Optical System Design Of Full Spectrum Hyperspectral Imaging Spectrometer

Hyperspectral imaging technology can simultaneously acquire geometric,radiation and spectral information of ground objects,and carry out three-dimensional spatial and spectral imaging of ground objects.It has outstanding advantages in fine classification and recognition of ground objects,and has become one of the important technical means for remote sensing of earth.At present,most of the mainstream spaceborne hyperspectral imaging systems at home and abroad only cover visible/near infrared and short wave infrared band,and most of them cannot obtain the spectral information of the full spectrum from visible to long wave infrared.In order to further broaden the range of hyperspectral imaging spectrum,the existing hyperspectral imaging system is generally realized by multiple sets of single-band imaging spectral instruments mounted on the same platform,which has the disadvantages of structural redundancy,large volume,no common field of view,and excessive occupation of satellite platform resources.In order to meet the needs of users in various fields to obtain the target full spectrum information,the research of common aperture full spectrum hyperspectral imaging spectrometer is of great significance.Based on the above background,this paper carried out the design and research of the optical system of the common-aperture full-spectrum hyperspectral imaging spectrometer:Firstly,the design index of full spectrum hyperspectral imaging spectrometer is determined according to the application requirement analysis.According to the common aperture requirements of the full-spectrum hyperspectral imaging spectrometer,the optical structure selection analysis was carried out,and the overall design scheme of the common aperture pre-off-axis three-mirror objective was proposed and the four spectral segments Offner convex grating spectrometer were respectively connected.Aiming at the problem that the main optical structure layout space of the common aperture off-axis three telescopic objective is limited,it is difficult to realize the high quality division of the common aperture four spectral segments,a method combining field separation and color separation was proposed to realize the spectrum division.Spectrometers with different magnifications were designed to meet the focal length required by each spectrum segment,so as to achieve the design width and spatial resolution requirements of each spectrum segment.Secondly,according to the design index,the initial structural parameters of the image side telecentric three-axis telescopic system are calculated,and the optical design of the image side telecentric three-axis telescopic system with three fields of view separation is completed.At the same time,the initial structural parameters of Offner spectrometer were calculated,and the optical system of Offner spectrometer was designed.Finally,the integrated optimization design of the optical system is carried out.The imaging quality of each spectrum segment is good,and the common aperture and full spectrum hyperspectral imaging are realized.The tolerance analysis results show that the tolerance of each spectrum optical system is reasonable and meets the assembly requirements.Finally,the optical and mechanical background thermal radiation of mid-long wave infrared spectrometer is analyzed and the suppression method is studied.The optical and mechanical model of the middle long wave infrared spectrum spectrometer was established.On the basis of calculating the average radiation flux in a single spectral channel of the middle long wave infrared spectrum when the target was 300 K,the optical and mechanical background thermal radiation of the spectrometer was analyzed by stray light analysis software Tracepro.A mid-long wave infrared radiation transfer model was established,the factors affecting the radiation transmission were analyzed,and the optical and mechanical background heat radiation of the spectrometer was simulated under the condition of refrigeration.The results show that this method has a significant effect on the suppression of optical and mechanical background heat radiation of the spectrometer.