The application of wavefront coding in the infrared optical system in the tokomak fusion reaction

Highlights: ► The IR thermography diagnostic equipment is playing an important role in tokamak. ► The IR thermography diagnostic equipment with wavefront coding is applied in tokamak. ► Because of the application of wavefront coding, the optical is less sensitive to the change of the temperature and the depth of field is enlarged. - Abstract: This article describes the principle of wavefront coding (WFC) technology and the role it plays in optical system. The infrared optical system in tokamak includes three parts: (1) the combination of the concave aspheric mirror and flat mirror; (2) the Cassegrain system; (3) the relay group lenses. Because of the application of wavefront coding, the optical system is less sensitive to the change of the temperature and the depth of field is enlarged. Comparing the modulation transfer function (MTF) of the original optical system and the improved system in different temperatures, the results show that the new system can be used in a larger range of temperature.