目标红外热像的等效辐射-汇聚法数值模拟

为得到红外成像阵列面上的目标辐照强度分布,提出等效辐射-汇聚法.将目标红外成像过程分解为目标表面辐射场的产生和空间传输与红外系统中的汇聚成像两个阶段.采用蒙特卡罗法模拟目标表面的等效辐射形成及其向红外系统的传输过程;利用光学成像位置和光强变换关系确定目标任意点的成像方位及汇聚到成像点的辐照强度.以SDM标准飞机模型为对象,采用该方法模拟获得了不同探测角度下的红外热像,并与从红外成像阵列面发射光线的反向蒙特卡罗方法进行了计算效率的对比.计算结果表明:对于单个探测方位,等效辐射法与反向蒙特卡罗的计算效率相当;而对于多个探测方位,由于目标等效辐射(或辐射传递因子)的独立性和可复用性,相对于反向蒙特卡罗法,等效辐射-汇聚法能够提高计算效率,更便于工程应用.

Simulating the infrared image of targets by an equivalent radiation-concentrating method

An equivalent radiation-concentrating method was developed for calculating the radiative flux of targets into sensor pixels array in an infrared (IR) detecting system. This method contains division of the imaging process: the formation and transfer of the radiation field of targets and the concentration of it in the IR optical system. In the first process, the Monte Carlo (MC) method is adopted for simulating the formation of the equivalent radiation and for simulating the transfer of it to the IR system. Then in the later process, the optical relations are employed for locating the image and for calculating the light intensity transformation. The developed method was applied for calculating the infrared image of the SDM airplane at different detecting azimuth, and the results were compared in terms of efficiency with those from the reverse Monte Carlo method that traced rays from the sensor pixels array. It is shown that for one single detecting azimuth, the developed method is closed to the reverse Monte Carlo method with respect to efficiency; for multiple detecting azimuths, compared to the reverse Monte Carlo method that coupled the generation and concentration of the effective radiation of targets, the developed method results in computing cost savings and so is more suitable in engineering applications.