We present a new ray tracing simulation of aero-optical effect through anisotropic inhomogeneous media as supersonic
flow field surrounds a projectile. The new method uses multiple gradient-index (GRIN) layers for construction of the
anisotropic inhomogeneous media and ray tracing simulation. The cone-shaped projectile studied has 19° semi-vertical
angle; a sapphire window is parallel to the cone angle; and an optical system of the projectile was assumed via paraxial
optics and infrared image detector. The condition for the steady-state solver conducted through computational fluid
dynamics (CFD) included Mach numbers 4 and 6 in speed, 25 km altitude, and 0° angle of attack (AoA). The grid
refractive index of the flow field via CFD analysis and Gladstone-Dale relation was discretized into equally spaced
layers which are parallel with the projectile’s window. Each layer was modeled as a form of 2D polynomial by fitting the
refractive index distribution. The light source of ray set generated 3,228 rays for varying line of sight (LOS) from 10° to
40°. Ray tracing simulation adopted the Snell’s law in 3D to compute the paths of skew rays in the GRIN layers. The
results show that optical path difference (OPD) and boresight error (BSE) decreases exponentially as LOS increases. The
variation of refractive index decreases, as the speed of flow field increases the OPD and its rate of decay at Mach number
6 in speed has somewhat larger value than at Mach number 4 in speed. Compared with the ray equation method, at Mach
number 4 and 10° LOS, the new method shows good agreement, generated 0.33% of relative root-mean-square (RMS)
OPD difference and 0.22% of relative BSE difference. Moreover, the simulation time of the new method was more than
20,000 times faster than the conventional ray equation method. The technical detail of the new method and simulation is
presented with results and implication.
This paper presents a real time implementation of Non Uniformity Correction (NUC). Two point correction and one
point correction with shutter were carried out in an uncooled imaging system which will be applied to a missile
application. To design a small, light weight and high speed imaging system for a missile system, SoPC (System On a
Programmable Chip) which comprises of FPGA and soft core (Micro-blaze) was used. Real time NUC and generation of
control signals are implemented using FPGA. Also, three different NUC tables were made to make the operating time
shorter and to reduce the power consumption in a large range of environment temperature.
The imaging system consists of optics and four electronics boards which are detector interface board, Analog to Digital
converter board, Detector signal generation board and Power supply board. To evaluate the imaging system, NETD was
measured. The NETD was less than 160mK in three different environment temperatures.
This paper presents an image seeker simulation including image processing, servo control, target model, and missile
trajectory. We propose a software architecture for a seeker embedded computer. It makes core processing algorithms
including image processing reusable at the source level through multiple platforms. The embedded software simulator
implemented in C/C++, the servo control simulator implemented in Matlab, and the integrated simulator combined the
both simulators based on Windows Component Object Module (COM) technology is presented. The integrated
simulation enables developers to practice an interactive study between image processing and servo control about
missions including lock-on and target tracking. The implemented simulator can be operated in low cost computer
systems. This can be used to algorithm development and analysis at the design, implementation, and evaluation.
Simulation examples for a short range ground-to-ground missile seeker are presented.