# Dual-Gratings Imaging Spectrometer
## 6 Conclusions  
Our main objective is to address the limited spectral range of the conventional imaging spectrometers, which are limited by the dispersion angle. We propose an innovative structure, namely, dual-gratings imaging spectrometer.The instrument can acquire ultra-spectral resolution spectral images for two wavebands, and has the potential to be applied to the sun's ultra-spectral imaging. This article introduces the structure of traditional imaging spectrometers, presents the advantages of dual-gratings and analyzes the practical issues caused by the double gratings-overlap of two spectra and double image offset problem. This paper studies the calculation process of dual grating rotation angle, the relationship between the image and the slit, the relationship between the angle between the dual gratings and the dual image offset, and the relationship between the reduction of the upper limit of MTF and the spatial frequency. This article also summarizes the shortcomings of this  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Dual-Gratings Spectrometer** & **Traditional Spectrometer** \\ \hline Output image & 2-D images (spectral and spatial) & 2-D images (spectral and spatial) \\ Spectral resolution & high & high \\ volume & small & big \\ suitable for satellite & Yes & Yes \\ Currently adopted & rare & rare \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of Traditional imaging spectrometer and Dual-gratings scheme.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Dual-Gratings Spectrometer** & **Filter** \\ \hline Output image & 2-D images (spectral and spatial) & Monochrome image \\ Spectral resolution & high & low \\ the acquisition speed & low (need time to scan) & real time \\ Features & Continuous spectrum data & High-precision spatial information \\ Number of spectrum data & Multiple & 1 (Adjustable ) \\ Currently adopted & Rare & Broadly used \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison of filter and Dual-partings scheme.  
structure and studies the applicable fields under these shortcomings. At last, we simulated a dual-gratings imaging spectrometer with optical design software and compared it with two traditional schemes. Compared with the birefringent filter, the dual-gratings imaging spectrometer can provide real-time continuous spectrum data. This gives more opportunities for discoveries in the spectral dimension. Compared with traditional imaging spectrometers, the dual-gratings imaging spectrometer has the same spectral resolution and spatial resolution, and is significantly smaller in volume.  
Conceptualization, R.O. and X.Z.; methodology, D.W. and R.O.; software, R.O.; validation, R.O. and D.W.; formal analysis, R.O. and L.J.; investigation, X.Z.; resources, L.J.; data curation, R.O.; writing--original draft preparation, R.O.; writing--review and editing, X.Z.; visualization, R.O.; supervision, X.Z. and L.J.; project administration, R.O.; funding acquisition, X.Z. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors thank [PERSON] for reimbursement of the funds, which significantly helped in this research.  
The authors declare no conflict of interest.