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A control software named as gated imaging lab (GIL) for 2D/3D underwater or atmospheric range-gated imaging has been introduced. First, a detailed analysis of the functional requirements of imaging system is made. Based on its operating principle and hardware components, functional modules of GIL are determined. It mainly includes zooming and focusing lens, setting gated intensified charge-coupled device (ICCD), changing laser divergence angle, controlling synchronization timing control unit and reconstructing three dimensional (3D) scenes based on captured images. MFC framework simplifies the method of software design and improves the degree of reuse and development efficiency of GIL. Experiments demonstrate that GIL system is stable, real-time and can meet the application demands.

A DSP based system is proposed to detect infrared small targets in thermal imaging. The core of the system is TMS320DM6467T, in which an ARM9 and a C64+ DSP are integrated. The system includes a video capture module, a video process module and a video output module. To detect small targets in the video, an algorithm based on maximum between-class variance method in wavelet domain is proposed. Video stream data is obtained by a thermal imager, and then processed in proposed system. Experiment shows that the system is capable of target detection for thermal imaging.

Traditionally, most spacecrafts with high security requirement use hardware redundancy to improve the system-level performance. However, the data exchange process and the coordination of multiple agents are very difficult to realize. In this paper, a Byzantine fault-tolerant GNC (Guidance, Navigation and Control) system is proposed based on the time-triggered architecture (TTA). This improved GNC system architecture applies the pairwise comparison algorithm, and is more simplified than the traditional one. Simulations are conducted on both SCADETM toolset and Simulink/Matlink platforms to verify the performance of the system.

Sepsis is a severe complication of critically ill patients that is characterized by the systemic inflammatory response syndrome (SIRS). The increased levels of B-type natriuretic peptide (BNP) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) are related with dysfunction of the cardiovascular system and systemic inflammation. In recent years, BNP and NT-proBNP have been the focus of studies evaluating the severity and prognosis of sepsis. In this study, we will review the role of BNP and NT-proBNP in sepsis.

In this paper a fault tolerant GNC system architecture is studied. It presents a new architecture to meet the requirements of CHINA Space Station of two faults tolerant and long life. This robust GNC architecture with broadcast communications, wraparound technology and fault handle strategy greatly reduces the effects and occurrence of Byzantine disagreement. The simulation results of rendezvous and docking process indicate the validity of the fault tolerant system.

In this paper a fault tolerant GNC system architecture is presented, which meets the high reliability requirements of human-rated Spacecraft. This robust GNC architecture with broadcast communications, wraparound technology and fault handling strategy greatly reduces the effects and occurrence of Byzantine disagreement. This paper proposes a formal analysis approach identifying properties of the fault tolerant system, which can be used to avoid design errors at early phases of system development. The simulation results indicate the validity of the fault tolerant system.

In underwater range-gated imaging (URGI), enhancement of low-brightness and low-contrast images is critical for human observation. Traditional histogram equalizations over-enhance images, with the result of details being lost. To compress over-enhancement, a lower-upper-threshold correlation method is proposed for underwater range-gated imaging self-adaptive enhancement based on double-plateau histogram equalization. The lower threshold determines image details and compresses over-enhancement. It is correlated with the upper threshold. First, the upper threshold is updated by searching for the local maximum in real time, and then the lower threshold is calculated by the upper threshold and the number of nonzero units selected from a filtered histogram. With this method, the backgrounds of underwater images are constrained with enhanced details. Finally, the proof experiments are performed. Peak signal-to-noise-ratio, variance, contrast, and human visual properties are used to evaluate the objective quality of the global and regions of interest images. The evaluation results demonstrate that the proposed method adaptively selects the proper upper and lower thresholds under different conditions. The proposed method contributes to URGI with effective image enhancement for human eyes.

We present a method of target detection against strong light based on gate viewing. In this method, a nanosecond-scale gate shutter is used to control the exposure time of CCD and reduce the collection of obtrusive light, and a nanosecond-scale pulsed laser is used to illuminate targets and increase signal energy. By matching them, the ratio between signal and obtrusive light will be significantly improved to detect targets against light disturbance. We have analyzed the method in theory, and performed it in experiment. In addition, a stroboscopic time sequence is used, and the setting of temporal parameters is also discussed.

3D range-gated imaging with stepping delay is a novel technology developed in recent years. 3D timing control signal based on delay line and logical AND gate technology is proposed innovatively in order to satisfy the distance precision of centimeter of 3D imaging in complex background. 3D timing control signal is produced through FPGA nanosecond timing generation module and picosecond timing adjustment module. Simulation and experiment show that the delay precision of the timing signal designed in this paper is 150 picoseconds, and the narrowest pulse width is close to the limitation of TTL signal (1ns level). The timing control signal designed in this paper can be widely used in 3D range-gated imaging because of its high timing control precision, compact construction and flexible parameter setting. Keywords: range-gated, picosecond, timing control, FPGA, delay line

We propose a surveillance photonic fence for night remote intrusion detection, especially in bad environmental conditions. The photonic fence is established by the synchronization of a pulsed infrared laser and a gated imaging sensor. Since the wavelength of the laser is invisible, the photonic fence is also invisible. Only when targets pass the fence, their image information can be collected. Objects and backgrounds out of the fence are all filtered directly which decreases the complexity of image processing about target extraction. For the fence, its location can be easily adjusted by the delay time between the laser pulse and the gate pulse, and its thickness can be set by changing the gate time and the laser pulse width. Furthermore, target space information can also be estimated in terms of the range information of the photonic fence.

We have presented the Echo Broadening Effect of range-gated active imaging. It can respectively generate a head signal part and a tail signal part both sides of the echo signal profile. Our research demonstrates that the head signal and the tail signal impact the depth of view, detection range and imaging quality, especially the head signal. In order to solve the problems, we establish a model of the echo broadening effect, and analyze the signal energy characteristics and atmospheric backscatter. We have given the depth of view under the effect, verified it in experiment, and found that the reasonable choosing of the illuminator laser pulse time and the camera gate time can mange the effect to optimize range-gated imaging systems.

Highly stable frequency-controlled optical frequency combs are key elements of many applications in time-frequency and optical-metrology domains. In this work, we demonstrate a highly stable frequency-controlled erbium-fiber-based optical frequency comb system. Its repetition rate is phase-stabilized to a continuous-wave laser with both an intra-cavity electro-optic modulator and a piezo-transducer; while the carrier-envelope-offset frequency is phase-locked to a radio-frequency signal generator by controlling the pump power. In-loop relative frequency stabilities of the comb are below 1 × 10−16 at 1 s, and integrate down to low 10−20 level at 104 s. The corresponding timing uncertainties are 100–200 as over the full measurement range.

622Mbits/s free space laser communication system is developed. IT's communication rate is 622Mbits/s. The whole system include three parts which are signal in and out circuit laser driver and receive circuit and optical antenna The communication principle is introduced The experiment result shows that the transmission of data and image are satisfied with demands of design. It have a definite market value.

The piezoelectric, elastic, dielectric, thermal, optical, mechanical, chemical, surface acoustic wave (SAW) and bulk acoustic wave (BAW) coupling, and propagation properties of new piezoelectric-crystal lithium tetraborate Li/sub 2/B/sub 4/O/sub 7/ (LBO) are reviewed. The growth and production of LBO crystal by the modified Bridgman (BR) technique (Fan's process) and its application to SAW and BAW devices are also discussed. Attention is also given to such features of LBO growth as the critical requirement of stoichiometric purity for raw material, very low crystal growth rate, a convex or plane solid-liquid interface in the growth, a suitable procedure of self-annealing, and the practicality of the BR technique for commercialization of LBO material with a large diameter of 82 mm and high quality. >

In four-dimensional flash trajectory imaging, temporal parameters include time delay, laser pulse width, gate time, pulse pair repetition frequency and the frame rate of CCD, which directly impact on the acquisition of target trajectories over time. We propose a method of optimizing the temporal parameters of flash trajectory imaging. All the temporal parameters can be estimated by the spatial parameters of the volumes of interest, target scale and velocity, and target sample number. The formulae for optimizing temporal parameters are derived, and the method is demonstrated in an experiment with a ball oscillating as a pendulum.

We present a depth fingerprint map to obtain three-dimensional (3D) spatial information from objects in a large deterministic background by active range-gated imaging, for night remote surveillance. This method first gives the depth fingerprint map of the region of interest in the background by gate viewing in the form of contour bands in range. The map is then embedded in the range-gated laser surveillance system. Finally, 3D spatial information such as target scale and location can be estimated by segmenting the target from the background and matching them with the depth fingerprint map. The measurement is performed by computer background processing. Therefore, the method has no influence on the frame rate of surveillance systems and can realize real-time surveillance. In this paper, the approach to acquisition of the depth fingerprint map is also demonstrated without an echo-broadening effect.