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Purpose Recently, high-precision radiotherapy systems have been developed by integrating computerized tomography or magnetic resonance imaging to enhance the precision of radiotherapy. For integration with additional imaging systems in a limited space, miniaturization and weight reduction of the linear accelerator (linac) system have become important. The aim of this work is to develop a compact medical linac based on 9.3 GHz X-band RF technology instead of the S-band RF technology typically used in the radiotherapy field. Methods The accelerating tube was designed by 3D finite-difference time-domain and particle-in-cell simulations because the frequency variation resulting from the structural parameters and processing errors is relatively sensitive to the operating performance of the X-band linac. Through the 3D simulation of the electric field distribution and beam dynamics process, we designed an accelerating tube to efficiently accelerate the electron beam and used a magnetron as the RF source to miniaturize the entire linac. In addition, a side-coupled structure was adopted to design a compact linac to reduce the RF power loss. To verify the performance of the linac, we developed a beam diagnostic system to analyze the electron beam characteristics and a quality assurance (QA) experimental environment including 3D lateral water phantoms to analyze the primary performance parameters (energy, dose rate, flatness, symmetry, and penumbra) The QA process was based on the standard protocols AAPM TG-51, 106, 142 and IAEA TRS-398. Results The X-band linac has high shunt impedance and electric field strength. Therefore, even though the length of the accelerating tube is 37 cm, the linac could accelerate an electron beam to more than 6 MeV and produce a beam current of more than 90 mA. The transmission ratio is measured to be approximately 30% ~ 40% when the electron gun operates in the constant emission region. The percent depth dose ratio at the measured depths of 10 and 20 cm was approximately 0.572, so we verified that the photon beam energy was matched to approximately 6 MV. The maximum dose rate was measured as 820 cGy/min when the source-to-skin distance was 80 cm. The symmetry was smaller than the QA standard and the flatness had a higher than standard value due to the flattening filter-free beam characteristics. In the case of the penumbra, it was not sufficiently steep compared to commercial equipment, but it could be compensated by improving additional devices such as multileaf collimator and jaw. Conclusions A 9.3 GHz X-band medical linac was developed for high-precision radiotherapy. Since a more precise design and machining process are required for X-band RF technology, this linac was developed by performing a 3D simulation and ultraprecision machining. The X-band linac has a short length and a compact volume, but it can generate a validated therapeutic beam. Therefore, it has more flexibility to be coupled with imaging systems such as CT or MRI and can reduce the bore size of the gantry. In addition, the weight reduction can improve the mechanical stiffness of the unit and reduce the mechanical load.

Linear accelerators (LINAC) that generate high energy X-rays have been widely used for radiotherapy. With the combination of advanced imaging modalities, an image-guided radiation therapy (IGRT) has greatly improved the quality of radiotherapy by acquiring instant knowledge of changes in tumor volume, radiation dose distribution, and effective tumoricidal doses during treatment. In this study, we developed a compact 9.3 GHz X-band LINAC system and installed on the gantry for potential applications in IGRT. We confirmed X-ray generation using radio frequency transmission tests and measured the X-ray dose rates while the gantry was rotating, which demonstrates stable and reliable operation of the developed system. The field size of an X-ray beam was $\pmb{10.31}\ \mathbf{cm}\ \times \ \pmb{10.31}\ \mathbf{cm}$ at the solid water phantom (depth 0 cm) of the film, and the standard deviation of the Xray dose was 0.016 while rotating. Therefore, we describe the design and test results of the X-band LINAC system mounted on the O-arm gantry. We expect the use of our design for the fusion system that integrates a diagnostic imaging instrument with a radiation therapeutic device.

In the field of radiotherapy, as the treatment method which is combined with imaging devices becomes important, there is an increasing demand for miniaturization and weight reduction of linear accelerator (LINAC), which is a core part of the radiotherapy equipment. To meet these requirements, LINAC has been developed by applying X-band RF technology and side-coupled structure. The developed LINAC is operated by an RF signal with a frequency of 9.3 GHz. The length of the RF cavity is 37 cm and the shunt impedance is 116 $M$ Ω/m. The electron beam can be accelerated up to 6.3 MeV with having about beam current of 80 mA by electric field strength of 16.8 MeV/m. Based on the design parameters, the dose rate is calculated to be more than 1000 cGy/min when the source to surface distance (SSD) is 80 cm.

Medical magnetrons to operate the medical linear accelerator (LINAC) are widely used for the radiation therapy systems. The operation performances of medical LINAC generating the high energy X-ray to treat the cancers depends on the RF performances of medial magnetron. The medical 9.3 GHz coaxial magnetron is investigated by using three-dimensional particle-in-cell simulation to analyze the RF performances. The maximum output power of 1.88 MW with the efficiency of 53 % is measured at the stable $\pmb\pi-\mathbf{mode}$ resulted from the 20-electron spokes. And, the frequency bandwidth controlled by the frequency tuner shows the 1.5 $\mathbf{MHz}/\pmb\mu \mathbf{m}$ with the bandwidth of 60 MHz.

A compact X-band linear accelerator (LINAC) system equipped with a small and lightweight magnetron was constructed to develop a high-precision image-guided radiotherapy system. The developed LINAC system was installed in an O-ring gantry where cone-beam computed tomography (CBCT) was embedded. When the O-arm gantry is rotated, an x-ray beam is stably generated, which resulted from the stable transmission of radio frequency power into the X-band LINAC system. Quality assurance (QA) tests, including mechanical and dosimetry checks, were carried out to ensure safety and operation performance according to the American Association of Physicists in Medicine's TG-51, 142, an international standard protocol established by accredited institutions. In addition, delivery QA of the radiotherapy planning system was conducted to verify intensity-modulated radiotherapy techniques. Therefore, it was demonstrated that the developed X-band LINAC system mounted on the O-arm gantry proved to be valid and reliable for potential use in CBCT image-guided radiation therapy.

Purpose: A beam-blocker composed of multiple strips is a useful gadget for scatter correction and/or for dose reduction in cone-beam CT (CBCT). However, the use of such a beam-blocker would yield cone-beam data that can be challenging for accurate image reconstruction from a single scan in the filtered-backprojection framework. The focus of the work was to develop an analytic image reconstruction method for CBCT that can be directly applied to partially blocked cone-beam data in conjunction with the scatter correction. Methods: The authors developed a rebinned backprojection-filteration (BPF) algorithm for reconstructing images from the partially blocked cone-beam data in a circular scan. The authors also proposed a beam-blocking geometry considering data redundancy such that an efficient scatter estimate can be acquired and sufficient data for BPF image reconstruction can be secured at the same time from a single scan without using any blocker motion. Additionally, scatter correction method and noise reduction scheme have been developed. The authors have performed both simulation and experimental studies to validate the rebinned BPF algorithm for image reconstruction from partially blocked cone-beam data. Quantitative evaluations of the reconstructed image quality were performed in the experimental studies. Results: The simulation study revealed that the developed reconstructionmore » algorithm successfully reconstructs the images from the partial cone-beam data. In the experimental study, the proposed method effectively corrected for the scatter in each projection and reconstructed scatter-corrected images from a single scan. Reduction of cupping artifacts and an enhancement of the image contrast have been demonstrated. The image contrast has increased by a factor of about 2, and the image accuracy in terms of root-mean-square-error with respect to the fan-beam CT image has increased by more than 30%. Conclusions: The authors have successfully demonstrated that the proposed scanning method and image reconstruction algorithm can effectively estimate the scatter in cone-beam projections and produce tomographic images of nearly scatter-free quality. The authors believe that the proposed method would provide a fast and efficient CBCT scanning option to various applications particularly including head-and-neck scan.« less

A microfluidic device was implemented to detect the enzymatic reaction of botulinum toxin A (BTA) using Förster resonance energy transfer (FRET). The microfluidic device comprised a main channel having two loading zones, a reaction chamber and a side channel perpendicular to the main channel. The reaction chamber defined by weir in the main channel was packed with microbeads. The movement of the peptide substrate and the BTA in the microfluidic device was controlled by electrophoresis, and the enzymatic reaction of the BTA was detected through the changes of the fluorescence intensity in the reaction chamber. As a result, it was observed that the enzymatic reaction was affected by the electric voltage applied for the movement of the BTA and the peptide and improved by packing the microbeads in the reaction chamber. The microfluidic device provides the tool to investigate the proteolysis of the substrate by the BTA.

The image of the current non-destructive testing system using a high energy accelerator is limited to conventional two-dimensional metaphysical information. Requirements for the present manufacturing industry are growing rapidly and include quantitative measurements, high-density component model extraction, reverse process development and precision inspection to meet the needs for the verification of manufactured goods. Therefore, industrial three-dimensional high-penetration tomography has emerged as the most promising method. In this study, in order to evaluate the applicability of a MeV-level high-energy accelerator, we developed a three-dimensional tomography system using a 450 kV X-ray generator. Evaluation of the three-dimensional tomography image is based on measurements of the penetration and the image resolution for high-energy X-rays.

Photon counting X-ray detectors with energy discrimination capabilities can discriminate the energy of incident X-ray photon, thereby spectral imaging is possible with them. Energy calibration is a process to find a linear mapping function between the amplitudes of electric pulses and their corresponding photon energy. For practical and efficient energy calibration, the X-ray tube voltage can be used as a reference. However, as the exposure time increases, the threshold giving 50 % of OFF pixels also increases without converging to a point. To reduce calibration errors due to this non-convergent behavior, we present an improved method for energy calibration with applying it to two commercial photon counting X-ray detectors, i.e., a CdTe Medipix2 detector and a CdTe Pixirad2 detector with PFXIE-II read-out ASIC. With the improved mapping function estimated by the improved method, we can better identify the iodine component in a phantom consisting of iodine and other components.

Fast and accurate energy calibration of photon counting spectral detectors (PCSDs) is essential for their biomedical applications to identify and characterize bio-components or contrast agents in tissues. Using the x-ray tube voltage as a reference for energy calibration is known to be an efficient method, but there has been no consideration in the energy calibration of non-convergent behavior of PCSDs. We observed that a single pixel mode (SPM) CdTe PCSD based on Medipix-2 shows some non-convergent behaviors in turning off the detector elements when a high enough threshold is applied to the comparator that produces a binary photon count pulse. More specifically, the detector elements are supposed to stop producing photon count pulses once the threshold reaches a point of the highest photon energy determined by the tube voltage. However, as the x-ray exposure time increases, the threshold giving 50% of off pixels also increases without converging to a point. We established a method to take account of the non-convergent behavior in the energy calibration. With the threshold-to-photon energy mapping function established by the proposed method, we could better identify iodine component in a phantom consisting of iodine and other components.

In the biosensing platform, label-free detection technique provides advantages such as the short analysis time and the cost-effectiveness. In this study, we showed the feasibility of the LSPR substrate with gold nanoparticle array for detecting low density lipoprotein (LDL) and high density lipoprotein (HDL) without labeling. The LSPR substrate was fabricated through the lift-off process with the anodized alumina mask, and its LSPR phenomenon was observed by measuring the optical transmission of substrate. The antibodies were immobilized on the gold nanoparticle array via the chemical binding, in which the 11-MUA was used as the linker to bind the antibodies. The binding of antibodies was confirmed by observing the shift of LSPR peak of the substrate. Finally, with the LSPR substrates with the antibodies immobilized, the detection of LDL and HDL was investigated. As a result, LDL and HDL could be detected in the clinically available concentration range, respectively.

S-band gain flattened distributed fiber Raman amplifier with a bandwidth from 1 488 nm to 1 541 nm (53 nm in width), an averaged gain of 10 dB and a gain ripple of ±0.6 dB is obtained successfully, in which a single-wavelength high power fiber Raman laser with wavelength of 1 427.2 nm is used as the pump and the chirped fiber Bragg grating is used as the gain flattening filter. Besides, filter wavelength division multiplexer (FWDM) is used as the multi-signal multiplexer and 1 427 nm/1 505 nm coarse wavelength division multiplexer (CWDM) is used as the pump-signal coupler. The gain media are G652 fiber of 50 km in length and dispersion compensation fiber (DCF) of 5 km in length. Moreover, the location arrangements of different type of fibers and the effect caused by gain flattening filter as well as their solutions are discussed in detail. It is very significant to extend the range of optical fiber communication band and increase the capacity of fiber communication especially for ultra-long haul and ultra-high capacity communication system.

In computed tomography (CT) imaging, radiation dose delivered to the patient is one of the major concerns. Among many technical solutions to lowering radiation dose while preserving clinical utilities of the images, sparse-view CT is promising technique. However, a fast power switching of an X-ray tube, which is needed for the sparse-view sampling, can be challenging in many CT systems. We have recently proposed a novel alternative approach to sparse-view circular CT that can be readily incorporated on the existing CT systems, and have successfully shown its feasibility. Instead of switching the X-ray tube power, one can place an oscillating multi-slit collimator between the X-ray tube and the patient to partially block the X-ray beam thereby reducing the radiation. In this study, an experimental study was performed to evaluate the performance of the proposed XT scan scheme. Industrial CT projection data of a CatPhan® 600 phantom was acquired by use of the oscillating multi-slit collimator. We used a sinusoidal motion of the collimator to the perpendicular direction of the rotation axis for the purpose of obtaining more uniform spatial sampling of the image. For image reconstruction, we used a total-variation minimization (TV) algorithm which has shown its out-performance in many sparse-view CT applications.

In computed tomography (CT) imaging, radiation dose delivered to the patient is one of the major concerns. Many CT developers and researchers have been making efforts to reduce radiation dose. Sparse-view CT takes projections at sparser view-angles and provides a viable option to reducing radiation dose. However, a fast power switching of an x-ray tube, which is needed for the sparse-view sampling, can be challenging in many CT systems. We have recently proposed a novel alternative approach to sparse-view circular CT that can be readily incorporated in the existing CT systems. Instead of switching the x-ray tube power, we proposed to use a multi-slit collimator placed between the x-ray source and the patient to partially block the x-ray beam thereby reducing the radiation. In this study, we performed a simulation study based on numerically acquired projection data to demonstrate a feasibility of using a multi-slit collimator in a helical CT. The XCAT phantom was used and a numerical collimator has been made to apply on the projection data. Numerical multi-slit collimator was designed to have equal size of slit-openings and radio-opaque rectangular areas, and the length dimension of the slits is perpendicular to the rotation axis. For image reconstruction, we used a total-variation minimization (TV) algorithm which has shown its out-performance in many sparse-view CT applications. We demonstrated that the proposed multiple fan-beam helical CT can provide a useful low-dose scanning option.

The backward cascaded stimulated Brillouin scattering in a backward pumped S band distributed fiber Raman amplifier was researched. The gain medium is G652 fiber. The Raman pump laser is a 1428 nm fiber Raman laser whose power is tunable between 0 and 1W. The signal source is a frequency tunable narrow spectral bandwidth (

Now the communication band of fiber focuses on C-band, but with increasing demand of fiber communication capacity, the communication band will extend to the S-band and L-band and fiber Raman amplifier will play a very important role in this process. In this paper, actual fiber Raman gain spectrum using single high power fiber Raman laser as pump was tested and the proper chirped Bragg fiber grating as gain flattening filter was designed to flatten actually tested gain spectrum. Besides, FWDM (film wavelength division multiplexer) is used as the multiplexer of signals and 1427nm/1505nm CWDM (coarse wavelength division multiplexer) is used as pump-signal coupler. The gain media are 50 km G652 fiber and 5km DCF (dispersion compensation fiber). The gain is 10dB of S-band fiber dispersion compensation Raman amplifier from1487.88nm~1541.88nm (total 53nm bandwidth) with gain ripple ± 0.6 dB was successfully obtained. Besides, the effect caused by different location ways of different type fibers was also discussed. It is very significant for extending range of communication band of fiber and increasing the capacity of fiber communication especially for ultra-long haul and ultra-high capacity communication system.

The forward and backward cascaded stimulated Brillouin scattering(SBS) in the backward pumped S band distributed G652 fiber Raman amplifier have been researched, pumped by the tunable power at 1428nm fiber Raman laser and signal source is a tunable power external cavity laser (ECL) with narrow spectral bandwidth (

The amplification effect on forward and backward stimulated Brillouin scattering lines in the forward pumped S band discrete DCF fiber Raman amplifier (FRA) has been studied. The pumped threshold power of the forward first order Stokes SBS (FSB 1 - ), second order Stokes SBS (FSB 2 - ) and third order SBS (FSB 3 - ) in the forward pumped FRA are 1.5 mW, 1.4 mW and 1.7 mW respectively. The Stokes SBS lines are amplified by FRA and fiber Brillouin amplifier (FBA) at the same time. The gain of amplification is given as G A =G R multiplied by G B where G R is Raman gain and G B is Brillouin gain. In the experiments, the saturation gain of FSB 1 - , FSB 2 - and FSB 3 - are about 52dB, 65dB and 65dB respectively. The saturation Raman gain of 10km DCF forward FRA is about 14dB, so the Brillouin gain of FSB 1 - , FSB 2 - and FSB 3 - are about 38dB, 51dB and 51dBrespectively. There are pumped threshold power of the first order, second order and third order Stokes backward SBS (B-SBS) line BSB 1 - , BSB 2 - and BSB 3 - in the forward pumped discrete DCF FRA, and they are about 4.7mW, 17.1mW and 67mW respectively. The saturation gain of the first order, second and third Stokes backward SBS line BSB 1 - , BSB 2 - and BSB 3 - are about 60dB and the saturation gain of 10km DCF forward pumped FRA is about 27dB, so the gain of FBA is about 33dB. The forward and backward cascaded SBS lines have been observed.

C-band and S-band fiber Raman gain spectrum pumped by single wavelength high power fiber Raman laser were tested and the proper chirped Bragg fiber grating as gain flattening filter was designed to flatten actually tested gain spectrum. Besides, FWDM (filter wavelength division multiplexer) and 1427nm/1505nm CWDM (coarse wavelength division multiplexer) are used as C-band and S-band fiber Raman amplifier pump-signal couplers respectively. The gain media are 50 km G652 fiber and 5km DCF (dispersion compensation fiber). C-band fiber dispersion compensation Raman amplifier with bandwidth from 1519nm to 1574nm (55nm) and average gain 15.2dB and ripple ±0.8dB was successfully obtained. S-band fiber dispersion compensation Raman amplifier with bandwidth from 1488nm to 1541nm (53nm) and average gain 10.1dB and ripple ±0.9dB was successfully obtained. During the test of C-band fiber Raman amplifiers, broadband ASE light source and WDM-emulator were used to simulate the DWDM (dense wavelength division multiplexing) signal source that can make the whole test more accurate. It is very significant for extending range of communication band of fiber and increasing the capacity of fiber communication especially for ultra-long haul and ultra-high capacity communication system. At last, the result of experiment using these setup and influence caused by gain flattening filter and different type fibers location arrangements (G652 fiber and DCF) and corresponding solutions were also discussed.

The forward and backward cascaded stimulated Brillouin scattering (SBS) in the backward pumped S band distributed G652 fiber Raman amplifier have been researched, pumped by the tunable power 1428nm fiber Raman laser and signal source is a tunable narrow spectral bandwidth (

A 30km long distance distributed optical fiber Raman temperature sensor (DOFRTS) system has been made, it use new measuring temperature principle of optical fiber amplified anti-Stokes Raman spontaneous scattering. In the system, 1550nm erbium-doped optical fiber laser, a highness speed data acquisition card and signal processing technique are used. By using these technique, the problem of weak signal detection is resolved and signal to noise ratio is increased. All components of system are put into an intellectualized constant temperature box and work in constant temperature condition. Stability and environment adaptability are improved. By appraisal, performance of the system is listed as follows: length of single mode fiber: 31km, temperature rang:0-100°C (can be expanded), temperature measuring uncertainty:±2°C, temperature resolution:0.1°C, measurement time:432s, spatial resolution :3m.

The cascaded forward stimulated Brillouin scattering (SBS) in the S band distributed G652 fiber Raman amplifier forward pumped and backward pumped by the tunable power fiber laser and signal source is a tunable narrow spectral bandwidth(

DCF optical fiber Stokes Raman forward scattering and backward scattering gain spectrum have been measured by Raman laser as a pump source and high spectral resolution four grating spectrometer. There are 15 phonon modes in the Stokes forward scattering region and 18 phonon modes in the Stokes backward scattering region. In the low frequency region, there are 3 characteristic phonon modes they are 41.4cm -1 , 68.0cm -1 and 96.7cm -1 . The characteristic Raman peaks of DCF fiber is 434.7cm -1 and 455.4cm -1 that are correspond to 440cm -1 and 490cm -1 of normal single mode fiber as a function of pump power has been measured. Measured DCF Raman gain spectrum is different form that in common reference and books. The reasons are the high GeO 2 concentration in DCF fiber and the developing of measuring technology.

Summary form only given. We have demonstrated, for the first time to our knowledge, operation of a novel Q-switched erbium doped fiber laser using a fiber Bragg grating placed in loop mirror (FBGLM) as an all-fiber wavelength-selective intensity modulator. The main advantage of this FBGLM modulator is that it provides not only the ability to adjust the reflectivity of the cavity mirror but also the ability of wavelength selection. Stable optical pulse output with 3 dB linewidth of 0.07 nm, pulse width of 1.0 /spl mu/s, and peak power of 1.267 W at 80 mW pump power and 8 KHz repetition frequency was obtained in experiments.

The backscattering spectrum of optical fiber has been measured by use 1427 nm Raman laser and Q8384 optical spectrum analyzer and Stokes and anti-Stokes ZX band backscattering spectrum has been first observed and discussed, ZX band frequency shift is 1THz, bandwidth 3THz(3dB). Optimum design of S-band negative dispersion DCF discrete fiber Raman amplifier has been researched by OPTIAMP DESIGN 3.3 SOFTWARE (made in Canada Optiwave Corporation) and gain spectrum and gain vs. power of DCF discrete fiber Raman amplifier have been measured, practical including Stokes ZX band backscattering gain effect. Pump on/off small signal gain is 13dB (pump power 700mw; fiber 5.1km) and gain band width is 88nm (1440nm-1528nm). The operation principle, configuration and performance of distributed fiber Raman temperature sensors system has been researched. Amplification of anti-Stokes spontaneity Raman scattering (ARS) effect of fiber and its temperature effect has been first observed and discussed. It has been applied to 30km distributed FRS system.

The optical fiber Raman temperature (OFRT) Lidar is a real time, on line and multi-point temperature measurement system. 30k spot temperature information on space field can be measured and located the position by 30km OFRT Lidar It is a new technology integration of optical-mechanic-electric and computer. The system can take real time, on line measurement of spatial temperature field. In the system, optical fibers are both transmission media and sensing media. The intensity of anti-stokes Raman backscattering of optical fiber is modulated by the spatial temperature field where the optical fiber is laid. After signal processing and demodulation, the information of temperature can be extracted from the noise and can be displayed in real time. In time domain, using the velocity of light wave in optical fiber, the time interval ofback-direction light wave and optical fiber OTDR technology The amplification of anti-stokes Rairan spontaneous scattering (ARS) and the temperature effect have been first observed and applied to OFRT Lidar. The performance of OFRT Lidar is following: fiber length : 25.2km; temperature measuring range: O-lOOC(can be expand) temperature uncertainty: 2 C : temperature resolution: 0. 1 ; spatial resolution: Sm: measurement time: 5mm; Main unit operation temperature range: O—40t .The optical fiber sensor probes and the software for signal processing are also discussed. Keywords: Optical Fiber Raman Temperature (OFRT) Lidar, Optic Time Domain Reflection (OTDR),distributed optical fiber Raman photons temperature sensors, the temperature effect of Raman backscattering, Rayleigh backscattering, ZX band backscattering spectrum, optical fiber sensor probe.

We present a double time-multiplexed interferometer based on Faraday mirrors, which can be used for two quantum cryptography channels. Two channel operation with "star" configuration, 1km + 1km telecom optical fibers, was demonstrated. Experiments show a fringe visibility of 0.96 for both channels. Crosstalk attenuation more than 70dB was observed.

The distributed optical fiber Raman Photons Temperature Sensors (DFRS) is a real time, on line and multi-point (30k points) measuring system for multi-parameter measurement of temperature etc. According to temperature effect of optical fiber Raman backscattering, the intensity of anti-stokes Raman backscattering of optical fiber is modulated by the spatial temperature field where the optical fiber is laid. Then after signal processing and demodulation, the information of temperature can be extracted from the noise and can be displayed in real time. It is a typical optical fiber sensors measuring network. In time domain, using the velocity of light wave in optical fiber, the time interval of back-direction light wave and optical fiber OTDR technology, the DFRS can locate the temperature spots. In this case, it is a typical optical fiber laser temperature radar system as well. The backscattering spectrum of optical fiber has been measured by fiber laser and optical spectrum analyzer. Raman backscattering spectrum and ZX band backscattering spectrum has been first observed. The amplification of anti-stokes Raman spontaneous scattering (ARS) and the temperature effect have been first observed and applied to DFRS. The performance of DOFS is following: fiber length : 25.2km;temperature measuring range: 0-1000C(can be expand) temperature uncertainty: ±200C : temperature resolution: 0. 1; spatial resolution: 5m: measurement time: 10mm; Main unit operation temperature range: 0—400C . The optical fiber sensor probes and the software for signal processing are also discussed.

This paper briefly introduces the operation principle and configuration of distributed optical fiber sensor (DOFS) system. A new demodulation method that uses Rayleigh back scattering photon flux to demodulate Raman back scattering photon flux is put forward, and the advantages of this new method are discussed. Methods to measure temperature, strain and pressure at the same time are researched. The performance of DOFS is following: fiber length: 10.2 km; temperature uncertainty: +/- 2 degree(s)C: temperature resolution: 0.1 degree(s)C; spatial resolution: 4m: measurement time: 5 min; Main unit operation temperature range: 0 - 40 degree(s)C. The DOFS system have been applied to coal mine.

In this paper a new structure all fiber Q-switched Erbium-doped fiber laser by using all-fiber wavelength selective intensity modulator based on fiber grating loop mirror (FGLM) was reported. This Q-switched scheme not only modulates loss of the cavity but also selects wavelength. Stable optical pulse with 3 dB linewidth of 0.07 nm, pulse width of 1.4 microsecond(s) , average power of 14.2 mW, and peak power of 1.267 W at 80 mW pump power and 8 KHz repetition rates was obtained in experiments. The generation of single laser pulses and its stability were discussed.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The operation principle of distributed optical fiber Raman gain amplifier has been discussed. The amplification phenomena have been observed in the 1410-nm wavelength range pumped by the 1320-nm solid laser using 23-km single-mode GI optical fiber. The Raman gain is depending on optical fiber interaction length . The optical fiber effective interaction lengths are 15.5 km and 10.5 km when pump pulse peak power are 50W and 30W. The relation between the gain of Raman amplifier and pump power at different effective interaction length of optical fiber is discussed. The Raman gain of optical fiber is 0.62x10-15 m/W during 50W pump power and the effective interaction area of optical fiber is 30 micrometers 2. The effective interaction area of optical fiber is 41.4 micrometers 2 during the pump power is 30W.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The temperature effect of fiber optics Raman back-scattering have been researched at high temperature (1000 degree(s)C) condition. A distributed fiber optics Raman and Rayleigh back-scattering sensor measuring network have been design and fabricated. The performance of high temperature measuring network is following: temperature measuring range: 0-1000 degree(s)C; temperature uncertainty

The miniature fiber optic Fabry-Perot pressure sensor with a silicon diaphragm was developed for medical applications. The configuration of this sensor was a 1-mm long fiber optic Fabry-Perot interferometer bonded to an 80 micrometers -thick diaphragm. The length of the sensor was about 1.5 mm and the area of the diaphragm was 1 mm x 1 mm. The phase shift of the interferometric sensor was proportional to the applied pressure. The relationship between the applied pressure and the phase change was nonlinear.

A new sampling correct technology of distributed optical fiber temperature sensor (DOFTS) has been researched to eliminate the instability of DOFTS system that caused by the change of environment temperature, gain of amplifier and voltage of power supply. Put the optical sampling loop into a constant temperature thermostat. A computer automatically corrects signal voltage of every point. Thus the stability of the system is improved.

The operation principle, technique character and measuring method of 10 km LDOFTS are discussed. The testing result of 10 km LDOFTS is given in this paper.

The DOFTS system that has applied to temperature automatically alarm system of coal mine and tunnel has been researched. It is a real-time, on line and multi-point measurement system. The wavelength of LD is 1550 nm, on the 6 km optical fiber, 3000 points temperature signal is sampled and the spatial position is certain. Temperature measured region: -50 degree(s)C--100 degree(s)C; measured uncertain value: +/- 3 degree(s)C; temperature resolution: 0.1 degree(s)C; spatial resolution

A 31 km long range distributed optical fiber Raman photon temperature sensor (DOFRPTS) system have been developed based on temperature effect of the amplified spontaneous Raman scattering in fiber, and using fiber laser as a pumped source. The results show that temperature measuring uncertainty is ±2 °C, temperature resolution is 0.1 °C, measurement time is 432 s, spatial resolution is less than 4 m.

We present a dynamic scheme north finder using a low accuracy fiber optic gyroscope which the random walk noise is around 1.5 deg/h/(root)Hz. North finder accuracy has been estimated and experimental data also are presented and error sources are discussed. Two lock-in-amplifier algorithm is proposed for signal processing.