A phase screen, in the context of optics and wave optics, refers to a surface or medium that introduces a phase delay to an incident wavefront passing through it. This concept is often used in the simulation and modeling of optical systems, particularly in the context of atmospheric optics and turbulence.
In the study of atmospheric optics, the Earth's atmosphere is not uniform, and its varying refractive index due to temperature, pressure, and humidity fluctuations causes light waves passing through it to experience phase distortions. These distortions can impact the performance of optical systems, such as telescopes or imaging devices.
To model and simulate these atmospheric effects, a phase screen is employed. The phase screen introduces a spatially varying phase delay to the incoming wavefront, mimicking the turbulence-induced distortions encountered in the atmosphere. This is particularly relevant in fields like adaptive optics, where researchers and engineers aim to correct for these distortions in real-time to improve the quality of astronomical observations or other optical applications.
In a broader sense, the term "phase screen" may also be used in other contexts where phase variations are introduced intentionally or as a part of an experimental setup, such as in holography or certain types of wavefront manipulation in optics. The goal is to understand or control the phase characteristics of light for specific applications.