LWIR Optical System Based On Meta-surface Lens And Traditional Optical Elements

As an important part of infrared imaging,the infrared optical system is responsible for the functions of collecting,propagating and focusing the infrared rays radiated from the scene.Its performance also affects the imaging quality of the imaging system.With the continuous development of science and technology,infrared focal plane detectors with smaller pixels and higher integration have come into being.Correspondingly,infrared optical systems must continue to meet higher imaging quality requirements.For this reason,traditional infrared optic system inevitably uses a large number of lens groups and aspheric structures,making the system bulky and complicated and difficult to process.In recent years,the meta-surface lens,which has received much attention,can realize the regulation,propagation and focusing of light waves through a simple structure.However,the current research on meta-surface lenses is relatively advanced,the processing technology is still immature,and there are still major deficiencies in achromatic.Considering the actual engineering technology,this subject designed a LWIR composite optical system based on a meta-surface lens and traditional refractive elements,aiming to achieve functional complementarity between the two parts.On the one hand,the addition of a meta-surface lens simplifies the structure of the optical system.On the other hand,the use of traditional reflective elements shares the power of the meta-surface lens and makes up for the deficiencies of the meta-surface lens in achromatic.This subject has mainly completed the following works:(1)Structural design and performance simulation of the system: A system integration design scheme based on a meta-surface lens and a traditional refracting element is proposed.A LWIR composite optical system model consisting of a double-cascaded meta-surface structure and a traditional lens group was established.Based on the ZEMAX software,the structure of the designed optical system was optimized,and performed from the spot diagram,aberration characteristics,MTF,thermal defocus,and image surface illumination.The optical system has good aberration and thermal characteristics,and the imaging effect of the system is close to the diffraction limit.(2)Tolerance analysis and lens barrel design of the system: Tolerance analysis was performed on the designed optical system,and the RMS radius of the spot diagram and MTF values were used as evaluation criteria.After three tolerance allocations,the tolerance distribution of the optical system was determined.On the basis of guaranteeing the simulated processing yield,the system has a lower tolerance level and is easy to process.A detachable double-buffered lens barrel structure is designed for the composite optical system,which reduces the maintenance cost of the system and effectively protects the precision structure of the meta-surface lens.