Abstract:The error sources of pulsed laser range finders are analyzed and the factors which have influences on the random error of a pulsed laser range finder are primarily considered. It is found that improving the time resolution of a TDC, using a high speed threshold discriminator chip and reducing the rising edge of a pulsed signal are the effective methods for improving ranging precision. Among them, the reduction of a pulsed signal can be realized by using a narrow-pulse laser and a receiving circuit with a properly designed bandwidth. Simulation shows that the minimum bandwidth required to keep a 5ns rising edge from extending is 90MHz. Then, a high-precision laser range finder is designed and tested. The test result shows that the system has a single-shot precision (3σ) from 0.077m to 0.117m for the targets at different distances within 500m and has a precision better than 0.1‰D+0.05m (D stands for the distance) for the targets at different distances from 500m to 3km. Compared with the formerly designed systems using different lasers and different bandwidths, this system has obviously improved its single-shot precision.

Abstract:Calculation of the auto-focusing evaluation function for infrared images is time-consuming and has a great influence on the real-time auto-focusing. By selecting the most important target area in an image as an auto-focusing evaluation object, the problem that the traditional focus window selection method is not suitable for moving targets can be solved effectively. To find the most important target area in an image effectively, a moving target focus window selection method based on template matching is proposed. With this method, the focus window can be shrinked and locked in the target area. Experimental results show that this method has the advantages of low calculation complexity and better pertinence etc. and its auto-focusing curve sensitivity is better.

Abstract:On the basis of the vector theory of optical reflection and the mirror rotation theorem, the two-dimensional scanning imaging characteristics of a LIDAR are analyzed in terms of the deviation between a rotation axis and the surface of a scanning mirror. The formula of the single point two-dimensional scanning is given and the emulation image is obtained. At the same time, through the theoretical calculation of the reflection of a line-shape laser beam, the coupling matrix of a two-dimensional scanning mirror is given and the length and deflection of the line-shape laser beam projected on the object after being reflected on two scanning mirrors are obtained. This provides a basis for the subsequent data processing. Finally, the shapes of the two-dimensional scanning mirrors are designed. This design utilizes the surface of a scanning mirror maximally while the requirement of the receiving field of view is satisfied. Thus, the rotation inertia of the scanning mirrors and the power of the load motor are reduced.

Abstract:In order to let airships be more efficient in the future battlefield, the feasibility of loading an infrared search and track (IRST) sensor on an airship is proposed after the characteristics of the airship and the IRST sensor are analyzed. The loading of an IRST sensor on an airship is greatly helpful to the early warning and air defense in the future and can overcome the weakness of a radar etc..

Abstract:The aircraft stealth technology is developed correspondingly with the development of infrared imaging detection and tracking technologies. To let an aircraft be stealth, the infrared signatures of it should be analyzed. The main factors which have influence on infrared radiation characteristics are analyzed. On the basis of the traditional calculation methods, a method for calculating the infrared radiation from the exhaust gas, nozzle and skin of an aircraft and the solar radiation reflected from the aircraft skin is given. The calculation result shows that the calculation method is practical and reliable and can meet the requirements of engineering calculation and practical application.

Abstract:In the traditional spectral mixture analysis method, each endmember is assumed to have a constant spectral signature. However, there are always differences in endmember spectra for same ground objects. In order to restrain the effect of different endmember spectra of the same object on mixed image decomposition, a new method based on Fisher discriminant null space for decomposition of mixed pixels in hyperspectral images is proposed. In the Fisher discriminant null space method, the linear transformation of hyperspectral image data can make the endmember spectra have no variability inside each endmember group and have large differences among different endmember groups. Therefore, the negative impact resulted from the endmember spectral variability can be decreased to a larger extent by using the transformed spectra. The experimental results of both artificial data and actual remote sensing images in Indiana and Cuprite regions show that the proposed algorithm has a higher decomposition accuracy for the mixed pixels in hyperspectral images.

Abstract:In order to implement automatic human face detection and tracking in infrared video images, an infrared image detection method based on the Adaboost algorithm is proposed. In the method, the Haar-like characters and integral pictures are used to describe the basic characters of the human face and the Adaboost algorithm and Cascade algorithm are used to improve the veracity and celerity of automatic human face detection. It has a detection velocity of 15frames/s and a detection precision of 98.4%. Experimental results show that the Adaboost algorithm has its predominance in the automatic human face detection in infrared images.

Abstract:The current tracking methods based on the anterior cusp of an aircraft have a problem of unstability and low damage probability. To solve this problem, an aircraft tracking method based on the points of interest is discussed. By using this method, an aircraft can be tracked stably and may not be lost and hence the aircraft damage probability can be improved. In this method, the sin-coding is used to convert the infrared gray level images into the false color images firstly. Then, the temperature fluctuation region between the anterior cusp and the engine of an aircraft is obtained. Finally, the center of the region is used as a tracking point so as to complete the terminal guidance of a missile to the aircraft.

Abstract:While calculating the bound state energy eigenvalues of a superlattice, the wave functions on both sides of the interface between a potential well and a potential barrier are extended into a set of linear equations which can be described with a matrix equation. Then, according to the requirement that the energy eigenvalues must satisfy the condition in which the coefficient determinant of linear equations is equal to zero, the energy region is scanned point by point. Thus, the corresponding energy eigenvalues can be determined with a function of the matrix determinant in MATLAB. Compared with other methods such as iteration and transfer matrix, the method does not need more efforts in programming and is simple in concept, convenient in operation and practical.