Ray tracing algorithm ray tracing in optical design

The name and principle of ray tracing in computer graphics originated from the ancient technology in optical lens design that appeared in the first decade of the twentieth century. Geometric ray tracing is used to describe the transmission characteristics of light through lens system or optical instrument, and to create the imaging attribute model of the system. This is used to optimize the design of optical instruments before construction, such as reducing chromatic aberration or other optical aberrations. Ray tracing is also used to calculate the optical path difference in the optical system. The optical path difference is used to calculate the optical wavefront, and the optical wavefront is used to calculate the diffraction effect of the system, such as point spread function, modulation transfer function, Strehl ratio and so on. Ray tracing can be used not only for lens design in photography field, but also for longer wavelength applications, such as microwave design and even radio systems, and also for shorter wavelength fields, such as ultraviolet or X-ray optics.

The basic principle of ray tracing used in computer graphics and optical design is similar, but the technology used in optical design is usually stricter, which can reflect the ray behavior more accurately. Especially, the dispersion and diffraction effects of light and the characteristics of optical coating are very important in the design of optical lenses, but not so important in the field of computer graphics.

Before the computer appeared, ray tracing needed to be calculated manually by trigonometry and logarithmic table. Many traditional optical formulas of photographic lens are optimized by many people, and each person can only handle a small part of the calculation. Now, these calculations can be done on optical design software, such as OSLO or TracePro, Code-V or Zemax of Lambda Research. A simple version of ray tracing is ray transfer matrix analysis, which is usually used in the design of laser optical resonator.