Highly collimated beams are required in numerous applications and techniques. Different methods have been proposed for collimating monochromatic point light sources during the recent years. In this work, we analyze how a finite size and polychromatic light source can be collimated using only one diffraction grating and a CMOS camera placed after the source and the collimating lens. For this, we determine the period of the fringes diffracted by the grating and compare it with the period of the grating. Analytical equations are obtained to predict the amplitude of the fringes and their period. Since self-images disappear for finite size polychromatic sources at long distances from the grating, the period has to be measured close to the grating. In addition, we give an analytical equation to determine the error in the positioning of the source in terms of the source size and the setup parameters. Finally, we experimentally corroborate the obtained analytical formalism using a white LED of size s=0.6 mm collimated by a lens with focal length f=25 mm, and a Ronchi binary grating of period d=250 μm. In this case, we achieve an experimental error in the positioning of the source with respect to the focal plane of the lens of δz=92 μm.
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http://dx.doi.org/10.1364/AO.56.003628 | DOI Listing |
Pak J Med Sci
January 2025
Sasankoti Mohan Ravi Prakash, DMD, MDS, BDS Dentist and Independent Researcher, Hope Health Inc, 360 N Irby St. Florence, South Carolina, USA 29501.
Background & Objective: Currently, there are many implants in clinical use, making it hard to choose the right one for the patient. The success rate of an implant depends on its diameter, length, and direction of insertion in bone. In implant dentistry, Finite Element Analysis (FEA) simulates intraoral conditions in vitro and analyzes the effects of implant material, diameter, size, and other components related to oral structure on the implant and peri-implant tissues.
View Article and Find Full Text PDFMed Phys
January 2025
Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
Background: The spatial resolution of new, photon counting detector (PCD) CT scanners is limited by the size of the focal spot. Smaller, brighter focal spots would melt the tungsten focal track of a conventional X-ray source.
Purpose: To propose focal spot multiplexing (FSM), an architecture to improve the power of small focal spots and thereby enable higher resolution clinical PCD CT.
Plants (Basel)
January 2025
Departamento de Fitotecnia, Instituto de Horticultura, Universidad Autónoma Chapingo, km 38.5 Carretera México-Texcoco, Chapingo 56230, Estado de México, Mexico.
A synthetic variety (SV) of maize may not become stable if the sample size representing each parental line (m) is small. This research aimed to evaluate the effect of m on the inbreeding coefficient (IC) of the SV (FSynL) and on the stability of its genetic constitution. An SV formed by randomly mating l unrelated lines whose inbreeding coefficient is F was considered, and a random sample was taken from the genotypic array of the progeny produced by selfing a parental line A1A2 (GA) This sample was visualized as a set of g groups of four plants whose genotypes are all four of the GA and e represented the number of plants that failed to form a group.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Department of Industrial Engineering, University of Salerno, 84084 Fisciano, SA, Italy.
This paper presents a comprehensive numerical investigation to simulate heat transfer and residual stress formation of Ti-6Al-4V alloy during the Laser Powder Bed Fusion process, using a finite element model (FEM). The FEM was developed with a focus on the effects of key process parameters, including laser scanning velocity, laser power, hatch space, and scanning pattern in single-layer scanning. The model was validated against experimental data, demonstrating good agreement in terms of temperature profiles and melt pool dimensions.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Department of Mechanical Engineering, Jeju National University, 102 Daehak-Ro, Jeju-si 63243, Republic of Korea.
The microstructure of metallic materials plays a crucial role in determining their performance. In order to accurately predict the dynamic recrystallization (DRX) behavior and microstructural evolution during the hot deformation process of GCr15 bearing steel, a microstructural evolution model for the DRX process of GCr15 steel was established by combining the level set (LS) method with the Yoshie-Laasraoui-Jonas dislocation dynamics model. Firstly, hot compression tests were conducted on GCr15 steel using the Gleeble-1500D thermal simulator, and the hardening coefficient and dynamic recovery coefficient of the Yoshie-Laasraoui-Jonas model were derived from the experimental flow stress data.
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