Joint research between GIST Professor Euiheon Chung and Caltech Professor Changhuei Yang has developed a novel holographic focusing method

Figure 1. Simultaneous generation of arbitrary patterns at different focal lengths

Focusing light is usually achieved with a lens or curved mirror that has a fixed focal length. However, variable light focusing allows the focal distance of a lens to be changed, and this is an important capability to have when optically interrogating a three-dimensional object. There are various approaches to achieve variable light focusing, such as zoom lenses or liquid-crystal lenses, but these are not adequate for microscale applications.

To overcome this limitation, a joint research team from the California Institute of Technology (Caltech) under Professor Changhuei Yang and the Gwangju Institute of Science and Technology (GIST) under Professor Euiheon Chung of the Department of Biomedical Science and Engineering have developed a holographic focusing method that enables variable light focusing without any physical modification to the lens element.

The researchers used an optical phase conjugation assisted scattering lens that generated a micron-sized focal spot over a wide range of focal distances. An advantage of this approach is that it can create multiple foci simultaneously or sequentially.

Their paper entitled "Optical phase conjugation-assisted scattering lens: variable focusing and 3D patterning" was published on April 6, 2016, in Scientific Reports and was authored by Jihee Ryu, Mooseok Jang, Tae Joong Eom, Changhuei Yang, and Euiheon Chung.

Professor Euiheon Chung noted, "The optical phase conjugation-assisted scattering lens provides great flexibility for variable-light focusing and light patterning, and can be used for a broad range of applications. In addition to its applications in imaging, the scattering lens can be a powerful tool for manipulating particles and activating biomolecules or materials. For example, it can be combined with optogenetics technology for interrogating three-dimensional neural networks at cellular resolution."