the light source, filter motor, beam splitter, paraboloid mirror, PbSe detector, and so on. An experimental setup is also established with two different infrared wavelengths by two different bandpass optical filters. The stability of the measurement system is tested to be only about 0.3% in 10 min. The experiments show the feasibility of the proposed double-wavelength infrared transmittance method for film thickness measurement.

Three-dimensional (3D) measurement based on structured light, as a non-contact, active, and high-precision measurement technology, is widely applied in the diverse fields of industrial detection, face recognition, reverse engineering, and so on. We adopted an adjustable grating-stripe coding as the dynamic structured-light mode, which can continuously cover the entire measured surface to guarantee high accuracy. A one-axis resonant-mode MEMS mirror combined with a linear laser was used to project the desired adjustable grating stripes, leading to a miniaturized module size. To make the scanning angle of the MEMS mirror matching the intensity distribution of the linear laser, we further introduced a single-chip microcomputer (STM32) to receive the feed-back signals from MEMS mirror, and synchronously controlled the laser power with corresponding function relationship output. Here, the MEMS mirror could provide a resonant frequency of 1.15 kHz, a scanning optical angle of ±30°, a feed-back scanning-angle resolution of 0.05°, and a reflected mirror size of 3 mm-diameter circle, respectively. Also, the laser source could generate a line width of 70 μm at a 300 mm focused distance. To decrease the error in the energy amplitude of each cycle of the structured light stripes, the empirical mode decomposition (EMD) was used to perform principal component analysis and recombination of the structured light stripes. In addition, total harmonic distortion (THD) is used to evaluate the quality of structured light stripes. Finally, the structured light based on the scanning of the MEMS mirrors exhibits a good sinusoidal stripes and high refresh rate, implying high adaptivity for the 3D reconstruction.

As a fundamental geometric indicator, high precision roundness measurement is the basis evaluation index of cylindrical or spherical parts. In most roundness measurements, the rotation platforms are used to bring certain rotation error to the measurement result. Two-probe method is a typical roundness measurement strategy with error separation technique, coming from three-probe method with low cost, online integration, flexible installation, etc. We developed a roundness measurement system with three chromatic confocal displacement sensors with flexibility and high axial-resolution. As the measurement start, two sets of displacement data are achieved to take part in the frequency calculation. A typical cylindrical workpiece was measured for its roundness, which was very close with the measurement result by an ultra-precision roundness meter. In a word, the chromatic confocal roundness measurement system is feasible to provide high precision roundness with two-probe method.

The planer grating with large area plays an important role in the optical encoder for large stroke measurement. Compared with the conventional fabrication techniques such as interference lithography and mechanically ruling for large-area manufacture, splicing small-area grating units into a large integral mosaic grating is promising to reduce the technical difficulty and time-consumption. We proposed a novel grating splicing method to construct large-area mosaic grating applicable for optical encoder. The splicing apparatus is capable of providing four degree-of-freedom including one outof-plane straight motion (ΔZ) and three rotation motions (Δθx, Δθy, Δθz) for mechanically adjusting the grating units. The diffracted beams from the spliced gratings are utilized to guide the adjustment, i.e., zero-order diffracted beams for ΔZ, Δθx, Δθy and first-order diffracted beams for Δθz, respectively. The diffracted-beams orientations of the first grating were adopted as the basic reference, and the posture of the other gratings are continuously adjusted by matching the position of the diffracted beams. Five grating units with 20×20 mm2 area and 1 μm period were spliced together. Finally, a coordinate measuring machine was utilized to evaluate the flatness of the mosaic gratings, showing a good flatness as small as ~60 μm. It is demonstrated that our proposed splicing method is promising to achieve good flatness of mosaic grating potentially applied for large-stroke optical encoder.

The signal filtering of the grating encoder is of great significance to the measurement accuracy, aiming at eliminating the background noise potentially from the temperature changes, airflow fluctuations, and mechanical vibrations. Compared with the traditional time-frequency analysis methods, including wavelet transform, fast Fourier transform (FFT), and time Fourier transforms (TFT), the empirical mode decomposition (EMD) algorithm owing to no basis functions and high adaptability, is widely applied for signal decomposition. Here, we extended the EMD algorithm for the background-noise-based signal filtering in a grating encoder, with the experimental parameters of 5 µm/s moving speed and ~19 mm stroke. Simultaneously, a laser interferometer, as a reference, was additionally assembled to calibrate the measurement results of the grating encoder. The measurement signal was collected by NI acquisition card with a 1000 Hz sample rate and processed by EMD algorithm. Here, EMD decomposed the signal into multiple intrinsic mode functions (IMFs), which were reconstructed by removing the noise and DC components according to the correlation coefficients. Compared with the measurement results of the laser interferometer, the measurement displacement with a 6.2 µm error was solved by the phase correction and arctangent calculation from the reconstructed signals. Finally, our proposed signal-filtering approach based on the EMD algorithm exhibits a stable, accurate, and real-time calculation performance applicable for the grating encoder with ultra-high precision positioning.

For specular reflection surface detection, high reflectivity is a large challenge to effectively extract the depth information of surface. Phase Measuring Deflectometry (PMD) based three-dimensional shape measurement is proposed for solving this problem. In this study, PMD method based on the characteristic of high specular reflectivity is used to perform structured light imaging on the glass surface to obtain depth information on the surface of the glass panel. In this paper, we propose a new image reconstruction method suitable for imaging specular reflection surface defects. According to the characteristic of the glass panel, the proposed method has a phase pre-unwrapping process and improves the least square method of unfolding and folding the phase algorithm. The experimental results show that the proposed method is more robust for imaging and detection of high-reflective plane than the traditional least squares method.

A flexible calibration method with high precision was proposed for calibration of structured laser triangulation in the applications of 3D reconstruction and point cloud processing. The camera coordinate system was chosen as the ultimate reference coordinate. In this calibration process, be required only a planar pattern placed at different orientations and positions for obtainment of the camera intrinsic parameters. And then two or more non-coplanar sets of three collinear points were calculated for the laser projection plane coefficients. A line laser triangulation measurement system is established, consisted of laser diode, cylindrical lens module and camera imaging system. Experimental results based on the constructed structured laser triangulation system revealed that accuracy of the profile measurement is less than ±0.005mm, which can meet the majority of industrial inspection applications.

Among various nano-scale linear displacement sensors, grating scales have been widely used in industrial fields due to their strong anti-interference ability, cost-effectiveness and compactness. The main development directions of the scale are: high precision, large range, high speed, high dimension and absolute type. Our team has completed the optical layout design of the absolute two-dimensional grating rule, which brings new challenges to the design data acquisition and processing hardware system due to the requirements of multiple dimensions and high speeds. There is no real-time data processing system suitable for absolute two-dimensional scales. This paper presents our latest progress in designing and implementing an absolute two-dimensional grating distance measurement real-time data processing platform. Our platform mainly contains four different functional modules. First, the circuit conditioning module performs I-V conversion and signal amplification and filtering on the weak current signal output from the photodiode. Secondly, an 8- channel high-speed data acquisition module with 14-bit resolution and 80 MSPS maximum sampling rate was designed to convert analog laser pulse signals into digital signals. Third, we have established a real-time data processing module that allows 16 bits of data to be entered in the FPGA to calculate the absolute two-dimensional scale distance. Finally, a data transfer module based on 128MB DDR SDRAM and USB 2.0 was added so that we can easily debug the platform on a PC. The performance of our system is evaluated in real time. The test platform consists of a laser, a twodimensional grating optical path, and our data processing system. The absolute two-dimensional scale has a moving speed of 1m/s, a signal frequency of 10MSPS, a laser emitting signal wavelength of 540nm, and a moving distance of 10-15mm. Experimental results show that our system can output at a rate of 2500 points per second. Measurement results, measurement deviation is less than 50nm.

In this paper, an orthogonal type two-axis Lloyd’s mirror interference lithography technique was employed to fabricate two-dimensional planar scale gratings for surface encoder application. The two-axis Lloyd’s mirror interferometer is composed of a substrate and two reflective mirrors, which are placed edge by edge perpendicularly. An expanded and collimated beam was divided into three beams by this interferometer, a direct beam and two reflected beam. The unnecessary beam section was blocked by a home designed filter. These two reflected beams interfere with the direct beam respectively, generates perpendicularly cross patterns for forming two-dimensional scale gratings. The two reflected beams also interfere with each other and generate an undesired grating pattern along a 45 degree direction, which influence the pattern uniformity in a certain degree. The undesired grating pattern can be eliminated by polarization modulation, yet which will influence the grating area. Theoretical and experimental study was carefully carried out to evaluate the fabrication quality with and without polarization modulation. Two-dimensional scale gratings with a 1 μm period in X- and Y-directions were achieved by using the constructed experiment system with a 442 nm HeCd laser source. Atomic force microscope (AFM) images and diffraction performances verified that the two-axis Lloyd’s mirror interferometer with a small undesired interference between two reflected beams under an order of nominal value of 0.1 can provide a better fabrication result for scale gratings application.

In this research, a key optical component for multi-degree-of-freedom (MDOF) surface encoder was designed, fabricated and evaluated. In a MDOF grating interferometry system, there are four diffraction beams from the scale grating and reference grating. For further modulation, these beams will propagate more than 100 mm, which makes paralleling these beams necessary. In previous researches, separate prisms and a home fabricated diffraction device by combining four separate one-axis line gratings in a glass substrate have been demonstrated. However, large power loss and assembly complicity makes this technique less competitive. For solving this problem, this research proposed a new lens module, which is an improved type prism, quadrangular frustum pyramid. The prism is designed in such a way that these four reflected beams from the grating are symmetrically incident into the prism through the upper surface, total reflected on the inner sides of the prism, and then paralleling propagate through the bottom surface. A prism that allows an incident beam diameter of 1 mm and four paralleling beams with a 10 mm distance between the two diffraction beams along one direction was designed, fabricated and tested. Testing results based on an entire grating interferometry system verified that the proposal in this research is greatly effective in beam paralleling in terms of less power loss and high paralleling and greatly reduce the assembly complicity, which will eventually be beneficial for grating interferometry application.

A line encoder composed of a two-probe reading head an arrayed scale grating stitched by multiple separate gratings was proposed, constructed and evaluated in this research for expanding the measurement range. The scale grating is stitched by multiple separate short gratings fabricated by a holographic lithography that is able to provide sub-micron order grating period. Differing from the conventional stitched grating, in which the gap of the adjacent two gratings should be strictly controlled so that a continuous phase can be ensured, the gap in this research is not necessary to be controlled, neither the gap width nor the phases, by using a two-probe reading head. In contrast to the reading head in conventional linear encoder, the two-probe reading head was designed in such a manner that a collimated laser beam with a diameter of 1mm was divided into two parallels probes (probe A/B) by a specially designed prism lens. These two probes are projected perpendicularly onto the transmission type arrayed scale grating. Taking probe A as an example, after passing the grating, the positive and negative first-order diffraction beams follow a typical grating interferometry principle, including propagating direction changing, co-path by a beam splitter and a polarize for a phase delay module and finally interfere with each other, from which the displacement can be obtained. The two probes propagate along similar optical path. The two probes can ensure as least one can be projected onto the grating. By stitching the two probe outputs suitably, the continuous output of the scale grating can be measured accurately. The jig for stitching the separate gratings was investigated and tested. The two-probe reading head prototype was constructed and evaluated.

In the traditional fluorescence detection, samples are tested in the solvent, and the mutual effect of solvent, micro impurity and sample affects the fluorescence characteristics. Meanwhile, such effect includes vibrational relaxation, electron rearrangement of solvent molecule, special role of the sample with the solvent molecules and so on. The experiment of fluorescence quantum efficiency at atmosphere reduces the interference, because the distance between molecules is much larger in gas phase. In addition, the research of quantum efficiency can also promote the understanding of LIF and expand the range. In this paper, the fluorescence quantum efficiency of 3 different samples at atmosphere was compared, and the electrospray ionization source was selected for its soft ionization characteristics. The ionization method did not spoil the fluorophore of the sample, and the drift tube of ion mobility spectrometry (IMS) was used for ions transport and desolvation. The ionization source was on the one side of the drift tube and the test point was on the other side. The paths of excited laser and emission light were orthogonal at the test point. Meanwhile, stable ions flowed through the drift tube. The emission light was captured by the camera, which was coupled with a long-wave pass filter. The test samples were Rhodamine 6G，Rhodamine B and amino copper indium sulfide quantum dots of the same mass fraction. The energy of excited laser was between 30 mW and 150 mW. Then the results showed that the emission intensity was proportional to the laser power in gas phase, and the sort of the fluorescence quantum efficiency was the quantum dots>Rhodamine 6G>Rhodamine B.

This paper proposed a new method for reference position detection with high precision for linear encoders by using a home designed scale grating and a coherence function algorithm. Differing from the traditional methods, in which the reference position alignment and calibration of reference position was achieved by detecting the peak of the signal with a negative pulse at the reference position, the method in this paper no longer detects the single peak of the signal, but matching and aligning the integral shape of reference position signal through the algorithm based on the coherence function. The proposed method does not require a complex design and precision manufacturing of reference position. Due to the coherence function algorithm, a multi-pulse reference position signals design is available, which not only reduces the difficulty of reference position design and manufacturing, but also shortens the length of reference position area so that the negative effect on the grating diffraction efficiency is limited. What is more, robustness of the reference detection method introduced here is greatly enhanced. Experimental results show that the accuracy of reference detection can still achieve 2 times of resolution even under the low signal to noise ratio (SNR) of 2dB.

A three-DOF surface encoder can be used to measure the three translational degree of freedom (DOF) displacement of a moving table. A measurement uncertainty of the developed three-DOF surface encoder was systematically investigated to confirm its feasibility on the precision positioning of planar motion stage. An expanded uncertainty of 124.4 nm has been calculated in the measurement results of testing three-axis translational motions over a range of 2.5 μm. Among those error sources, cross-talk errors caused by misalignment existing in experimental setup were identified to be the largest error source.

In this paper, an underwater ranging system based on photoacoustic effect occurring on target surface is proposed. In this proposal, laser pulse generated by blue-green laser is directly incident on target surface, where the photoacoustic effect occurs and a sound source is formed. And then the sound wave which is also called photoacoustic signal is received by the ultrasonic receiver after passing through water. According to the time delay between transmitting laser and receiving photoacoustic signal, and sound velocity in water, the distance between the target and the ultrasonic receiver can be calculated. Differing from underwater range finding by only laser, this approach can avoid backscattering of laser beam, so easier to implement. Experimental system according to this principle has been constructed to verify the feasibility of this technology. The experimental results showed that a ranging accuracy of 1 mm can be effectively achieved when the target is close to the ultrasonic receiver.

Ion Mobility Spectrometry (IMS), having an advantage in real-time and on-line detection, is an atmospheric pressure detecting technique. LA-IMS (Laser Ablation Ion Mobility Spectrometry) uses Nd-YAG laser as ionization source, whose energy is high enough to ionize metal. In this work, we tested the signal in different electric field intensity by a home-made ion mobility spectrometer, using silicon wafers the sample. The transportation of metal ions was match with the formula: Td = d/K • 1/E, when the electric field intensity is greater than 350v/cm. The relationship between signal intensity and collection angle (the angle between drift tube and the surface of the sample) was studied. With the increasing of the collection angle, signal intensity had a significant increase; while the variation of incident angle of the laser had no significant influence. The signal intensity had a 140% increase when the collection angle varied from 0 to 45 degree, while the angle between the drift tube and incident laser beam keeping the same as 90 degree. The position of ion gate in LA-IMS(Laser Ablation Ion Mobility Spectrometry) is different from the traditional ones for the kinetic energy of the ions is too big, if the distance between ion gate and sampling points less than 2.5cm the ion gate will not work, the ions could go through ion gate when it closed. The SNR had been improved by define the signal when the ion gate is closed as background signal, the signal noise including shock wave and electrical field perturbation produced during the interaction between laser beam and samples is eliminated when the signal that the ion gate opened minus the background signal.

The paper presents a dual-beam interference lithography technology for fabrication of diffraction gratings for surface encoders by using cost-effective 405 nm blu-ray laser diodes. In this system, an amplitude division interferometer system is employed. A laser beam raying from a blu-ray laser diode is collimated and then divided into two beams by a beam splitter. These two beams are changed their propagation directions and interfere with each other. Generated interference fringes are exposed on the photoresist coated substrate. Grating line spacing d can be adjusted by changing the incident angle between these two beams. Grating width Wc that determines the measurement of the surface encoder is decided by the coherence length Lc of the laser diode and the grating line spacing d. Calculation and simulation were carried out to decide the grating width. Lc was experimentally obtained. A fabrication system was constructed to verify the feasibility of this technology. Diffraction gratings with a 2.5 micron line spacing and a 2.5 mm width was obtained.

The real-time distance measurement system with dual femtosecond comb lasers combines time-of–flight and interferometric measurement. It has advantages of wide-range, high-accuracy and fast speed at the rate about 10000 pts/s. Such a distance measurement system needs dedicated higher performance of the data acquisition and processing hardware platform to support. This paper introduces the dedicated platform of the developed absolute distance measurement system. This platform is divided into three parts according to their respective functions. First part is the data acquisition module, which function is mainly to realize the A/D conversion. In this part we designed a sampling clock adjustment module to assist the A/D conversion module to sample accurately. The sampling clock adjustment module accept a 250MHz maximum reference clock input, which from the same femtosecond laser source as the optical measurement system, then generate an output clock for the A/D converter that can be delayed up to 20ns with a resolution of 714ps. This data acquisition module can convert the analog laser pulse signal to digital signal with a 14 bits resolution and a 250 MSPS maximum sample rate. Second is the data processing and storage module consists of FPGA and DDR3 modules. The FPGA module calculates the test distance by the 16 bits digital sampling signal from the front data acquisition module. The DDR3 module implements sampling data caching. Finally part is the data transmission and peripheral interfaces module based on three DB9 and USB2.0. We can easily debug the platform in the PC and implement communication with upper machine. We tested our system used dedicate test bench in real-time. The scope of the measurement system range is 0 to 3 meters and the measurement deviation is less than 10um.

Fabrication of a new type hybrid plane optics, Grating-Fresnel (G-Fresnel) lens for miniature spectrometer is presented in this research. A polydimethylsiloxane (PDMS) based soft lithography technology is employed. In this method, the grating surface and Fresnel surface of the G-Fresnel lens are formed simultaneously by sandwiching the PDMS layer between a reverse Fresnel mold and a grating. Surface anti-adhesive treatment method has been proposed to solve the innate adhesion of PDMS layers. A fabrication system is constructed and a G-Fresnel with grating line spacing of 1.11μm (900 lines/mm) and Fresnel lens with a diameter of 25.4 mm and a focal length of 25 mm was successfully fabricated. Three-dimensional surface profilometry has been performed to examine the device quality. Measured results show that replicas remain high fidelity to its primary master mold. A miniature spectrometer system was constructed to evaluate the performances of this fabricated G-Fresnel lens. Experimental results show that the spectrometer can provide about 2 nm resolutions at wavelengths of 450nm, 532 nm, and 650 nm, which verified the effectiveness of this fabrication method.

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.

Laser-induced breakdown spectroscopy (LIBS) is characterized as a powerful tool in in-situ online analysis with its fast and multiple detecting abilities. But in the area of detecting trace sample in aqueous solution of low concentration, the turbulence, scattering, absorbance and cooling effect of liquid medium limits its performance. Traditional method includes liquid jet, liquid-solid transformation and pre-concentration on other medium, yet the procedure of sample preparation is complicated and time consuming. In this work, we propose a new method to achieve pre-concentration, in which filter paper and electro-spray ionization (ESI) are used. In our experiment, we choose MnSO 4 as sample. The surface of filter paper is sprayed with MnSO 4 aqueous solution of different concentration by an ESI. The pulsed laser is focused on the surface of filter paper and the plasma is formed in the focusing area. Through an optical fiber the spectrum of plasma is detected by a spectrometer. The ESI system, pulses generator system and the UI on PC are home-made. The spectra lines of Mn at 257.6nm, 259.4nm and 260.6nm are analyzed. Results show that the limit of detection at 257.6nm is sub-ppb and the R 2 of calibration curve is more than 0.93. Compared with traditional method, like soak and drip processing, our method can increase the concentration of the sample by simply expanding spraying time, achieving a higher signal-to-noise ratio (SNR) and a lower limit of detection (LOD). In addition, the consumption of sample solution is as low as several hundred μl in each detection.

Ion mobility spectrometry (IMS) is widely used in the field of chemical composition analysis. Faraday cup is the most classical method to detect ions for IMS in the atmospheric pressure. However, the performance of Faraday plate was limited by many kinds of factors, including interfering electromagnetic waves, thermal(Johnson) noise, induced current , gain bandwidth product, etc. There is a theoretical limit in detection of ions at ambient condition which is approximately 106 ions per second. In this paper, we introduced a novel way using laser-induced fluorescence (LIF) to bypass the limitation of Faraday plate. Fluorescent ions which were selected by IMS get excited when they fly through the laser excitation area. The fluorescence emitted by the excited ions was captured exponentially and amplified through proper optoelectronic system. Rhodamine 6G (R6G) was selected as the fluorochrome for the reason that excitation wavelength, emission wavelength, and fluorescence quantum yield were more appropriate than others. An orthometric light path is designed to eliminate the adverse impact which was caused by induced laser. The experiment result shows that a fluorescence signal from the sample ions of the IMS could be observed. Compared with Faraday plate, the LIF-IMS may find a potential application in more system at the atmosphere condition.

Ion mobility spectrometry (IMS) is an attractive material analysis technology for developing a miniaturized volatile organic compounds (VOCs) on-site monitoring sensor. Having simple instrumentation, IMS is especially suitable when portability and sensitivity are required. In this work, we designed an ion mobility spectrometer with UV ionization. The geometric parameters of the UV-IMS were optimized based on a numerical simulation. The simulation results demonstrated that the drift electric field in the drift region was approximately homogenous and in the reaction region had an ion focusing effect, which could improve the sensitivity and resolving power of the IMS. The UV-IMS has been constructed and used to detect VOCs, such as acetone, benzene, toluene and m-xylene (BTX). The resolution of these substance measured from the UV-IMS in the atmospheric conditions are about 30 and the limit of detection (LOD) is low to ppmv. The ion mobility module and electric circuit are integrated in a main PCB, which can facilitate mass production and miniaturization. The present UV-IMS is expected to become a tool of choice for the on-site monitoring for VOCs.

Equipped with the mini camera, UAVs can be used as a surveillance device, which can be widely used in both civil fields as well as military fields. The real time video output by camera can be transferred down to the ground station and is processed to detect and localize the interested targets. A low-cost and real time circular targets detection and localization algorithm is proposed in this paper. The target is detected by image analysis based recognition method and the position is represented in UAV's coordinate frame. Further, the position is transferred to the world coordinate frame by using UAV's guidance data (position and attitude) to localize the targets. Experiment results are also given and show that the algorithm can be run in real time.

After more than ten years' research efforts on the Micro Aerial Vehicle (MAV) since it was proposed in 1990s, the stable flying platform has been matured. The next reasonable goal is to implement more practical applications for MAVs. Equipped with a micro radio-localizer, MAVs have the ability of localizing a target that transmitting radio signals, and further can be a novel promising Anti-Radiation device. A micro radio-localizer prototype and its localization principle and localization algorithm are proposed. The error analysis of the algorithm is also discussed. On the basis of the comparison of the often-used radio localization method, considering the MAVs' inherent limitation on the dimension of the antennas, a signal intensity and guidance information based localization method is proposed. Under the assumption that the electromagnetic wave obeys the free-space spreading model and the signal's power keeps unchanged, the measuring equations under different target motions are established. Localization algorithm is derived. The determination of several factors such as the number of measuring positions, numerical solving method and initial solution is discussed. Error analysis of the localization algorithm is also proposed by utilizing error analysis theory. A radio-localizer prototype is developed and experiment results are shown as well.

Micro machine vision system is an important part of a micromanipulating system which has been used widely in many fields. As the research activities on the micromanipulating system go deeper, micro machine vision system catches more attention. In this paper, micro machine vision system is treated as a kind of machine vision system with constrains and characteristics introduced by specific application environment. Unlike the traditional machine vision system, a micro machine vision system usually does not aim at the reconstruction of the scene. It is introduced to obtain expected position information so that the manipulation can be accomplished accurately. The architecture of the micro machine vision system is proposed. The key issues related to a micro machine vision system such as system layout, optical imaging device and vision system calibration are discussed to explain the proposed architecture further. A task-oriented micro machine vision system for biological micromanipulating system is shown as an example, which is in compliance with the proposed architecture.

The synchronization control technique is one of the most key techniques in the laser range gated (LRG) imaging system. Conventional control circuits are composed of discrete components and Medium Scale Integration (MSI) and Small Scale Integration (SSI), which have bad reliability and poor ability of anti-interference. The idea of using the Complex Programmable Logic Device (CPLD) to realize the monostable trigger circuit is introduced. On the basis of analyzing the performance requirement to the synchronization control of the laser range gated imaging system, a new synchronization control circuit based on CPLD is presented. The circuit based on CPLD is very compact and flexible and has high reliability and strong ability of anti-interference. The synchronization control circuit based on CPLD can provide a wide selection of gate widths, pulse widths and delays. The synchronization control circuit is successfully used in our experiment and the expected result is obtained.

A MEMS based micro colloid thruster (including an source emitter array and an extractor) is designed, fabricated and tested. Source emitter array of the thruster is silicon column etched by ICP. The negative electrode on the extractor can be controlled separately. After bonding together, a single emitter and extractor works on an electrical colloid propulsion principle, and produce µN order thrust. Such a small and controllable thrust is the urgent requirement for a micro-satellite. Thrust test for the micro colloid thruster is made in high vacuum box. Thrust is acted on a cantilever beam, and the displacement of cantilever beam is detected by a current vortex sensor. Analysis to the recording data shows that the maxim thrust produced by a single emitter is about 2 µN, which is agreement with theory estimate.