To solve the problem of poor real-time measurement caused by a hyperspectral imaging system and to simplify the design in passive ranging technology based on oxygen absorption spectrum, a filter-based non-imaging ranging method is proposed. In this method, three bandpass filters are used to obtain the source radiation intensities that are located in the oxygen absorption band near 762 nm and the band's left and right non-absorption shoulders, and a photomultiplier tube is used as the non-imaging sensor of the passive ranging system. Range is estimated by comparing the calculated values of band-average transmission due to oxygen absorption, τ , against the predicted curve of τ versus range. The method is tested under short-range conditions. Accuracy of 6.5% is achieved with the designed experimental ranging system at the range of 400 m.

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Experimental program is designed to analyze the influence of background radiation on the accuracy of passive ranging based on oxygen spectral absorption; an acousto-optic tunable hyper spectral imaging spectrometer is used as the measuring device and a halogen light as the target. Firstly, the basic principles and experimental program of passive ranging technology based on oxygen absorption are introduced; then the halogen light spectral distribution at different distances during the night is collected using the acousto-optic tunable hyper spectral imaging spectrometer. Oxygen absorption rate is calculated and the relationship model between the oxygen absorption rate and the path is established according to the principle of oxygen spectrum absorption passive ranging. Then the oxygen absorption rate of the target is collected and calculated at the distance of 2360 m for different time. The measuring ranges during the day are solved by the model and the errors are analyzed, the influence of background radiation on the passive ranging is gained finally. Results show that according to the model, the maximum ranging error is 6.74% during the daytime, and the error becomes smaller with the elevation angle of the sun becoming smaller and the background darker. The results give 1.10% ranging error during the nighttime.

A four-dimensional imaging spectrometer with a fiber optic dimension transform element has the ability to capture all four dimensions of data (2D spatial, spectral and temporal) with a single, radiometrically calibrated sensor at a single exposure, which satisfies the need to record transient events and fast changing phenomena of interest. In order to analyze the corresponding relation between the input light intensity and the output light intensity of a four-dimensional imaging spectrometer with a fiber optic dimension transform element, this paper utilizes the Fourier optics theory and complex Gaussian functions expansion method to derive and analyze the transmission characteristics of the imaging spectrometer optical system. This paper introduces the light intensity distribution formula when the detector is fixed on the negative first order spectral image plane and establishes and simulates the corresponding relation between the light intensity distribution of the detector and the spatial/spectral information on the target space. The research results show that the target information can be extracted and analyzed directly according to the corresponding relation.

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