Ultra-broadband achromatic imaging with diffractive photon sieves.

Xiaonan Zhao,Jingpei Hu,Chinhua Wang,Feng Xu,Xiaojun Zhu,Linsen Chen,Donglin Pu,Yu Lin

doi:10.1038/srep28319

Abstract

Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element.

Highlights

Diffractive optical elements (DOEs) have increasingly shown a promising type of optical imaging components in modern optical systems, such as ultra-large space telescope primaries[1], high-resolution microscopy[2,3], spectroscopy[4], THz optics for tomographic imaging[5], X-ray or EUV lithography[6] that are difficult, or even impossible, with conventional glass-based refractive optics, because of their unique characteristics of compact size, light weight, and high degree of design flexibility
Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one
The proposed methodology of coding micro-structure pattern in a diffractive element breaks the limit of inherent wavelength-dependence in conventional diffractive elements and opens up new possibilities for manipulating wavefront phase and achieving new applications or new functionalities of diffractive optical elements

Summary

Conclusion

We propose and demonstrate a novel achromatic imaging with diffractive photon sieves that works in broad bandwidth covering the whole visible spectral range. The pinhole pattern in a photon sieves is wavefront coded and generates equal focusing power for a wide range of operating wavelength in a single thin-film element without any auxiliary elements. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves of a focal length of 500 mm and a diameter of 50 mm. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm with a selected coding parameter α= 30πcompared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with an ultra-wide bandwidth of 300 nm (in whole visible region from 400 nm to 700 nm) is performed with a wavefront coded photon sieves integrated with a refractive lens. The proposed methodology of coding micro-structure pattern in a diffractive element breaks the limit of inherent wavelength-dependence in conventional diffractive elements and opens up new possibilities for manipulating wavefront phase and achieving new applications or new functionalities of diffractive optical elements

Methods

Author Contributions

Additional Information