| With the constant pursuit on light, thin, short, small, high reliability and low power consumption of the modern electronic products, the execution speed, precision and operation stability of modern electronic manufacturing equipment is put forward higher requirements. The high speed and high precision operation of modern electronic manufacturing equipment involves visual technology, in which the lighting design and lighting technology affect the performance of this kind of equipments directly. Visual positioning and recognition with high speed and high precision requires to obtain high quality target image under complex conditions within a very short time, leading the ighting design for this type of high speed movement execution system to playing a key role in the image capture.With the development of semiconductor lighting technology, light emitting diode (LED) is regarded as a new green-lighting strategy in21st century owing to its attractive advantages over conventional light source. These attractive features lead LED to a wide-range practical significance. In the imaging optical system, Illuminance uniformity and illuminating efficiency are always the key problems of lighting system design. With the requirements on light source design for electronic manufacturing equipment, the LED lighting system design is researched. For the purpose of solving the difficult balance problem between high illuminance uniformity and high illuminating efficiency, the new method of LED lighting system design is firstly presented, considering illuminance uniformity and illuminating efficiency simultaneously. The theory to obtain optimization lighting system design is studyed. The merit function of design system is proposed and the parameters of lighting system are optimizd automatically by programming. The optical system design with lens and reflector are realized respectively to obtaining radiation patterns with uniform illuminance and high illuminating efficiency, and the beam tracing result is analyzed to further verify the design accuracy. The main research contents are listed as following:(1) The research on vision technology of electronic manufacturing equipment is reviewed. The requirement of light source design on illuminance uniformity and illuminating efficiency for high speed and high precision equiment operation is discussed.The domestics and foreign research present situation of current lighting source design in nonimaging optics is investigated, the type of the lighting sources is analyzed and LED is selected to be the lighting source of the imaging optical system. The LED lighting design problems are indicated that it is hard to obtain high uniform illuminance and high illuminating efficiencysimultaneously.(2) For the purpose of nonimaging optics design, several key physical quantities of nonimaging optics, expectly the concept of lagrange invariant (etendue) and concentration of nonimaging concentrators is presented. Relationship between the generalized etendue and the maximum concentration in theory is established. The influence of optical aberration on concentration and the lambert luminescent property of LED are also analyzed. Meanwhile, the vector method of beam tracing theory and illuminance calculation based on the Monte Carlo stochastic theory of optical tracing simulation software (TracePro) are presented. LED lighting model is analyzed by nonimaging optical parameters, determining the type of LED. First optical design and secondary optical design are also discussed. The normal equation for conic aspheric is also presented as the design of LED lighting system mainly adopting reflector and lens,, as the theoretical basis for the optical system design.(3) The influence of LED lighting system parameters as conic constant K and paraxial radius of curvature R on obtaining uniform circle pattern is studyed. The merit function is advanced, considering both illuminance uniformity and illuminating efficiency. The designed optical system parameters are adjusted automatically by using TracePro software Scheme language programming to achieve optimum optical system design, resulting in uniform and efficient light pattern in the receiving surface. Based on the above theory and method, a new reflection optical module is studyed to realize high illuminance uniformity and illuminating efficiency. Using the macro commands, an effective process for finding the optimum design for the geometries of reflector, by adjusting the K2and R2of the reflector, is presented, and the merit function is used as the optical quality objective to find out the optimum design parameter of K2, R2and the displacement between LED source and reflector. Finally, a uniform circle pattern with40mm diameter over100mm distance from LED is achieved, with optimum illuminance uniformity of1.50and optimum illuminating efficiency of69.0%. The results of ray tracing simulations indicate that the optimum design system is better than the ideal paraboloid reflector system, with the value of merit function closer to ideal value, increasing about29.9%.(4) A new lens optical module is furture studyed as lens has greater degree of design freedom, compared with the height restriction of reflector. The merit function of lens system is avanced to find out the optimum lens design parameter of K2, R2. Finally a circular light pattern with120mm diameter is achieved over800mm distance from LED, with optimum illuminance uniformity of1.51and optimum illuminating efficiency of51.7%. The optimum design system is better than the system when only R is adjusted, with the value of merit function closer to ideal value, increasing about22.5%.(5) For the purpose of obtaining different pattern in different applications, a suitable aspherical surface to create a rectangular and uniform illumination is further researched by studying the influence of optical aspheric parameters. The optical system is design optimally for obtaining a rectangular pattern with20mm*20mm square over500mm distance from LED. The geometrical optics is used to analyze the transmission equation of the LED beam and the minimum divergence angle is calculated out by numerical simulation. The relationship between the divergence angle and some parameters of the lens is further researched by using the normal equation for conic aspheric. The K2of the lens’s second surface is modified and verified to a rectangular and uniform illumination on the receiver. The final divergence angle is6.049mrad, close to the theoretical calculation value1.92mrad, and the illumination uniformity of the predetermined illumination area on the receiver is better than93.02%. Compared with paraboloid lens and hyperboloid lens, ellipsoid lens can get a better uniform rectangular illumination, the illumination uniformity increased by13.81%and13.22%respectively.Finally, a summary of the study in this dissertation is included and the further research direction is given together. |
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