This PDF file contains the front matter associated with SPIE Proceedings Volume 12075, including the Title Page, Copyright information, and Table of Contents.

Scanning lidar scans the target region point-by-point and measures the time of flight (TOF) of laser signal at each point to obtain the 3D information of the target surface. By using fixed size of scanning spot, the resolution of reconstructed depth image is consistent with the number of scanning points. Therefore, traditional scanning lidar is hardly to achieve high resolution and scanning efficiency simultaneously. Aimed to address this issue, we propose a method of interested region selection and depth image super-resolution reconstruction. By constructing a simulation target region with 10 m × 10 m, the proposed method is used to scan this region. The position of the interested region is obtained by scanning the full field of view (FOV) with a large spot. Then the interested region with 4 m × 8 m is fine scanned with reduced scanning spot. By using the super-resolution reconstruction method of depth image, the resolution of the depth image obtained by fine scanning with 40 × 80 points is increased by two times. And the depth image of the interested region with 80 × 160 pixels is obtained. The simulation result shows that the lidar based on this method can give consideration to both high scanning efficiency and the resolution of reconstructed depth image.

The gas sensors based on organic thin-film transistor (OTFT) have drawn considerable attention due to the advantages of low-cost, flexible, and room-temperature operation. Herein, poly(3-hexylthiophene) (P3HT) blend with surfactants as an active layer for high-performance OTFT based nitrogen dioxide (NO2) sensors was reported. With the introduction of the surfactant (4-(1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol, Triton), the gas sensors exhibited 7 times greater response to 30 ppm NO₂ than pure P3HT films. The studies in morphology of the blend film reveal that a large number of grain boundaries (GBs) are formed by introduction of surfactants, which can promote the diffusion of NO₂. In addition, the hydroxyl functional groups of the surfactants in blend films can efficiently adsorb polar molecules such as NO₂, thus enhance the sensing performance. The gas sensors also showed great potential for ultralow concentration detection with a response of 61% to 500 ppb, which are important for the practical applications. This work demonstrates that the surfactants can be applied to improve the NO₂ sensors with simple solution process, which expands the material choice of OTFT based gas sensors.

As a parameter of the process of an event, the measurement of decay time constant has been widely used in many fields such as electronic information, economy, chemistry and biology. How to quickly and accurately obtain the decay time constant of various kinds of decay signals has always been a hot issue in the field of testing technology. In this paper, research and carding are carried out on the fast and accurate decay acquisition method of time constant of single exponential decay signal. The main purpose is to comprehensively grasp the main methods adopted in current engineering technology and scientific research, and on this basis, a set of fast and accurate acquisition scheme of attenuation time constant based on ZYNQ system is proposed, It lays a foundation for the development of cavity ring down loss measurement and spectrum measurement system.

The detecting CCD of a space astronomical telescope needs to be cooled to -75℃ to suppress the dark current for faint target detecting in the universe, and coplanarly spliced with two fine guidance sensor(FGS) which needs to be cooled to -40°C for the stability as long time observation. Two one stage thermos-electric cooler(TEC) was connected to actively cool the detector to ensure the working temperature and the temperature control accuracy, the Structural of the actively cooling detector assembly and the focal plane component were presented and the power dissipation of the TEC was calculated. In order to ensure the coplanarity of the focal plane component on the working temperature, the finite element method was used to analyze the thermal distribution on the detector surface and the thermal deformation of the supporting structure of the FGS with different materials. The analysis results showed that the lowest cooling temperature of the detecting CCD is -75°C, the temperature control accuracy was better than 1°C, and the coplanar error of the detection CCD and the fine guidance sensors did not exceed 20μm. The thermal equilibrium test showed that the lowest cooling temperature was -74.9°C~-75.1°C for the detecting CCD, The temperature control accuracy was 0.1°C. The thermal optical test showed that the defocus of the FGS was 4μm after focusing, which verified the thermal and structural design performance of the focal plane component.

Optical coherence tomography (OCT) is a new imaging technique for observing biological tissue structure. Polarization-sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT, which uses polarized light to probe the sample and extract the polarization properties by detecting the change of the polarization state. In the practical application environment, the optical characteristics of biological samples and the instability of the system will reduce the contrast of the image. Traditional contrast enhancement methods are mostly based on histogram equalization and histogram matching to improve the global quality, which causes the loss of some details of the image and the excessive enhancement of noise. To solve this problem, a local contrast enhancement method is proposed in this paper. The target region and the background region are processed differently by threshold segmentation to enhance the contrast of the signal region and restrain the excessive enhancement of the background noise at the same time. The experimental results showed that this method can enhance the contrast of PS-OCT images and improve the image quality effectively. We believe that this method may play an important role in the application of PS-OCT technology in clinical research.

Plasma synthetic jet actuators are widely used in active flow control of high-speed flow field due to their advantages such as no need for external gas source, wide operating frequency band and great intensity of jet. In this paper, the chemical composition, electron temperature and electron density of the plasma jet of a designed synthetic actuator were experimentally studied by using the diagnosis method of emission spectrum of plasma. It is obtained that there are N atoms, N+ ions, Ar atoms, Ar+ ions, C atoms, O atoms, H atoms in the jet. The maximum of the average electron temperature is 5248.8K. With the increase of capacitance of the capacitor, the electron temperature of plasma increases. With the increase of the distance between the anode and the cathode, the electron temperature of plasma decreases. The impact of the distance between the anode and the cathode of the actuator on the electron temperature is greater than that of the discharge power of the actuator. The maximum plasma density was 5.47e23m^-3. The plasma density increases with the increasing capacitance, and the plasma density first increases and then decreases with the increase of the distance between the anode and the cathode. In this experiment, the optimal discharge condition is the spacing between anode and cathode being 1.9mm and the capacitance being 0.48uF.

A feedforward control method based on sensor fusing is proposed to improve the bandwidth of disturbance suppression for compound axis servomechanism tracking system (CASTS). This method takes advantage of the fiber-optic gyroscope (FOG) and the fine charge couple device (FCCD). Two sensor signals are decoupled and fused to obtain a precise observation of the disturbance. The FOG signal contains disturbance information and target moving information, yet the target information cannot be used for feedforward because it’ll deteriorate target tracking capability of the system. The high-pass filter is designed to filter out the low-frequency target signal. However, the high-frequency sampling of the fine FCCD sensor is insufficient. To avoid the inappropriate high-frequency signal of the FCCD, the complementary low-pass filter is applied to the FCCD. An accurate disturbance observation can be achieved by decoupling and fusing the FOG signal and the FCCD signal. The fused disturbance is fed forward to the fast- steering mirror (FSM) which possesses a higher control bandwidth to achieve the line-of-sight (LOS) stabilization control. Finally, comparative simulations are conducted to verify the disturbance rejecting performance of the proposed method. The results indicate that the disturbance suppression performance of the system can be significantly improved by applying the proposed method. A higher disturbance rejection band and a higher disturbance rejection ratio (DRR) can be obtained compared to the conventional control method.

Circulating tumor cells (CTCs) are generally considered as seeds for metastases, serving as a clinical biomarker for cancer diagnosis and prognosis. However, they are difficult to detect due to their low content in the blood of cancer patients. Consequently detection of CTCs normally requires an antibody-mediated biological enrichment process, which is very time-consuming. In this work, we demonstrate an antibody-free, efficient, fast and cost-effective way of detecting CTCs. That is, CTCs are physically isolated by size using filtration, and subsequently characterized in an optical way via laser scanning. The filtered and stained blood sample, which is placed on a moving and spinning stage, is illuminated by a 405nm diode laser. Then the scattered optical signals are focused using an ellipsoidal mirror for a better photon collection. Eventually CTCs in the scanning image are identified and counted by the clustering algorithm. Our method has advantages in high efficiency and low cost, holding great promise for early diagnosis and prognosis prediction of cancer patients.

A set of ignition and combustion test system of blasting fuse has been designed to study the transfer law of black powder combustion surface within the blasting fuse. The test system consists of metal bracket, thermometric infrared imager, igniter and blasting fuse to be tested. According to the experimental results, the average combustion velocity of the blasting fuse used in the test is 118 s/m or 0.0085m/s. Compared with the average combustion velocity, the combustion velocity of the blasting fuse is fluctuating during the flame transfer process, and the range of velocity variation is about 6.9%, which indicates the combustion velocity is relatively stable. The maximum surface imaging temperature of the blasting fuse combustion process is 255 ℃, which is far higher than the normal atmospheric temperature. In conclusion, an infrared thermal imager can clearly detect the migration process of the combustion surface inside the blasting fuse, and can accurately measure the linear velocity of the fuse combustion. Furthermore, the stability of the combustion process can be analyzed scientifically by the change of the linear velocity of blasting fuse in different time periods.

Fiber Bragg Gating (FBG) is widely used in the distributed and in-situ measurements of strain and temperature such as structural health monitoring and vibration detection. However, the low interrogation speed of FBG limits its application of many conditions. In this work, a novel ultrafast FBG interrogation method is proposed using a micro-resonator based broadband Kerr frequency comb (soliton microcomb, SMC) of which 3 or 5 independent optical modes are employed to interrogate a FBG sensor. The proposed method has the efficiency tens of times over conventional methods and even can be implemented using only analog circuit because only a few simple calculations is included in the deriving process. To assess the feasibility and performance of the proposed method, related influencing factors and several parameters were detailed analyzed, and it was also compared with the conventional methods under different signal to noise rates (SNR). We demonstrated continuous heating experiment (with mean square error 0.624 pm) and high-frequency vibration measurement experiment (10 kHz) with an ultrafast FBG interrogator prototype featuring ultrafast rates up to 300 MHz based on a ~50 GHz-repetition-rate SMC. All the analysis, simulation and experiments reveal the splendid advantages of simple construction, compact and ultra-efficient of the proposed ultrafast interrogating method that highlights the prospects of this method with future in various application fields such as uhf vibration measurement.

Here, an effective and economic ternary ammonia gas sensor with Au nanoparticles (NPs) hybrid polyaniline (PANI)- titanium dioxide (TiO₂) nanocomposites on a flexible polyimide substrate has been successfully fabricated. In this work, high catalytic and controllably synthesized near-spherical Au NPs with size of sub-100 nm was interestingly employed, meanwhile, a facile in-situ oxidative polymerization was used to composite the Au NPs with the conventional binary PANI- TiO₂. Analysis and characterization of the structures, compositions, and the gas-sensing performances of the designed ternary ammonia gas sensor were systematically explored. The results show that the Au and TiO₂ NPs were evenly distributed among the PANI fibrous networks, favoring the construction of the practical gas sensors. Besides, the gas sensor with 1 wt% of Au and 20 mol% of TiO₂ dispersed into PANI showed an excellent gas-sensing performance: the response and recovery rates of the sensors respectively reach 32 s and 111 s to 100 ppm concentration of ammonia at room temperature, and the response value approach to 123%, which is approximately 1.9 times and 1.2 times higher than the pure PANI and PANI-TiO₂. Furthermore, the designed gas sensors exhibited significant stability, selectivity and response-concentration linearity (correlation coefficients R²=0.9984). It is expected that our concerned and designed ternary gas sensors may find great potential applications such as in flexible wearable devices and the medical health monitors.

Speckle projection provides rich textures for correlation, and has been widely used in three-dimensional(3D) reconstruction. However, for objects with high dynamic range(HDR) surface, conventional uniform speckle projection usually causes over-exposure and over-dark regions simultaneously in the captured images, leading to miss-match and errors in 3D result. It is difficult to perform defect elimination via adjustment of speckle intensity globally or the camera exposure time. To tackle this problem, this paper proposed a novel adaptive speckle projection method to distinguish the appropriate projection intensity of specific parts in the speckle pattern, thereby avoiding over-exposure, while the dark regions not being affected. First, uniform intensity patterns of multiple gray-levels are projected onto the surface of testing object, the appropriate projection intensity at each pixel position in the camera coordinate system is calculated, and the saturated area in the captured image is marked. Then, a set of orthogonal fringe patterns are projected onto the testing object to establish the coordinates mapping relationship between the camera and the projection system, and the adaptive speckle pattern under the projection coordinate system is generated. Finally, the generated adaptive speckle pattern is used to scan the testing object, and the spatial-temporal correlation algorithm is used for 3D shape retrieval. Experimental results demonstrate feasibility of 3D shape reconstruction of HDR surfaces with the proposed method, and obvious advantages compared with the traditional methods in terms of reconstruction completion and measurement accuracy. Keywords: adaptive speckle, high dynamic range, coordinates mapping, spatial-temporal correlation, 3D reconstruction

ABSTRACT The continuous emission of greenhouse gases leads to the sharp rise of environmental temperature. Its content and distribution also affect the atmosphere radiation, climate characteristics, stratosphere troposphere exchange (STE) and circulation in the near-tropopause region. Methane is the second most important greenhouse gas after carbon dioxide, and its concentration has strong gradients near the tropopause. Therefore, the sensitivity, accuracy of methane detection approach in extreme environment have been greatly restricted, and this has become a technical bottleneck for low-temperature and low-pressure gas detection. To address this, a novel 3-dimensional compensation model of temperature and pressure is reported based on the simulation of methane absorption characteristic. Through a detailed investigation, the simulation system and compensation model are evaluated, the detection accuracy is improved by an order of magnitude; the minimum detection limit is ~0.012ppm with integration time is 59s.

Optical coherence tomography (OCT) is a biomedical imaging technology that uses interference information generated by two light waves to measure and evaluate biological tissues. Because of its high sensitivity, high resolution, and non-destructive testing, it is widely used in various fields. In this paper, OCT is used to detect and evaluate the reproduction of the three bacteria. At the same time, we also use a 20-fold objective lens to observe the morphology of the three bacteria at the position of the sample arm of the OCT. In the experiment, three groups of experimental data were collected, which were pictures collected after two hours, four hours, and five hours of bacterial culture. From the experimental data, the morphology and colony reproduction changes of the three bacteria can be observed; after 4 hours of reproduction, the morphology of E. coli and aeruginosa can be observed; Morphological structure of the three bacteria could be observed after 5 hours of reproduction; through the three-dimensional reconstruction of the experimental data, the three-dimensional morphology of the bacteria can be seen more clearly, which is more conducive to the identification of bacterial species. Experimental results show that OCT can be used to detect bacterial organisms on the order of micrometers, and can observe the reproduction process and morphology of bacteria in different periods, to identify bacterial species. This is of great help in the non-invasive identification of bacterial types in clinical applications of biomedicine.

Cavity enhanced absorption spectroscopy (CEAS) technology is one of the new types laser absorption spectroscopy technique with high sensitivity and relatively simple detection principle, which is developing rapidly and becoming more and more popular in the field of trace gas detection. A scheme of high sensitivity infrared optical feedback cavity enhanced absorption spectroscopy system is established, based on the high quality optical passive resonator made of ultralow expansion coefficient glass-ceramics, combined with the optical feedback effect of semiconductor laser which can narrow the output laser linewidth and stabilize the laser frequency. The spectral scanning of the system is realized by simultaneously scanning the cavity length of the resonator and tuning the laser current, and the spectral resolution of 0.003 cm^-1 and the noise equivalent absorption sensitivity are better than 2×10^-9 cm^-1Hz^-1/2. The system is expected to be applied to real-time analysis of respiratory gas and realize the application of the technology in human breath diagnosis.

An ultrafast contactless sensing system with remotely placed optical fiber sensors based on in-fiber grating is presented for the first time. The in-fiber grating, namely 45° tilted fiber grating (45° TFG), is used as 1) a highly efficient waveguide coupler between the compact and portable interrogation elements and the optical fiber sensors; 2) a lateral diffraction grating enables free-space passive beam scattering due to its lateral diffraction feature; 3) an in-fiber polarizer realizes polarization control thanks to its polarization sensitive characteristic. A standard fiber Bragg grating (FBG) sensor, serves as a remotely placed optical sensor, is applied to measure the variations of strain. A Superluminescent light emitting diode (SLED) and a pulsed light beam with a repetition rate of 50MHz from mode-locked laser both are employed as the light sources. The light of interrogation element is coupled into the 45° TFG and serves as the input of the FBG. Reflected light from the FBG sensor is coupled back to the same 45° TFG. Here, the 45° TFG has the merit of inherently compatible with fiber links without insertion loss and hence highly efficiency is achieved. Also, the 45° TFG is employed as the light receiver and transmitter of light at the same time and as the key element fulfill the purpose of ultrafast contactless sensing. The proposal has great potential in ultrafast sensing applications with the benefit of contactless and a proof-of-principle demonstration of the proposed system for strain sensing application have been successfully presented.

With its incomparable advantages over other motion capture technologies, the application of optical motion capture systems has become more and more extensive, and it has become a major technical means for obtaining motion data. This paper mainly studies the camera calibration and 3D reconstruction technology of the optical motion capture system based on the marker, and designs an optical motion data capture system, which describes the acquisition of three-dimensional motion data, as well as the processing and analysis of motion posture feature data. By summarizing the methods and techniques of camera calibration, marker point placement, and motion drive, it effectively solves the problems of data jitter, data point loss, motion distortion, etc. generated during the motion capture process.

The cable is the most important part of suspension bridge, which is related to the structural safety, and can easily be damaged by environmental factors. It is difficult to record and feedback the damage of the cable in suspension bridge with the existing non-destructive measurement technology. It is also very difficult to calculate the extent and location of the cable damage according to the measurement results. By using two-parameter distributed fiber optical sensor, the strain, amplitude and frequency of the cable can be measured accurately at the same time, and the information for damage identification of the cable can be directly fed back in time. According to the characteristics of the cable, the key parameters measured by the two-parameter distributed fiber optical sensor can also be further calculated, and the results will be verified by each other to improve the accuracy and reliability of the test. The two-parameter distributed fiber optical sensor can realize long-term detection, which is beneficial to the integrity and reliability of the operating information of suspension bridge.

Oyster is one of the largest cultured shellfish in the world, though it remains a challenge to shuck oysters automatically by mechanical systems, which has attracted interests of research for a long time. We design a low-cost high-temperature steam beam to heat the adductor muscle attachment area with high precision to shuck the oysters. This approach, compared to the overall heating processes, causes much less damage to the quality and physiological structure of the oysters. The key issue of our method lies in locating the adductor muscle outside of the shells as there is no obvious feature of judgment due to the irregular shapes and variant sizes of the oysters. To this end, we proposed a deep learning method for predicting the position of the adductor muscle based on the YOLOv3 algorithm. In this paper, we establish an image dataset containing 520 oyster pictures, 120 of which are labeled pictures. These images are trained in the deployment environment of GTX 1060. Experiments show that the accuracy of the model is up to 99.5%, the prediction accuracy of the adductor muscle position reaches 79.17%, and the average time to detect one single image is around 0.03s.

Ultraviolet imaging technology is a non electric corona testing technology, which uses ultraviolet imager to detect ultraviolet produced by air discharge ionization, and then determine the position and intensity of corona discharge, it has high accuracy and reliability. For the detection and calibration of UV / visible image coincidence of UV imager, the LED integrating sphere light source with UV and visible light is installed to illuminate the star point hole on the focal plane of reflective collimator to simulate the discharge of infinite target. After receiving by the ultraviolet imager, the star point on the focal plane of the collimator will be imaged as a bright spot on the detector surface of the UV imager. The coincidence degree of the ultraviolet and visible light can be obtained by calculating the center position deviation of the imaging spot in two different spectral ranges. This equipment can be used for high-precision calibration of the non-coincidence of the UV imager.

Traditional imaging lidar exhibits an obvious trade-off between the resolution and the size of its optical system. In order to realize a miniaturized super-resolution (SR) imaging lidar, Fourier ptychography (FP) has been introduced to break through the diffraction limit of the camera lens. FP, derived from synthetic aperture method, is capable of acquiring high resolution and large field-of-view reconstructed images without increasing the aperture size by capturing multiple images with diverse incident angles before computationally combining with phase retrieval algorithm. In this work, a SR imaging lidar system was proposed by using reflective-type FP, which mainly consists of a s-CMOS camera, a Nd:YAG laser, and a 2-D translation stage so as to achieve aperture scanning on the x and y axes. To validate this technique experimentally, a set of images of a positive USAF chrome-on-glass target were obtained for quantitative analysis, and an uneven 1 yuan nickel-on-steel RMB coin was used to simulate the applicability of the SR imaging lidar in practical applications. The observations show that the obtained images based on FP technique have an obvious improvement in resolution, contrast, and clarity. It is worth mentioning that the resolution of these reconstructed images is increased over 3 times in the experiment on the USAF target. Moreover, the images under different apertures were collected, processed and analyzed, which suggest the initial image quality has a non-negligible influence on the reconstructed results. This technique not only improves the performance of the imaging lidar while maintaining low costs, but also bring new vitality in remote image recognition and analysis.

A novel highly sensitive displacement sensing method based on the intensity detection of the resonant spectrum, which arises from a fiber-based surface nanoscale axial photonics (SNAP) resonator, is proposed. By means of dissipative and dispersive coupling mechanisms, the changes of the relative position between the SNAP resonator and fiber taper not only bring the shift in a resonant wavelength, but also lead to the variation of the linewidth and extinction ratio of the whispering gallery mode (WGM) in spectrum. Instead of the wavelength shift, we utilize the extinction ratio changes to realize the displacement sensing, which is robust against lasing and microresonator frequency noise in the detecting system. Using the analytical expression of the transmission spectrum, the extinction ratio as a function of the displacement for different axial modes is obtained. It is proved that a large range and high resolution displacement sensor can be achieved by simultaneously tracking the extinction ratio of multiple axial modes. The fiber-based SNAP resonator can be fabricated into a probe-type sensor, making it potential and a powerful tool for many displacement sensing applications such as microstructure measurements in both aerospace and nano-lithography fields.

This paper proposed a novel pressure sensors based on polymer film with surface microstructures. Polymer film with surface microstructures have displayed unique optoelectronic and electrical properties due to the triboelectric effect. The micro-deformation and moving of polymer microstructures can product electrostatic charge. The pressure sensors can convert external pressure or mechanical deformation into electrical signal. The pressure sensor consists of one polymer film with surface microstructures and one conductive electrode layer. The regular microstructures increase the film roughness and contact triboelectric area to enhance the electrostatic effect. To enhance the performance of the pressure sensor, high-precision microstructures on soft polymer sensitive layers are fabricated using UV nanoimprint lithography to generate more triboelectric charges. The pressure sensor is prepared, which consists of grating with 3 μm- period on the surface of the elastic layer and an indium tin oxide electrode thin film. By converting the friction mechanical energy into electrical power, a maximum power of 423.8 mW/m² and the sensitivity of 0.7 V/kPa at a frequency of 5 Hz are obtained, which proves the excellent sensing performance of the sensor.

Convolutional neural networks (CNN) has significant advantages in processing image classification and was widely used in image analysis in the fields of autonomous driving, aerospace, and biomedicine. However, image classification and analysis need large matrix multiplication, which imposes many challenges to the realization of high performance and low power consumption of CNNS. Here, a photoelectric hybrid neural network (PHNN) was developed to reduce the CNN’s power consumption. The optical interference unit (OIU) composed of Mach-Zehnder interferometers (MZI) arrays, used as convolution kernel, performs multiplication and accumulation operations. The convolution kernel is split and reorganized effectively to form a new unitary matrix to reduce the number of MZIs. Simultaneously, this method can modularize the OIU, which is beneficial to field-programmable gate array (FPGA) encoding and modulation. FPGA realizes nonlinear calculation, data scheduling and storage, and phase encoding and modulation. Our PHNN has an accuracy rate of 93.3%, which reduces power consumption by 3 times of magnitude compared with traditional electronic products.