The author demonstrates a relationship between the pattern of straight interference fringes formed in Young's experiment and the circular fringes produced at infinity by a Michelson interferometer. The two patterns can both be considered to be produced by the interference of light from two coherent point sources. It is shown that the pattern given by these sources on a large sphere centred midway between them reduces to Young's fringes in the vicinity of zero path difference and to the Michelson pattern in the vicinity of maximum path difference.
The author demonstrates a relationship between the pattern of straight interference fringes formed in Young's experiment and the circular fringes produced at infinity by a Michelson interferometer. The two patterns can both be considered to be produced by the interference of light from two coherent point sources. It is shown that the pattern given by these sources on a large sphere centred midway between them reduces to Young's fringes in the vicinity of zero path difference and to the Michelson pattern in the vicinity of maximum path difference.
The changes in the interference pattern in Young's interference experiment, produced by placing two identical narrow-band filters in front of the pinholes, are analyzed. It is shown theoretically that, in general, the fringes will not become sharp (i.e., their maximum visibility will not tend to unity) even when the filters have arbitrarily narrow passbands. The analysis brings out a relationship between the complex degree of coherence in the space-time and the space-frequency domains. When the passbands of the filters are narrow enough, the filtered light is found to be cross-spectrally pure.
We describe an experiment in which the white-light interference fringes appearing at the output of a Michelson interferometer are observed through a spectrograph. In this manner the relative positions of monochromatic interference fringes come into sight and it allows a better understanding of the formation of the white-light fringes. A simple model is described for determining the shape of the spectrally resolved white-light interference fringes. An expression for the relationship between the slope of the fringes and the arm length difference of the interferometer is derived and is demonstrated experimentally. In addition, an intuitive explanation based on this experiment is given for the washing out of the white-light fringes.
In Young's Double Slit Experiment (YDE) and improved versions, waves causing interference travel different distances.As speed of light is constant, waves require different time spans to reach the point of interference.Thereby, if the waves are generated simultaneously at the slits/source, they cannot meet on the screen anywhere outside the mid-line.Formation of fringes is commonly interpreted as interference caused by the meeting (super-positioning) of two waves generated simultaneously.The reality is that fringes are formed by interference of waves generated at different times.However, unless impacted by other phenomena, two waves generated at different times converging to form fringes, as this paper shows, will mandatorily come in same phase to the interference point, producing constructive interference.Interference observed, however, is not only constructive.The effect on the phase of waves while bending (diffraction) is also to be considered.Consequently, it addresses three phenomena causing phase shifts: (1)different starting times,(2)bending at slits, and (3)distances traveled (In contrast, the first two are overlooked by the conventional approach).(Dirac and Feynman Path Integral methods on quantum particles have different approaches).The paper reveals the widespread misconception in the analysis of YDE and would impact the wave/particle and other YDE interpretations.
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.
Fringes formed in a Michelson interferometer never localize in any plane, in the detector plane and in the localization plane. Instead, the fringes are assumed to localize at infinity. Except for some explanation in Principles of Optics by Born and Wolf (1964 (New York: Macmillan)), the fringe localization phenomena of Michelson's interferometer have never been analysed seriously in any book. Because Michelson's interferometer is one of the important and fundamental optical experiments taught at both undergraduate and graduate levels, it would be appropriate to explain the localization of these fringes. In this paper, we analyse the localization of Michelson interferometer fringes using Fourier optics and temporal coherence, and show that they never localize at any plane even at infinity.
Summary New non-localized interference fringes, produced with a small source and a Fabry-Perot interferometer, are described. These extend into space in the form of cones, producing sharp rings when allowed to fall upon a screen. The properties of these rings are examined. A striking characteristic is that without lenses sharp rings of great diameter can be produced (diameter of first ring equal to half a metre). Complex patterns are produced with various slit sources. Possible applications of the new fringes are considered.