The linear Doppler effect has been widely used to detect the translational motion of objects. However, it suffers difficulties in measuring the angular motion of a rotating target. In recent years, the rotational Doppler effect based on a vortex beam has been helpful to solve the problem of rotational measurement and has attracted extensive attention in remote sensing. This paper expounds the theoretical and experimental basis of the rotational Doppler effect and briefly summarizes its development for the detection of macro and micro targets. Specifically, the properties and analysis methods of a rotational Doppler shift when the vortex beam is misaligned with the rotation axis are described in detail. In addition, the existing problems and further developments in rotation detection based on the rotational Doppler effect are discussed.

Volumetric additive manufacturing is a novel additive manufacturing method, offering advantages such as fast printing speed and isotropic mechanical properties. As the important branch of volumetric additive manufacturing, computed axial lithography based on the azimuthal projections and rotational printing has attracted great attentions and been widely used in recent years. Here, we focus on the projection algorithms of computed axial lithography, which is critical to the printing quality including its fidelity and accuracy. Different optimization methods including iterative optimization of projection space and objective model, optimization for the optical influences of materials and the optimizations cooperating with hardware upgrade are summarized. The features and advantages of different projection optimization algorithms are also analyzed and discussed, which may promote the applications and development of volumetric additive manufacturing.