Design of optical imaging system with high resolution, long-focus, wide angle and low distortion

Current optical imaging system in the three-dimensional measuring instrument with high precision and full view cannot satisfy the technological demands of large viewing angle, high resolution and low distortion simultaneously, we therefore designed a kind of optical imaging and distortion correction system, which could overcome above defects. To improve the imaging quality of the system, the design of f-θ lens was performed with a complicated double-Gauss structure, and the aspheric surface was introduced. The optical imaging system was machined and tested.Results show that the optical system designed has the characteristics of long focal length, wide angle, low distortion and high resolution, it can achieve the field-of-view of 90°, the distortion of < -0.001 67% and the modulation transfer function(MTF) of 0.4@100 lp/mm without reducing the image quality obviously in the large working range of 3 m~100 m under the ambient temperature of -10℃~70℃. Moreover, it is found that the surface figure accuracy of aspheric lens in optical system has a great influence on the imaging quality, tolerance analysis shows that the imaging quality of optical system can meet the requirement, when the surface accuracy peak-valley(PV) value of aspheric surface is less than 0.17 μm. In actual machining process, the PV value of aspheric surface can reach 0.158 μm, and the MTF can also meet the design requirements. Hence, the imaging quality of the system can be improved.