High-Resolution 3D Printed Rotation Optics

In this paper, written by leading researchers of KNMF/KIT, design and manufacture of a 3D printed varifocal freeform optics is presented. The optical refraction power can be tuned continuously by mutual rotation of two helically shaped lens bodies of azimuthally varying curvatures. Since no additional space for axial or lateral lens movement is required, rotation optics allow for a highly compact design of varifocal optics. The additive manufacturing of the optics was conducted by means of the high-resolution optical 3D printing process at Luximprint. Results of tactile surface measurements are presented as well as imaging through the lens.

In general, freeform optics are lenses with surfaces without rotational symmetry. An interesting approach is forming varifocal optics based on freeform optical elements. One example of such optics with tunable refraction power is the principle invented in the 1960’s by Luis Alvarez. According to this principle, the refraction power in an optical system consisting of two cubic-type lens parts is varied by mutually shifting both lens parts in a lateral direction to the optical axis.

3D Printed Alvarez Lenses

In this research, Alvarez-lenses were studied extensively and proposed for different applications. The Alvarez-principle, however, requires additional lateral space for lens movement. Extra space is also required in conventional lens systems, the refraction power of which are tuned by a mutual shifting of lens groups along the optical axis. To prevent additional space requirements, a non-axial tuning motion is needed. The use of mutual rotation for tuning was shown using diffractive optical elements, such as spiral phase plates and for refractive optics. The concept of varifocal rotation optics would enable the application of tunable optics in optical systems with severe space limitations. Examples of such optics can be found in ophthalmology, e.g., as optics of an artificial eye lens or in zoom optics of handheld devices such as, e.g., smartphones or pocket projectors.

3D Printed Varifocal Rotation Optics

The paper presents the design and additive manufacturing of varifocal rotation optics as well as tactile surface measurements of the 3D printed lens parts and imaging results of the manufactured optical system. The organization of the paper is as follows: in Section 2, the basic principles are developed and a mathematical description of the surfaces is derived. Section 3 shows the results of surface measurements of printed components, while the 4th and last section addresses the imaging results of the rotation optics. Conclusions are drawn in the final section.

You can read the full Optics Express article online at the OE website, or just view and download the PDF summary directly.

Acknowledgements

This research paper was written by Ingo Sieber, richard Thelen and Ulrich Gengenbach and published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.

This work was carried out with the support of the Karlsruhe Nano Micro Facility (KNMF, www.knmf.kit.edu), a Helmholtz Research Infrastructure at Karlsruhe Institute of Technology (KIT, www.kit.edu). The authors would also like to acknowledge Marco De Visser and his team at Luximprint for data preprocessing and 3D printing of the optical structures.

Source: Optics Express | Vol. 28, Issue 9, pp. 13423-13431 (2020) | https://doi.org/10.1364/OE.391697

Figure 1 from Optics Express Publication 3D printed Alvarez lenses KIT Luximprint
Figure 2 from Optics Express Publication 3D printed Alvarez lenses KIT Luximprint
Figure 4 from Optics Express Publication 3D printed Alvarez lenses KIT Luximprint
Figure 5 from Optics Express Publication 3D printed Alvarez lenses KIT Luximprint
Figure 6 from Optics Express Publication 3D printed Alvarez lenses KIT Luximprint