Sculpting optical fields into caustic patterns based on freeform optics

Abstract

Manipulating flux transportation of optical fields holds great promise across various kinds of applications, encompassing laser micro-processing, optical trapping, microscopic imaging, and illumination engineering. In recent decades, freeform optics, lauded for its capacity to efficiently control the wavefronts of optical beams with high design freedom, has garnered significant attention as a potent tool for shaping light. Nevertheless, the predominant focus in current research has centered on the development of freeform optical elements (FOEs) tailored to project a designated two-dimensional flux density onto a specific target plane. This limitation confines the potential applications of freeform light shaping optics to a rather restricted domain. Moreover, the constraints imposed by geometric optics pose a further limitation on FOEs, particularly in their ability to sculpt coherent light, such as laser beams, as these are particularly susceptible to diffraction effects. Within the context of this study, we propose a design paradigm that harnesses freeform optics to craft light trajectories in three dimensions. This approach inherently gives rise to caustics, which are singularities within the realm of flux transfer in geometric optics. Crucially, our proposed method yields the capability to generate sharply defined light patterns, empirically giving better results for mitigating diffraction effects in contrast to previous design methodologies, which is observed by experiments. This design philosophy empowers FOEs to undertake new roles and functionalities by shaping caustics. To substantiate the potential of our proposal, we present a diverse array of design examples. These encompass scenarios ranging from the illumination of parallel planes to the sculpting of light propagation into three-dimensional curves, as well as the reshaping of beam intensities with an extended depth of field. We expect that the proposed work can broaden the scope of freeform optics, particularly within non-imaging applications, and propel freeform optical elements into hitherto unexplored territories.

Design Method for Freeform Off-Axis Three-Mirror Anastigmat Optical Systems with a Large Field of View and Low Error Sensitivity

“…In the process of designing large FOV off-axis TMA optical systems, it is difficult to achieve a large FOV with a simple surface type due to limited design degrees of freedom (DOFs), and the imaging width is restricted. Freeform surfaces, benefiting from their rich DOFs, is a hot topic within the realms of both imaging [9] and non-imaging optics [10,11]. Freeform surfaces can be applied in off-axis TMA optical systems to balance aberrations, expand the FOV, and improve image quality, bringing great convenience to the production of high-performance optical systems with large FOVs [12][13][14][15].…”

Real-time label-free exploration of the dynamics and interactions of bacteriophages

“…Traditionally employed in engineering to track the formation and propagation of cracks in materials, caustics offers a non-invasive method to assess structural integrity [13]. Further applications include enhancing optical systems and guiding light in photonic devices [14,15]. The usage of caustics has been also extended to the nanoscale to visualize and track nanoparticles as small as a few nanometers in diameter without labelling or invasive preparation techniques [16].…”