Design Of Catadioptric Omnidirectional System With Undistorted Imaging

Imaging with higher resolution and wider field of view has become development trends of contemporary traditional optical field. Higher resolution imaging achieves more details and wider field of view imaging achieves larger view. To form a more perfect optical system combining the advantage of the two, researchers proposed the concept of panoramic imaging and catadioptric omnidirectional imaging system with its unique advantages to become the forefront of current application.Catadioptric omnidirectional imaging system adopts flat cylindrical projection. Three dimensional spaces is projected to the limited two dimensional ring region, using refraction and reflection components, to achieve hemisphere of space filed of view imaging. Catadioptric omnidirectional imaging system consists of mirror and traditional imaging system with reflector type of spherical surface, conical surface, hyperboloid surface and other secondary and higher order rotational symmetry aspheric surface. Using a linear relationship of the pixel coordinates with the angle of incidence to control the relationship of system imaging and design the type of the reflector can achieve wider field of view imaging with undistortion. In the article the calculation method and characteristic analysis of the reflector type of the catadioptric omnidirectional system with undistorted imaging is discussed, optical design software CODEV is used to design a cadadioptric omnidirectional system with undistorted imaging, image coordinate transformation is done to achieve panoramic undistorted imaging and software POV-Ray is used to simulates the undistorted imaging of reflector type.Based on the previous, using the linear relationship between the angle of incidence and angle of reflection, the calculation method of reflection type for catadioptric omnidirectional system with undistorted imaging is derived. Relationship between the reflection type and the field of view and relationship between the reflection type and the sensitivity of the position deviation are analyzed providing evidence for the reflection type of system design.Basing on the reflection type formula and characteristic, reflector-type parameters and technical parameters of traditional imaging system are confirmed and appropriate initial structure of the system is selected. Optical design software CODEV is used to optimize and analyze MTF and spot diagram. Diffraction and deviation are also analyzed. Angle of reflection ray tracing method is introduced to evaluate the distortion of the system. Analysis shows that the design proves practicable.Catadioptric omniderectional system with flat cylindrical projection images at ring region, so transformation relationship between image coordinates is calculated to transform ring region image to cylindrical panoramic image which people familiar with. After the image coordinate transformation, the resolution of the center is lost and the resolution of the edge remains. Imaging resolution of the catadioptric omnidirection system with undistorted imaging is calculated with higher resolution in the center of the original image and lower resolution on the edge of the original image. Last but not least, software POV-Ray is used to simulate the imaging of the reflector of the undistortion system, the result matches the theory.