Diffraction grating parameter retrieval using non-paraxial structured beams in coherent Fourier scatterometry

In recent years, a lot of works have been published that use parameter retrieval using Orbital Angular Momentum (OAM) beams. Most make use of the OAM of different Laguerre-Gauss modes. However, those specific optical beams are paraxial beams and this limits the regime in which they can be used. In this paper, we report on the first results on retrieving the geometric parameters of a diffraction grating by analysing the corresponding complex-valued (i.e., amplitude and phase) Helmholtz Natural Modes (HNM) spectra containing both the azimuthal (i.e., n) and radial (i.e., m) indices. HNMs are a set of orthogonal, non-paraxial beams with finite energy carrying OAM. We use the coherent Fourier scatterometry (CFS) setup to calculate the field scattered from the diffraction grating. The amplitude and phase contributions of each HNM are then obtained by numerically calculating the overlap integral of the scattered field with the different modes. We show results on the sensitivity of the HNMs to several grating parameters.

Enhancing conceptual understanding via Diffraction Grating Innovative Media (DIAGRAM)

Diffraction grating innovative media (DIAGRAM) is a physics experimental tool that can be implemented in the learning of diffraction grating material. This research endeavored to analyse students’ conceptual understanding on diffraction grating material after using the diffraction grating innovative media (DIAGRAM). Pre-experimental design was used as the method in this research with one-group pretest-posttest as the design and 10 female students and 1 male students from three schools in Indonesia which are in Banjaran, Pamarayan and Makassar participated. Starting from interpretation test using multiple choices test consisting of 8 questions and using google form, the stage then carried out learning activity utilizing the DIAGRAM and given a posttest in the end of the class. At the last data had been analysed by N-Gain. The come about of this consider were gotten by students’ increment in high category which is 0,73. To sum up, diffraction grating innovative media (DIAGRAM) can make enhancement of senior high school students’ conceptual understanding in diffraction grating material.

Precise Linear Positioning Method Based on Transmissive Two-Stage Diffraction Grating System

This paper mainly studies the precise linear positioning method based on the transmissive type two-stage diffraction grating system. Starting from the analysis of the two-stage diffraction principle, the mathematical model of the two-stage grating diffraction is established, and the positioning characteristics of the differential positioning method and the modified positioning method are discussed. The simulation experiment of the linear positioning device is carried out to study the displacement characteristics. The experimental results show that the precise positioning based on the diffraction grating can obtain a positioning accuracy of ±0.4 μm.

Explanation of Frequency Distinguishing in Human Ear (Using Computer Model)

The inspiration for this model ware possibilities of the human ear to distinguish the frequency of sounds and a diffraction grating. Detection takes place after max. 15 length of the wave (arbitrary choice). The range of frequencies to detect for tests – 800-3200 Hz: detection every 5 Hz in the range 800-1600 Hz and 10 Hz in the range 1600-3200 Hz (arbitrary choice). It can explain the residual hearing effect (missing tone f is heard when harmonic tones 2f, 3f and 4f are played). The algorithm can be used as an alternative for FFT. Model uses only memory for delay line end for results, and adding operation, so it should be fast and cheep, and can work on-line in real-time. Testing program was written in Perl.