Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Young's Double-Slit Experiment Revisited: Geometric Evidence for Center-to-Center Slit Spacing at 650 nm

Mathias Colin

Published Aug 31, 2026• 0 citations
Publisher

Abstract

This paper replicates Young’s double-slit experiment using a 650 nm laser to analyze how light waves interfere. By measuring the resulting fringe patterns, the study reveals that the manufacturer's nominal values actually represent the outer-to-outer edge spacing of the slits rather than the true center-to-center distance.
DOI
10.5281/zenodo.22216777

Related papers

A Theoretical Reformulation of the Classical Double Slit Interference Experiment

Joseph Ivin Thomas

In 1801, Thomas Young devised what is now known as the Classical Double Slit Experiment. In this experiment, light waves emanating from two separate sources, interfere to form a pattern of alternating bright and dark fringes on a distant screen. By measuring the position of individual fringe centers, the fringe widths and the variation of average light intensity on the screen, it is possible to compute the wavelength of light itself. The original theoretical analysis of the experiment employs a set of geometric assumptions which are collectively referred to here as the Parallel Ray Approximation. Accordingly, any two rays of light arising from either source and convergent on an arbitrary point on the screen, are considered very nearly parallel to each other in the vicinity of the sources. This approximation holds true only when the screen to source distance is very large and the inter-source distance is much larger than the wavelength of light. The predictions that naturally follow are valid only for fringes located near the center of the screen (e.g. the equal spacing of fringes). But for those fringes located further away from the screen center, the precision of these predictions rapidly wanes. Also when the screen to source distance is comparable to the inter-source separation or when the inter-source distance is comparable to the wavelength of light, the original analysis is no longer applicable. In this paper, the theoretical foundations of Young’s experiment are re-formulated using a newly derived analytical equation of a hyperbola, which forms the locus of the points of intersections of two expanding circular wavefronts (with sources located at the respective centers of expansion). The ensuing predictions of the new analysis are compared with those of the old. And finally, it is shown that the latter approach is just a special instance of the former, when the Parallel Ray Approximation can be said to hold true.

•Dec 1, 2014•0 citations

Asymmetric Slit in Young's Experiment: Experimental Evidence for In-Slit Interaction

dong ZHANG

Young’s double-slit experiment is usually analyzed in terms of propagation before and after the slits, while the physical interaction of light with the material forming the slit receives less attention. In an ordinary double slit, the complete structure is geometrically symmetric, but each individual slit is locally asymmetric: one side faces the narrow central strip and the other faces the much wider outer material. This observation motivates a simpler experiment in which the two sides of a single slit are deliberately made physically different. We constructed a single asymmetric slit using copper foil on one side and stainless-steel foil on the other. Both foils were 0.1 mm thick. A green laser passing through the slit produced an asymmetric fringe pattern. Because the two sides of the slit were assembled separately, geometrical imperfections, including small differences in alignment, could not be excluded as a possible source of the observed asymmetry. We therefore performed a flip experiment. The complete slit assembly was rotated by 180°, exchanging the positions of the copper and stainless-steel sides while preserving the relative geometry of the assembled slit. The asymmetry of the observed pattern reversed correspondingly. This behavior was reproduced with multiple slit assemblies and repeated flip measurements. The experiment does not by itself determine the physical mechanism responsible for the observed asymmetry. We propose that the different materials on the two sides produce an asymmetric electromagnetic environment within and near the slit and that interaction with this local environment may contribute to the outgoing light distribution. The results therefore motivate treating the slit as a physical interaction region rather than solely as a geometrical boundary condition. They provide experimental support for including an in-slit stage in a global description of Young’s experiment.

•Sep 19, 2026•0 citations

The Classical Double Slit Interference Experiment: A New Geometrical Approach

Joseph Ivin Thomas

The double slit experiment was first conceived of by the English physician-physicist Thomas Young in 1801. It was the first demonstrative proof that light possesses a wave nature. In this experiment, light is made to pass through two very narrow slits that are spaced closely apart and a screen placed on the other side captures a pattern of alternating bright and dark stripes called fringes, formed as a result of the interference of ripples of light emanating from either slit. The relative positions and intensities of the fringes on the screen can be calculated by employing two assumptions that help simplify the geometry of the slit-screen arrangement. Firstly, the screen to slit distance is taken to be larger than the inter-slit distance (far field limit) and secondly, the inter-slit distance is taken to be larger than the wavelength of light. This conventional approach can account for the positions and intensities of the fringes located in the central portion of the screen with a fair degree of precision. It however, fails to account for those fringes located in the peripheral portions of the screen and also, is not applicable to the case wherein the screen to slit distance is made comparable to the inter-slit distance (near field limit). In this paper, the original analysis of Young’s Experiment is reformulated using an analytically derived hyperbola equation, which is formed from the locus of the points of intersections of two uniformly expanding circular wavefronts of light that emanate from either slit source. Additionally, the shape of the screen used to capture the interference pattern is varied (linear, semicircular, semielliptical) and the relative positions of the fringes is calculated for each case. This new approach bears the distinctive advantage that it is applicable in both the far field and the near field scenarios, and since no assumptions are made beyond the Huygens-Fresnel principle, it is therefore, a much more generalized approach. For these reasons, the author suggests that the new analysis ought to be introduced into the Wave Optics chapter of the undergraduate Physics curriculum.

American Journal of Optics and Photonics•Jan 1, 2019•15 citations

ANALYSIS OF LIGHT DIFFRACTION INTERFERENCE PATTERNS IN YOUNG'S DOUBLE SLIT EXPERIMENT

Putri Asnita Gulo

Young's double-slit experiment is a classic and fundamentaldemonstration in physics that strongly supports the wave nature of light throughthe phenomenon of interference. The study aims to deeply analyze the formationof diffraction and interference patterns of light that arise due to the pathdifferences between two coherent light sources. The experiment uses a simple yeteffective setup involving a monochromatic light source, two narrow slits placedclose together, and a screen placed at a certain distance to capture the resultinginterference pattern. Several variables are analyzed in the study, including thewavelength of the light used,the distance between two gaps and the distance fromone gap to anotherThe experimental results confirm the occurrence ofconstructive and destructive interference, resulting in the formation of stripesmoving from bright to dark in the layer. These stripes arise due to the phasedifference between overlapping light waves, and their spacing and clarity areaffected by the physical parameters of the setup. The analysis shows that thespacing between the stripes increases with longer wavelengths and decreases withwider slit spacing. In addition, the cohesion of the light source plays an importantrole in producing a clear and stable interference pattern. This experiment not onlyserves as a concrete verification of the theoretical wave principle in physics, butalso has broader implications in modern optical technologies such as diffractiongratings, holography, and quantum mechanics. This experiment is also relevantfor educational purposes because it provides an experiential learning opportunityfor students to understand the behavior of light and wave interactions. Therefore,this study is expected to be a useful reference in supporting the teaching andlearning of wave optics, especially in demonstrating the dual nature of light andits applications in real-world phenomena.

Journal of Frontier Research in Science and Engineering•Jun 30, 2025•0 citations

Strange patterns of light

Tao Tang

In a modern version of Young's double slit experiment, a laser beam passes through two narrow slits and creates an interference pattern of bright and dark fringes on a distant screen. We place magnifying glasses between the double-slit and the screen, and when a laser beam passes through the double-slit and magnifying glasses, strange patterns will appear on the screen.

•Oct 14, 2025•0 citations

Strange patterns of light

Tao Tang

In a modern version of Young's double slit experiment, a laser beam passes through two narrow slits and creates an interference pattern of bright and dark fringes on a distant screen. We place magnifying glasses between the double-slit and the screen, and when a laser beam passes through the double-slit and magnifying glasses, strange patterns will appear on the screen.

•Oct 14, 2025•0 citations
In 1801, Thomas Young devised what is now known as the Classical Double Slit Experiment. In this experiment, light waves emanating from two separate sources, interfere to form a pattern of alternating bright and dark fringes on a distant screen. By measuring the position of individual fringe centers, the fringe widths and the variation of average light intensity on the screen, it is possible to compute the wavelength of light itself. The original theoretical analysis of the experiment employs a set of geometric assumptions which are collectively referred to here as the Parallel Ray Approximation. Accordingly, any two rays of light arising from either source and convergent on an arbitrary point on the screen, are considered very nearly parallel to each other in the vicinity of the sources. This approximation holds true only when the screen to source distance is very large and the inter-source distance is much larger than the wavelength of light. The predictions that naturally follow are valid only for fringes located near the center of the screen (e.g. the equal spacing of fringes). But for those fringes located further away from the screen center, the precision of these predictions rapidly wanes. Also when the screen to source distance is comparable to the inter-source separation or when the inter-source distance is comparable to the wavelength of light, the original analysis is no longer applicable. In this paper, the theoretical foundations of Young’s experiment are re-formulated using a newly derived analytical equation of a hyperbola, which forms the locus of the points of intersections of two expanding circular wavefronts (with sources located at the respective centers of expansion). The ensuing predictions of the new analysis are compared with those of the old. And finally, it is shown that the latter approach is just a special instance of the former, when the Parallel Ray Approximation can be said to hold true.
Young’s double-slit experiment is usually analyzed in terms of propagation before and after the slits, while the physical interaction of light with the material forming the slit receives less attention. In an ordinary double slit, the complete structure is geometrically symmetric, but each individual slit is locally asymmetric: one side faces the narrow central strip and the other faces the much wider outer material. This observation motivates a simpler experiment in which the two sides of a single slit are deliberately made physically different. We constructed a single asymmetric slit using copper foil on one side and stainless-steel foil on the other. Both foils were 0.1 mm thick. A green laser passing through the slit produced an asymmetric fringe pattern. Because the two sides of the slit were assembled separately, geometrical imperfections, including small differences in alignment, could not be excluded as a possible source of the observed asymmetry. We therefore performed a flip experiment. The complete slit assembly was rotated by 180°, exchanging the positions of the copper and stainless-steel sides while preserving the relative geometry of the assembled slit. The asymmetry of the observed pattern reversed correspondingly. This behavior was reproduced with multiple slit assemblies and repeated flip measurements. The experiment does not by itself determine the physical mechanism responsible for the observed asymmetry. We propose that the different materials on the two sides produce an asymmetric electromagnetic environment within and near the slit and that interaction with this local environment may contribute to the outgoing light distribution. The results therefore motivate treating the slit as a physical interaction region rather than solely as a geometrical boundary condition. They provide experimental support for including an in-slit stage in a global description of Young’s experiment.
The double slit experiment was first conceived of by the English physician-physicist Thomas Young in 1801. It was the first demonstrative proof that light possesses a wave nature. In this experiment, light is made to pass through two very narrow slits that are spaced closely apart and a screen placed on the other side captures a pattern of alternating bright and dark stripes called fringes, formed as a result of the interference of ripples of light emanating from either slit. The relative positions and intensities of the fringes on the screen can be calculated by employing two assumptions that help simplify the geometry of the slit-screen arrangement. Firstly, the screen to slit distance is taken to be larger than the inter-slit distance (far field limit) and secondly, the inter-slit distance is taken to be larger than the wavelength of light. This conventional approach can account for the positions and intensities of the fringes located in the central portion of the screen with a fair degree of precision. It however, fails to account for those fringes located in the peripheral portions of the screen and also, is not applicable to the case wherein the screen to slit distance is made comparable to the inter-slit distance (near field limit). In this paper, the original analysis of Young’s Experiment is reformulated using an analytically derived hyperbola equation, which is formed from the locus of the points of intersections of two uniformly expanding circular wavefronts of light that emanate from either slit source. Additionally, the shape of the screen used to capture the interference pattern is varied (linear, semicircular, semielliptical) and the relative positions of the fringes is calculated for each case. This new approach bears the distinctive advantage that it is applicable in both the far field and the near field scenarios, and since no assumptions are made beyond the Huygens-Fresnel principle, it is therefore, a much more generalized approach. For these reasons, the author suggests that the new analysis ought to be introduced into the Wave Optics chapter of the undergraduate Physics curriculum.
Young's double-slit experiment is a classic and fundamentaldemonstration in physics that strongly supports the wave nature of light throughthe phenomenon of interference. The study aims to deeply analyze the formationof diffraction and interference patterns of light that arise due to the pathdifferences between two coherent light sources. The experiment uses a simple yeteffective setup involving a monochromatic light source, two narrow slits placedclose together, and a screen placed at a certain distance to capture the resultinginterference pattern. Several variables are analyzed in the study, including thewavelength of the light used,the distance between two gaps and the distance fromone gap to anotherThe experimental results confirm the occurrence ofconstructive and destructive interference, resulting in the formation of stripesmoving from bright to dark in the layer. These stripes arise due to the phasedifference between overlapping light waves, and their spacing and clarity areaffected by the physical parameters of the setup. The analysis shows that thespacing between the stripes increases with longer wavelengths and decreases withwider slit spacing. In addition, the cohesion of the light source plays an importantrole in producing a clear and stable interference pattern. This experiment not onlyserves as a concrete verification of the theoretical wave principle in physics, butalso has broader implications in modern optical technologies such as diffractiongratings, holography, and quantum mechanics. This experiment is also relevantfor educational purposes because it provides an experiential learning opportunityfor students to understand the behavior of light and wave interactions. Therefore,this study is expected to be a useful reference in supporting the teaching andlearning of wave optics, especially in demonstrating the dual nature of light andits applications in real-world phenomena.