Design Of Zoom Infrared Target Simulator Optical System

Infrared target simulator can simulate the infrared characteristics of real scene.It can provide precise,controllable and repeatable infrared scene experimental conditions for infrared equipments to be tested.In addition,it can effectively test various indicators and performance of the equipments.Applying the continuous zoom feature on the infrared target simulator enable evaluated devices obtain stable infrared images with different focal lengths and fields via the target simulator projection.This thesis designed zoom infrared target simulator optical system based on digital micromirror device(DMD).This system was able to achieve the field angle matching and continuous zooming with multiple focal lengths.The range of working band was 3 to 5 ?m.The caliber was 120 mm.The zoom ratio is 4 x.The zoom range can be reached was 127-508 mm.The angle of view changes from 2° to 8°.The main research content of this thesis has the following aspects: Firstly,On the basis of considering the composition structure and working principle of infrared target simulator,the working mechanism and structural parameters of DMD were studied.The scheme of target simulator's scene generator based on the DMD is determined.Secondly,The source of black body light was analyzed and selected.Illumination system was designed through the optical design software zemax.The irradiation source of black body can illuminate on the surface of the DMD evenly.Beam splitter prism was designed with suitable infrared materials to avoid mutual obstruction between illumination system and projection system.The geometric structure parameters of beam splitter prism were analyzed and calculated.In the end,The technical indexes of projection optical system were analyzed.The adiabatic design of projection system was carried out through the optical passive adiabatic method.Gaussian optical theory was applied to solve the zoom equation of mechanical compensated zoom system.The solution of zoom equation was found out to select the initial structure.The projection optical system was designed and optimized by zemax.The zoom curve of cam was designed to ensure zoom stability.The tolerance analysis was performed and the tolerance range was set on the system.Monte Carlo analysis was also utilized to ensure the machinability of projection optical system.The MTF of each focal length of the designed projection system is attached to the experimental pictures and the fidelity evaluation is carried out to simulate the imaging effect.The fidelity of all the images reaches more than 87%.It can be seen that the imaging quality of the optical system is good.This system has the superior characteristics of matching various infrared devices,excellent quality of image and smooth zoom curve without inflection points.The design results meet the requirements of the indicators.