凌永顺 LING Yong-shun’s scientific contributions

In order to know the influence of parameter of pulse laser on the temperature filed in the researches of protection to high power pulse laser, the change of temperature filed of the films was analyzed by thermal analysis module of ANSYS. The influence of laser facula radius, power density, pulse width and repetition frequency on the time and area size of the VO2 thin films phase transition was analyzed in the module. The results of analysis show that, the four parameters effect the transition reaching time of thin films together. The time can be shortened by amplifying laser facula radius and power density, but the proportion of area radius to laser facula radius can't be effected directly. Amplifying pulse width or repetition frequency can shorten the transition reaching time, while the former is better to amplifying the heat production by one pulse than the latter.

To overcome the shortness of traditional algorithms relying on the point source assumption, a freeform surface optimization method for the extended source was proposed based on the genetic algorithm. The optimal objects involve the radiation distribution function, the offset of origin and the size factor of receiver about the virtual point source. For each individual the reflector can be calculated numerically by solving the partial differential equations established according to the energy conservation law and Snell's law corresponding to the set of virtual parameters. The individual fitness concerning the uniformity of the object region and the transmission efficiency was obtained according to the simulation results with an actual extended source. The selection, crossover and mutation operations are implemented until the optimization results can meet the requirements. To verify the effectiveness of the proposed method, a uniform lighting system with cone angle of 10° was designed. The contrast experiments are carried out in Trace/Pro with a disc lambertian source with the size of 30 mm in diameter. The light tracing experiments show that the uniformity of the object region increases from 58.3% to 93.5%, and the transmission efficiency increases from 61.8% to 72.9%. Meanwhile, the optical quality has quite good stability at varying distances. The experimental results demonstrate that the method can achieve the adjustment of the spatial distribution of the extended source radiation which has significant guidance for the design of extended source system.

To overcome the disadvantage of the system uniformity reduction when a freeform surface constructed on the point source assumption is applied to the extended sources systems, a new feedback optimization algorithm based on the partial differential equation was proposed. Based on the point approximation, the initial surface structure were obtained through the numerical solution of the partial differential equation under the establishment of the radiation model of the extended light source. Then the shortcoming of the initial surface structure was analyzed when used for uniform illumination with extended sources under the circumstance that the rays transmission direction and the optical axis intersect. Therefore the proposed algorithm re-optimized the reflector to improve the uniformity by renewing the distribution of the target region, with the illuminance distribution in last simulation experiment as feedback. To illustrate the effectiveness of the proposed method, simulation experiments were carried out with TracePro. An extended light source with the size of 3 cm in diameter was used in experiments, in which total five million rays were computed. The light tracing experiments show that the uniformity of the object region increases from 60% to more than 90%, which demonstrates that the feedback design method can improve the illumination uniformity of the target surface effectively and provide some theoretical guidance for the improvement of the realistic lighting systems.

As the color ratio of radiation intensity of a target at different wavelengths will change along with the change of transmission distance, the color ratio of radiation intensity contains distance information. According the principle mentioned above, this paper proposed a scheme based on colorimetric method to range the target using its own infrared radiation. The relationship between the color ratio of radiation intensity for the target and its temperature, radiation transmission distance, atmosphere attenuation coefficient was deduced. By measuring the color ratio of radiation intensity at different wavelengths, the target was ranged when the atmosphere attenuation was certain and the infrared ranging equations of three-color ratio were deduced. According to a calculation model of radiation atmosphere transmission attenuation, three wavelengths of 8.5, 9.0, 9.5 μm were selected as color-ratio wavelengths, a 300 K blackbody 2 km away was used as a ranging target, and a color-ratio ranging figure was drawn. Analysis shows that the temperature and the distance of the target gotten from the figure are coincident with those of the target. Furthermore, it needs only once measurement to get the distance and temperature of the target by using this method.

In order to overcome the computation complexity of traditional correlation matching algorithm, a fast correlation matching algorithm is proposed based on fast Fourier transform and integral image. By analyzing and simplifying the equation of correlation coefficient, fast Fourier transform is employed to calculate the correlation between the template image and the base image, and integral image is employed to compute the window integral of the gray value of the base image and its energy. The computation complexity of the proposed algorithm is approximately independent on the size of the template image and thus is greatly decreased, without changing the results of traditional correlation matching. Experimental results for image matching under different illumination conditions and object tracking in complex situations show that the proposed algorithm is robust to interferences, and its implementation efficiency is 1 to 2 order times faster than traditional correlation matching algorithm.