Lunar dust is widely distributed on the lunar surface as tiny particles ranging from 30 nm to 20 μm. Currently, extensive research has been conducted on the physical, chemical, and hazardous properties of lunar dust. However, few studies focused on its motion patterns and related mechanisms. This paper aims to utilize non-contact imaging method for the first time to record and analyze the trajectory and velocity of lunar dust movement. The fundamental principle of this paper is to use a high-sensitivity camera to image the dust particles in the detection area within a certain exposure time, and to obtain the intensity of the scattered light from the particles in the detection area at that exposure time based on the grayscale value. In terms of velocity measurement, the spatial motion trajectory of lunar dust was recorded by the single frame multi-exposure imaging method, and the related algorithm based on gray value distribution of the motion trajectory image was used to calculate its velocity. In considering the small particle size of lunar dust would cause weak light scattering energy, during the construction of the principle prototype, the strong pulse laser technology was used to increase the illumination, and the sCMOS camera with a far-field optical lens was adopted to improve the signal detection sensitivity. The results showed that the prototype can identify particles from 0.3 μm to 20 μm, measure velocity from 1m/s to 100m/s, and the minimum detectable dust concentration is 1000pc/ft3. This study provides technical reserves for lunar dust environment exploration in future lunar exploration projects.
The traditional reflective parallel optical tube has a small field of view and a large off-axis aberration, so it is difficult to meet the high precision requirements of wide field of view and wide band. The design adopts the initial structure of wide-field eyepiece, and is optimized by the optical design software.The focal length of the system is 307mm, the field of view Angle is ±12°, the full field of view has no halo, the working wavelength is 450nm~900nm, and the transfer function is almost close to the diffraction limit, meeting the design requirements of large field of view, wide band and small distortion.
According to nonimaging optical principle and traditional LED free-form surface lens, a new kind of LED free-form tilted lens was designed. And a method of rapid modeling based on Scheme language was proposed. The mesh division method was applied to obtain the corresponding surface configuration according to the character of the light source and the desired energy distribution on the illumination plane. Then 3D modeling software and the Scheme language programming are used to generate lens model respectively. With the help of optical simulation software, a light source with the size of 1mm*1mm*1mm in volume is used in experiment, and the lateral migration distance of illumination area is 0.5m, in which total one million rays are computed. We could acquire the simulated results of both models. The simulated output result shows that the Scheme language can prevent the model deformation problems caused by the process of the model transfer, and the degree of illumination uniformity is reached to 82%, and the offset angle is 26°. Also, the efficiency of modeling process is greatly increased by using Scheme language.
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