Journals >Infrared and Laser Engineering
Contents
2005
Volume: 34 Issue 5
27 Article(s)
Export citation format
Research Article
Novel method of small target detection in infrared images
, and
Based on the characteris tic analysis of infrared naval vessel target under the sea-sky background, a new adaptive infrared small target detection method is developed, which uses the LOG operator to detect the outline of the target and then decides its center point as the seed point in the region growing procedure. In Based on the characteris tic analysis of infrared naval vessel target under the sea-sky background, a new adaptive infrared small target detection method is developed, which uses the LOG operator to detect the outline of the target and then decides its center point as the seed point in the region growing procedure. In the proposed approach, the parameters of the LOG operator are adaptively determined using the roughness estimation of the background.This procedure is a preprocessing method of the detection and recognition of the small target, and it can reduce the computation requirement, improve the detection speed, restrain the unnecessary seed points in region growing process, and increase the possibility of target detection..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 587 (2005)
Image restoration in T-ray imaging based on wavelet de-noising
, and
In order to improve the spatial resolution and reduce l/f noise of real-time THz pulses （T- ray） imaging system, a new method based on wavelet de-nosing and Jasson-Van-Cittert （JVC） image restoration algorithm was presented. After making wavelet transform to a T-ray image, generalized cross validation （GCV） was used toIn order to improve the spatial resolution and reduce l/f noise of real-time THz pulses （T- ray） imaging system, a new method based on wavelet de-nosing and Jasson-Van-Cittert （JVC） image restoration algorithm was presented. After making wavelet transform to a T-ray image, generalized cross validation （GCV） was used to estimate the optimal threshold and de-noising was done in the high frequency sub-bands respectively. The JVC image restoration algorithm was applied to the de-noised T-ray image for resolution improving. Experimental results show that this method can suppress l/f noise successfully and improve the resolution of T-ray image significantly..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 592 (2005)
Restoration of turbulence-degraded images based on phase retrieval algorithm
, , , and
To suppress the aero-optic effect on object images,the phase retrieval algorithm is applied together with aero-optic mechanism to restore turbulence-degraded images.The principle of this algorithm is to reconstruct object images from their Fourier transform magnitude and is equivalent to the principle of the reconstrucTo suppress the aero-optic effect on object images,the phase retrieval algorithm is applied together with aero-optic mechanism to restore turbulence-degraded images.The principle of this algorithm is to reconstruct object images from their Fourier transform magnitude and is equivalent to the principle of the reconstruction of the Fourier phase.Two methods for phase retrieval,namely the iterative Fourier transform （IFT） algorithm and a new de-autocorrelation algorithm, are discussed.The current de-autocor- relation algorithm is improved by using the conjugate gradient（CG）method to solve the Gauss-Newton equation in order to accelerate convergence.The reconstruction done by the IFT algorithm does not always converge to correct results,but combination of the IFT algorithm and the de-autocorrelation algorithm will reduce the stagnation of the IFT algorithm and increase the effectiveness of phase retrieval.Expermental examples of restoration of a simulated turbulence-degraded image with white noise at signal-to-noise ratio （SNR）of 20 dB are given. The experimental results show that the recommended method is an effective method and less sensitive to noise..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 597 (2005)
Sequence image stitching based on area feature and cross correlation
, , , and
A new stitching algorithm based on area feature and cross correlation for the sequence image with transformation of translation,rotation and isometric scaling is proposed.Firstly, feature areas are extracted by segmenting the image with the iterative threshold method,and pairs of homonymy areas through area features arA new stitching algorithm based on area feature and cross correlation for the sequence image with transformation of translation,rotation and isometric scaling is proposed.Firstly, feature areas are extracted by segmenting the image with the iterative threshold method,and pairs of homonymy areas through area features are established;secondly,the algorithm of the intensity around the feature pointscentroids of areas is used to calculate the Cross correlation;thirdly, the accurate transformation is obtained and the sequence images are stitched.The experimental result demonstrated the algorithm is accurate in matching..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 602 (2005)
Filter algorithm of passive location by IRSTS
, , and
First building the filter algorithm model of passive location by IRSTS by means of extended kalman filter, then aiming at the speciality of transcendental noise statistics and linearization error of measurement model effecting on filter precision during the study of extended kalman filter, adaptive extended kalman filtFirst building the filter algorithm model of passive location by IRSTS by means of extended kalman filter, then aiming at the speciality of transcendental noise statistics and linearization error of measurement model effecting on filter precision during the study of extended kalman filter, adaptive extended kalman filter algorithm for passive location by IRSTS by means of subjuctive noise technique is advanced. It improved on extended kalman filter algorithm and approximated subjuctive noise statistics. The algorithm degraded linearization error and enhanced the nonlinear filter precision. The simulation experimental results show the advantage of adaptive extended kaiman filter algorithm under the same condition, the algorithm supplied practical value of engineering..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 606 (2005)
Hardware design of new type image matching machine for imaging laser radar
, , , , and
Imaging laser radar is a new type imaging radar. Image matching machine is one of the key foundations for the radar used in imaging navigation application. In this paper, the demands of the machine are analyzed at first. Then the machine with the scheme of DSP ＋FPGA is designed and implemented.The scheme has great capaImaging laser radar is a new type imaging radar. Image matching machine is one of the key foundations for the radar used in imaging navigation application. In this paper, the demands of the machine are analyzed at first. Then the machine with the scheme of DSP ＋FPGA is designed and implemented.The scheme has great capability on calculating and extensibility.It has a steady and various communication interfaces. And the software implement of algorithm can be modified easily.The experimental results show that the system works well for the application with high real-time,high reliability,and flexible architecture..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 612 (2005)
Design and optimization of the XeCl excimer laser's stimuli circuit
, and
The stimuli circuit of the XeCl excimer laser has a great effect on the output characters of the laser. In order to improve the output character of the laser,the Spark Gap Switch（SGS） was originally and satisfactorily used to control the instant high current trigger signal of the XeCl excimer laser which was made by ouThe stimuli circuit of the XeCl excimer laser has a great effect on the output characters of the laser. In order to improve the output character of the laser,the Spark Gap Switch（SGS） was originally and satisfactorily used to control the instant high current trigger signal of the XeCl excimer laser which was made by ourselves.To begin with, the design of the structure of the XeCl excimer laser was discussed, and then the circuit parameter of the laser was determined. Secondly,to deal with the problems in the experiments,the current foldback, optical coupler insulation and electromagnetic shielding were used to optimize the circuit performance of laser. Finally, the measured data shows that the laser worked stably and the output characters reached the design values by the improved methods.Thus it would offer the reference of. the improvement of the laser＇s output characters..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 617 (2005)
Design of secondary planet interfere-spectrometer imaging data acquisition system
, , , and
Real-time data acquisition is a basic and important link on industry and aviation measure and control realm.How to increase the real-time quality of data collection and saving is a problem concerned by technical personnel.A high speed data acquisition system which has been used recording the secondary planet interferesReal-time data acquisition is a basic and important link on industry and aviation measure and control realm.How to increase the real-time quality of data collection and saving is a problem concerned by technical personnel.A high speed data acquisition system which has been used recording the secondary planet interferespectrometer imaging based on 32 bit high speed data collection card ADLINK PCI 7300A is described. The realization of high-speed data collection, saving and real-time displaying based on vc6.0 and Windows NT is elaborated.In the process the multithreading,timer,doublebuffer and synchronous object etc have been used, the system stability and real-time quality are effectively assured, the function of high speed digital image card is realized by digital I/O card..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 622 (2005)
Optic power control of LD drive circuit
, , , and
The design of digital contr ol system of LD driver circuit, including the optic power control system and the temperature control system is introduced. The singlechip is the core, combined with peripheral circuit, with the digital control instead of the analog circuit control. It is easy to control, and the precision isThe design of digital contr ol system of LD driver circuit, including the optic power control system and the temperature control system is introduced. The singlechip is the core, combined with peripheral circuit, with the digital control instead of the analog circuit control. It is easy to control, and the precision is high. The singlechip is the core of optic power of control system , and peripheral circuit includes power sampling and current driver. The PD control algorithm is used to control the electric current. So it can control the optic power of LD. The PD parameters are tuned in engineering experiments. Mathematics model is built to realize software control. In order to improve the control precision, the optic power is divided into 9 parts, and PD parameter of each part is adjusted. The power error of LD can be controlled within 0.02 W. The precision of the designed driver circuit is high. The circuit is well-real time, and reaches the requirement of design..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 626 (2005)
[in Chinese]
GaN epilayer by infrared spectroscopic ellipsometry
, , , and
Infrared spectroscopic ellipsometry from 9.5 to 12.5μm is used to study the nominally undoped GaN on sapphire. The parameters of the lattice vibration oscillators and the plasma are obtained by fitting with the experimental data. Then the anisotropic refractive index is calculated. Further-more, the carrier concentratiInfrared spectroscopic ellipsometry from 9.5 to 12.5μm is used to study the nominally undoped GaN on sapphire. The parameters of the lattice vibration oscillators and the plasma are obtained by fitting with the experimental data. Then the anisotropic refractive index is calculated. Further-more, the carrier concentration and the electron mobility from the plasma frequency and the damping constant are derived. The result is compared with that of the Hall measurement..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 544 (2005)
Numerical simulation on the optical transmission distortions throughout the laminar flow field
, and
The high speed flow optical transmission effect is a key to high speed missile using infrared image terminal guidance technology. In this paper, computing methods of the optical transmission distortions throughout the laminar flow field in aero-optical effects are described. Image shift and low blur brought by laminar The high speed flow optical transmission effect is a key to high speed missile using infrared image terminal guidance technology. In this paper, computing methods of the optical transmission distortions throughout the laminar flow field in aero-optical effects are described. Image shift and low blur brought by laminar flow are calculated using optical methods of ray trace and physical optics. The approaches and some simulation results are presented with computed data of high speed flow field. Comparison with the engineering results shows that the high speed flow field optical transmission theory model is correct and the numerical simulation software can be used to analyze the aero-optical effects.
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 548 (2005)
Structure of optical fibre coupler with the infrared spectrometer
, , and
To obtain excellent performance optical fiber couplers,the structural difference of SiO2 in couplers under different manufacturing technique was investigated with 740 FT-IR micro infrared spectrometer.The infrared absorption spectra of SiO2 in couplers fabricated at different drawing velocities was measured. Two characTo obtain excellent performance optical fiber couplers,the structural difference of SiO2 in couplers under different manufacturing technique was investigated with 740 FT-IR micro infrared spectrometer.The infrared absorption spectra of SiO2 in couplers fabricated at different drawing velocities was measured. Two characteristic peaks in 650-2000 cm^-1 are observed.One characteristic peak is at about 943 cm^-1, which attributes to Si-O-Si bond asymmetric stretching vibration, the other is at about 773 cm^-1, which attributes to Si-O-Si bond symmetric stretching vibration. From the infrared spectrum,it is found that the characteristic peaks changes while the manufacturing technique is different. And the changing amount is measured.It is concluded that the asymmetric vibration of Si-O-Si is stronger in the glass of fiber coupler,and the wavenumber shift is the most important to the performance of the optical fiber couplers..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 553 (2005)
New type of Doppler modulating technology
, , , , and
In the traditional modulating technology, the objects are illuminated by the modulated laser beams. In general, this kind of illumination must past through some optics systems. The modulating illumination occurs at every optics component which the modulated laser beams pass through. These optics component must have somIn the traditional modulating technology, the objects are illuminated by the modulated laser beams. In general, this kind of illumination must past through some optics systems. The modulating illumination occurs at every optics component which the modulated laser beams pass through. These optics component must have some blemishes, which could produce the same frequency of the modulated laser beams and idle signals of stable phase. If these signals are in the field of view, they can produce background disturbance, so signal-to-noise becomes low. A new type of Doppler modulator which bases on Michelson-Morlery dynamic interference technology is introduced. Compared with the traditional modulating technology, the Doppler modulating technology is that the Doppler shift of the sample＇s moving leads to alternating variation of coherent field, which is used as modulating frequency. It can decrease effectively the background noise from modulating except for the target. Stabilization of the signal frequency presented by this type of Doppler modulator is about 1%, which could satisfy the need of reference signal of the lock-in amplifier..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 556 (2005)
Drawback of Cassegrain antenna system based on space optical communication
, and
Antenna, which whether transmits or receives correct signal or not is our main care and our direction, is an important part in any communication systems. Because of the characteristics of laser different from radio, the antenna system of point-to-point laser communication system must be designed strictly. Newton systemAntenna, which whether transmits or receives correct signal or not is our main care and our direction, is an important part in any communication systems. Because of the characteristics of laser different from radio, the antenna system of point-to-point laser communication system must be designed strictly. Newton system, Green system and Cassegrain system are accepted commonly in optical antenna systems as field lens which include refraction system, inflection system and refraction-and-inflection system. In this paper, Cassegrain antenna is discussed. However, the potential problem of sheltering ratio in Cassegrain system leads to a loss of effective power of the optical system so called vignette phenomena. The other is related to optical aberration, because Cassegrain antenna sacrifices sight field for perfect image. We put forward some new solution and analyze theoretically how to reduce aberration based on the two considerations..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 560 (2005)
[in Chinese]
Development trends of short-range dogfight IR air to air missile
, and
In the recent local wars, air to air missile plays an very important role in controlling airsupremacy,for which many countries commence to develop and equip new generation air to air missile. Firstly, the modem air-combat＇s requirements for new generation short-range dogfight IR missile are analyzed in the article,and In the recent local wars, air to air missile plays an very important role in controlling airsupremacy,for which many countries commence to develop and equip new generation air to air missile. Firstly, the modem air-combat＇s requirements for new generation short-range dogfight IR missile are analyzed in the article,and it is pointed out that interception of cruise missile will be combat mission of new generation short-range dogfight IR missile.Then,the development trends of foreign new generation short-range dogfight IR missile are introduced, including U.S. AIM-9X,Britain ASRAAM and Germany IRIS-T.Finally,the key technologies generally used by new generation short-range dogfight IR missile,such as the advanced aerodynamic configuration/system design,IIR guidance,aerodynamic/TVC complex control and small strap-down inertial guidance system,are discussed..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 564 (2005)
Infrared apparent radiation model in short and middle wave for low cloud
, , , and
The disturbance of clouds is an important factor in detection and simulation for sky, therefore, the study of cloud radiation is important. In different IR wavelengths, the properties of cloud can be much different, in order to study the apparent radiation of different wavelengths, the calculation of spectral radiationThe disturbance of clouds is an important factor in detection and simulation for sky, therefore, the study of cloud radiation is important. In different IR wavelengths, the properties of cloud can be much different, in order to study the apparent radiation of different wavelengths, the calculation of spectral radiation of cloud is required. An apparent radiation model for typical detection is presented in this article, and the calculations of radiation contribute to the cloud radiation is studied. The acquirement of parameters in the model is in the light of traditional two stream approximation, in additional, an experience formula of spectral optical depth is introduced, consequently, the infrared spectral radiation characteristics of low clouds in short and middle wave are gained, and apparent spectral radiation is calculated in middle and short wave ,and the calculation time is saved. Result shows that actual measurements and data from the model are consistent, hence the model is applicable as the data source in the detection and simulation in the cloudy background..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 569 (2005)
Key design of uncooled infrared imaging digital module
Recently, with the development of thermal imaging technologies,the research and application of low-cost, high performance uncooled focal-plane-array infrared detectors have been attracted much attention in the field of thermal imaging. Based on the model of an 8-12μm uncooled focal-plane-array infrared detector IDML073Recently, with the development of thermal imaging technologies,the research and application of low-cost, high performance uncooled focal-plane-array infrared detectors have been attracted much attention in the field of thermal imaging. Based on the model of an 8-12μm uncooled focal-plane-array infrared detector IDML073-XX-V3 made by SOFRADIR,a French company, an infrared real-time imaging is performed,in which several key technologies have been used, such as DSP, FPGA,digital control and servo for detectors. The specification, control signals, imaging technology and implementing technique of the uncooled focal-plane-array infrared detectors are discussed, and the function and design means of DSP-FPGA digital signal processing circuit and the principle of digital temperature control detector are expounded. This module has compacted structure,image definition and performance stable, and can meet the requirement of industrial level..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 573 (2005)
Common aperture IR/Ladar dual-mode imaging seeker system
, , and
According to the characteristics of the terminal guidance phase of cruising missile,the scheme of common aperture IR/Ladar dual-mode imaging seeker system is proposed.The seeker system can precisely track and recognize the stationary and relocatable object on the ground.The seeker design scheme includes two imaging modAccording to the characteristics of the terminal guidance phase of cruising missile,the scheme of common aperture IR/Ladar dual-mode imaging seeker system is proposed.The seeker system can precisely track and recognize the stationary and relocatable object on the ground.The seeker design scheme includes two imaging modes,the passive IR imaging mode and active pulse laser imaging mode.The passive infrared imaging mode is used for the coarse object search and acquisition and the active pulse laser imaging mode is used for precise object recognition and tracking.At the same time,the two imaging mode use the common optics.So the seeker system can not only meet the requirements of the large field of view for object search and acquisition,but also meet the requirements of high resolution for object recognition and tracking..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 577 (2005)
Theoretical analysis of temperature field on the surface of ballistic missile warhead in midcourse
, , , and
The theoretical method calculating temperature distribution of ballistic missile warhead in midcourse is discussed.Based on the network method,an adequate model is established.The Runge-Kutta method is used to solve the heat balance equations,and the temperature field distribution at any time is obtained.In the end,varThe theoretical method calculating temperature distribution of ballistic missile warhead in midcourse is discussed.Based on the network method,an adequate model is established.The Runge-Kutta method is used to solve the heat balance equations,and the temperature field distribution at any time is obtained.In the end,various factors which influence the temperature field are analyzed quantificationally..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 582 (2005)
[in Chinese]
Design of novel absorptive thin film for laser welding in optoelectronic device capsulation
, , , and
A kind of absorptive thin film was designed and used in laser welding of SiO2, Si and LiNbO3. This absorptive thin film of three layer metal-dielectric-metal structure is designed for further reducing the high reflectance of the Nd：YAG laser beam on the surface of the thin layer that is utilized as solder between the tA kind of absorptive thin film was designed and used in laser welding of SiO2, Si and LiNbO3. This absorptive thin film of three layer metal-dielectric-metal structure is designed for further reducing the high reflectance of the Nd：YAG laser beam on the surface of the thin layer that is utilized as solder between the transparent parent materials. The actual absorption of laser energy in experiment exceeds 99%. This combination of absorber and solder transformed the laser energy into heat efficiently and decreased the minimum necessary incident laser power transmitting through the transparent parent materials. As a result, the damage of the parent materials, which is suffered from laser transmission, was avoided; On the other hand, mechanical stability of the welded materials had been improved. Experiment shows the difference between welding with and without the absorptive thin film.[.
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 505 (2005)
Beam quality of the high power DPL
, , , ... and |Show fewer author(s)
In order to acquire the high beam quality output laser, the high beam quality laser seeder is obtained by the method of twist mode. At the same time, compensation of birefringence, uniform pump cavity and phase conjugation mirror （PCM） were used to improve the beam quality of MOPA laser system. More than 4（10 mJ, 40 HzIn order to acquire the high beam quality output laser, the high beam quality laser seeder is obtained by the method of twist mode. At the same time, compensation of birefringence, uniform pump cavity and phase conjugation mirror （PCM） were used to improve the beam quality of MOPA laser system. More than 4（10 mJ, 40 Hz output laser with near diffraction limited beam quality was obtained. And it is very useful to design the high power laser..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 511 (2005)
Photon counting applied to imaging lidar
, , and
The system theory of imaging ranging lidar is researched and the 1064 nm lidar system with photon counting detection is described.The photon counting detection technique and the improvement of the signal-to-noise ratio are analyzed theoretically.The improved signal-to-noise ratio for the weak signal detection with pulsThe system theory of imaging ranging lidar is researched and the 1064 nm lidar system with photon counting detection is described.The photon counting detection technique and the improvement of the signal-to-noise ratio are analyzed theoretically.The improved signal-to-noise ratio for the weak signal detection with pulse accumulation technique is experimentally proved.The sub-duplicate relationship of photon accumulative pulse and the signal-to-noise ratio is presented experimentally with the different distant targets.In addition, the application of photon counting detection technique to the two difference imaging mode is discussed,The results indicate that the higher detection probability with broad beam emitting and photon counting detection can be obtained than the single-beam scanning mode.[.
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 517 (2005)
Models simulation of oriented prism laser resonator
, , , , and
In order to develop a field distribution program that resolves the model of stable resonator any cavity,the phase model of the cube comer prism is established using continuously the law of reflection of ray vector. A mathematical model of the oriented prism laser field distribution is developed at first. A field distriIn order to develop a field distribution program that resolves the model of stable resonator any cavity,the phase model of the cube comer prism is established using continuously the law of reflection of ray vector. A mathematical model of the oriented prism laser field distribution is developed at first. A field distribution program that resolves the model of stable resonator in any cavity is developed. And the modes of stable resonator consisting of directional prism are investigated with FOX-LI iterative method. The amplitude and phase distributions of the output mirror are presented.In the experiment,the avoidance adjust solid state laser is used. Both the experimental results about the output near-field speckle of laser, far-field speckle of laser and the result from the laser beam quality analyzer are compared with 3-D numerical simulation.The simulation results are in agreement with experimental results.A good effect is obtained in practical application..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 521 (2005)
Design and implementation of the laser range-gating imaging synchronization control system
, , , and
To overcome many shortcomings of the conventional LRG imaging system, such as need to know preset range delay and laser inner time delay. A kind of LRG imaging system based on the DSP is designed and realized, and its synchronization control technique is researched.The fast DSP controller is used to accomplish range meTo overcome many shortcomings of the conventional LRG imaging system, such as need to know preset range delay and laser inner time delay. A kind of LRG imaging system based on the DSP is designed and realized, and its synchronization control technique is researched.The fast DSP controller is used to accomplish range measurement and range delay and to provide several nanoseconds gated pulse to gate ICCD camera.Range-gating and the precision image definition control can be realized effectively,and the targets＇range information and range-gating image are obtained without any preconditions..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 526 (2005)
Applications of VO2 thin films on laser protection
, and
In the war field, the laser weapon has a higher request to laser protection with its constant development. A new kind of laser protection material the VO2 thin films is introduced,which based on nonlinear optical phase transition principle. Because the phase transition temperature of VO2 thin films is near to the room In the war field, the laser weapon has a higher request to laser protection with its constant development. A new kind of laser protection material the VO2 thin films is introduced,which based on nonlinear optical phase transition principle. Because the phase transition temperature of VO2 thin films is near to the room temperature and its optical and electrical properties are very good,VO2 thin films have become the most hopeful laser protection materials for infrared detectors in phase transition materials.In this paper,optical and electrical properties of VO2 thin films are introduced.Associated problems and developing trend of laser protection with VO2 thin films are also described..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 530 (2005)
New kind scheme of laser code in the laser terminal guidance ammunition round
, and
Upon analyzing the characteristics of laser code and wave gate setting, a new kind scheme of laser code in the laser terminal guidance ammunition round is proposed. Based on analysis it is concluded that the scheme has the advantages of both pulse interval coding and bit-limited random periodic code.It has the characteUpon analyzing the characteristics of laser code and wave gate setting, a new kind scheme of laser code in the laser terminal guidance ammunition round is proposed. Based on analysis it is concluded that the scheme has the advantages of both pulse interval coding and bit-limited random periodic code.It has the characteristics of easily identifying the first signal, and having no fixed pulse repetition or periodicity.The scheme which can easily be decoded by ourselves but not be recognized by enemy, and has the ability of countering active deception jamming..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 535 (2005)
Calculation and measurement of jitter in gain-switch F-P laser
, , and
In order to measure jitter of gain-switched laser precisely, we analyze theoretically the math model and measurement principle of harmonic spectrum analysis used to measure laser pulse jitter. The error in pulse jitter measurement, which based on power spectrum measurement and was established by David A. Leep etc., is In order to measure jitter of gain-switched laser precisely, we analyze theoretically the math model and measurement principle of harmonic spectrum analysis used to measure laser pulse jitter. The error in pulse jitter measurement, which based on power spectrum measurement and was established by David A. Leep etc., is corrected. The universal math formula for measuring pulse jitter was deduced and the power spectrum of pulse in different conditions was numerically simulated. The pulse jitter of gainswitched Fabry-Perot laser with external cw-light injection was experimentally investigated by using harmonic spectrum analysis. The time jitter is 0.905 ps and amplitude noise is 2.83%. Compared with the outcome of sample oscilloscope measurement, it indicates that the harmonic spectrum analysis measurement is more precise and the accuracy is up to the magnitude of fs in the case of small jitter high repeat frequency..
Infrared and Laser Engineering
- Publication Date: Oct. 31, 2005
- Vol. 34, Issue 5, 540 (2005)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20