Ray tracing simulation of aero-optical effect using multiple gradient index layer

Seul Ki Yang, Sehyun Seong, Dongok Ryu, Sug-Whan Kim, Hyeuknam Kwon, Sang Hun Jin, Ho Jeong, Hyun Bae Kong, Jae Wan Lim, Jong Hwa Choi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

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.

Original languageEnglish
Title of host publicationElectro-Optical and Infrared Systems
Subtitle of host publicationTechnology and Applications XIII
EditorsDavid A. Huckridge, Stephen T. Lee, Reinhard Ebert
PublisherSPIE
ISBN (Electronic)9781510603783
DOIs
Publication statusPublished - 2016 Jan 1
EventElectro-Optical and Infrared Systems: Technology and Applications XIII - Edinburgh, United Kingdom
Duration: 2016 Sep 282016 Sep 29

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9987
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Other

OtherElectro-Optical and Infrared Systems: Technology and Applications XIII
CountryUnited Kingdom
CityEdinburgh
Period16/9/2816/9/29

Fingerprint

Ray Tracing
Ray tracing
Projectiles
ray tracing
Mach number
rays
Projectile
Half line
boresight error
projectiles
Gradient
Refractive index
Flow fields
Anisotropic media
gradients
optical paths
line of sight
flow distribution
Refractive Index
Flow Field

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Cite this

Yang, S. K., Seong, S., Ryu, D., Kim, S-W., Kwon, H., Jin, S. H., ... Choi, J. H. (2016). Ray tracing simulation of aero-optical effect using multiple gradient index layer. In D. A. Huckridge, S. T. Lee, & R. Ebert (Eds.), Electro-Optical and Infrared Systems: Technology and Applications XIII [99870R] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9987). SPIE. https://doi.org/10.1117/12.2241399
Yang, Seul Ki ; Seong, Sehyun ; Ryu, Dongok ; Kim, Sug-Whan ; Kwon, Hyeuknam ; Jin, Sang Hun ; Jeong, Ho ; Kong, Hyun Bae ; Lim, Jae Wan ; Choi, Jong Hwa. / Ray tracing simulation of aero-optical effect using multiple gradient index layer. Electro-Optical and Infrared Systems: Technology and Applications XIII. editor / David A. Huckridge ; Stephen T. Lee ; Reinhard Ebert. SPIE, 2016. (Proceedings of SPIE - The International Society for Optical Engineering).
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title = "Ray tracing simulation of aero-optical effect using multiple gradient index layer",
abstract = "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.",
author = "Yang, {Seul Ki} and Sehyun Seong and Dongok Ryu and Sug-Whan Kim and Hyeuknam Kwon and Jin, {Sang Hun} and Ho Jeong and Kong, {Hyun Bae} and Lim, {Jae Wan} and Choi, {Jong Hwa}",
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Yang, SK, Seong, S, Ryu, D, Kim, S-W, Kwon, H, Jin, SH, Jeong, H, Kong, HB, Lim, JW & Choi, JH 2016, Ray tracing simulation of aero-optical effect using multiple gradient index layer. in DA Huckridge, ST Lee & R Ebert (eds), Electro-Optical and Infrared Systems: Technology and Applications XIII., 99870R, Proceedings of SPIE - The International Society for Optical Engineering, vol. 9987, SPIE, Electro-Optical and Infrared Systems: Technology and Applications XIII, Edinburgh, United Kingdom, 16/9/28. https://doi.org/10.1117/12.2241399

Ray tracing simulation of aero-optical effect using multiple gradient index layer. / Yang, Seul Ki; Seong, Sehyun; Ryu, Dongok; Kim, Sug-Whan; Kwon, Hyeuknam; Jin, Sang Hun; Jeong, Ho; Kong, Hyun Bae; Lim, Jae Wan; Choi, Jong Hwa.

Electro-Optical and Infrared Systems: Technology and Applications XIII. ed. / David A. Huckridge; Stephen T. Lee; Reinhard Ebert. SPIE, 2016. 99870R (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9987).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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AU - Yang, Seul Ki

AU - Seong, Sehyun

AU - Ryu, Dongok

AU - Kim, Sug-Whan

AU - Kwon, Hyeuknam

AU - Jin, Sang Hun

AU - Jeong, Ho

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AB - 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.

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Yang SK, Seong S, Ryu D, Kim S-W, Kwon H, Jin SH et al. Ray tracing simulation of aero-optical effect using multiple gradient index layer. In Huckridge DA, Lee ST, Ebert R, editors, Electro-Optical and Infrared Systems: Technology and Applications XIII. SPIE. 2016. 99870R. (Proceedings of SPIE - The International Society for Optical Engineering). https://doi.org/10.1117/12.2241399