Determining the limiting conditions of sampling interval and sampling angle for laser reflective tomography imaging in sensing targets with typical shapes

Abstract

Laser reflective tomography imaging (LRTI) is unique in the remote sensing of space targets because the resolution is independent of the distance. As it is usually difficult to obtain the 360-degree of reflectance projections, the estimation of the proper sampling interval and sampling angle becomes a key problem. In this paper, we conducted an LRTI experiment with a distance of 0.98-km and a wavelength of 1064 nm, and constructed three targets with typical shapes, namely, planar target, plane combination target, and closed-surface target. By comparing the evaluation indexes of retrieved images, the following was found: (1) When the sampling interval exceeds the maximum sampling interval derived by the Nyquist sampling law, the quality of reconstructed images deteriorates rapidly; (2) When the sampling angle is greater than 70 degrees and 90 degrees, the image of planar and plane combination target can be reconstructed excellently, respectively. However, contour image reconstruction requires full angle projection for closed-surface target; (3) When the sampling angle is fixed, the quality of reconstructed image is best for the vertical detection. This paper determines the limiting conditions of the sampling interval and sampling angle, which are of great practical significance in guiding the space-borne LRTI in sensing the space target with a long distance.