First-order optics computation for re-imaging infrared optical systems

In designing a high performance IR re-imaging optical system for thermal imaging handheld applications, one of the most changeling tasks is to achieve very compact and light weight optical configuration, and at the same, be able to incorporate a number of associated optical devices, such as micro-scanner mirrors, non uniformity correction device, dual FOV optical elements, focussing lens etc.., within the optical path. This paper describes the First Order Optics calculation for such optical configuration, which allows optics engineer to define a suitable optical layout before performing optical optimisation and analysis. A design example of a 3-5um FPA re-imaging optics system is presented.