The field of optics has witnessed a significant breakthrough with the development of compact, visible wavelength achromats through the integration of 3D printing and porous silicon. Researchers at the University of Illinois Urbana-Champaign, under the guidance of esteemed professors Paul Braun, David Cahill, and Lynford Goddard, along with former graduate student Corey Richards, have successfully created these high-performance micro-optics. This groundbreaking study, recently published in Nature Communications, paves the way for the advancement of miniaturized optical systems such as ultracompact visible wavelength cameras, portable microscopes, and wearable devices.
The Challenge of Achromatic Lenses
In imaging applications where multiple wavelengths of light are present, using a single lens leads to dispersion and a color-blurred image. To address this issue, multiple lenses are typically stacked together to form an achromatic lens, where all colors focus at the same point. However, the traditional approach of stacking lens elements results in a relatively thick and cumbersome lens system, making it impractical for modern compact technologies.
To overcome the limitations of classical achromatic lenses, the research team at the University of Illinois Urbana-Champaign developed a revolutionary hybrid imaging system. This system combines a refractive lens with a flat diffractive lens, effectively canceling out the different focal points for each constituent color. By integrating these two types of lenses, a thinner and more compact design can be achieved.
The researchers introduced a fabrication process called Subsurface Controllable Refractive Index via Beam Exposure (SCRIBE) to create the compact hybrid achromatic imaging system. This process utilizes 3D printing techniques to fabricate polymeric structures within a porous silicon host medium, providing mechanical support for the optical components. Liquid polymer is filled into the porous silicon, and an ultrafast laser converts it into solid polymer, seamlessly integrating the diffractive and refractive lens elements. By eliminating the need for external support structures, the volume of the lens system is minimized, facilitating ease of fabrication and achieving high-efficiency achromatic focusing.
Compared to traditional lens fabrication methods, the integration of lenses within a porous silicon medium offers several distinct advantages. When lenses are printed in air, separate support structures are required to stack them. However, in porous silicon, the lenses can be suspended over each other without the need for additional support. This seamless integration simplifies the manufacturing process and enables the creation of compact and lightweight optical systems.
The successful development of compact hybrid achromatic microlenses opens new possibilities in the field of optics. These microlenses can be arranged in arrays to capture light-field information, a significant challenge for conventional polymer microlenses. The integration of 3D printing and porous silicon technology paves the way for the development of light-field cameras and light-field displays. Furthermore, these advances have promising implications for various miniaturized optical devices, including ultracompact visible wavelength cameras, portable microscopes, and wearable devices.
The integration of 3D printing and porous silicon has revolutionized the field of miniaturized optics. The development of compact, visible wavelength achromats has overcome the limitations of traditional lens stacking methods. Through the combination of refractive and diffractive lenses, researchers at the University of Illinois Urbana-Champaign have achieved high focusing efficiencies while minimizing volume and thickness. The fabrication process, relying on the Subsurface Controllable Refractive Index via Beam Exposure (SCRIBE) technique, has enabled the seamless integration of lenses within the porous silicon medium, eliminating the need for external support structures. These advancements hold great promise for the future of miniaturized optical systems and open new avenues for applications such as light-field cameras and displays.