scholarly journals A practical comparison between the methods of determining the focal length of a convex lens

Keyword(s):  
Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 548
Author(s):  
Zhichao Hao ◽  
Yuankun Liu

This paper proposes a method for obtaining surface normal orientation and 3-D shape of plano-convex lens using refraction stereo. We show that two viewpoints are sufficient to solve this problem under the condition that the refractive index of the object is known. What we need to know is that (1) an accurate function that maps each pixel to the refraction point caused by the refraction of the object. (2) light is refracted only once. In the simulation, the actual measurement process is simplified: light is refracted only once; and the accurate one-to-one correspondence between incident ray and refractive ray is realized by known object points. The deformed grating caused by refraction point is also constructed in the process of simulation. A plano-convex lens with a focal length of 242.8571 mm is used for stereo data acquisition, normal direction acquisition, and the judgment of normal direction consistency. Finally, restoring the three-dimensional information of the plano-convex lens by computer simulation. Simulation results suggest that our method is feasibility. In the actual experiment, considering the case of light is refracted more than once, combining the calibration data acquisition based on phase measurement, phase-shifting and temporal phase-unwrapping techniques to complete (1) calibrating the corresponding position relationship between the monitor and the camera (2) matching incident ray and refractive ray.


2018 ◽  
Vol 16 (38) ◽  
pp. 56-65
Author(s):  
Nuha Ahmed Hussein

Laser-Induced Breakdown Spectroscopy (LIBS) has been documented as an Atomic Emission Spectroscopy (AES) technique, utilising laser-induced plasma, in order to analyse elements in materials (gases, liquids and solid). The Nd:YAG laser passively Q-switched at 1064nm and 9ns pulse duration focused by convex lens with focal length 100 mm to generates power density 5.5×1012 Mw/mm2 with optical spectrum in the range 320-740 nm. Four soil samples were brought from different northern region of Iraq, northern region (Beiji, Sherkat, Serjnar and Zerkary).The soil of the Northern region of Beige, Sherkat, Serjnar and Zarkary has abundant ratios of the elements P [0.08, 0.09, 0.18, 0.18] and Ca [0.61, 0.15, 0.92, 0.92] while it lack of Si [0.008, 0.004, 0.04, 0.02] element. The data analysis for these soils showed that the cities of Serjnar and Zarkary have soils better than of Sherkat. It is noticed from the obtained P [0.18], and Ca [0.92] elements concentrations of the soil that the cities of Serjnar and Zarkary have the best soil for cultivation.


2020 ◽  
Vol 56 (5) ◽  
pp. 223-225
Author(s):  
M. Kokkonen ◽  
S. Myllymäki ◽  
H. Jantunen

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