2005 Vol. 26, No. 3
The threat of antiship missile against surface ships and the limitation of antimissile defensive systems of the surface ships being in service are analysed. From the analyses,we come to the conclusion that there is a limit to antimissile ability active shipbased defensive systems,the surface ships are faced with a serious threat of antiship missile, and are in great need of new defensive means and weapons in order to enhance its antimissile ability. On the basis of the presentation mentioned above, the main characteristics of highenergy laser weapons are analysed briefly, the possible application and role of highenergy laser weapons on surface ship are also discussed. It theoreitically shows that highenergy laser weapons are the potential shortrange antimissile defensive weapons, and are of an important role in the surface ships’shortrange antimissile defense, antisatellite and highresolution optical warning.
There is a badly influence of the existence of ring laser gyro’s random walk on the performance of ring laser gyro strapdown inertial navigation system(SINS). In order to quantitatively study the influence of ring laser gyro’s random walk on SINS,an error formula is derived with a mathematical method. Simulation has been done according to the given flight trajectory and the given factor of ring laser gyro’s random walk.The simulation results are analyzed.
Laser diode (LD) is a current injected device whose characteristic and life are greatly dependent on the performance of LDused current supply. A novel current supply for middleandlow power LD has been designed, which operates on the principles of voltagetocurrent conversion, current amplification,and current negative feedback. A continuously adjustable output current from zero to three amperes can be achieved, and when the output current is two or three amperes, the current variation obtained in an experiment within five hours are smaller than one milliampere, corresponding to the stability of 5.0×10-4and 3.3×10-4. In addition, the current supply has multiple functions such as antisurgecurrent,current interruption protection, overcurrent protection,etc. Compared with the traditional current supply,this device has advantages of simple working principle and high stability, and it will be found wide applications in the fields of teaching, scientific research and production.
Based on the digital image intensifier performance allaround detection system,the detection method of image intensifier field defects is researched. After capturing a image with a defect, its property is known with digital imaging processing method. The field defect processing algorithm is based on the image gray feature extraction but not on the edge feature extraction. This algorithm is suitable to the objects which have quantitative and localized requirements. The experiment results show that this method can accurately detect field defects of the image intensifier.
The pressure sensing mechanism of fiber Bragg grating has been researched. Various physical effects that induce the center wavelength of the fiber Bragg grating to shift are discussed and the sensitivity coefficients of different physical effects under different types of pressure are calculated. The calculation results show that the pressure sensing coefficients under the axial and the transverse pressures are opposite in sign, and the pressure sensitivity can be increased through shielding either of them. The strain sensitivity induced by the waveguide effect is several orders of magnitude smaller than that induced by the strainoptic effect, so it can be neglected. The conclusion that the strainoptic effect has different contributes to the stress sensitivity under pressure in different directions is also drawn for the first time.
The superiority of fiberoptic distributed temperature sensor for tunnel monitoring is analyzed. The principle of distributed temperature measurement is introduced. Raman distributed temperature sensor and the highspeed sampling circuit are employed and connected to the temperature measuring system.Tunnel monitoring network is designed via the industrial computer and Modbus. The design process of hardware and software for the tunnel monitoring network is stated in detail. The application prospect of the monitoring system including the fiberoptic distributed temperature sensor will be brilliant in the future.
A novel chromatic measuring method using the array fiber sensor in teeth color measurement is proposed. This method can resolve the problems involving the complexity in teeth color measurement. With this method, the fast and accurate measurement in teeth color measurement can be realized. It can also compensate for the uneven chromatic dispersion of the surface grating multichromator.
Some regions and boundaries can be obtained after image segmentation.Usually, region of interest (ROI) is termed object and others background.The ultimate aim is to make a computer recognize these objects. To do this,description of object is necessary, that is to say,to provide some useful information and interact relationship. Comprehensive analyses of existing image description methods by means of three parts-region interior description, boundary description and relationship description are discussed in this paper.In the end,the future of image description methods is presented.
This article brings up the hereditary algorithm based on Gabor wavelet. This kind of algorithm has a special function of feature extraction and fusion, so the image contract speed and recognization efficiency are improved obviously. At last,the imitation result is given, showing up the feasibility of this algonithm.
In this paper,the principle of the nearfield optics microscope is introduced,the technique of nearfield optics microscope is explored, and the two key problems with the fabrication of nanoprobes and the control of distance between the nanoprobe and the nanoobject are researched. The operating mode of the NSOM nanoprobe is explained. The contrast type of nearfield optical imaging is expounded. The application of NSOM in many fields is introduced. Some personal opinions are proposed based on the great number of outcomes of scientific reseraches at home and abroad.
This article summarizes the character of isosceles rightangle prism of missile aiming system, gives the isosceles rightangle prism’s reflection equation based on the law of reflection and the refraction of light beam in vector form,and analyzes the application to the ballistic missile aiming.
Based on the Mie scattering theory, a formula to calculate the scattered light flux in a certain solid angle under the condition of polarized light input is derived form the formula for calculating scattered light intensity. The results are compared with the condition illuminated by a unpolarized light. The scattered light flux collected by the two common scattered light collecting systems of the airborne particle counter is calculated under the condition of different light sources but same light intensity. The result shows that the fluxe got by the nearforward scattered light collecting system is equal. On the contrary, with the right angle scattered light collecting system, they are not equal and with the lineary polarized light input, the collected light flux is related to the angle between the center of detector and the direction of polarization. Calculating results, based on MATLAB and worked out by the computer,indicate that the collected scattering light flux has extreme when the angle between the center of detector and the direction of polarization is 90°or 270°. The results may provide a reference for designing the transducer of airborne laser particle counter.
The detailed analysis of a highspeed optical analogtodigital (A/D) converter consisting of an array of coplanar waveguide (CPW) travelingwave interferometric modulators on xcut LiNbO3 substrate has been performed. The development of this kind of optical A/D converters is described. The relation of smallsignal bandwidth, impedance, microwave attenuation parameters and drive power to the trapezoidal CPW electrode parameters including the electrode thickness, the buffer layer thickness to the edge inclination of the central electrode and ground planes β1,βg by coformal mapping are analyzed. When the electrode thickness is 3μm and β1=βg=10°，the bandwidth of 4bit A/D converter is 7.3GHz and the requirement of drive power is 6.7W. The numerical results show that it is feasible to design a highspeed A/D converter using travelingwave interferometric modulator with moderate resolution.
The automatic highprecision system, which is composed of temperature control system,precision goniometer system, optical system and electrical control system for measuring the temperature coefficient of refractive index of infrared materials is introduced in the paper. The temperature coefficient of refractive index is measured with the improved autocollimating method. The key index of the instrument is as follows: its wavelength range is 2～12μm,temperature range is -50～150℃,uncertainty is 3%. The instrument can meet the measurement requirement of temperature coefficient of refractive index of the different infrared materials. With this instrument, the temperature coefficient of germanium material has been measured and the results has been reported.
With the 405nm LED source, a highresolution optical MicroSurvey system is setup. The distinct microimage of DVD disk with resolution of 400nm can be obtained using this system.Combing with CCD and the technology of image collection with computer, the systemcan perform the real time collection and computerized capture of microimages. Moreover, the collected microimages can be demarcated and analyzed by the imageanalyzed software.
Three methods of color measurment such as visualization, photoelectric integration and spectrophotometry are analyzed and compared. The most advanced method of color measurment is photoelectric spectrography. The history of color measurement is reviewed. The status quo of colorimeters being used at home and abroad is introduced briefly. The prospect of the colorimeters is discussed.
A method to measure the vitta’s position is given in this paper.The method takes use of collimated beam projection optics and highresolution CCD to obtain images. The image acquisition, image processing are all resolved by digital signal processing(DSP) system. The processing velocity is so fast as to realize the realtime measurement. In image processing, a suitable edge detection method is used to improve the measurement accuracy. Least square method is used to fit the curves of the vitta’s position images in the data processing.