Light Ray Tracing

The propagation of light rays through optical elements is described by a simple 2x2 matrix [1]. For example, propagation through a homogeneous medium with length d can be written as 

Spherical wavefronts emerging from a point source. Light rays are normal to wavefronts. 

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Fig. 8.32 Schematic of ray tracing picture of a resonant mode with light transmitted into the inner boundary. Reprinted from Ref. 68 with permission. 2008 Optical Society of America...

Fig. 1.16 Die-shaped devices (a) Blue GalnN emitter on SiC substrate with trade name Aton . (b) Schematic ray traces illustrating enhanced light extraction, (c) Micrograph of truncated inverted pyramid (TIP) AIGalnP/GaP LED. (d) Schematic diagram illustrating enhanced extraction (after Osram, 2001 ref. [52]).

The principle behind ray tracing is to model, on the computer, the passage of a light ray through a system of optical elements. The light ray is described by a vector and the optical operations of reflection and diffraction are simulated by vector operations. By tracing the paths of many rays, which illuminate the full geometric aperture of each component, it is feasible to ... 

The system of a small particle near a planar surface is of interest not only because the ray-tracing solution converges to the exact solution to very high accuracy, but also because the components that contribute to the coherent backscattering can be separated from the other components. Figure 5 shows the contribution of the polarization state of scattered light by the second-order reciprocal components of ray paths 2 and 3 (see Figure 2). The polarization... 

It was based on tracing light rays that form the real image and the shadow. 

In Figure 6.10 the basic principle of the ray tracing method is explained the data volume is scanned by one or more light ray sources. 

Endruweit A, Long A, Johnson M. Textile composites with integrated optical fibres quantification of the influence of single and multiple fibre bends on the light transmission using a Monte Carlo ray-tracing method. Smart Mater. Struct. 2008 17(1) 1—10. 

To obtain photorealistic representation in computer-generated images, effects must be applied that correspond to the mathematical laws of physics. In still images, computational techniques such as ray tracing and reflection must be used to imitate the effect of light sources and reflective surfaces. 

At an instant in time, the amplitude and direction of the electric field define a point on a plane perpendicular to the direction of the light ray. To an observer looking towards the source, this point would trace out a curve as the field varied. If the curve is simple and repetitive, the light is polarized and the form of the curve defines the state of polarization. If the curve is irregular and chaotic, the light is unpolarized. 

As discussed in the previous section, aberrations are important characteristics of lenses and affect the overall performance of the optical system integrating the lenses. There are a few ways to measure the aberrations. First, if the geometric profiles of the lens and the materials of which the lens is made (refractive indices) are known, ray tracing can predict how the rays would be bent as they pass through the lens and thus calculate the aberrations. This essentially utilizes the definitions of the aberrations described above. To obtain a lens profile, mechanical profilometers [5,6] or white light interferometry [5,7] can be used. 

Microfluidic channel design for 3D optofluidic lens. Cross sections show shaping of lens and refractive index step defined by choice of core and cladding fluids. Light path and lens shape are depicted by ray tracing simulation (Zemax EE). (Source Rosenauer, M. and M.J. Vellekoop. 

Ray tracing experiments to characterize variable focal length of and light intensity after combination of air-water-interface lens and PDMS lens at different flow rates of D1 water, (a) 0 pL/ min. (b) 10 pL/min. (c) 20 pL/min. (d) 30 pL/min. (e) 40 pL/min. (f) Intensity plots along white lines depicted in (a) through (e). Solid curves are fittings to experimental data. (Source Shi,... 

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