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A new compact static wind imaging interferometer, called the Birefringent Doppler Wind Imaging Interferometer (BIDWIN), has been developed for the purpose of observing upper atmospheric winds using suitably isolated airglow emissions. The instrument combines a field-widened birefringent delay plate placed between two crossed Wollaston prisms with an imaging system, waveplates and polarizers to produce four fixed 90 ∘ phase-stepped images of the interference fringes conjugate to the scene of interest. A four-point algorithm is used to extract line-of-sight Doppler wind measurements across the image of the scene. The arrangement provides a similar throughput to that of a field-widened Michelson interferometer; however, the interferometric component of BIDWIN is smaller, simpler to assemble and less complicated to operate. Consequently, the instrument provides a compact, lightweight and robust alternative that can be constructed and operated with lower cost. In this paper, the instrument concept is presented, and the design and optimization of a prototype version of the instrument are discussed. Characterization of the lab prototype is presented, and the performance of the instrument is examined by applying the instrument to measure a low-velocity two-dimensional Doppler wind field with a high precision (5 m s -1) in the lab. [ABSTRACT FROM AUTHOR]

The basic principle of the near-infrared static wind imaging interferometer (NIR-SWINDII) is expounded. The instrument can simultaneously detect the atmospheric wind speed, temperature, and ozone concentration in the middle and lower thermosphere (25–110 km). According to the optical transmission principle, the exact expression of the ideal and actual optical throughput of the NIR-SWINDII is obtained. To analyze and discuss the influence of the field of view, wavelength, and refractive index systematically, we select a high refractive index and a low refractive index glass matching schemes according to the "full compensation" principle of the wide-field Michelson interferometer, the simulation of NIR-SWINDII's optical throughput is carried out. For the high refractive index matching scheme, the results show that when the field of view is within 3 degrees, the transmittance of the NIR-SWINDII can reach 23.38%, and the optical throughput of the entire system is about 0.1024 cm2 ⋅ sr. Comparing with the parameters of other instruments, it is found that our instrument's optical throughput performance is comparable to other instruments. This research provides the theoretical basis and practical guidance for the throughput optimization of the NIR-SWINDII. [ABSTRACT FROM AUTHOR]

In a static wind imaging Michelson interferometer (SWIMI) developed by us, two-arm glasses are used to achieve the achromatic thermally compensation. The arm glass is cemented with the beam splitter. The tilt of the arm glass would cause a change to the optical path difference (OPD), thereby reducing the visibility of the interferogram and introducing phase error to the SWIMI system, which eventually responsible for errors in the inversion of temperature and wind velocity. In this paper, we present the principle of static wind imaging interferometer and derivate the variation of OPD caused by the two-dimensional tilt of arm glass in detail. By considering a rectangle incident beam, we analyze the effect of arm glass tilt on wind speed and temperature inversion. The results show that in order to realize the wind velocity error less than 3 m/s, the temperature error less than 3 K, and the instrument visibility greater than 0.8, the two-dimensional tilted angle of arm glass should be less than 1". The tolerance of tilted angle can expand by adjusting the refractive index of the medium on both two sides of the arm glass or by adjusting the reflector mirror of the interferometer precisely. The results would be helpful for the cement of arm glass, beam splitter of SWIMI, and provide a reference for the design of a field-widened wind imaging interferometer. [ABSTRACT FROM AUTHOR]