Design And Research Of The Vehicle-mounted Infrared Optical System With Dual Field Of View And Dual Band

In order to improve the detection ability for targets and scenarios, infraredoptical system is developing towards multi-spectral and multi-field direction. Atpresent, majority of the optical systems all switch between fields based on zoom,providing identification capability with small field and search and situationalawareness capability with larger field. It is difficult to provide scene informationaround target only with small field, and large field can’t complete identificationdetails of the target. Therefore, system have to repeat zoom to ensure that dual taskto be carried on simultaneously.This operation model has two disadvantages:1)the zoom process could easily lead to loss of target or scene;2) system precisionand lifetime will decline after zooming frequently. Aiming at these defects, a kindof infrared system whose dual fields could work simultaneously is presented.After analyzing the advantages and disadvantages of similar systems, aoptical design scheme of combining afocal system with imaging system is putforward based on dual-band detector’s aspect to read out independent spectraldata.According to the radiation characteristic of tank， working distance anddetection level of system are selected. Forecast principle of traditional modelbased on Johnson criterion and NVThermIP model for the performance of systemare analysed. First，the design parameter of system is confirmed with Johnsoncriterion,then system’s performance is evaluated using NVThermIP model. Itindicates that detection and recognition probability of dual fields both exceed50%.According to the system, the forecast error of Johnson criterion is large.Afocal system and imaging system are designed respectively，then overallsystem is optimized. Afocal system adopts off-axis three-mirror reflective structure.According to the design specifications, the basal structure is confirmed based onprimary aberration theory. Then the optimized afocal system is educed. Imagingsystem chooses a re-imaging structure. Paper adopts a dual-band optical systemwhich comes from patent to be the primary structure. After restricting focal length,reducing the amplification coefficient of the emendation lens and addingaspherical surface to correct advanced chromatic aberration, the imaging system isconfirmed.Afterwards, parameter of the afocal system is treated as variabl e, thewhole system is re-optimized.Then design of the infrared optical system with dualfield of view and dual band is completed. Subsequently, evaluation of imagingquality and tolerance analysis for the system are completed.