Tunable optical systems have always been a crucial component in the fields of three-dimensional (3D) biomedical imaging, industrial manufacturing and advanced spectroscopy. The core problem of designing tunable optical systems is how to quickly control the focal position of light in three-dimensional space. Only by realizing high-speed focus control can we improve the rate of target 3D retrieval in the imaging field and improve its processing output in the laser processing field.

Although mirrors and light deflectors can be used to achieve rapid control of light in the x and y directions, traditional methods based on optical components or mechanically moving samples control speeds of the z-focus direction are three orders of magnitude slower than in the x and y directions. Therefore, it is necessary to further improve the control speed of the tunable optical system in the z-focus direction to achieve a truly three-dimensional fast tunable optical system.

Recently, Craig B. Arnold [⏬] and others from Princeton University published a review in Nature Photonics, entitled "Variable optical elements for fast focus control", analyzing and introducing key technologies for high-speed zoom optical components that achieve submillisecond and microsecond response times, reviewing the application of this technology development in related technical fields, and discussing the important development prospects of this technology.

1. Key technologies for high-speed zoom optical systems

At present, the key technologies for realizing high-speed zoom optical systems are mainly developed in two directions: one is to improve the response time of materials; the other is to apply new tuning technologies. As shown in Table 1, there are tunable optical systems based on different working principles. In the article, the author provides a detailed introduction to three latest technologies: ferroelectric liquid crystal lens, adjustable acoustic gradient lens and adaptive optical technology.