Although laser scanning ideas and hardware solutions are well-known to experts in the field, there is still a large area for optimization. Especially, if long-range and high-resolution scanning is considered, the smallest defects in optical quality should be perfected. On the other hand, the simplicity, reliability, and finally the cost of the solution plays an important role, too. In this paper, a very simple but efficient method of optical correction is presented. It is dedicated to laser scanners operating from inside cylindrical glass domes. Such covers normally introduce aberrations into both the laser beam and receiving optics. If these effects are uncorrected, the laser scanner performance is degraded both in terms of angular resolution and maximum range of operation. It may not be critical for short-range scanning applications; however, if more challenging concepts are considered, this issue becomes crucial. The proposed method does not require sophisticated optical solutions based on aspheric or freeform components, which are frequently used for similar purposes in imaging-through-dome correction but is based on a simple cylindrical refractive correction plate.
The paper provides a detailed treatment of the expected range performance for the laser rangefinder (LRF) developed for the Polish ImAging SaTellites (PIAST) space mission, where the distance between satellites within a constellation has to be measured during orbital flight. The satellites are equipped with corner cube retroreflectors (CCR) to increase the efficiency of laser back-reflection. A theoretical signal-to-noise range-dependence model was developed to determine the maximum expected range of the measurements. This model included the tilt-angle-dependent properties of the CCR far-field diffraction patterns (FFDP) which were measured experimentally. In addition, the specific parameters of the receiving optoelectronic circuit used were considered. The obtained results show that in the case of the constructed PIAST LRF (peak laser pulse power of 100 W, laser beam divergence of 5 mrad, receiving optical aperture diameter of 2 in, CCR diameter of 2 in), depending on the CCR angular inclination, a maximum measurement distance of 15-40 km is expected.
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