This PDF file contains the front matter associated with SPIE Proceedings Volume 8332, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Accurate remote clock synchronization is the backbone of applications such as high-accuracy satellite navigation, digital and/or cryptographic communication systems, space-based interferometric surveillance, coherent distributed-aperture sensing at high frequencies, and geolocation. During the last decade, several clock synchronization schemes have been proposed based on quantum mechanical concepts. Quantum clock synchronization promises more precision and better security. In this paper, the various proposed quantum clock synchronization schemes are reviewed. We compare and discuss several different quantum clock synchronization schemes. The advantages and disadvantages of these schemes are investigated with emphasis on the application in space-based satellite navigation systems.

Taking the monitoring project of slope protection at Wuzhuaguan tunnel portal, Hejiaping segment of Yiwan railway as an example, through the analysis of mechanism of mechanical transmission and failure mode of component of flexible system for protecting slope, we put forward a kind of early warning and alarm system for railway slope protection based on Fiber Bragg Grating sensing technology. Compared with the conventional supervising techniques, the supervising system designed in this work possesses the merits of higher reliability, lower cost, easier to installation, fewer maintenance and so on. This early warning and alarm system can effectively enhance the protecting function of disaster prevention and reduction for railway slope protection.

Three examples of cavity-enhanced measurements of refractive index and optical absorption are discussed. Using microphotonic silicon-on-insulator ring-resonators we determine the concentration of cyclohexane and m-xylene at detection levels of 300-3000 ppm. The gases are first absorbed into a siloxane polymer and its refractive index change is detected by a characteristic wavelength shift of the cavity resonance. In a second device phase-shift cavity ring-down spectroscopy is applied to simultaneously measure the optical absorption at two wavelengths of either a dye, nucleic acids or a pharmaceutical component. Multiplexing the ring-down measurement permits dual wavelength absorption spectroscopy without the use of a dispersion element. Finally, a combination of resonance wavelength measurements and cavity ring-down spectroscopy is used to simultaneously determine the change in refractive index and the absorption induced by adsorption of ethylene diamine on a 300 μm silica sphere. A whispering gallery mode of the microsphere resonator is excited with intensity modulated light and the intensity and AM modulation phase of the Rayleigh backscattered light is measured.

An optical frequency domain technique is applied in this paper. The sampling method generally used is analyzed here. Calculations consequence shows that sampling signal from branch composed with double reflectors seems not so excellent in simulation, signal periods of this arm due to different distance of reflectors are compared, and consequence shows coincidence with principle and simulation. It means proportional relationship of frequency and distance of double reflectors. Strain is added to FBG sensor and measured at a point of optical fiber arm, with its location tested also.

Lithium niobate based (LiNbO₃) integrated optical sensor with Mach-Zehnder optical waveguide interferometer and tapered antenna array was designed and fabricated for measuring pulsed electric field with nanosecond width. The fabricated sensor exhibits relatively flat frequency response with a variation not more than 4 dB from 10 kHz to 5 GHz and minimum detectable electric field intensity of 0.4 V/m. A 103 V/m pulsed electric field with nanosecond width was also measured by this integrated optical sensor, the experimental results exhibit the information of EMP can be detected and extracted by this integrated optical sensor.

A theoretical investigation on a self-referencing and calibration SPR refractive index (RI) sensor based on microstructured optical fibers is presented. The finite element method (FEM) is used to study the channel discriminative property of the sensor. An average RI sensitivity of 6870nm/RIU in the range 1.34-1.38 is achieved as a self-referencing sensor. A self calibration sensor with high linearity and accuracy is also demonstrated.

Constant Fraction Discriminator (CFD) is one of the theoretic method which can locate the timing point at same fraction of the echo pulse in pulsed Time-of-Flight (TOF) laser rangefinding. In this paper, the theory of CFD method was analyzed in reality condition. The design, simulation and the PCB performance of the CFD circuit were shown. At last, the over amplify method was introduced. By which, the influence of DC bias error could be reduced. The experimental results show that our timing discriminator can set the timing point does not depend on the amplitude of echo pulse.

Photoisomerization from cis-2 [Ru(OAc)(2cqn)₂NO] (H2cqn=2-chloro-8-quinolinol) to cis-1 isomer was studied quantitatively and the effect of wavelength on isomerization was investigated. The main absorption band in UV-Vis region for cis-1 and cis-2 isomer was observed from 350 nm to 500 nm, and the kinetic study showed that the photoisomerization from cis-2 to cis-1 isomer was first-order and the rate constant (k) is 0.00022 (s^-1) at 420 nm, 0.00018 (s^-1) at 475 nm, 0.00011 (s^-1) at 550 nm, respectively. Density functional theory (DFT) calculation suggested that the electronic transition from a ligand based orbital to an antibonding overlap of the Ru(d) and π* NO(p) orbitals control the photo induced reactivity of [Ru(OAc)(2cqn)₂NO] complexes. The study provides basic information to design the molecular optical switches and advance optoelectronic materials based on nitrosylruthenium(II) complexes.

Digital cameras are now in widespread used. This paper reviews the current status of digital camera characterization using spectral sensitivity. It is believed that spectral sensitivity-based digital camera characterization can produce reasonable colorimetric estimates in all lighting conditions and can remove the problem of metamerism. Various digital cameras by different makers were tested using this method, and some of the results are reported in this paper. The technique could used to achieve accurate color measurement as well as faithful color reproduction for different applications.

In this paper, an armored-cable-based optical fiber Bragg grating (FBG) sensor array, for perimeter fence intrusion detection, is demonstrated and some of the field trial results are reported. The field trial was conducted at a critical local installation in Singapore in December 2010. The sensor array was put through a series of both simulated and live intrusion scenarios to test the stability and suitability of operation in the local environmental conditions and to determine its capabilities in detecting and reporting these intrusions accurately to the control station. Such a sensor array can provide perimeter intrusion detection with fine granularity and preset pin-pointing accuracy. The various types of intrusions included aided or unaided climbs, tampering and cutting of the fence, etc. The unique sensor packaging structure provides high sensitivity, crush resistance and protection against rodents. It is also capable of resolving nuisance events such as rain, birds sitting on the fence or seismic vibrations. These sensors are extremely sensitive with a response time of a few seconds. They can be customized for a desired spatial resolution and pre-determined sensitivity. Furthermore, it is easy to cascade a series of such sensors to monitor and detect intrusion events over a long stretch of fence line. Such sensors can be applied to real-time intrusion detection for perimeter security, pipeline security and communications link security.

In this paper, the design and development of a low power, low cost and portable FBG Interrogation System is presented. The FBG interrogator consists of a spectral analyzer module, a photo detection module, and an electronic processing module. By using volume holographic phase grating as the continuous dispersion spectral element, our interrogator can achieve a maximum scanning frequency as high as 5 KHz for a single channel with a total power requirement of 25 W.

High sensitivity is an important index of an accelerometer for seismic monitoring. In this paper, we have designed a new fiber Bragg grating accelerometer and, a theoretical structure is given. The theoretical analysis of the sensor is established, and the results show that the sensitivity of accelerometer device is 2131.5pm/g and resonance frequency is 28.01Hz theoretically. It has a higher precision than traditional accelerometer on magnitude. In the experiment, we have found that the output will react as a cosine signal while the input is a cosine signal. It indicates that the sensor has a good linear relationship between output and response. We demonstrated a strain sensing test of measuring central wavelength shifting by fiber Bragg grating.

Fiber Bragg Grating (FBG) refractometer for liquid refractive index monitoring and its applications have been widely studied in the past few decades. This paper proposes a novel fiber optic volatile organic compounds (VOCs) sensor, achieved by means of polymer film coated high performance FBG refractometer, i.e. cladding removed FBG or even core thinned FBG. Polymer film coated sensor has partial selectivity, which makes this kind of sensors suitable for optical nose systems. While being exposed to VOCs, the sensing layer swells and its refractive index changes at the same time. Transduction part of this sensor, the thinned FBG, works as both strain transducer and refractometer. The mathematical model of the FBG VOCs sensor is introduced and experimentally evaluated with OV-1 coated FBG refractometer, which shows partial selectivity to different vapors and about 100 ppm detection limit to toluene.

The light scattering properties of bubbles are very important for exploration underwater. The shape of bubbles usually treated as spheres, are apparently nonspherical in turbulent flow. The present methods for calculating light scattered by nonspherical particles are lack of efficient computation due to the large size of bubble, where geometrical optics approximation is considered a better method for calculating light scattering patterns. In this paper, the large spheroidal bubble with end-on incidence in water are researched based on ray tracing method. The angular distribution of light scattered by prolate and oblate spheroidal bubbles are interpreted that both shapes of bubbles have strong forward and low backward scattering with rapid ripple structure. The types of ray paths permeating the bubble are calculated to explain the physical mechanisms that cause various prominent intensity features. The results could provide the theoretical foundation for optimizing the turbulent bubbly flow measurements.

The visibility of underwater imaging has been of long-standing interest to investigators working in many civilian and military areas such as oceanographic environments, efforts such as image restoration techniques can help to enhance the image quality; however, the resolution is still limited. Image super resolution reconstruction (SRR) techniques are promising approaches for improving resolution beyond the limit of hardware; furthermore, with the prior knowledge of the imaging system such as the point spread function and diffration limit, performance of the super resolution reconstruction can be further enhanced, which can also extend the imaging range as well. In order to improve the resolution to a best possible level, an imaging model based on beam propagation is established and applied to image super-resolution reconstruction techniques for an underwater range-gated pulsed laser imaging system in the presented effort. Experimental results show that the proposed approaches can effectively enhance the resolution and quality of underwater imaging

Actual temperature distribution inside the transformer is unknown currently, since it is difficult to measure temperature of transformer winding by traditional transformer condition monitoring methods. To solve this problem, this paper proposes an on-line temperature measurement system based on fiber Bragg grating (FBG) which can obtain the actual temperature of winding during transformer operation. The measurement system is consist of FBG temperature sensors that are embedded in specially designed magnet wire, and FBG demodulator. Performance of those sensors was tested in the laboratory, the sensitivity and linearity of those sensors was analyzed. Finally, a prototype of transformer coil with FBG temperature sensors was built and simulation experiment was processed. Temperature variation was monitored during the experiment and temperature distribution in transformer coils was achieved. The experiment results prove the reliability and feasibility of the proposed transformer temperature measurement system.

There is currently considerable in developing underwater target detection, the underwater imaging system can be divided into active imaging system and passive system. The main feature of the active imaging system is that they use light sources to illuminate the targets and collect the reflection from targets. The advantages of active imaging system over passive imaging systems are high contrast and without the affection of environment sources. In this article, a range-gated underwater laser imaging system is built, which consists of laser illumination system, photoelectric imaging system and control system. The laser illumination system includes a light-pumped solid state doubled ND-YAG laser(532nm) which laser power and frequency can be adjusted and an optics expanding system of variable ratio. The photoelectric imaging system includes a gated Intensified CCD(ICCD) cameras which ICCD scheduling, gate width, delay time and gain can be adjusted and a optics received system of variable ratio. In order to acquire effectual target image using range-gated underwater laser imaging system, appropriate control parameters that include laser power and frequency, ICCD scheduling, gate width, delay time and gain, optics expanding system ratio and optics received system ratio must be given accurately. A control system which used C8051F320 and C8051F040 (MCU) as the core is designed, the control system can effectively control seven parameters that given above. The construction of software and hardware of the control system is introduced. And target image of underwater distance 25 m and 40m is given, Experimental results showed that the control system has high control precision, safe and stable operation and good speed adjusting performance can be achieved. It can be satisfied to apply to underwater target detection.

In the paper we present an alternative configuration for an interferometric distributed optic fiber sensor which adapts a combination of Mach-Zehnder and Sagnac interferometers different from that have published before. Based on the outputs of the Mach-Zehnder interferometer and sagnac interferometer, the place where the disturbance occurs to the sensing fiber can be obtained. Detailed theoretical analysis and corresponding experiments about this configuration are presented in this paper.

The Long Slit Spectrograph is one of instruments onboard The World Space Observatory-Ultraviolet. Both the FUV (102-1700nm) and NUV (160-320nm) channels of LSS choose micro-channel plates (MCP) detector with anode readout in the focal plane. The MCP detectors with anode readout are typically used to provide photon counting imaging. According to the desired performance of LSS, the Vernier anode may be the optimum readout scheme. The Vernier anode is famous for its high spatial resolution, however, the original decode algorithms of the Vernier anode is susceptible to wrongly decode, when the charge acquisition is not precise enough and the footprint size of charge cloud collected by Vernier anode is not small enough and eventually results in the deterioration of photon counting image. In this paper, the causes leading to image deterioration is analyzed. The least-squares method was used to calculate the phase value to correct imaging distortions caused by charge measurement accuracy. The area ratio of each electrode covered by charge cloud is accurately calculated to improving the imaging results. The corrected algorithms are verified by experimental results and the results show that the correction methods can obviously improve the quality of the original photon counting image.

When the incidence laser comes to the two-dimension random and rough sea surface, the reflected light is different from the light on the smooth sea surface. The rough sea surface can be divided into several tiny planes with several different normal directions. The width or length of every plane is much greater than the wave length of the incidence laser, so we can employ geometrical optical method to study the laser reflection from the random and rough sea surface. We simulate the two-dimensional random and rough sea surface based on JONSWAP spectrum, and divide the sea surface covered by the incidence laser facular into several tiny planes. After that, we simulate reflected laser beam from every minute plane with ray tracing, and then get the space distribution of intensity of reflected laser rays from sea surface. A program is developed to simulate reflected laser beam at different incedent angle and sea surface at different wind speed. The result shows that the intensity of specular reflection reduces and the intensity of diffuse reflection increases with the increasing roughness of the sea surface.

The structure of atmospheric boundary layer and its changes during the night at Wuhan in china are observed based on a Raman lidar. The heights of the mixed layer and the entrainment zone are measured by the visual inspection method and the SBH99 method. The SBH99 method is also improved to be based on aerosol extinction coefficient, which can avoid the errors brought in calculating the backscatter coefficient. The results indicate that the Raman lidar system has good ability to detect atmospheric boundary layer.

With the rapid development of the society and living standard, the water resources have been polluted more and more seriously, which is threatening the health of people and producing of the industry and agriculture. To protect the sustainable water resource, the monitoring of the water quality became an urgent task. There are some methods used to monitor the water quality, including the liquid chromatograph(LC), electrolysis method, electrochemical method, colorimetry method, atomic absorption spectrometric method, etc. But some drawbacks are existed in these methods. So, a fluorescence spectrophotometry method is adopted into this paper. And a novel water quality monitor(WQM) is designed. Meanwhile, in order to improve the spectral resolution and prevision, an improved spectrophotometer(SPM) based on holography concave (HC)grating is designed. In addition, the linear CCD with combined data acquisition (DAQ) card is used as the spectral detection system and virtual instrument(VI) technology based on LabVIEW is used to control the spectral acquisition and analysis. Experimental results show that the performances of the novel SPM for WQM are improved, its resolution can reach 2nm, the stray-light is less and the checking prevision of this WQM is higher than others. Therefore, the novel SPM for WQM has the potential value in the water quality monitoring and biochemical application.

This paper proposed a method which based on "the ommateum" staring system with multi-lens that had intelligence function and nothing blind-zone surveillance. The system used six normal lens which the field of view has 65° to encircle evenly, and made the neighboring two lens' view field have 5° overlap angles. A high speed DSP chip of TMS320DM6446 was used to central processing the six route video which for scanning method from one to six video by turns to realize the intelligence and real time processing. The system could track and recognition the moving object, calculate and record the parameter of object like speed, size and moving azimuth angle. In this paper, the improved algorithms of Auto-adapted Renewal Background Subtraction (ARBS) and the Fuzzy Auto-adapted Median Filter (FAMF) had been studied which could be detected the movement object and filter the image noise. The experiment result indicated that the staring ommateum system could be surveillance 360° scope with nothing blind-zone. The FAMF algorithm could filter the noise effectively, and the ARBS algorithm could be detection the moving object well and truly for anyone video and the parameter of object in the field of view could be calculated accurately. It had been achieved the requirement of seamless intelligence video surveillance at ultra wide range.

An unsymmetrical diarylethene derivative 1-(2,5-dimethyl-3-thienyl)-2-[2-methyl-5-(4-hydroxylphenyl)-3- thienyl]hexafluorocyclopentene (1a) was synthesized. At the same time, its photochromic properties and fluorescence switch were investigated in detail. The results showed that this compound exhibited reversible photochromism, undergoing reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in PMMA film, and its absorption maxima were observed at 547 nm in hexane and at 554 nm in PMMA amorphous film, respectively, upon irradiation with 297 nm UV light. The fluorescence intensity of diarylethene decreased dramatically along with the photochromism from open-ring isomer to closed-ring isomer upon irradiation with 297 nm UV light in hexane. In hexane the open-ring isomer of the diarylethene 1 exhibited relatively fluorescence at 507 nm when excited at 375 nm. This new photochromic compound also exhibited remarkable optical storage character.

A new photochromic diarylethene bearing an isoxazole unit has been synthesized, namely {1-(3,5-dimethyl-4-isoxazolyl),2-[2-methyl-5-(4-trifluoromethylphenyl)-3-thienyl]}perfluorocyclopentene. Its properties, including photochromic reactivity and fluorescence property both in solution and in PMMA film were investigated. It underwent reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in hexane and in PMMA. The isomeric compound also functioned as a fluorescence switch by photoirradiation both in solution and in PMMA film.

A new unsymmetrical photochromic diarylethene 1-(2-methylthiophene-3-yl)-2-[(2-n-butyl-5-formyl)thiophene-3-yl]perfluoroncyclopentene(1a), was synthesized and its optoelectronic properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous films, and the fluorescence spectra of diarylethene 1a was investigated. Using diarylethene 1b/PMMA film as recording medium and a linearly polarized 633 nm laser diode for recording and readout, polarization multiplexed image recording can be carried out in this film, which illustrated that the diarylethene can be potentially used as holographic optical recording medium.

A novel unsymmetrical photochromic diarylethene bearing a benzothiazole unit, 1-[ (2,5-dimethyl-3-thienyl) ]-2-[(2-methyl-5-(2-benzothiazole)-3-thienyl)]perfluoroyclopentene (1O) have been synthesized. Its photochromic, fluorescence and optical strorage properties were investigated. The compound exhibited obviously photochromism both in hexane and in PMMA film. In hexane, the fluorescence intensity of 1O declined along with the photochromism upon irradiation with 297 nm light. This new photochromic system also exhibited remarkable optical storage characters.

A novel photochromic diarylethene based on benzofuran moiety and a chlorine atom was synthesized, and its photochromic and fluorescent properties were investigated. This compound exhibited reversible photochromism, changing from colorless to violet after irradiation with UV light both in solution and in poly-methyl methacrylate (PMMA) amorphous film. Also, it exhibited remarkable fluorescence switching in PMMA film. The results indicated that the benzofuran moiety played a very important role during the process of photochromic reaction for the diarylethene derivative. Using this diarylethene 1c/PMMA as optical storage was performed successfully.

A new photochromic diarylethene compound [1-(2-methyl-1-naphthyl), 2-(2-methyl-5-(2-1,3-dioxolanephenyl)-3- thienyl)]perfluorocyclopentene 1o, and its photochromic properties, fluorescence switch and kinetic properties were investigated in detail. Diarylethene 1o changed the color from colorless to red when irraditated with 297 nm UV light, which the absorption maxima were observed at 503 nm in hexane solution. This new photochromic system also showed remarkable fluorescence switching in the solid state. Finally, using this diarylethene as recording medium, polarization optical recording was carried out successfully.

The influence of forward Raman amplification on Brillouin scattering signal of pulse light was investigated in experiments, including the spontaneous Brillouin scattering and the stimulated Brillouin scattering (SBS). The results of experiments show that the spontaneous Brillouin scattering is amplified by fiber Raman amplifier and fiber Brillouin amplifier, consequently the gain is high. For the amplification of SBS signal, it is only amplified by Raman amplifier in the fiber. As the Raman pump power reaches 600mW, it causes multi-order Brillouin scattering, and then the gain of the first order Stokes SBS starts to saturate and decline.

Reflectivity curve is always used for refractive index measurement. With the help of a mechanical scanning part, conventional method alters the incident angle of a collimated beam to obtain the reflectivity curve, but it has troublesome drawbacks that mechanical scanning is time consuming and would introduce mechanical error. In this paper, a proposed method exploits the reflection characteristic of divergent beam at the critical angle. Its principle using area CCD to obtain the reflectivity curve is demonstrated by simulation. The result shows that the proposed method can instantaneously obtain the reflectivity curve without mechanical errors.

In this paper, a novel algorithm is proposed for unsupervised segmentation that incorporates a local trinary pattern (LTP) operator representation of textures under a geometric active contour framework. First, by combining the gray levels of pixels with texture information of an image, this method can be used for segmentation of a texture image or a nontexture image. And then, the method is modified to avoid the additional computation problem without re-initialization repeatedly. The simulation experiments show that the proposed segmentation method is more efficient, accurate and fast.

A tracking algorithm based on arbitrary geometric shape and Unscented Particle Filter is proposed in this paper. Traditional tracking algorithm based on arbitrary geometric shape has following advantages, matching convenient, high precision, but when the geometric shape is not fully visible it results tracking failure so that restricts its use. Another tracking algorithm based on natural feature utilizes natural feature points to finish registration, there are disadvantages such as error accumulation as time goes by. This approach firstly uses arbitrary geometric shape to finish camera calibration, then use unscented particle filter to predict the possible location of the camera, and get 3-D registration matrix, it can reduce non-linear, non-Gaussian interfere brought by other issues. Experiment results show that this method can efficiently work under the circumstances of occlusion, large changes in illumination, and have a high accuracy.

In the test course of static transfer function of TDI CCD camera, because of the influence that gets environmental and artificial etc. factor, the value of static transfer function measured at any time is between unceasing fluctuation, so, make accuracy reduce. To solve this problem, a kind of accurate measurement technique of static transfer function is put forward. First, before carrying out the measure of static quiet of transfer function, the best test point of transfer function of the TDI CCD camera must be determined, it is parallel to guarantee the rectangle target surface of parallel optical pipe and camera focal plane maintenance parallel, and again guarantee target strip in rectangle target and TDI CCD in camera focal plane maintenance vertical. TDI CCD catches rectangle target image, per 1000 lines of target mark image as a measures sample of static transfer function, exclude because of atmosphere tremble twisted, vague rectangle target mark image, retain 500 distinct and steady target mark image as measure sample set. Then, calculate the static transfer function of each measure sample respectively, take the average of all static quiet transfer function in measure sample set as the static transfer function of camera. Finally, the measure of the static transfer function for TDI CCD camera makes error analysis. Experimental results indicate that the value of the static transfer function of TDI CCD camera measured with this kind of method is 0.2923, with before measurement technique comparison, the value of static transfer function has raised 0.02, makes the accuracy of the measure of static transfer function have gotten raising.

The underwater laser imaging detection is an effective method of detecting short distance target underwater as an important complement of sonar detection. With the development of underwater laser imaging technology and underwater vehicle technology, the underwater automatic target identification has gotten more and more attention, and is a research difficulty in the area of underwater optical imaging information processing. Today, underwater automatic target identification based on optical imaging is usually realized with the method of digital circuit software programming. The algorithm realization and control of this method is very flexible. However, the optical imaging information is 2D image even 3D image, the amount of imaging processing information is abundant, so the electronic hardware with pure digital algorithm will need long identification time and is hard to meet the demands of real-time identification. If adopt computer parallel processing, the identification speed can be improved, but it will increase complexity, size and power consumption. This paper attempts to apply optical correlation identification technology to realize underwater automatic target identification. The optics correlation identification technology utilizes the Fourier transform characteristic of Fourier lens which can accomplish Fourier transform of image information in the level of nanosecond, and optical space interconnection calculation has the features of parallel, high speed, large capacity and high resolution, combines the flexibility of calculation and control of digital circuit method to realize optoelectronic hybrid identification mode. We reduce theoretical formulation of correlation identification and analyze the principle of optical correlation identification, and write MATLAB simulation program. We adopt single frame image obtained in underwater range gating laser imaging to identify, and through identifying and locating the different positions of target, we can improve the speed and orientation efficiency of target identification effectively, and validate the feasibility of this method primarily.

At present, deep foundation pit supporting structure and slope soil deep displacement monitoring of conventional method is artificial repeated measurements, but sometimes pit instability is sudden, use this method to reach the purposes of real-time monitoring. This paper developed the instrument from the ordinary inclinometer, based on artificial measurement, improve it to the automatic measurement, monitoring personnel remain within doors can be remote, real-time control and obtaining measurement data, can really achieve real-time monitoring, can meet the requirements of building deep foundation pit monitoring needs, also has a geological disaster monitoring application prospect.

The paper present three different all-fiber heterodyne Laser Doppler Vibrometry (HLDV) for acousto-optic communication according to the theory of the coherent detection. A line width of 1 kHz single mode continuous fiber laser and one telescope with a 30mm aperture are used in all of three HLDV. The first HLDV is made up with one acousto-optic frequency shifter (AOFS) and one balanced detector, the second one is made up with two AOFSs and two balanced detectors, and the third one is made up with two AOFSs and one balanced detector. The corresponding vibration measurements on the piezoelectric ceramic were performed and the results were compared in view of the noise floor and the spectrum distribution under 1kHz. For the low-frequency vibration measurement, the HLDV with two AOFSs and two balanced detectors shows a good application potential.