Educational dataset for observing Haidinger's interference rings with microparticle scattering

This dataset accompanies the published article "Demonstration experiment for observing Haidinger’s interference rings using microparticles deposited on reflective surfaces" by Voronkin and Lushchin, published in Physics Education (2026), Volume 61, Article 045005. The dataset documents a lensless demonstration of fringes of equal inclination formed in backscattered laser light from plane-parallel glass plates and flat mirrors coated with microparticles. The materials allow qualitative visual comparison of different experimental configurations and quantitative reproduction of the interference analysis. All measurements were performed using a semiconductor laser pointer (λ ≈ 532 nm, <5 mW) and a screen placed ~85 cm from the sample. Root files Scheme_of_experimental_setup.png – Simplified diagram of the demonstration setup. Video_plane_parallel_glass_plate_HQ.mp4 – Example of observing rings with a plane-parallel glass plate. Video_mirror_HQ.mp4 – Example of observing rings with a household flat mirror. Compressed folders 01_plane_parallel_plate_3mm_config_1.rar Configuration 1 – Plane-parallel glass plate with microparticles on the front surface only (Section 3.1).Contents DSC_1063.JPG – Interference rings with only the front surface coated. interference_analyzer_1063.py – Python script for image processing and quantitative analysis. result_1.png, result_2.png – Radial intensity profiles (pixels and mm). 02_plane_parallel_plate_3mm_config_2.rar Configuration 2 – Microparticles on both front and rear surfaces of the same plate (Section 3.1).Contents DSC_1066.JPG – Interference pattern. DSC_1069.JPG – Pattern with ruler for spatial calibration. interference_analyzer_1066.py – Python analysis script. result_1.png, result_2.png – Radial intensity profiles with detected maxima. result_3.png – Console output confirming numerical reproducibility. 03_mirror_2mm.rar Mirror configuration, normal incidence (Section 3.2) Contents: DSC_1033.JPG – Full experimental setup. DSC_1038.JPG – Interference pattern for quantitative analysis. for_calibration_350_pixels=10mm.JPG – Ruler for pixel-to-mm conversion. interference_analyzer_1038.py – Python script (centre detection, radial averaging, peak detection, Δ(r²) calculation). result_1.png, result_2.png – Radial intensity profiles and console output. 04_mirror_2mm_tilted_incidence.rar Mirror configuration, tilted incidence (Section 3.2). Same mirror as 03, tilted about the vertical axis. Contents: DSC_1032.JPG – Experimental setup with displaced reflected beam. DSC_1055.JPG – Close-up of inverted ring pattern. For_calibration_350_pixels=10mm.JPG – Pixel-to-length calibration. interference_analyzer_1055.py – Python script with manual centre selection, Gaussian smoothing, and minimum-radius filtering. result_1.png, result_2.png – Radial intensity profiles and analysis output. 05_Numerical simulation.rar Theoretical simulations (Section 3.3) Physically motivated model: two-beam interference with Gaussian envelope and radially varying fringe visibility. Contents: haidinger_config1and2.py – Simulates radial intensity profiles for glass-plate configurations (single and both surfaces). haidinger_mirror.py – Simulates mirror configuration with normal incidence. 06_Optical_micrograph_Leica_M205.rar Optical microscopy of microparticles (Section 2.2) Contents: powder.tif – Optical micrograph of microparticles (Leica M205). powder_ImageJ.tif – Same image after ImageJ particle detection and segmentation. Results.xlsx – Particle parameters including equivalent diameters. Graph.png – Particle size distribution graph generated from Results.xlsx in Origin.