Ocean color is hard to be observed as the solar radiation on the ocean surface is only about 30% of the total radiation after being attenuated by the atmosphere, and only visible light can be transmitted to the water. Besides, water column exhibits a depth-exponential decay signal at different rates at each wavelength. The traditional concentric system spectrometer, with broad spectrum and high spectral and spatial resolution, can meet part of the requirements. However, the Dyson structure on it is hard to process and assembly due to the short distance between slit and detector.
Recently, a collaborated team led by Professor YU Lei from Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS), designed an imaging spectrometer for ocean color observation, which is easier to process and assembly with improved Dyson design.
The work was published in Optics Express and Applied Optics respectively.
In this study, HFIPS research team gave a solution for this dilemma of traditional spectrometer. They re-derived an advanced Dyson quasi-concentric spectrometer by giving the slit a perpendicular distance from the optical axis, which ensures a reasonable distance between the imaging surface and the optical axis of the system.
In their design, a reasonable distance was also given between the slit and the detector in the axial direction, without sacrificing high imaging quality. Besides, they further proved that the improved Dyson spectrometer structure has high optical performance and good engineering applicability in the final prototype test,.
The research work was supported by the National Natural Science Foundation of China (NSFC), the Research Instrument and Equipment Development Project of Chinese Academy of Sciences (CAS), and the Youth Promotion Council of CAS project fund.
Results of imaging using prototype at different wavelength.(Image by WU Su)
Optical system and prototype for advanced Dyson spectrometer (Image by WU Su)
Optical system and prototype for advanced Dyson spectrometer (Image by WU Su)