Dual-Band Co-Aperture Infrared Optical System Design For Irradiance Measurement

A high performance irradiance measurement system for infrared target simulator has significant application value in military use and civil use, especially when target can’t fill up the field of view, this system can measure the irradiance more precisely.As for infrared target simulator irradiance measurement system, it features in developing irradiate light beam energy distribution, and focus the energy onto the detector. The system includes MWIR and LWIR wavebands, according to the different developing situation and features of the single-color IRFPA(infrared focal plane array)and dual-color IRFPA home and abroad, the paper designs two different optical systems for different types of IRFPA based on optical design software ZEMAX.The optical system with dual-color IRFPA adopts triple-lens structure, the design results show that the entire structure is simple, MTF response is higher, and the utility is better; but for the single-color IRFPA system, the paper adopts Cassegrain system as objective of the system, and splits two waveband light beams by using light filter, the result shows that the entire structure is relatively complicate, however, it can be used in the requested optical system.The result of the system is:simultaneously adjusts the aberrations both in the waveband of middle infrared3-5μm waveband and long infrared8-12μm waveband, system distortions are both small, the biggest distortion is about0.7%; and the MTF approaches the diffraction limit.