# Integrated Deep Ultraviolet Doublet Metalens for Projection Imaging
## 4 Conclusions  
A series of problems are observed in the existing deep ultraviolet optical system, such as complex and large systems, limited ray incidence angles, and complex system aberration. The metalens provides a new design idea for optical systems because of its powerful wavefront control ability. Based on the transmission metalens, an integrated deep ultraviolet all-dielectric doublet metalens that can reduce beams and realize projection imaging is proposed. Based on the design idea of the Huygens electromagnetic metasurface, a series of high-transmittance and controllable dielectric artificial atoms covering the 2\(\pi\) transmission phase are combined to realize the metalens. On this basis, an integrated ultra-violet all-dielectric doublet metalens is designed to convert the large beams of a large deep ultraviolet facility into beams with a smaller diameter. We find that the light intensity per unit area of the emitted light is 7.39 times that of the incident light unit area. At the same time, the projection imaging of the mask is simulated, which proves that the doublet metalens can achieve clear and discernible projection imaging. Its resolution and angle tolerance are analyzed, showing good results. We can adjust the size and focal length of the two metalenses according to the required imaging ratio to obtain a pattern corresponding to the ratio of the propagation distance of the clear pattern. The doublet metalens is suitable for the objective lens systems of deep ultraviolet lithography machines, with the advantages of being ultra-light, ultra-thin, and easy to integrate. The doublet metalens also has the advantages of a simple structure, stability, and low installation precision. At the same time, the doublet metalens can also be used as an expanding mirror, and it has some application prospects in laser beam combination and deep ultraviolet space camera lighting systems,  
Figure 11: Resolution analysis of doublet metalens. (**A**) The setting of the bright and dark stripes, where the interval between the two bright stripes is \(\delta\), is the intensity obtained when \(\delta\) is 0.5 \(\upmu\)m. (**B**) Intensity diagrams at a propagation distance of 2 \(\upmu\)m when the light-transmitting fringe width a is 0.5, 0.6, 0.7, 0.8, 0.9, and 1 \(\upmu\)m, respectively. (**C**) Change in the value of the interval \(\delta\) between the two bright stripes to obtain the intensity.  
opening up new opportunities for micro-nano optical imaging and optoelectronic equipment. The optical system can also be used as a beam expander. It can effectively reduce the number of lenses in the ultraviolet system, with high transmittance and low energy loss. It opens up a new path for ultraviolet optical imaging and optoelectronic equipment.  
Conceptualization, X.S. and Z.L.; methodology, X.S. and F.Y.; software, X.S. and E.H.; validation, X.S., F.Y. and E.H.; formal analysis, X.S.; investigation, X.S.; resources, X.S.; data curation, X.S.; writing--original draft preparation, X.S.; writing--review and editing, X.S.; visualization, X.S.; supervision, Z.L.; project administration, Z.L.; funding acquisition, Z.L. All authors have read and agreed to the published version of the manuscript.  
Distinguished Young Scholars of Jilin Province (2023010135 IJC); Scientific and Technological Development Project of Jilin Province (20220201080 GX); National Natural Science Foundation of China (61735018); Excellent Member of Youth Innovation Promotion Association of the Chinese Academy of Sciences (Y201836); Leading Talents and Team Project of Scientific and Technological Innovation for Young and Middle-Aged Groups in Jilin Province (20190101012 JH).  
Not applicable.  
Data Availability Statement: Data are contained within the article.  
The authors thank [PERSON] of the Northeast Normal University for the technical assistance in the figure drawing and literature investigation.  
The authors declare no conflicts of interest.  
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