Theoretical Analysis And Key Technology Research On The Optical System Of Infrared Dual-band Fourier Transform Imaging Spectrometer

As a high-tech integrating optics,spectroscopy,precision mechanics,electronic technology and computer technology,imaging spectroscopy technology can simultaneously acquire two-dimensional spatial information and one-dimensional spectral information of the measured target.Imaging spectrometer is a new generation of optical remote sensing instrument developed based on imaging spectroscopy technology.It has achieved rapid development and is widely used in the study of spectral radiation characteristics,environmental monitoring,meteorological observation,resource investigation,military target reconnaissance and biomedicine diagnosis and other fields.Fourier transform imaging spectrometer,as a typical representative of imaging spectroscopy technology,can be divided into temporal modulation type(TMIFTS),spatial modulation type(SMIFTS)and spatio-temporal mixed modulation type(TSMIFTS)according to different optical path difference modulation methods.Among them,TSMIFTS does not contain a precision-driven moving mirror system and a slit that restricts luminous flux,has unique advantages such as strong environmental applicability,high stability,and fast response speed.It is used in environmental protection,pollutant detection,and emergency response.It has broad application prospects.Based on the current development status and application requirements of TSMIFTS,this paper proposes a TSMIFTS based on stepped micro-mirrors,and conducts theoretical analysis and optical system design research on it.The stepped mirror structure replaces the moving mirror system in the Michelson interferometer,realizing static optical path difference spatial sampling.But at the same time,it is difficult to obtain a large optical path difference with a finite-size ladder structure,which makes it difficult to improve the spectral resolution.Although the static interference system avoids the random sampling error caused by the movement of the moving mirror,it cannot eliminate the fixed initial Error;the structure of the large steps will cause the edge image surface to be out of focus,which brings difficulties to the panoramic image stitching in the later stage.The co-aperture design will cause serious chromatic aberration,and the tilted parallel plate will also cause a large order of magnitude astigmatism in the imaging optical path.This subject carries out research on the key technologies of TSMIFTS.The main research contents and innovations are as follows:(1)A new type of dual-spectrum,dual-interference channel TSMIFTS is proposed.The static interference structure based on the stepped micro-mirror greatly improves the anti-vibration stability of the instrument.The system does not contain slits and has the advantage of large luminous flux.Analyzed the interference and imaging process of the system based on the stepped structure,and gave a solution for obtaining spatial high-resolution panoramic images and realizing high-resolution spectra.According to the technical indicators of the system,the parameters of the optical system and the interference system of the imaging spectrometer were calculated.(2)The analysis of the optical system of the TSMIFTS was completed.According to the aberration theory,the front common-aperture telescope and the rear middle and long-wave secondary imaging system were analyzed and designed,and an optical system with reasonable structure,high imaging quality and meeting design specifications was obtained.The physical model of the imaging spectrometer was established,and the imaging process of the imaging spectrometer was simulated.Images and interference data were successfully obtained.The interference data was processed to obtain a high-precision reconstructed spectrum,the feasibility of the optical path difference modulation method and the reliability of the optical design are verified.(3)The theoretical derivation of the setup error model of the interference system was carried out,and the influence of the tilt error on the contrast and signal-to-noise ratio of the interferogram was studied,and the setup error tolerance of the interferometric system is obtained.The main source of stray light of the interference imaging system was analyzed,the stray light analysis model of the imaging spectrometer is established,the generation path of stray light was simulated,and the corresponding stray light suppression scheme was proposed.(4)Completed the mechanical design and sub-system integration of the imaging spectrometer,studied the high-precision setup and integration scheme of the infrared interference imaging system,and proposed a high-precision setup method that simultaneously performs spectral calibration and system integration.The experimental optical path of the optical platform was built to verify the principle of the instrument and the performance of the test instrument.The experimental results showed that the various indicators basically met the design requirements.The later installation and adjustment plan of the whole machine was studied,and a second installation and adjustment method was proposed to ensure the high-precision alignment of the interference system.