Diffraction Testbed for Use in Remote Teaching

The need for remote teaching tools in all education levels has experienced a big increase due to COVID-19 pandemic. Laboratory practical sessions have not been an exception, and many online and offline tools have been made available to respond to the lockdown of teaching facilities. This paper presents a software testbed named OPTILAB for teaching diffraction experiments to engineering students. The software simulates classical diffraction apertures (single slit, double slit, circular slit) under a wide variety of conditions. Explanation about the Physics behind the diffraction phenomenon is also included in OPTILAB to increase the students’ self-learning experience. Originally conceived as a complement to on-site teaching, due to COVID-19 pandemic OPTILAB has been adopted as the basic tool to build a brand-new, virtual laboratory session about diffraction in Physics III course (biomedical engineering) at Carlos III University of Madrid. Results obtained by the students taking this virtual lab during Fall 2020 are presented and discussed.

Fraunhofer Diffraction Description In The Approximation Of The Light Field Theory

The wavelength is that natural scale that determines the applicability domains of the ray approximation and the wave approximation of light. If the change of the radiation power spatial density is significant at the wavelength scale, then we deal with the light diffraction phenomenon, which is a subject to the wave optics. Consider the diffraction phenomenon at the diaphragm. It is possible to distinguish the near zone with significant wave inhomogeneities (i.e. the Fresnel zone) and the far Fraunhofer diffraction zone, in which the wave becomes close to homogeneous (the so-called quasi-homogeneous) and the ray approximation is possible. The problem is that there is no explicit relationship between the radiance of the rays before and after diaphragm. Method for determining the boundary conditions for the radiance in the Fraunhofer zone through the radiance of the incident radiation is proposed in the paper. This approach for computing the radiance field in the Fraunhofer zone can be generalized to other problems of optics, thereby providing the possibility of using computationally efficient ray-approximation-based methods to determine the light fields.

KAJIAN DISTRIBUSI INTENSITAS CAHAYA PADA FENOMENA DIFRAKSI CELAH TUNGGAL DENGAN METODE BAGI DUA DAN METODE NEWTON RAPHSON

Abstrak Telah dilakukan penelitian tentang distribusi intensitas cahaya pada fenomena difraksi celah tunggal dengan tujuan menerapkan metode Bagi Dua dan metode Newton Raphson untuk memperoleh solusi jarak antara dua titik intensitas dalam fenomena difraksi celah tunggal, menetukan jarak antara dua intensitas pada pita terang, memperoleh grafik distribusi intensitas cahaya terhadap jarak pada kasus difraksi cahaya Franhoufer celah tunggal, serta membandingkan kekonvergenan metode Bagi Dua dan metode Newton Raphson. Solusi jarak antara dua intensitas pada pita terang pada kasus difraksi cahaya Franhoufer celah tunggal diperoleh dengan mencari akar-akar persamaan intensitas cahayanya. Hasil penelitian menunjukan jarak yang semakin besar ketika intensitasnya makin kecil. Ada tiga puncak intensitas, yang pertama puncak untuk intensitas maksimum pada terang pusat yang berada pada jarak 0 cm dan dua puncak untuk terang pertama setelah terang pusat yang mana intensitasnya tinggal 0.05I0 dan berada pada jarak 0.154875 cm sebelah kiri dan sebelah kanan dari intensitas maksimum. Grafik antara jarak dengan perbandingan intensitas terhadap terang maksimum berbentuk sinusoidal, terdapat tiga puncak intensitas. Puncak pertama menunjukan intensitas maksimum yang terdapat pada pita terang pusat dan dua puncak dengan intensitas 0.05I0 yang berada pita terang pertama. Pada kasus ini diperoleh hasil bahwa metode Newton Raphson lebih cepat konvergen dari metode Bagi Dua karena hanya memerlukan 4 iterasi untuk memperoleh solusi, sedangkan metode Bagi Dua membutuhkan 20 iterasi. Metode Newton Raphson juga memiliki nilai error pendekatan lebih kecil dari metode Bagi Dua yaitu 6.43929 x 10-13 sampai 7.52642 x 10-7 sedangkan metode Bagi Dua 1.90735 x 10-6. Abstract Research on the distribution of light intensity in the phenomenon of single slit diffraction has been carried out with the aim of applying the Bisection method and the Newton Raphson method to obtain a solution between two points in a single slit diffraction phenomenon, determining the distance between two point of intensity in the bright band, obtaining a graph of the light intensity distribution to distance in the case of Franhoufer single slit light diffraction, and comparing the speed of convergence of the Bisection method and the Newton Raphson method. The solution of the distance between two intensities in the bright band in the case of Franhoufer light diffraction in a single slit obtained by looking for the roots of the light intensity equation. The results of the study show that the greater the distance when then intensity gets smaller. There are three peak intensities, the first peak for the highest intensity in the central bright band which is located at a distance of 0 cm and two peaks in the first bright with the intensity is 0.05I0 and is 0.154875 cm left and right of the maximum intensity. The graph between the distance and intensity ratio is sinusoidal, which is three peak intensities. The first peak shows the highest intensity in the central bright band and the two peaks with the intensity of 0.05I0 which is the first bright band. In this case the results of the Newton Raphson method are converged faster than the method of Bisection because it only requires 4 iterations to obtain a solution, while the Bisection method requires 20 iterations. The Newton Raphson method also has a smaller error value than the Bisection method, which is 6.43929 x 10-13 to 7.52642 x 10-6 when the Bisection method is 1.90735 x 10-6.

Plasmon-mediated discrete diffraction behaviour of an array of responsive waveguides

We investigate the discrete diffraction phenomenon in a Polymer-Liquid Crystal-Polymer Slices (POLICRYPS) overlaying a random distribution of gold nanoparticles (AuNPs, plasmonic elements).

Self-assembly of anisotropic red blood cell (RBC)-like colloidal particles

The diagram shows a highly ordered periodic crystalline array, multilayer structure, Bragg diffraction phenomenon and well-patterned binary colloidal crystals, respectively.