Research On Multi-Aperture Imaging Technology Based On Plastic Imaging Fiber Array

Optical fiber array imaging device generally refers to optical fiber image bundles and imaging fiber(complex filament): optical fiber image bundles is a number of optical fibers at both ends according to one to one correspondence or some other corresponding relationship to array arrangement of optical fiber devices,the middle part of the fiber is spread out to achieve bending,image Mosaic and other functions;Imaging fiber(complex filament)is an optical fiber device with thousands of optical fibers tightly stacked together from beginning to end.It has the basic image transmission function,but in order to facilitate bending,the diameter is generally small.Optical fiber array imaging devices are widely used in medical,industrial and aerospace fields due to their flexible and passive imaging characteristics.The imaging system based on such optical fiber array imaging device is usually called optical fiber imaging system(such as the endoscope using optical fiber imaging bundles or imaging fiber),generally consists of three or four parts: imaging objective lens,optical fiber array imaging device,observation eyepiece or coupling eyepiece,and CCD or CMOS camera.At present,the resolution of the objective lens/eyepiece can reach more than 100 LP/mm,and the number of pixels of the camera can also reach tens of millions.However,the number of pixels of common optical fiber array imaging devices is usually only tens to hundreds of thousands.Especially when the size of the outer diameter of the system is fixed,the production process of the existing optical fiber array imaging devices is difficult to significantly increase the number of pixels.The resolution of optical fiber image transmission system is limited by the number of pixels of optical fiber array imaging device.At present,it is difficult to combine pixel diameter(monofilament)with pixel number in optical fiber array imaging devices on the market.The thinner the monofilament diameter is,the more difficult it is to fabricate high pixel number optical fiber array imaging devices due to technological limitations.However,from the user’s point of view,it is always expected to obtain enough fine monofilament diameter and enough pixel number to achieve small optical system diameter size and high image resolution,because the product of monofilament diameter and pixel number directly affects the total diameter size of the device.Therefore,in order to solve the bottleneck of improving the resolution of optical fiber imaging system,this paper has carried out the following exploration and research:1)According to the imaging principle of optical fiber image transmission system,the reasons for the limited number of pixels in the current optical fiber image transmission system are explored,and a multi-aperture imaging technology based on plastic optical fiber array is proposed to solve this problem.Compared with the existing image transmission system of single plastic optical fiber image bundles,the number of pixels in the same size is increased by more than 2 times.2)Taking the indoor non-electric lighting monitoring system in flammable and explosive environment as the application scenario,a set of multi-aperture optical fiber imaging system consisting of main lens,microlens array,imaging fiber bundles array,coupled lens and CMOS camera is designed.Microlens array solves the information loss caused by the gap of the image transmission fiber bundles array,and the main lens is used to adjust the repetition rate of microlens array imaging,and an experimental platform is built to test the system.Experimental results show that the system has an effective pixel number of 400,000,a field Angle of view of 88 degrees,a image spatial resolution of 40 lp/mm and a object spatial resolution of 2.2 mm.3)The experimental pictures of the system were processed,and the camera was calibrated by Zhang Zhengyou calibration method.According to the calibration results,the distortion correction of the output pictures of the system was carried out.By using the backward mapping method based on coordinate transformation and the translation algorithm based on Harris corner detection,the 48 original sub-images were rotated and splice,and the full field of view images were obtained.Experimental results show that the design scheme of the imaging system is reasonable and feasible,which has important theoretical guiding significance for large pixel number imaging of optical fiber image transmission system.