为了提高图像的分辨率,提高红外系统的探测距离和探测精度,满足多种条件下的使用要求,基于最新的非制冷型384x288凝视型焦平面阵列探测器,设计了折射/衍射混合长波红外连续变焦光学系统。系统工作波长为8-12μm,F数1.5,变倍比25:1。设计过程中,系统引入衍射面构成折/衍射混合结构,校正色差和高级像差,减少了透镜的使用数量,简化了系统结构。最后利用CODEV光学设计软件进行了优化设计和像质评价,设计结果表明,系统在探测器的Nyquist频率(20lp/mm)处,所有变焦距位置和视场的MTF值均大于0.4,接近系统的衍射极限。系统具有变倍比大、分辨率高、像质好、结构简单等特点,可应用于众多光电探测领域。
A refractive/diffractive long wavelength infrared continuous zoom system was designed based on the new staring focal plane array (384 pixel×288 pixels) in order to improve the resolution of image, detecting distance and accuracy of the infrared system and to satisfy multifarious situations. The operating wavelength of this system ranged from 8μm to 12μm, F number was 1.5 and the zoom ratio was 25:1. The binary surface was introduced to correct the lateral color and other high order aberrations and to modify the system. Moreover, detailed design and image quality were given by CODE V optical design software. When spatial frequency was 20 lp/mm, modulation transfer function (MTF) in the whole field of view exceeded 0.4', approaching diffraction limit. The final results show that this optical system has large zoom ratio, high resolution, small volume and excellent image quality. Thus, it can be applied in many kinds of optoelectronic detection fields.